Hermann Genz

Kamal Badreshany

Mathilde Jean

BLACK WHEELMADE WARE IN LEBANON: A VIEW FROM THE NORTH

Ever since its first discovery at Megiddo in the 1930s, "B lack Wheelmade Ware" has sparked the interest of researchers, especially regarding its origin. Most of the research so far has focused on northern Palestine. Lebanon has occasionally been mentioned as a possible region of manufacture, but so far without providing any detailed evidence. In this article, we discuss the occurrence of "Black wheelmade Ware" in Lebanon and provide the results of the first petrographic and geochemical data from this region.

Introduction

In the southern Levant, the transition from the EB III to the EB IV, now dated around 2500 BC according to recent radiocarbon dates (Regev et al. 201 2;[START_REF] Hoflmayer | Radiocarbon Evidence for the Early Bronze Age Levant: The Site of Tall Fadous-Kfarabida (Lebanon) and the End of the Early Bronze III Period[END_REF], is accompanied by marked changes. Almost all urban settlements of the EB II-III disappear in the EB IV or shrink to the size of villages [START_REF] Mazar | BCE[END_REF][START_REF] Palumbo | The Early Bronze Age IV in the Southern Levant. Contributi e materiali di Archeologia Orientale 3[END_REF]Dever 1995;Mazar 2006), with the exception of Khirbat Iskandar in southern jordan, explored by Richard and her collaborators since 1980 [START_REF] Richard | Khirbat Iskander. final Report on the Early Bronze IV Area C "Gateway" and Cemeteries[END_REF]. Marked changes are also noticeable in the ceramic repertoire. Large platters as well as jars and pithoi with pattern-combed surfaces dominate the EB II-III assemblages, while drinking vessels are hardly attested [START_REF] Genz | Die {riihbronzezeitliche Keramik von Hirbet ez-Zeraqon, Nordjordanien. Mit Studien zur Chronologie und funktionalen Deutung fruhbronzezeitlicher Keramik in der sudlichen Levante. Deutsch-jordanische Ausgrabungen in Hirbet ez-Zeraqon[END_REF][START_REF] Bunimovitz | Revealed in Their Cups: Syrian Drinking Customs in Intermediate Bronze Age Canaan[END_REF]). In the EB IV, however, platters and combed jars completely disappear, whereas a variety of chalices, goblets, teapots and other types related to drinking customs abound [START_REF] Bunimovitz | Revealed in Their Cups: Syrian Drinking Customs in Intermediate Bronze Age Canaan[END_REF]Bunimovitz and Greenberg 2006;[START_REF] D'andrea | The Southern Levant in Early Bronze Age IV: Issues and Perspectives in the Pottery Evidence[END_REF][START_REF] Welton | Caliciform Ware[END_REF]. Especially in the pottery, a marked regionalism is noticeable, which has led to the definition of various pottery families (Amiran 1970, 79-89;[START_REF] Dever | New Vistas on the EB IV ("MB I") Horizon in Syria-Palestine[END_REF][START_REF] D'andrea | The Southern Levant in Early Bronze Age IV: Issues and Perspectives in the Pottery Evidence[END_REF]. Marked Syrian influences in the pottery repertoire were noticed from early on [START_REF] Guy | Megiddo Tombs[END_REF]Amiran 1970,83;[START_REF] Bunimovitz | Revealed in Their Cups: Syrian Drinking Customs in Intermediate Bronze Age Canaan[END_REF][START_REF] Welton | Caliciform Ware[END_REF]D'Andrea and Vac ca 2015).

In the northern Levant, on the other hand, there is a much stronger evidence for continuity between the EB III and IV, both in terms of settlement patterns and ceramic production (Genz 2012, 621;Thalmann and Sowada 2014, 358;see, for example, Ebla).

Black Wheelmade Ware: Definition and history of research

The term Black Wheelmade Ware was coined only recently by Greenberg (Greenberg et al. 1998, 23;Greenberg 2002, 53), whereas formerly it was known as the "Megiddo Group" (Amiran 1970, 81-2). Dever subsumed this pottery under his families Nand NC (Dever 1980, 46-47). This pottery was first identified in Megiddo in the 1930s [START_REF] Guy | Megiddo Tombs[END_REF], but since then has been found at various sites in the jezreel Valley, Galilee and the Hula Valley in Palestine, as well as in Lebanon in the Beqa' and along the coast, as well as in southern Syria (D'Andrea 2014 , fig. 5.3; Bechar 2015 , fig. 14).

This ware is characterized by a rather limited repertoire: teapots, goblets and small flasks dominate the assemblages, whereas jars are only rarely attested (D'Andrea 2014, 153-169;[START_REF] Bechar | A Reanalysis of the Black Wheel-Made Ware of the Intermediate Bronze Age[END_REF]. The fabric is generally dark grey to black, but reddish hues are attested as well (D'Andrea 2014, 153;Bechar 2015, 39). Most vessels show white painted decoration in their upper parts, mainly simple horizontal bands, but wavy lines framed by horizontal bands are also attested. Reserved painting, in which parts of the white paint are removed with a pointed instrument to expose the dark surface of the vessels, is mainly attested in southern Syria. Another characteristic is the rather high firing temperature perhaps approaching 800 or 850 2 C (Bechar 2015, 40; but see also below).

Contrary to earlier assumptions that this pottery was wheelmade (Guy and Engberg 1938,148-149;Greenberg 2002, 53), a recent detailed study of the manufacturing technique revealed that the vessels are only wheel coiled (Bechar 2015, 39-40). Concerning the proper definition of the ware, some discrepancies can still be noted. Whereas D'Andrea (2014,(158)(159) distinguishes a "western" group, encompassing the finds from northern Palestine and Lebanon, from an "eastern" group which is found in southern Syria, Welton and Cooper (2014, 335) only see the examples from southern Syria as "related," Bechar (2015, 43-47), however, counts all of these as Black Wheelmade Ware.

Earlier researchers generally traced the origin of the Black Wheel made Ware to the Middle Orontes Valley (Guy and Engberg 1938,148;Dever 1980, 50-52) and regarded the vessels attested in the southern Levant as imports. Already in 1978, Tadmor (1978, 10) cautiously suggested a local origin for the Black Wheelmade Ware from Kadesh in the northern Hula Valley. The first petrographic analyses of Black Wheelmade Ware were conducted on material from Tell Naama (Greenberg et al. 1998, 23), which suggested Lower Cretaceous clay as the raw material. Such clays are attested in the Upper Hula Valley and the Lebanese Beqa'. A Lower Cretaceous origin of the clay was excluded in a more recent petrographic study (Bechar 2015, 42-43; see also [START_REF] Cohen-Weinberger | A Note on the Provenance of Black Wheel-Made Vessels from A Burial Cave West ofTel Hazor[END_REF] . In both studies, few details were published in support of these conclusions, so they should be treated with caution. The production location (or locations) of the Black Wheelmade Ware remains poorly understood.

The most recent studies of the distribution of the Black Wheelmade Ware (D'Andrea 2014, 157-158 and fig. 5.3;[START_REF] Bechar | A Reanalysis of the Black Wheel-Made Ware of the Intermediate Bronze Age[END_REF] have shown that its distribution encompasses northern Palestine, Lebanon and southern Syria, with Tall Hizzin in the Lebanese Beqa' and Yabroud in southern Syria so far representing the northernmost extension of the distribution (but see below for new finds from Tall Fadous-Kfarabida and Tall Arqa). However, it is not attested in the Orontes Valley; thus, an import from that region can be excluded. The Lebanese Beqa' remains one of the potential areas of origin of this ware, but except for a few general statements in passing, this option has not yet been seriously investigated. In this contribution, we will review the evidence for Black Wheel made Ware in Lebanon and present the first petrographic investigations for this ware in Lebanon.

Black Wheelmade Ware in Lebanon

The distribution of Black Wheelmade Ware in Lebanon has recently conveniently been summed up by D'Andrea (2014, 157 and fig. 5.3) and Bechar (2015,43-46). It has to be kept in mind, however, that the state of research regarding the EB IV in Lebanon is scanty at best (for a recent summary, see Genz 2010). Black Wheel made Ware is represented at six sites in Lebanon: Tall Hizzin and Rafid are situated in the Beqa', while Tyre, Byblos and Tall Fadous-Kfarabida are located on the coast. Tall Arqa, located in the Akkar plain, produced a few sherds of Black Wheelmade Ware (Figure 21.1).

Tall Hizzin is located in the Beqa' Plain, 11 km southwest of Baalbek. Although excavated by Emir Maurice Chehab already in 1949 and 1950, the results remained unpublished except for a few short notes (Chehab 1949(Chehab -1950, 109;, 109;[START_REF] Chehab | Decouvertes Pheniciennes au Liban[END_REF], 167 ;Marfoe 1995, 241). In the spring of 2007, a team from the Department of History and Archaeology of the American University of Beirut started cataloguing the material located in the National Museum of Beirut for a future publication of the results of this rather important site (see Genz and Sader 2008a;Genz 2010, 209-210 for preliminary assessments).

The discovery of a number of EB IV vessels came as a complete surprise, as this period was never mentioned for Tall Hizzin before (Marfoe 1995, 241). So far, this period only seems to be represented by tombs. There are at least eight tombs, which have produced EB IV pottery. Unfortunately, no information as to the location, layout and number of interments is available; except for the material stored at the National Museum in Beirut and several photographs taken during the excavation, no documentation is available. None of the old excavation photographs provides any information concerning the tombs of this period. As all of the tombs that contained EB IV pottery have produced later material as well, it may be speculated that they were cave tombs which could be entered and reused in later periods. However, no proof for this assumption is available.

The material consists of pottery types such as goblets, teapots, bottles and amphoriskoi. What is remarkable is the high percentage of vessels of Black Wheelmade Ware (Figure 21.2: 1-4). of the 20 EB IV vessels available from the site, nine (two goblets, five teapots and two bottles) are Black Wheelmade Ware (Genz and Sader 2008a, 187 and pI. I). A few sherds represent further Black Wheelmade Ware vessels, but as body sherds generally do not seem to have been kept, the actual percentage of Black Wheelmade Ware at the site remains unknown. There is no evidence for EB IV habitation layers at Tall Hizzin, as all evidence for domestic activities represented by vessels such as cooking pots is missing completely.

