John B Creech
email: john.creech@mq.edu.au

Frédéric Moynier

Christian Koeberl

Volatile loss under a diffusion-limited regime in tektites: evidence from tin stable isotopes

Keywords: tektites, volatiles, tin, stable isotopes, impacts

Tektites are glasses derived from near-surface continental crustal rocks that were molten and ejected from the Earth's surface during hypervelocity meteorite impacts. They are among the driest terrestrial samples, although the exact mechanism of water loss and the behaviour of other volatile species during these processes are debated. Based on the difference in magnitude of the Cu and Zn isotopic fractionations in tektites, and the difference of diffusivity between these elements, it was suggested that volatile loss was diffusionlimited. Tin is potentially well suited to testing this model, as it has a lower diffusivity in silicate melts than both Cu and Zn, but a similar volatility to Zn. Here, we analysed the Sn stable isotopic composition in a suite of seven tektites, representing three of the four known tektite strewn fields, for which Zn and Cu isotopes were previously reported. Tin is enriched in the heavier isotopes (≥2.5‰ on the 122 Sn /118 Sn ratio) in tektites, correlated with the degree of Sn elemental depletion in their respective samples as well as with Cu and Zn isotope ratios, implying a common control. While the isotope fractionation of Sn, Cu and Zn is a result of

INTRODUCTION

Tektites are distal impact glasses, typically up to a few cm in size, formed by rapid melting of terrestrial upper crustal rocks during hypervelocity impacts on the Earth's surface (e.g., [START_REF] Shaw | Age and provenance of the target materials for tektites and possible impactites as inferred from Sm-Nd and Rb-Sr systematics[END_REF][START_REF] Koeberl | The geochemistry of tektites: an overview. Tectonophysics, Cryptoexplosions and catastrophes in the geological record, with a special focus on the Vredefort structure[END_REF][START_REF] Koeberl | The geochemistry of tektites: an overview. Tectonophysics, Cryptoexplosions and catastrophes in the geological record, with a special focus on the Vredefort structure[END_REF][START_REF] Koeberl | Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms[END_REF][START_REF] Koeberl | Impact origin of the Chesapeake Bay Structure and the source of the North American tektites[END_REF][START_REF] Melosh | How Does Tektite Glass Lose Its Water? Presented at the Lunar and Planetary Science Conference[END_REF]. Tektites have chemical and isotopic compositions similar to that of the terrestrial upper crust, and thus are thought to have formed by fusion of the target rocks/sediments rather than from the impactor itself (e.g., [START_REF] Shaw | Age and provenance of the target materials for tektites and possible impactites as inferred from Sm-Nd and Rb-Sr systematics[END_REF][START_REF] Koeberl | The geochemistry of tektites: an overview. Tectonophysics, Cryptoexplosions and catastrophes in the geological record, with a special focus on the Vredefort structure[END_REF][START_REF] Koeberl | Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms[END_REF].

Although tektites are generally chemically and isotopically similar to the upper crust, they are characterized by extremely low water contents [START_REF] Beran | Water in tektites and impact glasses by fourier-transformed infrared spectrometry[END_REF]; 0.002-0.02 wt.%; [START_REF] Koeberl | Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms[END_REF], indicating a depletion of water (and potentially other volatiles) from their precursor rocks (typically sediments, with >1% water) while the tektites were molten.

The mechanism for this depletion and, more broadly, the behaviour of volatile elements and molecules during tektite formation is not well understood. Volatilization is known to fractionate elemental and isotopic abundances of volatile elements, and isotopic fractionation of moderately volatile elements has been recorded, for example, in lunar samples (e.g., Cl, Ga, K, Zn, Rb; [START_REF] Sharp | The Chlorine Isotope Composition of the Moon and Implications for an Anhydrous Mantle[END_REF][START_REF] Paniello | Zinc isotopic evidence for the origin of the Moon[END_REF][START_REF] Kato | Extensive volatile loss during formation and differentiation of the Moon[END_REF][START_REF] Boyce | The chlorine isotope fingerprint of the lunar magma ocean[END_REF][START_REF] Kato | Gallium isotopic evidence for extensive volatile loss from the Moon during its formation[END_REF][START_REF] Pringle | Rubidium isotopic composition of the Earth, meteorites, and the Moon: Evidence for the origin of volatile loss during planetary accretion[END_REF][START_REF] Wang | Potassium isotopic evidence for a high-energy giant impact origin of the Moon[END_REF]. Recently, even relatively refractory elements (e.g., Mg, Si, Ca, Ti) have been shown to have isotopic variations that are attributed to high-temperature volatility-related processes in the early Solar System (e.g., [START_REF] Richter | Non-traditional fractionation of non-traditional isotopes: Evaporation, chemical diffusion and Soret diffusion[END_REF][START_REF] Pringle | Silicon isotopes in angrites and volatile loss in planetesimals[END_REF][START_REF] Hin | Magnesium isotope evidence that accretional vapour loss shapes planetary compositions[END_REF][START_REF] Davis | Titanium isotopes and rare earth patterns in CAIs: Evidence for thermal processing and gas-dust decoupling in the protoplanetary disk[END_REF]. As such, developments of additional tools to investigate such processes are timely. Given that tektites were rapidly heated, molten, and quenched over timescales that are likely to capture kinetic effects related to volatility, stable isotopes of volatile elements are well-suited to studying tektite formation and the isotopic effects thereof.