At Rafid, located in the Wadi Taym southeast of Kamid Loz, an EB IV chamber tomb was discovered during construction work in 1966 and excavated in 1967 [START_REF] Mansfeld | Bericht iiber die Ergebnisse der Ausgrabungen in Kamid el-Loz (Libanon) in den Jahren 1966 und[END_REF]Prag 1974, 115;Marfoe 1995, 190-191). Unfortunately, in the meantime, the tomb had been robbed, so that mainly the material rescued in 1966 is preserved. The subterranean chamber, which measures ca. 3.00 x 1.50 m, was covered by one monumental stone slab of3.40 x 2.30 m. The height of the chamber is 1.1-1.2 m. The location of the entrance remains unclear due to damage during the discovery. The chamber was probably covered by a stone tumulus. The finds consist of 13 ceramic vessels, all wheelmade, one dagger, one toggle-pin and one awl or needle, as well as several stone beads and pendants and one carnelian bead. The number of interments remains unclear. Black Wheelmade Ware is represented by four vessels, three goblets and one bottle (Mansfeld 1970, 123-124 and taf. 38, 5, 7;taf. 39,7-8). Interestingly, white painted decoration is not mentioned in the published descriptions.

In the deep sounding in the Old City of Tyre conducted by P. and XIX can be attributed to the EB IV according to typical pottery such as teapots, amphoriskoi and envelope ledge handles (Bikai 1978, 6 and pIs. LIV-LVI). unfortunately, no architectural remains were encountered in the rather limited sounding. Black Wheelmade Ware seems to be restricted to Stratum XX. No quantitative information on the pottery is available, but out of the 17 published sherds and vessels from this stratum, four can be attributed to Black Wheelmade Ware. Three of them belong to teapots, while the fourth one is just a body sherd (Bikai 1978, pI. LVI, 10-13).

Byblos is certainly one of the most fascinating archaeological sites in Lebanon. unfortunately, the inadequate excavation and recording techniques employed by the early excavators have led to great controversies on the exact dating of buildings and objects uncovered there. According to Dunand, the EB III settlement ended in a great conflagration, which he attributes to the invading Amorites (Dunand 1952, 86-90;see Genz 2010, 207 for further comments). Unfortunately, the final publication of the third millennium material is still lacking; but according to studies of the third millennium levels at Byblos undertaken by Saghieh, the site continued to show urban structures during the EB IV, such as religious and probably public buildings (Saghieh 1983, 93-98). [START_REF] Thalmann | Tall Arqa-1. Les niveaux de l'dge du Bronze. Bibliotheque Archeologique et Historique 177[END_REF] has recently published a comparison of the EB IV pottery from Tall Arqa and Byblos. Black Wheelmade Ware is represented by only one teapot from squares 16-17/23 (Dunand 1954, 117 and fig. 114, 7585; for comments on the findspot, see Saghieh 1983, 72 and 95).

Situated 12 km north of Byblos directly on the coast, the recently discovered site of Tall Fadous-Kfarabida has so far produced only scanty evidence of EB IV habitation. EB IV pottery was mainly found in topsoil contexts and a few pits (Genz and Sader 2008b, 154 and pI. 4; Genz et al. 2009, 78 and pI. 3; Genz et al. 2010, 247 and pI. IQ).

Some rooms of the EB III Building 4 seem to have been reused by squatters in the EB IV. From a fill in Room 3 in this building comes a sherd of a Black Wheel made Ware goblet (Figure 21.2:5). The EB IV pottery from Tall Fadous-Kfarabida finds its best comparisons in the material from Stratum 15 at Tall Arqa (Thalmann 2006,19-32).

Tall Arqa, located on the southern edge of the Akkar Plain in northern Lebanon, has yielded abundant evidence for the EB IV [START_REF] Thalmann | Tall Arqa-1. Les niveaux de l'dge du Bronze. Bibliotheque Archeologique et Historique 177[END_REF](Thalmann , 2010)). Noteworthy is the urban layout with multiroom buildings up to three stories in height, separated by narrow streets. Among the large number of EB IV vessels, very few sherds of Black Wheelmade Ware are attested-one of them from the beginning of Stratum 15, the late EB IV phase, is analyzed here. While no spout is preserved, according to the short neck and the globular body it most likely represents the upper half of a teapot with three horizontal bands in white paint Further EB IV sites, such as the dolmens around Mengez in the Akkar plain (Tallon 1964;[START_REF] Steimer-Herbet | Etude des monuments megalithiques de Mengez (Liban) d'apres les carnets de fouilles du R. P. M. Tallon (1959-1969[END_REF] , the Hourriye Cave in the Qadisha Valley [START_REF] Beayno | Mgharet al-Hourriye (Karm Sadde, Casa de Zgharta). Rapport Preliminaire de la fouille de[END_REF], Baalbek in the Beqa' (Van Ess et al. 2008, 110-111 and pI. 2: 9), and the so-far unpublished EB IV tombs in the hinterland of Sidon at Bna'foul (Saidah 1967, 171), Chhim (Saidah 1967,171), Sarafand (Dahr el-Zaatar) (Saidah 1967, 171;Prag 1974,115), and Wadi Leymoun (Copeland and Wescombe 1966, 161;Saidah 1967, 171) have not yet produced any evidence of Black Wheelmade Ware.

Petrographic and chemical characterization of Black Wheelmade Ware sherds from Lebanon

Archaeometric analysis of the samples of Black Wheelmade Ware (Table 21.1) was undertaken by ceramic petrography and by Inductively Coupled Plasma-Atomic Emission Spectroscopy and -Mass Spectrometry (rCP -AES and -MS) (Table 21.2) with the aim of reinforcing conclusions of their typological/macroscopic study along three specific lines of enquiry. The goals of these analyses are as follows:

1.To better inform our understanding of raw material preferences, manufacturing processes, firing temperature, degrees of standardization and the degree of the centralization of production of these vessels. It must be stated that the limited occurrence of the Black Wheelmade Ware in Lebanon means that this study is based on only six samples-too few for statistical significance. In order to overcome the limited nature of the data set and provide greater context, a comparative analysis will be conducted using all published petrographic examples of Black Wheelmade Ware. Additionally, the geochemical information will be combined with a published database of contemporary goblets, bowls and jars from Tall Nebi Mend, Qatna, and the Horns Regional Survey, which are very similar in terms of typology, fabric and technology to the Black Wheelmade Ware (Kennedy et The aim of a comparison with the Horns area assemblages is to investigate whether the production and technology of the Black Wheelmade Ware is closely related to the "Caliciform" tradition of that area in particular, as recently suggested by [START_REF] Kennedy | Drinking on the Periphery: The Tall Nebi Mend Goblets in their Regional and Archaeometric Context[END_REF]. If so, it could be posited that the Black Wheelmade Ware vessels were strongly linked conceptually and functionally with forms in contemporary assemblages found in the Horns area; if not, this may indicate that these vessels filled an alternative, but highly specialized role with EB IV societies in Lebanon and northern Palestine.

Analytical methods

The samples were first studied in transmitted light using a Leitz petrographic microscope. Light micrographs were taken with a Leica EC3 digital camera mounted on the microscope. The thinsections were described using terminology and values proposed by [START_REF] Stoops | Guidelines for Analysis and Description of Soil and Regolith Thin Sections[END_REF] , [START_REF] Quinn | Ceramic Petrography: The Interpretation of Archaeological Pottery and Related Artefacts in Thin Section[END_REF], and [START_REF] Klein | Earth Materials: Introduction to Mineralogy and Petrology[END_REF]. The measurement and quantification of the aplastic fraction of each sample and grain measurements were completed using the digital image analysis software Jmicrovision (Rod it 2007;www.jmicrovision.com). Tiled images of an area on each thin-section measuring one cm 2 were produced for this purpose.

Five samples were analyzed by ICP -AES and -MS. Chemical analysis using ICP, yields the inorganic elemental composition of each sample, providing a chemical signature that can be used to determine whether different ceramics were made using clays from the same outcrop which can imply a shared production location (Orton and Hughes 2013, 168-183) or, conversely, the use of different clay sources. As the chemical signature can vary even within the same clay outcrop, very close signatures suggests production from a geographically and, potentially, temporally proximate batch of materials, and thus likely the same production location and a similar date.

Following the methodology employed by Hughes (2005), powders were obtained from the profile of each sherd using a 12-volt dental drill fi tted with a two mm diameter solid tungsten carbide bit. The samples were prepared at the Durham Archaeomaterials Research Centre (DARC). The powders were acid digested using hydrofluoric acid and analyzed by ICP-AES and ICP-MS at the Department of Earth Sciences, Durham University. The analysis measured for 39 elements (Table 21.2). The major elements, analyzed by ICP-AES as weight percentage oxide, include A1203, Fe203, MgO, CaO, Na20, K20, Ti02, P20S and MnO. The minor and trace elements analysed by ICP-MS as parts per million (ppm) include Co, Cr, Cu, Ni, Sc, Sr, V, Zn, Rb, Y, Zr, Nb, Cs, Ba, pb, La, Ce, Pr, Nd, Srn, Eu , Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

A principal components analysis (PCA) (Orton and Hughes 2013, 176-80) incorporating the remaining elements was conducted using SPSS v.22 to plot the similarity of the "chemical fingerprint" of each sample (Figure 21.5). A number of elements were removed from multivariate statistical analyses as various processes can affect them during deposition and sample preparation, including CaO, P20S, Co, Ba and Zr. As the thin-section analysis indicated that closely related clay sources were used for the production of these vessels, the geochemical analysis focused primarily on the rare earth elements (henceforth REE). REI are ideal for geochemical fingerprinting in clays, as they are largely immobile during low-grade metamorphism, weathering, and hydrothermal alteration [START_REF] Rollinson | Using Geochemical Data: Evaluation, Presentation, Interpretation[END_REF]). As such, REE values, more than other elements, are a good indicator of the original composition of the parent rock. Moreover, recent studies show that there is no fractionation of these elements as a result of the firing process [START_REF] Finlay | Trace Element Fingerprinting of Ceramic Building Material from Carpow and York Roman Fortresses Manufactured by the VI Legion[END_REF](Finlay et al. , 2389)). The REE values used for the light REE and heavy REE sums and ratios were normalized using the values for chondritic meteorites as presented in Rollinson 1993 (tab. 2).

Results of the petrography

The petrographic analysis shows that a related set of petrofabrics and preparations, utilizing mostly fine-grained quartz-rich calcareous fabrics, was used fo r the EB IV Black Wheelmade Ware from Lebanon. In contrast, ongoing work (Badreshany et al., 2020) shows that unrelated coarser calcareous and shale derived fabrics dominated in the area during the EB II-III and into the EB IV at Arqa (Jean 2020). Likewise, Cohen-Weinberger (2016,22), in an analysis of Black Wheelmade Ware from northern Palestine, indicated that a comparison with thousands of samples from the IAA collection provided no clear parallels with earlier material from northern Palestine. Thus, Black Wheelmade Ware shows a lack of continuity with the traditions common in earlier periods within its known distribution area. The disconnect in production modes betrays significant functional and, perhaps, conceptual divisions between the early and late third millennium BC ceramic repertoires in Lebanon and northern Palestine supporting ideas first put forth by Bunimovitz and Greenberg that the Black Wheelmade Ware represented the emulation by local populations of the contemporary Syrian drinking customs [START_REF] Bunimovitz | Revealed in Their Cups: Syrian Drinking Customs in Intermediate Bronze Age Canaan[END_REF]; Bunimovitz and Greenberg 2006).

Similar to the dominant fabrics in the area of Tall Nebi Mend and the Horns Regional Survey during the EB IV, the Black Wheel made Ware can be described broadly as "Quartz-Calcareous" fabrics. They consist of a clay-rich matrix with a fine texture. The ground mass is dark reddish-brown to brown-black in ppl, indicating firing, at least at some stage, in a reducing atmosphere. The ground mass is rich in microcrystalline calcite, and in some cases an optically active crystalic b-fabric is observed. The ground mass is sometimes wellsintered, and elongate channel voids can occur.

The samples are composed of a similar suite of non-plastic inclusions, but two sub-fabrics, A and B, can be differentiated according to their coarseness (Figure 21.3 and Figure 21.4). Sub-fabric A, consisting of the samples from Tall Arqa and Tall Fadous-Kfarabida, along with Tall Hizzin samples 4 and 5, is fine grained, whereas sub-fabric B consisting of Tall Hizzin samples 1, 2 and 3 is much coarser. Sub-fabric A consists of at least one teapot (Arqa) and one goblet (Tall Fadous-Kfarabida), showing that the fabric crosscuts larger and smaller types.

The typology of the Tall Hizzin samples is problematic as permission was granted only to sample body sherds. The thickness and curvature of these sherds, however, strongly suggests they are larger vessels, probably jars or teapots. Sub-fabric B, the coarser of the two fabrics, therefore, is only found on larger vessels so far, though with such a small data set solid conclusions about how this subfabric relates to Black Wheelmade Ware typology cannot yet be drawn. Additionally, the chronological relationship of these two sub-fabrics remains unclear, though the sample from Arqa belonging to sub-fabric A is found in stratum 15 at Tall Arqa (probably dating between 2250-2100 BC). Due to a lack of stratified data, it remains unclear if the coarser sub-fabric B is earlier, contemporary, or later than sub-fabric A.

The aplastic inclusions in the samples are generally subangular to subhedral. Less commonly rounded spherical and elongate grains are noted. Equant grains of fine to medium sand sized quartz commonly occurred. Some samples contained silt sized grains of quartz. The grains were sometimes well rounded, but most often were subangular to subhedral. Pieces of fine to coarse sand sized grains of degraded micritic lime mudstone occur in the samples in varying degrees. Grains of fine sand sized calcite occurred rarely. The samples are generally low in calcium (between ca. 2.5 -7.0%), as indicated by the ICP analysis (see below). Rarely, rounded red optically active fine sand sized grains occurred, which were in high relief. These bodies are clay rich and are likely glauconite chlorite, or some form of iddingsite. Iddingsite seems less likely, however, as no evidence of igneous rocks was otherwise noted in the samples.

Sub-fabric A denotes the finest grained fabrics, where the total aplastic inclusions made up 10-12 % of the sample. The average size of the inclusions rarely exceeds that of fine sand (under 150 microns), and silt sized grains of quartz are commonly noted. The samples belonging to sub-fabric B are similar in composition to those of A but are much coarser. Aplastic inclusions make up 15-20% of the samples belonging to fabric B. Additionally, 'i:j I the inclusions have a larger average size with a number of medium sand sized quartz fragments measuring 300-500 microns observed. The samples belonging to this sub-fabric contain comparatively less limestone relative to those of sub-fabric A. Lastly, in one of the samples of sub-fabric B a few argillaceous rock fragments surrounded by shrinkage voids (perhaps shale) were observed.

Results of the geochemistry

The results of ICP analysis reinforced the petrography, showing two clear groups corresponding to sub-fabrics A and B. For the PCA (Figure 21.5), three components were extracted cumulatively explaining 83.8% of the variation in the dataset. The loading plots associated with the PCA analysis showed that the REE had the most impact on the variability between samples. l ......

• .. . • ••

~.

••

The PCA charts show the sub-fabrics A and B form two individual chemical groupings. Though distinct, the ratios of LREE/HREE and total REE data are comparable for both of the Black Wheelmade Ware sub-fabrics, indicating these groups are broadly related and probably composed of clay materials derived from a related geology.

The PCA and REE data indicate that the Black Wheelmade Ware sub-fabrics are distinct from the Tall Nebi Mend, Qatna, and Homs Regional Survey ceramics, though composed of related materials, especially in the case of sub-fabric A. Compared to the wider dataset from the Homs area, the Black Wheelmade Ware samples generally show ratios of LREE/HREE on the higher end of the range. Likewise, these samples are higher in total REE, especially those from sub-fabric B, which have the highest values of all samples in the combined data- The results of the petrogra phic and geochemical analyses suggest that Black Wheelmade Ware was made from at least two distinct but closely related sets of materials. The vessels are similarly distinct from contemporary Tall Nebi Mend/Homs area EB IV grey and buff ware ceramics. Materials and preparations preferred for both the production of Black Wheelmade Ware and the Tall Nebi Mend/Homs area EB IV grey and buff wares ceramics, however, indicate that they stem from related traditions of craft production and utilize shared technologies.

• •• , • • • • • • •• • • • • • • • , • • •

Provenance, comparative petrography and technological considerations

The petrographic and geochemical analyses demonstrate that Black Wheelmade Ware was made using centralized production modes utilizing a fine quartz-rich calcareous clay. The samples, drawn from a wide geographical area, fell entirely within one of two petrographic and chemical groupings .

Caution must be exercised with any interpretation because of the small size of the dataset, though it is worth noting that these findings are in agreement with the typological and petrographic data pre- As noted by other authors [START_REF] Bechar | A Reanalysis of the Black Wheel-Made Ware of the Intermediate Bronze Age[END_REF] Cohen-Weinberger 2016), the well-refined nature of the clay makes identifying a provenance for the Black Wheelmade Ware quite difficult. As will be explained further below, the samples are consistent with a wide range sedimentary rock sources found commonly in Lebanon and in northern Palestine. The samples share a particular affinity with the Homs area samples, which suggests they were similarly made of clay formed from Miocene/ Pliocene calcareous marls [START_REF] Kennedy | Drinking on the Periphery: The Tall Nebi Mend Goblets in their Regional and Archaeometric Context[END_REF] see Ponikarov 1967, 147-148 for a description of these deposits), though without geoprospection and more data it is not possible to confirm that the Black Wheelmade Ware samples were produced using clays formed on these rock types.

This study shows the potential of geochemical analyses to further group samples beyond what is possible with petrography alone, which could contribute substantially to our understanding of the provenance of these vessels, but the data set is currently restricted to five samples analyzed as part of this study. Given the well-refined nature of the samples, a much larger geochemical dataset and a program of geoprospection will be needed before a convincing assessment of the provenance of Black Wheelmade Ware can be made. Here, all of the known data will be organized and examined, which will serve to definitely exclude some areas as possible locations for workshops and identify others as potential areas to focus future work for sample collection and geoprospection.

Black Wheelmade Ware is found exclusively in Lebanon, southern Syria and northern Palestine; therefore, potential production location(s) are very likely located somewhere in these areas. The Black Wheelmade Ware is most closely related to contemporary assemblages in the Homs area in terms of typology, technology, and materials selection (as defined by the petrography), especially when compared to earlier EB II-III pottery from Lebanon and northern Palestine. The evi-dence indicates that both assemblages stem from shared knowledge networks between the two assemblages, which suggests geographical proximity. A production location, therefore, should perhaps be sought in areas adjacent to the Homs area, where similar clay materials to those used to produce pottery in the Homs Region could be found. The sharing of technology and knowhow would be facilitated by such a geographical situation, partially accounting for the uniformity of paste preparation and shared elements of ceramic style across the two traditions. Such areas exist in the northern and central Beqa', where Miocene/Pliocene conglomerates, very similar to those around Tall Nebi Mend (Figure 21.6), outcrop extensively and near Tall Arqa in the Akkar Plain where more limited outcrops of these rocks can be found (Dubertret 1955; Ponikarov et al. 1963).

The above assessment is circumstantial, and it is certainly possible the Black Wheelmade Ware originated in areas not adjacent to the Horns Region and using materials formed on different types of outcrops. The available data, especially the geochemistry, do however indicate that the use of sources for making Black Wheelmade Ware similar to those selected for the contemporary assemblage of the Horns area, in part through broad similarities in fabrics between the samples of both areas and in part through the exclusion of certain geographical locations and geological outcrops. Areas adjacent to highly fossiliferous outcrops can therefore also be excluded. The primary fossil bearing outcrops in Lebanon are some limestones of Cretaceous age and especially foraminiferous chalks from the upper Cretaceous and Paleogene age. Geological maps suggest that most of southern costal Lebanon can probably be excluded as a possible production area along with many parts of the southern Beqa' [START_REF] Dubertret | Carte Geologique du Liban au 1/200000[END_REF], since fossiliferous chalk outcrops are very common in these areas. A large-scale petrographic analysis by Badreshany (2013) showed that areas of the southern and northern Beqa' usually did not produce microfossils, whereas parts of the central Beqa' (north of Zahle and south of the source of the Litani River) did so with some frequency (though not exclusively). Petrographic analyses conducted on assemblages from the north of Lebanon (Badreshany et aI., 2020; Jean 2020; Badreshany and Genz 2009) again show microfossils are common in the ancient pottery of the areas, though ceramics without fossils are also frequent.