So far, studies of isotopic fractionation in tektites have yielded equivocal results. (Esat andTaylor, 1987, 1986), K [START_REF] Herzog | Potassium isotope abundances in Australasian tektites and microtektites[END_REF][START_REF] Humayun | Potassium isotopic composition of Australasian tektites[END_REF][START_REF] Jiang | Implications of K, Cu and Zn isotopes for the formation of tektites[END_REF], B [START_REF] Chaussidon | Boron content and isotopic composition of tektites and impact glasses: Constraints on source regions[END_REF], and Li [START_REF] Magna | Lithium in tektites and impact glasses: Implications for sources, histories and large impacts[END_REF] in tektites found that vapour fractionation (at least for those elements) did not play an important role during tektite formation, and that isotope ratios reflect the compositions of their source materials. However, those elements lie towards the more refractory end of the moderately volatile elements. Among the more volatile of the moderately volatile elements, Cd is enriched in the heavy isotopes in one Muong Nong-type Australasian tektite, which could reflect evaporative loss of light Cd isotopes [START_REF] Wombacher | Stable isotope compositions of cadmium in geological materials and meteorites determined by multiple-collector ICPMS[END_REF], although with only one sample, this finding is inconclusive. [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF] reported Zn and Cu isotope compositions, respectively, for a suite of tektites from all strewn fields. These results were reaffirmed by a study of moldavites and sediments of the Ries crater [START_REF] Rodovská | Implications for behavior of volatile elements during impacts-Zinc and copper systematics in sediments from the Ries impact structure and central European tektites[END_REF].

Studies of Mg

Both Cu and Zn show significant isotopic fractionation that correlates with their elemental depletions, consistent with preferential evaporative loss of light isotopes [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF], and the larger isotopic fractionation in Cu was attributed to the greater chemical diffusivity of Cu over Zn due to their differences in ionic charge (i.e., Zn 2+ vs. Cu + ; [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF]. However, this model is based on only two elements, and further testing is required to validate this hypothesis.

Tin is amongst the more volatile of the moderately volatile elements, and is potentially more volatile than both Cu and Zn. No quantitative estimates exist for the temperature of volatilization of these elements in conditions relevant to tektite formation. Cosmochemical condensation temperatures, based on condensation from a gas of solar nebular composition at a partial pressure of ~10 -4 atm. [START_REF] Lodders | Solar System abundances and condensation temperatures of the elements[END_REF], are often used as a first order estimate of volatility. These would suggest the relative volatilities of these elements increase in the order Cu << Zn ≲ Sn. Recent vaporization experiments of basalts at higher oxygen fugacities suggest that the relative volatilities of these elements increase in the order Zn<Cu<Sn (Zn is getting relatively less volatile under oxidizing conditions, while Sn stays the most volatile element; [START_REF] Norris | Earth's volatile contents established by melting and vaporization[END_REF]. However, another recent vaporization study under more oxidising conditions suggests that Zn remains more volatile than Cu [START_REF] Sossi | Evaporation of moderately volatile elements from silicate melts: experiments and theory[END_REF], although unfortunately [START_REF] Sossi | Evaporation of moderately volatile elements from silicate melts: experiments and theory[END_REF] do not provide data for Sn. Here, we assume an order of volatility is maintained under tektite forming conditions whereby Sn and Zn have similar volatility, and Cu is less volatile than Sn and Zn.

Understanding the isotopic behaviour of Sn during evaporation will be central to understanding isotopic data in planetary materials and in impact-related samples. Tin isotope cosmochemistry is a new field, and so far, published data have been limited to conference abstracts [START_REF] Bourdon | Isotope Fractionation during Partial Condensation[END_REF]Creech and Moynier, 2017;[START_REF] Fitoussi | Tin Isotope constraints on the Formation of the Moon[END_REF] and one paper [START_REF] Creech | Tin and zinc stable isotope characterisation of chondrites and implications for early Solar System evolution[END_REF]. However, the discovery of a light isotopic composition of Sn in lunar samples compared to the Earth [START_REF] Fitoussi | Tin Isotope constraints on the Formation of the Moon[END_REF] is unique amongst isotopic systems analysed so far. Tektites can be used as natural experiments to test the behaviour of Sn during evaporation.

Here, we report the first Sn stable isotope data in a suite of tektites from three of the four major tektite strewn fields in which Cu and Zn isotopic composition had been previously reported [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF]. We use these data to investigate the processes leading to the chemical and isotopic compositions of tektites, and, in turn, the effect of volatility related processes on the isotopic composition of tin. By comparing the isotope fractionations of Cu, Zn, and Sn, as well as their relative diffusivities, we test the previous model of [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF] of volatile loss in a diffusion-limited regime. These constraints on the isotopic behaviour of Sn during evaporation will be central to understanding isotopic data in planetary materials and in impact-derived samples, and will assist in interpretation of future analyses of other cosmochemical samples, such as lunar rocks and chondrites.

MATERIALS AND METHODS

Sample descriptions

The Sn isotopic composition of a total of seven tektites were analysed in this study, comprising all samples from previous Zn and Cu work with sufficient remaining sample material for Sn isotope analysis. Details of the samples are summarized in Table 1. These tektite samples represent three of the four identified tektite strewn fields, comprising:

Central European tektites: Four moldavite tektites were studied, three of which are from the vicinity of Jankov (Jankov 1, Jankov 2, Jankov 3) and one is from the vicinity of Chlum (Chlum). Of these samples, three have been previously analysed for Zn isotope ratios by [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF], and three for Cu isotope ratios by [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF] -see Table 1.

North American tektites: One North American tektite (BED 8402), which is from the bediasite sub-strewn field (Texas). This sample has been previously described in [START_REF] Weinke | Trace elements in two bediasite tektites[END_REF], and analysed for Zn and Cu isotope ratios by [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF].

Australasian tektites: Two Australasian tektites, both indochinites, were analysed in this study. These comprise one Muong Nong type tektite from Thailand (MN 8309) and one splash-form tektite from Hainan, China (HSF1). Both of the Australasian tektites have been analysed for major and trace element compositions by [START_REF] Koeberl | Geochemistry and origin of Muong Nong-type tektites[END_REF] or [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF]; Cu and Zn isotope data have also been published by [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF].

For comparison with terrestrial compositions, isotopic and concentration data for four commonly used USGS terrestrial reference materials are also given in Table 1. Note that in the following discussion, a generic terrestrial upper crust δ 122 / 118 Sn (the per mil deviation of the 122 Sn/ 118 Sn ratio from the IPGP_Sn standard) composition is approximated as 0.00-0.50‰, with [Sn] of 0.65-2.50 µg g -1 , based on data from Creech et al. (2017) and [START_REF] Badullovich | Tin isotopic fractionation during igneous differentiation and Earth's mantle composition[END_REF]; the exact composition of the tektite source rocks may be further constrained in the future as Sn isotope data for more geological materials become available.

Analytical methods

Tin purification and isotopic analysis were conducted using the same methods as described by Creech et al. (2017;2019). Powders comprising 55-380 mg of tektite samples were digested in a mixture of concentrated HF:HNO3 in closed teflon beakers on a hotplate at 120 ˚C. Dissolved tektite samples were evaporated to incipient dryness at 100 ˚C, taken up in a small volume of concentrated HCl and dried down again before being taken up in 2 mL of 0.5 M HCl for loading on to columns. Biorad columns were prepared with 1.5 mL per column of TRU resin and cleaned prior to sample loading by repeated rinsing with 0.5 M HNO3, 0.5 M HCl and milli-Q water. After loading, matrix was rinsed off the column with 4 mL of 0.5 M HCl and 7 mL of 0.25 M HCl, and Sn was subsequently eluted in 10 mL of 0.5 M HNO3.

Prior to sample digestion, samples were doped with a 117 Sn-122 Sn double-spike to give approximate proportions of 40% Sn from the double-spike and 60% from the sample, as detailed by Creech et al. (2017). Tin stable isotope measurements were carried out using a Thermo-Scientific Neptune Plus MC-ICPMS at the Institut de Physique du Globe de Paris, France, under analytical conditions identical to those described by Creech et al. (2017).

Isotope results are reported in δ 122/118 Sn notation. Sufficient material was only available to measure each tektite sample once. Creech et al. (2017) reported an external reproducibility for this technique of (conservatively) ±0.065‰ on δ 122/118 Sn, or ca. 0.016‰ on a per amu basis.

Uncertainties on figures represent either the internal error of the respective analysis or the external reproducibility, whichever is larger.

Data reduction was conducted offline using the freely available double-spike data reduction tool IsoSpike (www.isospike.org; [START_REF] Creech | IsoSpike: Improved Double-Spike Inversion Software[END_REF].

RESULTS

Tin isotopic and concentration data for tektites are presented in Table 1, along with literature data for Zn and Cu for the same tektite samples. Tektites are strongly fractionated towards heavy Sn isotopic compositions relative to those of terrestrial upper crust samples (Table 1; Fig. 1). Overall, the tektites span a range in δ 122 / 118 Sn of ca. 2 ‰, which is significantly larger than any natural Sn isotopic variation so far reported for geological samples. The single North American tektite has a δ 122/118 Sn = 1.40 ± 0.18‰, whereas the Central European tektites span a range from δ 122/118 Sn = 1.35 ± 0.03‰ (Jankov 1) to 2.53 ± 0.15‰ (Chlum). The Australasian tektites are more variable; the splash form tektite from Hainan (HSF1) has a similar isotopic composition to the North American and Central European tektites (δ 122/118 Sn = 1.60 ± 0.10‰), while the Muong Nong-type tektite MN8309 is less fractionated, with a composition more similar to terrestrial upper crust (δ 122/118 Sn = 0.46 ± 0.18‰; basalt, [START_REF] Badullovich | Tin isotopic fractionation during igneous differentiation and Earth's mantle composition[END_REF].

DISCUSSION

We observe a general shift towards heavy isotope compositions in tektites that is correlated with decreasing Sn content (Table 1, Fig. 1). This observation is consistent with evaporative loss of the light Sn isotopes during the molten phase of tektite formation, as previously observed for Cu and Zn [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Rodovská | Implications for behavior of volatile elements during impacts-Zinc and copper systematics in sediments from the Ries impact structure and central European tektites[END_REF]. In Figure 1 we show calculated isotopic compositions based on mass-dependent fractionation by Rayleigh distillation, which describes the isotopic evolution of a system from which a phase is continuously extracted. The isotopic composition of the tektites is well reproduced by a Rayleigh distillation, following a fractional distillation relationship for Sn as given in equation (1):

/ / = [ ] [ ] (1)
where α is the isotope fractionation factor, and the subscript 0 indicates initial values. The initial composition is an assumed terrestrial upper crust composition (note: on the scale of isotopic fractionation observed in tektites, varying the initial composition within the range observed in terrestrial samples has little effect on the shape of projection, although it does change the relative position). In an ideal case, the kinetic fractionation factor, α, is dependent on the square root of the ratio of the masses involved (i.e., = / , where M 118 Sn and M 122 Sn are the masses of 118 Sn and 122 Sn, respectively; in the case of Sn, αideal = 0.983), although in natural samples fractionation factors are found to deviate from this ideal case (e.g., [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Day | Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon[END_REF][START_REF] Wimpenny | Experimental determination of Zn isotope fractionation during evaporative loss at extreme temperatures[END_REF].

Suitable natural samples can thus be used to derive empirical kinetic fractionation factors that may be useful in interpreting volatility related isotope effects in other settings (with the caveat that additional factors/reactions may also affect isotopic fractionation). Tektites are well suited for this purpose.

As shown in Figure 1, the Sn isotopic compositions of most tektites are very close to predicted compositions from fractional distillation, for α values of 0.998 (Central European and North American tektites) or 0.999 (Australasian), and an initial composition of δ 122/118 Sn0 = 0.13‰ and [Sn]0 = 1.6 µg g -1 . This match between observed and predicted isotope fractionation behaviour supports that during kinetic evaporation of a silicate melt the lighter isotopes of Sn are preferentially lost in the vapour.