Another factor excluding some areas as production locations for the Black Wheelmade Ware is the nature of the quartz grains observed in the samples. The quartz grains found in the samples are generally sub-angular, likely indicating transportation by wind (aeolian) (Singer 2007). The clays and/or sands used as tempering materials are thus likely not derived from well-transported fluvial or coastal sources. Aeolian angular grains can be expected throughout the study area, but it is worth noting that well rounded and subrounded quartz grains are normally found with some frequency in known coastal EB II-IIl calcareous fabrics (Badreshany et aI., 2020; [START_REF] Badreshany | Pottery Production on the Northern Lebanese Coast During the Early Bronze Age II-III: The Petrographic Analysis of the Ceramics from Tall Fadous-Kfarabida[END_REF]. With this evidence in mind, it can be cautiously suggested that the Black Wheelmade Wares were made using materials from inland sources that were not transported to a great degree by rivers, though more data is needed to confirm this. The fabrics found at Tall Nebi Mend and in the greater Horns region exhibit quartz grains showing a similar angularity profile to those found in the Black Wheelmade Ware fabrics.

The results of the geochemistry of the Black Wheelmade Ware similarly show they are made with materials that represent a complete break with the calcareous sources used in northern and central coastal Lebanon during the EB II-IIl for potting. Despite observing some calcareous material in thin-sections of the Black Wheel made Ware, the geochemistry shows they are much lower in calcium than samples dating to the EB II-III from northern coastal Lebanon. Low calcium values are generally reported for shale tempered fabrics from the Beqa', even when compared to coastal shale fabrics (Badreshany et aI., 2020), as well as for few samples from the Horns Region (Kennedy et al. 2020, tab. 5). The comparatively low calcium values for Black Wheelmade Ware and samples from the Beqa' could suggest a geographical link between the two fabrics, but again more work will be needed to confirm this.

The REE values of the Black Wheelmade Ware are generally much higher in both total value and in LREE/HREE ratios than values reported for coastal vessels. The Black Wheelmade Ware values are a good fit with some values reported for contemporary quartz-calcareous vessels from the Horns Region. The REE values and LREE/HREE ratios for the Black Wheelmade Ware generally show values higher than those reported for coastal calcareous fabrics and lower values than reported for shale wares in the Beqa'. The REE data further suggests a break with northern coastal Lebanese fabrics dating to the EB II-IIl and some general relationship with quartz-calcareous fabrics from the Homs area .

The petrographic and geochemical evidence presented above, though limited, suggests that the Black Wheelmade Ware analyzed in this study was likely not produced on or in the region of the Lebanese Coast. The sample from Tall Fadous-Kfarabida, therefore, probably originated some distance from the site. In central and northern Lebanon, Tall Arqa is the only site that has so far shown clear evidence of a continuous ceramic tradition spanning the EB III and IV (Thalmann and Sowada 2014; Jean 2020). The site is also located near appropriate clay sources as defined earlier. These two factors could make the region of Arqa a good candidate for the production area of the Black Wheelmade Ware; however, there are two factors that also speak against the Arqa as a source area. First, the petrography of the EB IV ceramics from Tall Arqa showed they have different characteristics from the Black Wheelmade Ware samples [START_REF] Jean | Pottery Production in Tall Arqa during the Third Millennium: Characterisation of Ceramic Raw Materials[END_REF] . Second, only very few samples are known from the well-investigated EB IV layers and the extensive pottery assemblage yielded from them [START_REF] Thalmann | Tall Arqa-1. Les niveaux de l'dge du Bronze. Bibliotheque Archeologique et Historique 177[END_REF] . If Black Wheelmade Ware was produced at or near Tall Arqa, a larger number of examples would be expected. Samples from Tall Arqa dating to the EB IV have been submitted for geochemistry, and the results when available will provide better understanding of how the chemistry of the broader EB IV ceramic assemblage of Tall Arqa relates to that of the Black Wheelmade Ware.

Although limited, the available evidence, including Cohen-Weinberger's (2016) assessment that no matches for these Black Wheelmade Ware petrofabrics could be made for northern Palestine, suggests that the areas of the northern and southern Beqa' and the Wadi Taym would be the most logical place to focus geoprospection efforts with the aim of identifying possible source areas for the Black Wheelmade Ware. The proximity of the northern Beqa' to the similar traditions found in the Horns Region perhaps makes that region a particularly good place to conduct investigations for at least one of the source areas for the Black Wheelmade Ware.

The usage and preparation of clays for making Black Wheelmade Ware finds close parallels with the pottery of Tall Nebi Mend, confirming the close conceptual link between the two traditions as suggested by [START_REF] Kennedy | Drinking on the Periphery: The Tall Nebi Mend Goblets in their Regional and Archaeometric Context[END_REF]. Technologically, the use of a quartz rich fabric would have contributed to the creation of a hard and durable vessel. The samples of sub-fabric A are so fine that it seems likely that they were levigated (see [START_REF] Maritan | The Provenance and Production Technology of Bronze Age and Iron Age Pottery from Tall Mishrifeh/Qatna (Syria)[END_REF]

for comparative Middle Bronze

Age examples of levigated fabrics). Additionally, the use of low calcium clay sources would have allowed for relatively high firing temperatures, while avoiding the negative impacts of the decarbonation of calcium carbonate, including spalling and vessel failure, which are often encountered during the high temperature firing of more calcareous clays (Rice 2005, 98). The high temperatures would have further contributed to the creation of hard and durable vessels.

Bechar suggested firing temperatures of above 850°C (2015,40) for Black Wheelmade Ware vessels, though she provided no supporting evidence. Consistently and accurately estimating the firing temperature of the samples in this data set based on their petrographic characteristics proved difficult due to their relatively fine grain size, homogeneity, and composition. The samples were mostly composed of quartz, a mineral of little use for the visual assessment of firing temperature [START_REF] Maggetti | phase Analysis and its significance for Technology and Origin[END_REF]. X-ray diffraction, though commonly used to estimate firing temperature in ceramics, could not be used in this study due to the limited amount of sample available. Based on the vitrification of the groundmass in a few samples, it is possible to suggest the firing temperature exceeded 800°C in some cases (Quinn 2013,191). The samples analyzed in this study were relatively well-fired. The oxidized profiles and reduced surfaces commonly exhibited on Black Wheelmade Ware vessels indicate a multi-stage firing in both oxidizing and reducing atmospheres, strongly suggesting the use of built kilns. A larger data-set and more work will be needed to understand exactly how the Black Wheelmade Ware samples were fired and to provides insights into the adoption and development of their associated firing regime.

The potters of the Black Wheelmade Ware made consistent use of specific and carefully prepared materials that could be fired to relatively high temperatures in purpose built structures to produce attractive and hardwearing vessels, indicating they were experienced craftsman possessing a good deal of know how.

The petrographic and geochemical analyses supports the ideas of As for the chronological position of the Black Wheelmade Ware, the evidence from Lebanon adds some crucial information, as at least some of the material derives from well-stratified sequences. D'Andrea (2014,; see also Bechar 2015, 53) has recently proposed a dating of the Black Wheelmade Ware to the EB IVB, mainly based on typological arguments in comparison to western Syrian assemblages. The most important evidence to confirm such a dating comes from Tall Arqa. At this site, an uninterrupted sequence from the Early to the Middle Bronze Age is attested (Thal-mann 2006). The EB IV is represented by Strata 16 and 15, that is, the EB IV A and B respectively. The Black Wheelmade Ware sherd of probably a teapot derives from Stratum 15, that is, the EB IVB.

Based on the evidence from Tall Arqa, the EB IV material from Tall Fadous-Kfarabida can be paralleled with Stratum 15. As the EB IV A does not seem to be present at the site, the unstratified Black Wheelmade Ware sherd can be attributed with certainty to the EB IVB.

The situation in Tyre is unfortunately less clear. Stratum XXI should be assigned to the EB III according to the pottery (Bikai 1978, 69-70). If one accepts the proposed dating of Strata XX and XIX to the EB IVB-again based on the pottery (Bikai 1978, 70)-then a hiatus spanning the duration of the EB IVA has to be postulated. Unfortunately, no indication for such a hiatus in the stratigraphic record is mentioned (Bikai 1978,5-6).

The finds from Byblos, Tall Hizzin and Rafid do not provide any information regarding the chronology of the Black Wheelmade Ware.

Despite the low number of finds, a clear pattern of the distribution of Black Wheelmade Ware in Lebanon is discernable. This ware is well represented in the Beqa' and in Southern Lebanon, whereas it appears only sporadically along the northern coast (Figure 21.1).