The Muong Nong-type tektite MN8309 is closest in composition to terrestrial upper crust. This is consistent with previous observations that these tektites are less depleted in volatiles than splash form tektites, contain mineral remnants of the target, and were possibly deposited closer to the site of impact, having experienced lower formation temperatures [START_REF] Glass | Mineral Inclusions in Muong Nong-Type Indochinites: Implications Concerning Parent Material and Process of Formation[END_REF][START_REF] Koeberl | Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms[END_REF][START_REF] Koeberl | Geochemistry and origin of Muong Nong-type tektites[END_REF]. Muong Nong-type tektites were also found to be less isotopically fractionated for Zn and Cu [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF]. These results reflect the temperature-time regime (i.e., likely shorter periods of melting and evaporation)

experienced by this group of tektites.

The Sn isotope data from tektites show strong correlations with Cu and Zn isotope data (Table 1, Fig. 2). The correlations between these different isotope systems suggest that they have been fractionated by a common process. Linear regressions through the data yield R 2 values of 0.94 and 0.73 for Sn vs. Cu and vs. Zn, respectively (note that the moldavite from Chlum appears to be an outlier in Cu isotope space, and was excluded from that regression). Considering the similar relative mass differences of the respective isotope ratios (i.e., 3.13% for 66 Zn/ 64 Zn, 3.17% for 65 Cu/ 63 Cu, and 3.39% for 122 Sn/ 118 Sn), the slopes of the regressions in Figure 1 represent the relative rate of isotope fractionation for each element, which may result from e.g., volatility or diffusion rates, as discussed below. We find that the rate of Sn isotope fractionation in tektites is ca. 94% that of Zn isotopes (i.e., not significantly distinguishable within uncertainties), and ca. 17% that of Cu isotopes. If we assume volatilities decrease as Sn ≥ Zn > Cu, as described above, this fractionation must be partially moderated by another factor.

In the model of [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF], molten tektite droplets are viscously stirred, with differential evaporation occurring at the surface. While the evaporation is controlled by volatility, the availability of elements at the surface for evaporation is governed by the rate of diffusion, which depends on many factors (e.g., T, melt composition, ionic radii). Where the diffusion rate of an element is slow, a diffusion-limited regime predominates, and evaporative loss of the element is restricted. Thus, elements that diffuse slowly in a melt are expected to be less isotopically fractionated, than elements that diffuse quickly, and for a fixed evaporation flux, the relative isotopic fractionation between volatile elements will be controlled by the diffusivity.

In anhydrous melts, the relative diffusivities of these elements increase in the order Sn < Zn << K, Cu [START_REF] Behrens | Trace element diffusion and viscous flow in potassium-rich trachytic and phonolitic melts[END_REF][START_REF] Zhang | Diffusion data in silicate melts[END_REF][START_REF] Yang | Cassiterite dissolution and Sn diffusion in silicate melts of variable water content[END_REF][START_REF] Ni | Cu and Fe diffusion in rhyolitic melts during chalcocite "dissolution": Implications for porphyry ore deposits and tektites[END_REF][START_REF] Ni | Cu diffusivity in granitic melts with application to the formation of porphyry Cu deposits[END_REF]; see Supplementary Material for further discussion). Given the similar volatility of Sn relative to Zn, the larger relative fractionation in Zn is therefore likely a consequence of the slower diffusion of Sn in molten droplets. The relatively large isotope fractionation observed in Cu isotopes [START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF], despite its lower volatility than Sn (and possibly Zn), is largely due to the greater availability of Cu resulting from the faster diffusion of Cu + .

CONCLUSIONS

Tektites are enriched in the heavier isotopes of Sn, and the isotopic composition correlates with the degree of elemental Sn depletion in these samples. This is consistent with evaporative loss of light Sn isotopes in to the vapour phase during tektite formation. The observed Sn isotopic fractionation in tektites is consistent with calculations of fractional distillation of Sn, with corresponding kinetic fractionation factors (α) of ca. 0.998-0.999. A relationship is observed isotopic fractionation in Sn, Zn and Cu, suggesting a common fractionation process. The smaller relative isotopic fractionation of Sn compared to Zn, despite similar volatility, and the much larger isotopic fractionation of Cu reflects the availability of these elements at the droplet surface, which is limited by the rate of diffusion.

Figure 1 .

 1 Figure 1. Sn isotopic composition versus Sn content in tektites, showing predicted isotopic fractionation (calculated using equation 1) from an initial terrestrial upper crust composition as Sn is lost from the reservoir. The different colour lines represent calculations using different hypothetical fractionation factors (i.e., α values), as indicated. The half-filled symbol indicates the Muong Nong type tektite, MN8309. Error bars reflect the internal error or the external reproducibility, whichever is larger. Where error bars are not visible, uncertainties are smaller than the data point.

Figure 2 .

 2 Figure 2. Comparison between tektite data for Sn isotopes and a) Cu isotopes and b) Zn isotopes. Dashed lines represent linear regressions through the data, with R 2 values as indicated on the figure. The half-filled symbol indicates the Muong Nong type tektite, MN8309. The upper-most symbol indicates the moldavite Chlum, which was excluded from the linear regression on plot (a) as it is an outlier in both Cu and Sn isotope space. Error bars reflect the internal error or the external reproducibility, whichever is larger. Where error bars are not visible, uncertainties are smaller than the data point.

TABLE CAPTION Table 1 .

 CAPTION1 Tin, Cu, and Zn isotopic and concentration data for tektites and USGS reference materials.Table1footnote. Tin isotope and concentration data for USGS reference materials are fromCreech et al. (2017). Zinc isotope data are from[START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF], with the exception of AGV-2, which is from[START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF], and all Zn isotope data are relative to JMC-Lyon. Copper isotope data from[START_REF] Moynier | Isotopic fractionation of Cu in tektites[END_REF], with the exception of BCR-2 which is from Chen et al. (2016), and all Cu isotope data are relative to NIST SRM 976. Cu and Zn concentration data for USGS reference materials are GeoReM recommended values.

  [START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Weinke | Trace elements in two bediasite tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Moynier | Isotopic fractionation of zinc in tektites[END_REF][START_REF] Beran | Water in tektites and impact glasses by fourier-transformed infrared spectrometry[END_REF]

								North American
								Central European
								Australasian
	Field	Type	Sample ID	δ	122/118 Sn (‰)	y = 1.017x -0.159 ± [Sn] R 2 = 0.73 (2 sd) (µg g -1 )	δ	65/63 Cu (‰)	± (2 sd)	[Cu] (µg g -1 )	δ	66/64 Zn (‰)	± (2 sd)	[Zn] (µg g -1 )
	North American Bediasite	BED 8402		1.400	0.180	0.754		2.60	0.10	6.5		1.46	0.09	26
	Central EuropeanMoldavite	Jankov 1		1.352	0.028	0.853						1.92	0.09	29
	Central EuropeanMoldavite	Jankov 2		2.230	0.120	0.570		6.98	0.10	0.1		1.93	0.09	23
	Central EuropeanMoldavite	Jankov 3		1.725	0.051	0.619		4.41	0.10	0.1				24
	Central EuropeanMoldavite	Chlum		2.530	0.150	0.486		1.99	0.10	0.4		2.27	0.09	19
	Australasian	Hainan	HSF1			1.600	0.100	0.379		3.11	0.10	2.2		2.16	0.09	8
	Australasian	Muong Nong MN8309		0.460	0.180	1.000		0.02	0.10	11.4		0.61	0.09	74
	BHVO-2 BCR-2	Field Basalt Basalt		Type		Sample ID 0.452 0.027 0.404 0.650	δ 122/118 Sn (‰) 1.90 2.36		± (2 sd) 0.10 0.20	[Sn] (µg g -1 ) 0.07 0.09	δ 65/63 Cu (‰) 129.3 19.7	± (2 sd) 0.25 0.27	[Cu] (µg g -1 ) 0.01 103.9 δ 66/64 Zn (‰) 0.06 129.5	± (2 sd)	[Zn] (µg g -1 )	n	Major elements (Moynier et al. 2009) Si Al	Fe		Mg	Ca	Ti	K	Na	H2O	H2O Beran and Koeberl	Major elements (Weinke and Koeberl 1985) SiO2 Al2O3	FeO	MgO	CaO	TiO2	K2O	Na2O
	GSP-2	North American Bediasite Granodiorite		BED 8402 0.180 0.220	1.400 8.32		0.180	0.754	2.60 43.0		0.10	6.5	120.0	1.46	0.09	26		BED 8402		4.44	2.22	0.37	0.47		1.63	1.04	0.027	77.8	12.14	3.01	0.62	0.69	0.59	2.38	1.65
	AGV-2	Central European Moldavite Andesite		Jankov 1 0.310 0.120	1.352 2.07		0.028 0.10	0.853 0.11	51.5		0.25	0.09	86.7	1.92	0.09	29		Jankov 1		5.54	1.34	1.17	1.78		3.01	0.35	0.529251	0.777305	0.603036	0.724691	0.599343	0.830148	0.741857
		Central European Moldavite		Jankov 2	2.230		0.120	0.570	6.98		0.10	0.1		1.93	0.09	23		Jankov 2		5.2	1.3	1.52	2.29		2.85	0.31	6.43	2.34	0.37	0.50	0.35	1.98	1.22
		Central European Moldavite		Jankov 3	1.725		0.051	0.619	4.41		0.10	0.1				24		Jankov 3
		Central European Moldavite		Chlum	2.530		0.150	0.486	1.99		0.10	0.4		2.27	0.09	19		Chlum		3.84	1.17	1.49	2.45		2.39	0.2
		Australasian	Hainan		HSF1		1.600		0.100	0.379	3.11		0.10	2.2		2.16	0.09	8		HSF1		4.41	2.81	0.93	1.15		1.79	0.82
		Australasian	Muong Nong MN8309	0.460		0.180	1.000	0.02		0.10	11.4		0.61	0.09	74		MN8309									0.024
		BHVO-2		Basalt				0.452		0.027	1.90	0.10		0.07	129.3	0.25	0.01	103.9
		BCR-2		Basalt				0.404		0.650	2.36	0.20		0.09	19.7		0.27	0.06	129.5		SiO2	Al2O3	FeO	MgO	CaO	TiO2	K2O	Na2O	H2O
		GSP-2		Granodiorite		0.180		0.220	8.32				43.0				120.0		BED 8402	77.8	8.39	2.86	0.61	0.65	0.59	1.96	1.40	0.027
		AGV-2		Andesite				0.310		0.120	2.07	0.10		0.11	51.5		0.25	0.09	86.7		Jankov 1		10.47	1.72	1.94	2.46		3.63	0.47
																					Jankov 2		9.83	1.67	2.52	3.16		3.43	0.42
																					Jankov 3
																					Chlum		7.26	1.51	2.47	3.38		2.88	0.27
																					HSF1		8.33	3.62	1.54	1.59		2.16	1.11
																					MN8309									0.024
																						0.529251	0.777305	0.603036	0.724691	0.599343	0.830148	0.741857
																					Weinke and Koeberl 1985

ACKNOWLEDGMENTS

We are grateful to three anonymous reviewers for their detailed and constructive comments on the manuscript, and to Don Porcelli for his editorial handling. F.M. acknowledges funding from the European Research Council [ERC Starting grant agreement 637503-Pristine] to as well as the financial support of the UnivEarthS Labex program at Sorbonne Paris Cité [ANR-10-LABX-0023 and ANR-11-IDEX-0005-02] and a chaire d'excellence ANR-Idex Sorbonne Paris Cité. We are grateful to three anonymous reviewers for constructive comments on an earlier version of this manuscript. Parts of this work were supported by IPGP multidisciplinary program PARI, and by Region île-de-France SESAME Grant no. 12015908.