One of the most important problems is the location of the production area(s) of Black Wheelmade Ware. Due to the limited number of samples available for this study, the production area(s) still cannot be precisely located. Yet, with the results of both the petrographic and the geochemical studies, several areas can be excluded. This is likely the case for the coastal plain of Lebanon and the southern Beqa'. While the Akkar Plain has limited outcrops of Miocene/Pliocene conglomerates, the scarcity of Black Wheelmade Ware at Tall Arqa makes a production in this region highly unlikely. The geology of the central and northern Beqa', on the other hand, matches the composition of the Black Wheelmade Ware. The evidence from Tall Hizzin and Rafid shows furthermore that Black Wheelmade Ware is well represented in these regions. A production site around Tall Nebi Mend or farther north in the Orontes Valleywhile possible from a geological point of view-is highly unlikely given the absence of Black Wheelmade Ware in this area. Yet typologically Black Wheelmade Ware was inspired by pottery from this region. The long-standing tradition of grey, hard-textured wares in the upper Orontes Valley, reaching back to at least the EB IVA (D'Andrea 2017), further strengthens the possibility that Black Wheelmade Ware originated from an area in the immediate vicinity of this area. Thus, there is a strong possibility that Black Wheelmade Ware may have been produced at one or several sites in the central and northern Beqa'. As this area is not well researched, especially for the Bronze Age, more work is definitely needed to confirm (or refute) this theory. hout: Brepols. Hermann Genz received his phD from the University ofTiibingen in 1998. Since 2004 he has been Professor of Archaeology at the American University of Beirut. He directs excavation projects in Lebanon at Tall Fadous-Kfarabida (2004[START_REF] Cohen-Weinberger | A Note on the Provenance of Black Wheel-Made Vessels from A Burial Cave West ofTel Hazor[END_REF]), Baalbek (2012-ongoing) and Tall Mirhan (2016-ongoing). His research focuses on the Bronze and Iron Ages of the Eastern Mediterranean, especially the Levant and Anatolia, including the transition from village communities to more complex forms of socio-political organization, often called "City-states" in the late fourth/early third millennia, and the ultimate incorporation of the Levant into large empires in the second millennium BC and the accompanying socio-economic changes. Kamal Badreshany received his phD from the University of Chicago in 2013. He specializes in the analysis and geological characterization of ancient ceramics using archaeometric techniques, including ceramic petrography, scanning electron microscopy and X-ray diffraction. Although incorporating data at the micro-level, he is a landscape-oriented anthropological archaeologist interested in human adaptation to changing social, economic, and environmental conditions, especially as related to increasing settlement density and early empires. His research focuses on understanding the social and economic changes that accompanied the development of the first urban and imperial landscapes of the ancient Levant. He is especially interested in using a combination of archaeometric and landscapes approaches to assess changes in the modes of ceramic production and distribution that paralleled increased settlement nucleation during the Bronze Age in the Levant.

Mathilde Jean obtaioned her phD in Near-Eastern archaeology at the University Paris 1 Pantheon-Sorbonne and has been a member of the French Mission at Tall Arqa since 2012. Her phD thesis investigates the evolution of pottery production and diffusion in the northern Levant during the Early Bronze Age through petrographiC analyses. While focusing on Tall Arqa, she also incorporates other regional assemblages such as Enfeh, Qatna and Ras shamra. She received a three-years research contract from The Hautes Ecoles Sorbonne Arts et Metiers University for her phD and is a member of the UMR 7041 ArScAn/VEPMO in the CNRS.

Figure 21 . 1

 211 Figure 21.1 Distribution of Black Wheelmade Ware in Lebanon.

(

  Figure 21.2: 6) and a potmark incised before firing on the shoulder. Still unpublished radiocarbon dates place the absolute dating for Stratum 15 between 2250±50 and 2000 BC.

  '\,/ ",,\ ~' , \:. ~: ' , ' j1. ~• " ~','. , ' , I '\ ... " .~ ... " ,' . .. : ... • ~~:., ... . . .

Figure 21

 21 Figure 21.5 plot of the factor scores generated from the principle components analysis of the chemical data generated by ICP-AES and MS sorted by Fabric. The samples of Black wheelmade Ware were plotted against samples from the Horns Region.

  sented by other authors (Kennedy et al. 2020; Bechar 2015; Cohen-Weinberger 2016), which are based on much larger datasets. All of the currently published data points to a tradition centered on a few workshops in an as of yet undefined area or areas (see below). The data from this study shows clear overlap between samples from the Lebanese Coast and Beqa' (for fabric A) indicating the Black Wheelmade Wares were distributed widely, some distance from their place of origin.

  Figure 21.6 General Geological Map of Lebanon with key sites (after Dubertret 1955, scale 1:200000).

Table 21 .

 21 1 List of samples analyzed for petrography. To understand the degree of petrographic and geochemical Similarity between Black Wheelmade Ware samples throughout its known distribution area in Lebanon and northern Palestine. A high degree of similarity of Black Wheelmade Ware would indicate products of a uniform and centralized production as suspected by some authors(Bechar 2015, 53). Conversely, a low degree of similarity would indicate dispersed and variable production modes. If the latter is true, this study seeks to identify any differences between vessels found on the Lebanese Coast, in the Beqa' Valley, and in northern Palestine. 3. Lastly, an attempt will be made to identify the production location(s) of the Black Wheelmade Ware vessels.

	Sample number	Site
	Arqa 02/112.001	Arqa
	Hizzin1	Tall Hizzin
	Hizzin2	Tall Hizzin
	Hizzin3	Tall Hizzin
	Hizzin4	Tall Hizzin
	Hizzin5	Tall Hizzin

Fadous F AD10.305/295.63.3

Tall Fadous-Kfarabida 2.

Table 21 .

 21 al. 2020; Kennedy

	Date	Type	Fabric	ICP Data
	Arqa phase P	Teapot	A	Yes
		Large Vessel	B	Yes
		Large Vessel	B	Yes
		Large Vessel	B	Yes
		Large Vessel	A	Yes
		Large Vessel	A	Yes
	phase V	Goblet	A	No

2 ICP-AES and -MS values for the six analyzed samples and LREE to HREE ratios and sums. Ta pb Th U LREE/HREE LREE+HREE 2015; philip et al. 2002; philip et al. 2005; Philip and Bradbury 2010; Maritan et al. 2005).

  [START_REF] Kennedy | Drinking on the Periphery: The Tall Nebi Mend Goblets in their Regional and Archaeometric Context[END_REF] that the Black Wheelmade Ware tradition, with its typological and technological similarities to the upper Orontes horizon of the Horns area, can be described specifically as an emulation of the upper Orontes goblet tradition. The Black Wheelmade Ware tradition, though part of the broader ceramic trends of the "Caliciform" heartland further to the north, is more closely related to those traditions. The ceramic parallels perhaps betray in the Beqa' a shift after the end of the EB III from high levels of socio-economic integration with Lebanese coastal areas toward the development of close links with areas farther to the north in the Orontes Valley. The close ceramic parallels with the Horns Region seem to continue on into the Middle Bronze Age[START_REF] Genz | Tall Hizzin: Digging Up New Material from an old Excavation[END_REF]) perhaps suggesting the continuation of strong socio-economic ties between the Beqa' and areas farther north.

	Conclusion
	Although the number of Black Wheelmade Ware
	vessels currently known from Lebanon is much
	smaller than the material available from the Jez-
	reel Valley, Galilee and especially the Hula Valley,
	the much lower number of excavations in Leba-
	non relating to this period definitely has to be
	taken into account.
	Regarding the typology, almost all types attested
	farther south are present in Lebanon as well, even
	in similar percentages. Goblets and teapots are
	dominant, while bottles are much rarer. No jars
	are attested yet, but even in the southern Levant
	these are only attested by very few examples.


Peter Ford Dominey
email: peter.dominey@inserm.fr

Timothy M Ellmore
email: tellmore@ccny.cuny.edu

Jocelyne Ventre-Dominey
email: jocelyne.ventre-dominey@inserm.fr

Effects of Connectivity on Narrative Temporal Processing in Structured Reservoir Computing

Keywords: reservoir computing, narrative, fMRI, cortex, network topology, DTI, white matter

Computational models of language are having an increasing impact in understanding the neural bases of language processing in humans. A recent model of cortical dynamics based on reservoir computing was able to account for temporal aspects of human narrative processing as revealed by fMRI. In this context the current research introduces a form of structured reservoir computing, where network dynamics are further constrained by the connectivity architecture in order to begin to explain large scale hierarchical network properties of human cortical activity during narrative comprehension. Cortical processing takes place at different time scales depending on the position in a "hierarchy" from posterior sensory input areas to higher level associative frontal cortical areas. This phenomena is likely related to the cortical connectivity architecture. Recent studies have identified heterogeneity in this posterior-anterior hierarchy, with certain frontal associative areas displaying a faster narrative integration response than much more posterior areas. We hypothesize that these discontinuities can be due to white matter connectivity that would create shortcuts from fast sensory areas to distant frontal areas. To test this hypothesis, we analysed the white matter connectivity of these areas and discovered clear connectivity patterns in accord with our hypotheses. Based on these observations we performed simulations using reservoir networks with connectivity patterns structured with an exponential distance rule, yielding the sensory-associative hierarchy. We then introduce connectivity short-cuts corresponding to those observed in human anatomy, resulting in frontal areas with unusually fast narrative processing. Using structured reservoir computing we confirmed the hypothesis that topographic position in a cortical hierarchy can be dominated by long distance connections that can bring frontal areas closer to the sensory periphery.

I. INTRODUCTION

We are witnessing an interesting conjuncture in developments in neural network models of language in machine learning, the computational neuroscience of language, and structured reservoir computing. Neural representations in certain classes of language models are measurably similar to neural representations in the human brain [START_REF] Schrimpf | The neural architecture of language: Integrative modeling converges on predictive processing[END_REF]. In this context, the temporal dynamics of reservoirs have been demonstrated to display human-like coding properties for narrative event structure [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF]. Finally, structured reservoir computing is beginning to investigate how constraining reservoir topology based on human connectivity can produce interesting computational properties [START_REF] Kawai | A small-world topology enhances the echo state property and signal propagation in reservoir computing[END_REF].

The current research addresses a dimension of language processing that has gained increasing visibilitythe temporal processing of language in a cortical hierarchy [START_REF] Hasson | A hierarchy of temporal receptive windows in human cortex[END_REF][START_REF] Lerner | Topographic mapping of a hierarchy of temporal receptive windows using a narrated story[END_REF][START_REF] Baldassano | Discovering event structure in continuous narrative perception and memory[END_REF][START_REF] Chang | Information flow across the cortical timescales hierarchy during narrative comprehension[END_REF][START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. Intuitively, sensory-driven cortical responses should be rapid and reflect the temporal structure of the input, while cortical activity underlying higher level cognitive functions that may involve reasoning and memory will have longer time-scales of processing [START_REF] Quintana | From perception to action: temporal integrative functions of prefrontal and parietal neurons[END_REF]. Computational models of cortical processing that emphasize local connectivity naturally demonstrate such hierarchies, with fast processing in nodes that receive input from the periphery, and a progressive slowing in areas farther from the periphery, as activity propagates along the hierarchy [START_REF] Chaudhuri | A diversity of localized timescales in network activity[END_REF]. However, while the majority of cortical connections are local [START_REF] Markov | Weight consistency specifies regularities of macaque cortical networks[END_REF], the primate (and particularly the human) brain is riddled with white matter bundles that create direct connection short-cuts between topographically distant cortical areas [START_REF] Lebel | Diffusion tensor imaging of white matter tract evolution over the lifespan[END_REF].

Here we address the effects of such topological constraints on narrative processing in the context of a new variant of reservoir computing as illustrated in Fig. 1. where inputs (dotted lines) are uniformly distributed into the network, and there is no restriction on the length input connections into the reservoir nor of recurrent connections (small solid lines) within the reservoir. B. Structured reservoir, where input connection are restricted to a small set of reservoir neurons, and recurrent connections are restricted by distance (i.e they are local). This creates a flow of information from input driven neurons to more distant peripheral "associative" neurons across local connections. C. Structured reservoir with direct connection short-cuts between topographically distant cortical areas, corresponding to white matter bundles.

The current research examines the relation between the different structures of network connectivity, as illustrated in Figure 1, and the resulting temporal selectivity of different cortical areas.

Based on an analysis of human neurophysiology of narrative processing, different temporal processing for different cortical areas, and the underlying white matter anatomical connectivity, we develop a form of structured reservoir computing that provides a coherent explanation for these data.

A. Temporal hierarchy in cortical processing

A temporal processing hierarchy has been observed in the human processing of narrative [START_REF] Hasson | A hierarchy of temporal receptive windows in human cortex[END_REF][START_REF] Lerner | Topographic mapping of a hierarchy of temporal receptive windows using a narrated story[END_REF]. Chien and Honey [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF] demonstrated how the time scale of narrative integration increases along such a hierarchy from primary auditory cortex to the highly integrative temporal parietal junction (TPJ). They developed a task and analysis that we refer to as the Narrative Alignment Task. While recording fMRI they exposed separate subject groups to an intact narrative and a scrambled narrative. From time to time the two groups thus heard the same narrative segment. The authors compared brain activity across the two groups as they made the transition from listening to different narrative segments to listening to the same narrative segment. They aligned their analysis on this transition from different to same, and characterized the time constant for the alignment or correlation of the brain activity across the two groups as they began to hear the same narrative. Interestingly, they observed a hierarchy of alignment time constants, with fast time constants in areas near the sensory periphery (primary auditory cortex), medium time constants in intermediate areas, and slower time constants in high level integration areas (TPJ). This is consistent with related studies that identify temporal processing hierarchies for narrative processing.

One hypothesis to explain such a hierarchy of processing is that areas that are close to the sensory periphery will quickly be influenced directly by inputs, and thus in the Narrative Alignment Task will become aligned rapidly. In contrast, cortical areas that are far from the sensory periphery will take more time to respond to inputs which must traverse multiple cortico-cortical connections before arriving.

B. Modeling the temporal hierarchy

Chaudri [START_REF] Chaudhuri | A diversity of localized timescales in network activity[END_REF] examined a family of recurrent network models in order to characterize the relation between network architecture and temporal processing. He investigated this by using an exponential distance rule (EDR) to constrain connectivity, where the probability of a node being connected to its neighbor falls off exponentially, as schematized in Fig. 1B. This favors local connectivity. Information thus propagates through local connections from the input driven periphery to more distal nodes, with a progressive increase in the time constant for response along the resulting hierarchy. Interestingly, Chaudri further examined the effects of the introduction of long distance connections, as schematized in Fig. 1C, and demonstrated that connections from fast nodes near the base of the hierarchy to slower nodes near the top of the hierarchy can render the latter faster, thus producing a discontinuity in the hierarchy. Such long distance connections can thus produce discontinuities in the hierarchy, such that an area that is more frontal may have response properties that are faster than an area that is more posterior. Indeed Chaudri and colleagues indicate that this appears to be the case in models constrained by the neuroanatomical connectivity of the non-human primate [START_REF] Chaudhuri | A large-scale circuit mechanism for hierarchical dynamical processing in the primate cortex[END_REF]. An open question concerns how these connectivity effects can influence the time-course of narrative processing.

C. Modeling narrative context construction

A recently developed model of human narrative processing based on reservoir computing was used to simulate aspects of this narrative processing [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF], modeling the Narrative Alignment Task of [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. The model simulated narrative processing by using 100 dimensional word embeddings from Wikipedia2Vec [START_REF] Yamada | Wikipedia2Vec: An Efficient Toolkit for Learning and Visualizing the Embeddings of Words and Entities from Wikipedia[END_REF] as inputs to a 1000 unit reservoir model of cortex. The activation of the reservoir, driven by narrative input in the form of word embeddings, thus served as a proxy for human brain activity during narrative listening. The model was demonstrated to display human-like representations of narrative event structure [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF]. The model was also shown to display human-like neural representations in the Narrative Alignment Task.

Paired models were presented with narrative input (682 words) with intact (ABCD) and scrambled (ACBD) structure, respectively. The transitions CD and BD in inputs to the two models constitute the construction or integration context in the Narrative Alignment Task of [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. That is, two models are initially exposed to different inputs (C) and (B), then to the same input (D). At the transition when both begin receiving the same input, one can measure the time constant for them to converge to the same activity. Thus, measuring the time constant for the two networks to converge to the same activity pattern when they both begin to receive common input (D) after having different inputs (C and B respectively) allows the authors to measure the alignment/convergence time. In this way the reservoir was demonstrated to simulate the Narrative Alignment Task.

Sorting the network units by these alignment times revealed a smooth distribution of alignment times from 4 to 50 time-steps, analogous to the distribution of alignment times observed in different cortical areas in humans in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. Interestingly, a linear integrator model of cortical function did not yield this distribution of alignment time constantsall units have the same time constants, so the distribution of time constants is a property of the flow of information in the recurrent connectivity within the reservoir.

Here we will use this narrative context construction time constant for examining the temporal processing of narrative structure, comparing across human subjects from [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF], and in structured reservoir simulations, based on [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF].

D. Model performance in narrative comprehension

In the current research, we will analyze the temporal processing properties of the structured reservoir that is exposed to narrative. We thus focus on the activity of the reservoir neurons themselves, rather than on trained readouts. However, it is important to note that we have previously characterized the ability of trained reservoirs to perform integrative comprehension of narrative that includes making inferences about human event structure [START_REF] Uchida | A Model of Online Temporal-Spatial Integration for Immediacy and Overrule in Discourse Comprehension[END_REF].

In [START_REF] Uchida | A Model of Online Temporal-Spatial Integration for Immediacy and Overrule in Discourse Comprehension[END_REF] the readout was trained to produce an integrated representation of the input narrative as a vector average of the accumulated word embeddings constituting the narrative. These narrative embeddings were then compared to embeddings for words that were, or were not, related by inference to the narrative, following human comprehension experiments [START_REF] Metusalem | Generalized event knowledge activation during online sentence comprehension[END_REF]. The model reproduced human performance by generating narrative mbeddings that were closer to the embeddings for words that were related to the narrative by inference. In addition, these trained narrative representations evolve in real-time during the word-by-word presentation of the narrative, again simulating human behavior in real-time integration of discourse [START_REF] Hagoort | Beyond the sentence given[END_REF]. Given this confirmation that the reservoir model can generate human-like performance in narrative/discourse comprehension, we now investigate the underlying representations within the reservoir. In particular we investigate how structural constraints on the reservoir topology can produce human-like temporal brain dynamics.

E. Current research hypotheses and objectives

While the notion of a temporal processing hierarchy for narrative holds at a global level, details in certain studies indicate that along the posterior to anterior gradient there are inconsistencies, where more anterior areas have faster processing times than would be expected by their topographic position (e.g. [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]). We hypothesize that these discontinuities in the temporal hierarchy can be explained by long distance connections via white matter pathways between faster posterior areas and otherwise slower frontal areas that thus become faster. We test this hypothesis in a twofold approach:

First, we identify a set of cortical areas from [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF] that reveal a discontinuity in the temporal processing hierarchy vs topographic hierarchy. We then analyze white matter tractography of these cortical areas, and demonstrate that indeed, the temporal processing discontinuity is correlated with the pattern of long distance white matter connections for these areas.

In order to demonstrate a causal role for long distance connections in modification of the temporal processing hierarchy, we perform structured reservoir computing simulations where the connectivity structure is organized according to an exponential distance rule, as schematized in Fig. 1B. We submit these networks to the Narrative Alignment Task of [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. This reveals a clear gradient of temporal processing time constants within the reservoir, along the sensory-associative axis. We then introduce long distance connections corresponding to white matter bundles in the human cortex, as schematized in Fig. 1C, and demonstrate that these connections can produce discontinuities in the temporal processing hierarchy.

II. NEURAL DYNAMICS AND NETWORK ANATOMY

In [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF] the narrative context construction times obtained in the Narrative Alignment Task were determined for ~70 distinct cortical areas. The authors generally observed a hierarchical gradient, as sensory cortices aligned most quickly, followed by mid-level regions, while some higherorder cortical regions took more than 10 seconds to align.

A. Discontinutities in the temporal processing heirarchy

Interestingly, there are discontinuities in the temporal processing hierarchy. Figure 2 illustrates three frontal cortical areas whose alignment times are in opposition to their position along the posterior-anterior topography, in data from [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. That is, the most anterior of the three medial frontal areas indicated in the red box in Figure 2 is the fastestin contradiction to the expected observation that the more frontal area is farther from the periphery, should be more integrative and thus have a longer time constant.