Hélène Brissart
email: h.brissart@chru-nancy.fr

Mélanie Planton

Mathias Bilger

Christine Bulteau

Natacha Forthoffer

Victoria Guinet

Sophie Hennion

Catherine Kleitz

Virginie Laguitton

Hélène Mirabel

C Mosca

N Pécheux

S Pradier

S Samson

E Tramoni

V Voltzenlogel

M Denos

M Boutin

French neuropsychological procedure consensus in epilepsy surgery

Keywords: AEDs, antiepileptic drug, EEG, electroencephalogram, FLAE, French League Against Epilepsy, FSIQ, full-scale intelligence quotient, GAI, general ability index, ILAE, International League Against Epilepsy, MRI, magnetic resonance imaging, NAP, neuropsychological assessment procedure, PRI, perceptual reasoning index, PSI, processing speed index, TLE, temporal lobe epilepsy, VCI, verbal comprehension index, WMI, working memory index

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction: Neuropsychological assessment is an integral component of the surgical procedure in patients with epilepsy. As no French consensus for neuropsychological assessment was available, the main goal of this work was to define French neuropsychological procedure consensus in regard to literature review. Method: A panel of expert in neuropsychology was created within the framework of the French League Against Epilepsy. A systematic search of publications from 1950 to 2017 listed in PubMed database was conducted leading to a classification of articles according to their level of scientific evidence. French neuropsychological procedure consensus was then carried out with an expert panel of expert. Results: Low scientific evidence of neuropsychological data was reported. A panel of expert proposed a comprehensive neuropsychological assessment procedure including the exploration of intellectual efficiency, long-term memory, short-term and working memory, attention, executive functions, processing speed and motor skills, language, visual processing, praxis, psychobehavioral, and social cognition. Discussion: A common procedure for assessing cognitive and psychobehavioral function is now available in patients with epilepsy undergoing surgical evaluation have been established, they may help to improve the quality of care and the patient experience. This work highlights the need of furthers investigations and the necessity to develop specific tools with normative data.

Introduction

Epilepsy is one of the most common chronic neurological disorders. According to International League Against Epilepsy's (ILAE) definition, "epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiological, cognitive, psychological, and social consequences of this condition" [START_REF] Fisher | Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE)[END_REF]. Cognitive disorders are frequent at the onset of the disease (up to 70%) [START_REF] Witt | Should cognition be screened in new-onset epilepsies? A study in 247 untreated patients[END_REF] and are a major supplementary factor in occupational, social, and family disability in addition to those caused by seizures. Epilepsy surgery may represent a very successful treatment option for many patients not responding to pharmacological treatment [START_REF] Engel | The current place of epilepsy surgery[END_REF]. The main goal is to stop seizures; however, it is not without cognitive risk [START_REF] Sherman | Neuropsychological outcomes after epilepsy surgery: systematic review and pooled estimates[END_REF].

The role of neuropsychological assessment is crucial in presurgical patients diagnosed with drug-resistant epilepsy. In this context, neuropsychological assessment procedure (NAP) aims to identify epilepsyrelated cognitive impairment and their etiologic attribution to lesions, drug treatment, and mood. The results of NAP contribute to each individual patient's postsurgical deficits risk prediction [START_REF] Chelune | Hippocampal adequacy versus functional reserve: predicting memory functions following temporal lobectomy[END_REF]. Major predictors of neuropsychological outcome include presurgical tests performances, which reflect functional integrity of the resected tissues and cognitive reserve capacities [START_REF] Chelune | Hippocampal adequacy versus functional reserve: predicting memory functions following temporal lobectomy[END_REF][START_REF] Helmstaedter | Prediction of memory reserve capacity[END_REF].

A special report from ILAE Neuropsychology Task Force [START_REF] Wilson | Indications and expectations for neuropsychological assessment in routine epilepsy care: report of the ILAE Neuropsychology Task Force[END_REF] summarizes the role of the neuropsychological assessment and its framework. An inventory of current standard neuropsychological assessment in Europe has been published [START_REF] Vogt | Current standards of neuropsychological assessment in epilepsy surgery centers across Europe[END_REF] showing high variability with 186 different tasks used. Authors argue that neuropsychological tests are not selected according to strong scientifice v i d e n c e( fidelity, sensitivity, parallel form, etc.), but rather based on institutional constraints or personal choices. Currently, no international consensus for NAP has been published in epilepsy surgery. Furthermore, NAP is very dependent on native language and cultural background, which need to be taken into consideration within each country.

The main goal of this work is to define French neuropsychological procedure consensus in regard to neuropsychological systematic literature review.

Methods

In 2016, with the support of the French chapter of the ILAE, all centers dispensing epilepsy surgery in France were consulted about their neuropsychological practice. An online interview was sent to all neuropsychologists including ten questions about the organization of the surgery unit, the duration of systematic neuropsychological assessment and the tests used to assess cognitive functioning [see Appendix A for details]. Fifteen out of the 16 centers responded. Analysis of these results reported a high variability in neuropsychological assessment duration ranging from 1.5 to 6.5 h. Regarding cognitive dimensions, the only consensus found concerned global efficiency with Wechsler intelligence scales [START_REF] Wechsler | Wechsler Adult Intelligence Scale-IV (WAIS-IV)[END_REF], highlighting the heterogeneity and disparity in neuropsychological practices, as reported in the European survey [START_REF] Vogt | Current standards of neuropsychological assessment in epilepsy surgery centers across Europe[END_REF].