B. Discontinuities in connectivity due to white matter bundles

In order to determine whether the temporal processing discontinuities observed by [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF] for these three regions could be related to differences in white matter connectivity, we used diffusion tensor imaging [START_REF] Catani | A diffusion tensor imaging tractography atlas for virtual in vivo dissections[END_REF] to characterize white matter pathways issued from these regions of interest (ROIs). Diffusion tensor data obtained from 19 subjects in [START_REF] Jouen | Beyond the word and image: II-Structural and functional connectivity of a common semantic system[END_REF] were analysed in order to characterize the white matter pathways issued from the three ROIs using DSI Studio (https://dsistudio.labsolver.org). Figure 3 illustrates white matter pathways that project from these three regions of interest (ROIs). These were generated using ROIs specified in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF], based on the atlas in [START_REF] Schaefer | Local-global parcellation of the human cerebral cortex from intrinsic functional connectivity MRI[END_REF]. The observation of a distinction between the long anterior-posterior projections for areas PFCd and PFCmp that is not seen in FrMed was confirmed by a statistical analysis of the mean lengths of the tracts issued from these three areas. Analysis of variance by repeated measure ANOVA revealed a significant effect for Region (F(2,36) = 42, p < 0.0001). Post-hoc (Scheffe) tests revealed that the mean lengths for FrMed were significantly shorter (55mm) than for PFCd and PFCmp (70, 75mm respectively), while there was no difference between the lengths for PFCd and PFCmp.

Thus, the fastest area has significantly longer white matter pathways than the slowest area. Examining these pathways in Figure 2, we can observe that the pathways from PFCd and PFCmp project into posterior cortex, while those from FrMed (blue fibers) do not take this path into more posterior cortical areas.

III. STRUCTURED RESERVOIR MODELING

These results argue in favor of the hypothesis that differences in white matter connectivity can influence the temporal processing characteristics of cortex. To test this in an empirical model of cortical dynamics we developed a structurally modified version of the narrative integration reservoir using the open access reservoir model from [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF].

A. Narrative Integration Reservoir

The classic reservoir architecture is illustrated in Fig. 1A. Our model is based on a classic echo state network with leaky integrator tanh units. A set of recurrently connected nodesthe reservoiris stimulated by inputs. This produces a dynamic reverberation of activation throughout the reservoir as information propagates through the recurrent connections.

The basic discrete-time, tanh-unit echo state network with N reservoir units and K inputs is characterized by the state update equation :

x(t+1) = (1-α)x(t)+α•f(Wx(t) + W in u(t) ) (1)
where x(n) is the N-dimensional reservoir state, f is the tanh function, W is N×N reservoir weight matrix, Win is the N×K input weight matrix, u(n) is the K dimensional input signal, α is the leaking rate. The matrix elements of W and W in are drawn from a random distribution.

The reservoir was instantiated using easyesn, a python library for recurrent neural networks using echo state networks (https://pypi.org/project/easyesn/) [START_REF] Thiede | Easyesn: a library for recurrent neural networks using echo state networks[END_REF]. We used a reservoir of 1000 neurons, with input and output dimensions of 100. The W and W_in matrices are initialized with uniform distribution of values from -0.5 to 0.5, with 20% non-zero connections. The leak rate was 0.2. The reservoir is relatively robust to changes in these values, as long as the reservoir dynamics are neither diverging nor collapsing. To simulate narrative processing, words were presented in their sequential narrative order to the reservoir. Stop words (e.g. the, a, it) were removed, as they provide no semantic information [START_REF] Silva | The importance of stop word removal on recall values in text categorization[END_REF]. Similar results were obtained in the presence of stop words. Words were coded as 100 dimensional vectors from the Wikipedia2vec language model. This language model is developed based on using the word2vec language model that is trained on the entire Wikipedia 2018 corpus

The reservoir model illustrated in Fig. 4 receives as input the 100 dimensional word embedding from Wikipedia2Vec for the next word in the 682 word input narrative, based on the story "It's Not the Fall that Gets You" by Andy Christie (https://themoth.org/stories/its-not-the-fall-that-gets-you). Using two identical copies of this model we can simulate the Narrative Alignment Task. One model gets the intact input narrative with segments ABCD. The second gets the scrambled narrative with segments ACBD. As illustrated in Fig 5, when the inputs are different, the activation differences are clearly visible. When the inputs become the same, then the activations progressively align and the difference goes to zero. The time constant of this alignment is the behavior of interest. Thus, it is important to note that we are analyzing the intrinsic dynamics of the reservoir itself, and not the behavior of a trained readout layer.

Figure 5 illustrates the difference between reservoir activity in two identical copies of the same reservoir that are exposed to the intact ABCD narrative vs. the shifted ACBD narrative. When the activations in the two reservoirs are identical, the difference is null. In the beginning the intact and shifted narratives are the same, which yields a zero difference. Then they become different and we observe the large activity in the difference signal. Finally, the two narratives again become the same. There, we see a gradual reduction in the difference as the two narratives converge to the same activity, based on the same input. The time constant of this convergence is the measure we use to characterize temporal processing of narrative based on the same measure in human subjects in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF].

B. Topography of Temporal Processing

In the classic reservoir, the connections in the recurrent networkthe reservoirare randomly initialized with a Gaussian distribution between -0.5 and 0.5 with 20% non-zero connections. Thus, there is no structured topography within the reservoir. This is schematically illustrated in Figure 1A. In particular, there is no influence of topographical distance between neurons influencing the probability of connections. Such a reservoir configuration, and its behavior in the Narrative Alignment Task is illustrated in Figure 6. Figure 6 illustrates a standard, random reservoir, where the input matrix projects the inputs over the whole reservoir, and where there is no length restriction on connections between reservoir units, corresponding to Fig. A. There, in Panel C we see that across the different subsets of neurons there is a uniformity of time constants across the different subsets of cortical neurons. In the primate brain, this is not the case. The probability of two neurons being connected fall off exponentially with the distance between them [START_REF] Ercsey-Ravasz | A predictive network model of cerebral cortical connectivity based on a distance rule[END_REF]. This is illustrated schematically in Figure 1B. In structured reservoir computing (S-RC) we can introduce structure constraints such as the exponential distance rule, and restriction of input to "sensory" areas, corresponding to the schematic in Figure 1B.

To implement this, we start with a standard reservoir connection matrix W, and then restricted it according to a exponential distance rule as described in the pseudo-code in Fig. 7. There, for neurons 1..1000, no connection can longer than 600, and those connections are scaled by an exponential factor of the length. In addition the connections are scaled by a proximal to distal factor, that increases with the distance of the source (From) neuron from the input.

In Fig. 8 we see the resulting restricted input matrix, and the structured connectivity matrix for the reservoir with an exponential distance rule applied. Values closest to the diagonal represent connections strengths between closely neighboring neurons. Values that are farther from the diagonal are for neurons that are farther apart. We thus see a density along the diagonal that falls off exponentially. As illustrated in Fig. 8, the EDR connectivity imposes a topographical structure on processing. While inputs directly influence "lower" areas (neurons 1-300), higher areas receive input-related activity only as it is propagated along local connections. The highest neurons will receive input-related activity only after it has traversed multiple intermediate local connections to finally arrive at the highest neurons. Panel C illustrates the functional consequences of this. Neurons are grouped into virtual areas of 100 neurons, and the mean Narrative Alignment Task time constants are displayed. We observe a progressive increase in the alignment time constants along the cortical hierarchy.

C. Impact of Long Distance Dense Connections

This corresponds to a brain model that strictly follows local connectivity imposed by an exponential distance rule. However, recalling Figure 2 we know that thick bundles of axons provide dense connections between distant cortical areas. This corresponds to white mattermyelinated neural axonsthe wire of the brainwhich makes up almost half of the volume of the human brain [START_REF] Lebel | Diffusion tensor imaging of white matter tract evolution over the lifespan[END_REF]. Thus in addition to local connectivity there is ample possibility for long distance "hotlines" between cortical areas. In order to simulate the effects of such a long distance connection we introduced a connection bundle from fast input driven neurons to slower neurons far away in the hierarchy. This is illustrated in Fig. 8 panel B showing the W connectivity matrix, as the small square of values at From 100-200 to To 800-900. That is, this simulated white matter pathway connects neurons 100-200 which receive direct sensory input, to neurons 800-900 which are far from the sensory periphery. These units normally have a relatively high time constant in the absence of the long distance connection as illustrated in Fig. 8C. As illustrated in Figure 9, the introduction of this connection produces a significant speedup in the time constant for the Narrative Alignment Task for the cortical area that receives input from the area lower in the hierarchy. This demonstrates that introduction of long distance connections can significantly modify the time constant for a given cortical area in the Narrative Alignment Task.

Code and data for running these simulations is available in the repository: github.com/pfdominey/StructuredReservoirComputing

IV. INTERPRETATION AND DISCUSSION

The current research has scientific impact along two related dimensions. The first is the further development of a new field of investigation of structured reservoir computing where the structure of the input and recurrent connections are systematically modified based on anatomical constraints in order to produce new computational properties [START_REF] Kawai | A small-world topology enhances the echo state property and signal propagation in reservoir computing[END_REF]. The second is within the context of computational neuroscience of language and narrative processing [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF], and particularly the temporal component of this processing. Interestingly, these two dimensions intersect, as the analysis of computational properties of human-like connectivity in structured reservoirs will shed new light on the computational neuroscience of human narrative processing.

A. Structured reservoir computing

Recent research in structured reservoir computing addressed how constraining the reservoir with small world connectivity enhances certain computational properties [START_REF] Kawai | A small-world topology enhances the echo state property and signal propagation in reservoir computing[END_REF]. There, long distance connections allowed a propagation from restricted input-receiving units to distant output units. In their analysis, while the authors addressed the effects of the small world reservoir on several important aspects of reservoir computing, including the propagation effects of long distance shortcuts, effects on temporal processing and information flow were not directly addressed.