Thereafter, a task force of experts in neuropsychology was created within the French Chapter of the ILAE. Every neuropsychologist meets at least 25 patients per year for more than two years as defined by Rosenow et al. [START_REF] Rosenow | Revised version of quality guidelines for presurgical epilepsy evaluation and surgical epilepsy therapy issued by the Austrian, German, and Swiss working group on presurgical epilepsy diagnosis and operative epilepsy treatment[END_REF]. A systematic literature review from 1950 to 2017 listed in PubMed database was conducted by a panel of experts using a combination of MeSH search terms. Keywords used were related to epilepsy and cognition (see Appendix B for details). For all citations, raters conducted an abstract review and excluded studies according the following criteria: 1) absence of cognitive data, 2) sample size inferior to 20 patients, 3) nonsurgical population, 4) patients with others etiologies, 5) patients with palliative treatment, 6) studies dealing with stimulations (EEG [electroencephalogram], Stereo electroencephalogram (SEEG), cognitive rehabilitation), and 7) animal's studies. All remaining citations then underwent a full text review using a clinical, neuropsychological, and methodological reading grid designed for this work. In details, for each study, demographic, clinical, and neuropsychological data, information on study design, and setting were extracted (see Appendix C). In addition, data characterizing neuropsychological assessment utilized in each study were categorized into cognitive groups based on the domains they are known or assumed to measure (IQ; speed processing; executive functions; memory; language; visual processing/spatial/constructive abilities; social cognition; and psychobehavioral data). Finally, each article was assigned a 4 point class scale depending on the strength of its methodological quality adapting the criteria used by the French Health Department (Haute Autorité de Santé). Class 1 included high statistical power randomized controlled trials and decision analysis based on well-conducted studies. Class 2 included low statistical power randomized controlled trials, well-conducted nonrandomized controlled studies and cohort studies. Class 3 included case-control studies. Class 4 included comparative studies with significant biases, retrospective studies, and case series. According to this classification, Class 1 corresponds to established scientific evidence, Class 2 corresponds to scientificp r e s u m p t i o n ,a n d Classes 3 and 4 correspond to a low level of evidence.

Results

Analysis of the literature review

Of the 1920 originally identified abstracts extracted from PubMed database, 613 met the initial inclusion criteria. Further selection based on full text resulted in a final selection of 332 articles (see Fig. 1). Systematic literature review demonstrated a low evidence for neuropsychological purposes in these scientific reports with 0.9% of Class 1 studies, 8.1% of Class 2 studies and more than 90% of Classes 3 and 4 studies. Classes 3 and 4 studies were justified by retrospective design, missing data, absence of longitudinal design, absence of control group, and low statistical properties. No French studies are reported in Classes 1 and 2. Only 11 (3,3%) studies are reported with French language (nine conducted in France, one in Swiss, one in Canada).

Thus, as literature review reports very small number studies with high statistical power, and only 11 French studies are reported with low statistical power. Expert agreement has been voted. A panel of experts defined neuropsychological consensus procedure for French patients according to psychometric determinants of cognitive tests, specificity of epilepsy, surgery context, French culture, and literature reports. More specifically, objectives and framework for NAP and test selection were defined. Experts voted for each cognitive domain assessment based on their clinical experience and the strength of supporting evidence. Each task or procedure was defined with more than 90% of approval.

Neuropsychological consensus procedure based on the opinion of the expert panel

Objectives of NAP

There are numerous reasons for conducting a neuropsychological assessment for patients with epilepsy including documenting the cognitive profile, learning about the patient's strengths and weaknesses, assessing cognitive behavior related to antiepileptic treatment, measuring cognitive changes over time, and suggesting adequate cognitive and behavioral counseling and therapy [START_REF] Wilson | Indications and expectations for neuropsychological assessment in routine epilepsy care: report of the ILAE Neuropsychology Task Force[END_REF][START_REF] Samson | L'évaluation neuropsychologique dans la chirurgie de l'épilepsie[END_REF][START_REF] Brissart | Evolution des fonctions cognitives après chirurgie du lobe temporal[END_REF].

In the case of surgery as a treatment for drug-resistant epilepsy, a neuropsychological evaluation is crucial to: 1) describe the neuropsychological profile and establish baseline before surgery; 2) contribute to lateralizing and localizing cognitive dysfunction in relation to the epileptic syndrome (e.g., focus, seizure frequency, antiepileptic drugs (AEDs), age at onset, disease duration); 3) estimate cognitive outcome relative to functional adequacy model and mental reserve capacities [START_REF] Chelune | Hippocampal adequacy versus functional reserve: predicting memory functions following temporal lobectomy[END_REF][START_REF] Helmstaedter | Prediction of memory reserve capacity[END_REF]: determine risks and benefits in regard to surgery; 4) take into consideration psychological status in the final surgery decision; 5) estimate the need for neuropsychological rehabilitation and/or psychosocial and/or behavioral therapies pre-and postoperatively; 6) assess cognitive outcome following surgery.

Neuropsychological assessment procedure

This consensus follows ethical and clinical considerations [START_REF] Thomas-Antérion | Neuropsychologie en pratique (s)[END_REF]. French neuropsychological procedure includes:

1) an exhaustive report on demographical, socioeducational variables, personal and cultural background, patient's complaints and expectations, handedness, epileptic variables (age at onset, focus, seizure frequency, disease duration) and comorbidities, medication, fatigue and sleep, psychoactive substance use, past or ongoing assessments, treatments and therapies; 2) a psychological and behavioral interview and questionnaires (see Table 1);

3) a comprehensive neuropsychological testing using required and optional tools (see Table 1); 4) a restitution of test results.

In France, assessment must be conducted by a clinical neuropsychologist. In the surgical context, NAP should be performed in optimal conditions: usual AEDs, far from last seizure, without sleep deprivation, in a quiet office. The minimal estimated duration required to complete the tests is approximately 5 h, distributed into two sessions with breaks. It is important to take into consideration additional time (3 h) for interpretation, restitution to the patient and medical team, and report redaction. Preoperative NAP should be performed within the year preceding Judgment Orientation Lines (JOL) 23 Parallel form : no Visual Field test (Test of Attentional Performance) 9 Parallel form : no

Perceptual reasoning

Perceptual Reasoning Scale WAIS-IV 1 Parallel form : no -

PSYCHOBEHAVIORAL AND SOCIAL COGNITION Depression

Beck Depression Inventory (BDI) 24 Mini International Neuropsychiatric Interview (MINI) 25