A clear physical phenomena is that network topology influences temporal processing [START_REF] Chaudhuri | A diversity of localized timescales in network activity[END_REF]. When information flows from input driven areas to more distant areas, as schematized in Fig 1B, that flow takes time. We can refer to this flow of information across successive connections as the network distance. This network distance is roughly correlated with topographic or physical distance along a flattened cortical sheet. Such a network would give the flowing temporal processing properties as illustrated in Fig 8 . However, the human brain is riddled with white matter (almost half the brain volume) [START_REF] Lebel | Diffusion tensor imaging of white matter tract evolution over the lifespan[END_REF]. White matter is constituted of axonal bundles which form cables that traverse the network and completely dissociate network distance from topographic distance. This is schematically illustrated in Fig. 1C. Such shortcuts should influence the temporal processing properties of their target cortical areas. In the current research this new perspective on reservoir computing is highly relevant, not only as a new avenue of reservoir computation, but also in providing a method to understand complex aspects of the human neuroscience of narrative processing. Indeed we were motivated by a clear case in human neurophysiology where network distance and topographical distance do not correspond, based on data in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. That is, a more frontal area had a much faster time constant for narrative processing than more posterior neighboring areas. We hypothesized that this discontinuity could be due to different connectivity profiles for these areas. We performed DTI analysis to determine that indeed, the most frontal area which most deviated from the temporal processing according to topographical distance had a connectivity pattern that significantly varied from its neighbor that had a better correspondence between topographic and network distance (i.e. it is far from the sensory periphery, and relatively slow). In particular the faster area had more extensive connections into posterior cortical areas that are closer to the sensory periphery.

To further test the hypothesis that such long distance connections can produce speedup in temporal processing, we performed neural network simulations using a novel form of reservoir computing that we refer to as Structured Reservoir Computing.

In structured reservoir computing, we introduce structure in the matrices that describe connections from the input to the reservoir, and the recurrent connections, following related research that has investigated the effects of small-world connectivity on reservoir processing [START_REF] Kawai | A small-world topology enhances the echo state property and signal propagation in reservoir computing[END_REF]. In particular, we create a more physiologically realistic reservoir topology, basing connectivity on an exponential distance rule, while retaining the reservoir principle of non-modifiable recurrent connections that are used to generate high-dimensional spatiotemporal projections of the inputs. By employing a connectivity structure where connection strength is based on an exponential function of the connection distance, we can produce structured reservoirs that display a more physiologically realistic spatial distribution of processing time constants such as observed in humans. Likewise, by introducing additional structure in the form of long distance white matter pathways that in a sense violate the exponential distance rules, we can achieve increasing realistic modeling of temporal processing as observed in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF].

An interesting and prevalent phenomena in the human processing of narrative is that across different brain areas, there are differences in the temporal granularity of narrative integration and event processing [START_REF] Hasson | A hierarchy of temporal receptive windows in human cortex[END_REF][START_REF] Lerner | Topographic mapping of a hierarchy of temporal receptive windows using a narrated story[END_REF][START_REF] Baldassano | Discovering event structure in continuous narrative perception and memory[END_REF][START_REF] Chang | Information flow across the cortical timescales hierarchy during narrative comprehension[END_REF][START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. It will be of great interest to use structured reservoir computing to model this diversity of cortical processing, including the processing of meaning at different structural levels (e.g. word, sentence, paragraph, narrative pattern, etc.). An initial step in this direction was taken in [START_REF] Dominey | Narrative Event Segmentation in the Cortical Reservoir[END_REF]. There we demonstrated that within a classic reservoir, there was a broad distribution of narrative processing time constants as revealed in the Narrative Alignment Task. When the reservoir neurons were sorted by their alignment time constants, the distribution of alignment time constants was strikingly similar to that observed across wide distribution of cortical areas in humans [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. In the current research we demonstrate how such a distribution of alignment time constants can be ecologically produced by imposing the exponential distance rule structure on the reservoir connectivity topology.

B. Temporal hierarchy in narrative processing

While cortical neurons have similar intrinsic time constants, due to their similar geometry and membrane properties, there is a vast diversity of time constants of neural processing across the cortical sheet [START_REF] Chaudhuri | A large-scale circuit mechanism for hierarchical dynamical processing in the primate cortex[END_REF]. This is particularly present in narrative processing [START_REF] Hasson | A hierarchy of temporal receptive windows in human cortex[END_REF][START_REF] Lerner | Topographic mapping of a hierarchy of temporal receptive windows using a narrated story[END_REF][START_REF] Baldassano | Discovering event structure in continuous narrative perception and memory[END_REF][START_REF] Chang | Information flow across the cortical timescales hierarchy during narrative comprehension[END_REF][START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF]. A major open question in modern neuroscience concerns both the origin of this diversity, and its functional consequences. One hypothesis would hold that specific cognitive processes, such as integration of narrative structure over an extended portion of narrative input, requires a long time constant of processing, and so these high level functions will impose this temporal structure on their associated brain areas or networks that are involved in such processing. In this hypothesis, the question remains as to what is the origin of the function that imposes these temporal constraints. An alternative hypothesis holds that the gross temporal processing constraints are imposed by architecture itself. As we observe, areas far from the sensory periphery naturally have slower time constants. In this hypothesis, these areas will naturally be adapted to processes that involve long time scale integration. Thus, long time scale structure of narrative will naturally self-allocate to these regions.

This modeling work examines the emergence of a temporal processing hierarchy based on network topology. It provides evidence that the distribution of narrative construction time constants observed in [START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF] might be accounted for by cortical network structure, rather than by an adaptation of different cortical areas to different processing requirements.

In other words, the different narrative integration processes (that operate e.g. at the word, sentence, paragraph, chapter levels) naturally migrate to the brain regions that have the corresponding connectivity structure that yields the appropriate processing time constant. This is in opposition to the notion that different brain areas adapt their processing time constants for different tasks. This is a rather binary analysis. It is possible that the truth is a compromise, whereby processing time constants can be constrained both by network connectivity properties, and by on-line modulatory processes. This provides a rich framework for future research on the interaction between network structure, processing time constant dynamics modulated by input driven and intrinsic processes in biological and artificial networks [START_REF] Bernacchia | A reservoir of time constants for memory traces in cortical neurons[END_REF].

On a final note, this research illustrates the tight potential link between the topological connectivity structure of the brain, and the hierarchical structure of narrative. This provides a novel and potentially fruitful approach for investigating the co-evolution of human narrative, including its spatio-temporal complexity and hierarchical event structure, and the corresponding neural architecture that provides the substrate for creating and comprehending this narrative structure. In the context of reservoir computing this is quite exiting. We already have the example of how reservoir computing has helped to characterize and understand the neuroscientific importance of mixed selectivity for higher cognitive function [START_REF] Rigotti | The importance of mixed selectivity in complex cognitive tasks[END_REF][START_REF] Enel | Reservoir Computing Properties of Neural Dynamics in Prefrontal Cortex[END_REF]. This new research in structured reservoir computing and narrative opens a new avenue of research that one can hope will be equally productive.

Fig. 1 .

 1 Fig. 1. Structured Reservoir Computing. A. Standard reservoir topology, where inputs (dotted lines) are uniformly distributed into the network, and there is no restriction on the length input connections into the reservoir nor of recurrent connections (small solid lines) within the reservoir. B. Structured reservoir, where input connection are restricted to a small set of reservoir neurons, and recurrent connections are restricted by distance (i.e they are local). This creates a flow of information from input driven neurons to more distant peripheral "associative" neurons across local connections. C. Structured reservoir with direct connection short-cuts between topographically distant cortical areas, corresponding to white matter bundles.

Fig. 2 .

 2 Fig.2. Alignment times in contrast to topography. Within the red boxed frontal zone, regions PFCd_1 (brown), PFCmp_1(orange) and FrMed_2 (yellow), lie along a topographic gradient from anterior to posterior. Their alignment times are in opposition to this topographic gradient, with the more anterior regions displaying faster alignment times. Modified from[START_REF] Chien | Constructing and forgetting temporal context in the human cerebral cortex[END_REF].

Fig. 3 .

 3 Fig.3. White matter connectivity for PFCd_1 (Red), PFCmp_1 (Green) and FrMed_2 (Blue). Right is anterior. Red-boxed zone same as in Fig.2. Note that Red and Green pathways extend in a signifant manner into posterior regions, while the blue pathways have less extension into posterior regions.

Fig. 4 .

 4 Fig. 4. Narrative Integration Reservoir. Successive words in the input narrative are used to retreive the corresponding word embeddings from Wikipedia2vec, a word2vec model trained on the 2018 Wikipedia corpus. Successive word vectores are input to the 1000 unit reservoir model which performs a temporal-spatial transformation of temporal seqeunce of word inputs into a trajectory of spatial activation vectors.

Fig. 5 .

 5 Fig. 5. Simulation of Narrative Alignment Task. Difference in reservoir neural activity for two reservoirs exposed to intact and scrambled narratives respectively. At the transition from Different to Same, we measure the time constant for the two reservoirs to become aligned for each of 1000 neurons.

Fig. 6 .

 6 Fig. 6. Classic reservoir architecture and "flat" temporal processing hierarchy in the Narrative Alignment Task. A. Input matrix: 100 input elements project into 1000 reservoir units. B. Recurrent connectivity matrix of the reservoir. Gaussian distribution, no structural topography. C. Narritive Alignment time constants for neuron subsets 300-399, 400-499, … 900-999. Note uniformity of time constants across these "cortical areas".

Fig. 7 .

 7 Fig. 7. Pseudocode for creating the structured weight matrix for the recurrent reservoir connections.

Fig. 8 .

 8 Fig. 8. Canonical topography of temporal processing. A. In the network of 1000 neurons, inputs are provided to the the first 300 neurons. B. The connectivity matrix indicates that neurons are connected to their local neighbors according to the EDR. C. Alignment time constant based on the Narrative Alignment Task in [8].

Fig. 9 .

 9 Fig. 9. Modification of the temporal heirarchy by introduction of long distance hot-line connections. A. Input matrix. Unchanged from Fig. 7. B. Connectivity matrix W. In addition to the local EDR defined connections (seen along the diagonal) we introduce an additional white matter pathway as a direct connection from neurons 100-200 to neurons 800-900. C. Modified hierachy. Comparing to Fig 7 C, we see that that later area 6 now has a significanly reduced alignment time in the narrative alignment task. .

  gradient= 0.00075;gain = 1.75;breadth=600;expon=3 for i in 1 to 1000: for j in 1 to 1000: if abs(i-j) <= breadth: esn.W[i,j] = (breadth-abs(i-j)/breadth)**expon* esn.W[i,j]* (1 + i * gradient)*gain else: esn.W[I,j]=0

ACKNOWLEDGMENT

Reservoir simulations were performed using the easyesn toolkit https://github.com/kalekiu/easyesn.

Grant ANER 2019 RobotSelf.