Anxiety

The State-Trait Anxiety Inventory (STAI) 26 -

Apathy

Apathy Evaluation Scale (AES) 27 The Lille Apathy Rating Scale (LARS) 28

Social cognition R N Emotional recognition (NR)

and / or Faux pas 29 and / or False belief task 30, 31

QUALITY OF LIFE

Quality of life

Quality of Life in Epilepsy Inventory -31 32 Quality of Life in Epilepsy Inventory -89 33 RESTITUTION 5'

Tests references (1 to 33) are provided in Appendix D in Supplementary data. surgery. Postoperative NAP should be performed between six and twelve months following surgery, and repeated at two and five years after [START_REF] Helmstaedter | Cognitive outcomes more than 5 years after temporal lobe epilepsy surgery: remarkable functional recovery when seizures are controlled[END_REF]. A systematic exploration of several cognitive domains, according to ILAE [START_REF] Wilson | Indications and expectations for neuropsychological assessment in routine epilepsy care: report of the ILAE Neuropsychology Task Force[END_REF], is recommended: intellectual efficiency, long-term memory, short-term and working memory, attention, executive functions, processing speed and motor skills, language, visual processing, praxis, psychobehavior, and social cognition. Table 1 summarizes required and optional neuropsychological tests for French patients. Approximate duration of required test is 8 h, including anamnesis and restitution.

Discussion

A French Chapter of the ILAE of experts in the neuropsychology of epilepsy discuss and define a common procedure for assessing cognitive and psychobehavioral function in surgical French patients in regard to systematic literature review.

Low scientific evidence of neuropsychological data was reported in this literature review. Indeed, in epilepsy surgery, a lack of randomized control trials and prospective studies with large samples of participants is reported, especially regarding neuropsychological assessment [START_REF] Vogt | Current standards of neuropsychological assessment in epilepsy surgery centers across Europe[END_REF].Furthermore, there is a high variability in neuropsychological tools, and few of them were not validated in French language with robust psychometric qualities, parallel forms, recent, and appropriate normative data.

In epilepsy surgery, NAP is part of a multidisciplinary approach in connection with other examinations such as clinical semiology, magnetic resonance imaging (MRI), functional MRI, positron-emission tomography (PET)-scan, and EEG recordings. Neuropsychological profile contributes to the location of the epileptogenic focus in focal epilepsy, as cognitive and/or behavioral impairment can provide evidence of lateralization and location of the epileptogenic network.

With consensus, a panel of experts recommends a systematic exploration of the following dimensions, as reported by ILAE [START_REF] Wilson | Indications and expectations for neuropsychological assessment in routine epilepsy care: report of the ILAE Neuropsychology Task Force[END_REF]: intellectual efficiency, long-term memory, short-term and working memory, attention, executive functions, processing speed and motor skills, language, visual processing, praxis, psychobehavior, and social cognition. Test selection has been established according to psychometric determinants, specificity of epilepsy, surgical context, French culture, and literature reports.

Concerning intellectual efficiency, a consensus was obtained for the use of Wechsler Adult Intelligence Scale fourth edition [START_REF] Wechsler | Wechsler Adult Intelligence Scale-IV (WAIS-IV)[END_REF] in the epileptic population. This scale is used to detect specific developmental learning deficits, and/or disharmony in competencies. Four indices can be computed: the verbal comprehension index (VCI), the perceptual reasoning index (PRI), the processing speed index (PSI), and the working memory index (WMI). The full-scale intelligence quotient (FSIQ) is calculated only if indices are homogenous. Full-scale intelligence quotient may significantly underestimate levels of general intellectual ability in people with epilepsy. Inaccurate representations of FSIQ due to selective impairment in working memory and reduced processing speed obscure the contextual interpretation of performance on other neuropsychological tests, and subtle localizing and lateralizing signs may be missed as a result. With this fourth edition, a general ability index (GAI) that lowers the impact of processing speed and working memory, can be calculated. Moreover, GAI-FSIQ discrepancies are correlated with the number of AEDs, age at onset, and duration of epilepsy [START_REF] Baxendale | Epilepsy & IQ: the clinical utility of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) indices in the neuropsychological assessment of people with epilepsy[END_REF].InNAP,theGAI-FSIQ provides an intellectual profile and a frame for the choice and interpretation of all cognitive tests.

Memory impairment is frequently reported before and after epilepsy surgery in particular in temporal lobectomy [START_REF] Sherman | Neuropsychological outcomes after epilepsy surgery: systematic review and pooled estimates[END_REF][START_REF] Helmstaedter | 15 years epilepsy surgery in Bonn: cognitive and seizure outcome[END_REF][START_REF] Helmstaedter | Neuropsychological outcomes of different surgical approaches in temporal lobe epilepsy[END_REF]. Episodic memory must therefore be explored using a rigorous examination. We recommend testing both verbal and nonverbal modalities. Using more than one task in each modality will provide information on encoding, learning, remembering, and forgetting processes as well as memorization of structured, unstructured, associative, abstract, or concrete material. Suggested French tools include immediate and delayed recalls, however, maximum delay available is 35 min. In this context, accelerated forgetting (delay more than 4 h) frequently observed in temporal lobe epilepsy [START_REF] Blake | Accelerated forgetting in patients with epilepsy: evidence for an impairment in memory consolidation[END_REF][START_REF] Tramoni | Long-term consolidation of declarative memory: insight from temporal lobe epilepsy[END_REF] cannot be explored. Currently, many research studies focus on this important phenomenon [START_REF] Manoli | Extension to one week of verbal memory consolidation assessment[END_REF][START_REF] Lemesle | Accelerated long-term forgetting and au-452 tobiographical memory disorders in temporal lobe epilepsy: one entity or two?[END_REF], and French normative data is expected in the future with 4 h, 24 h, and a one-week delays.

Concerning short-term and working memory, spans are widely recognized as a useful assessment task in verbal and nonverbal modalities. Regarding working memory, required tests explore mental load, and optional tests are provided to assess updating.

Assessing attentional processes in epilepsy is required by ILAE [START_REF] Wilson | Indications and expectations for neuropsychological assessment in routine epilepsy care: report of the ILAE Neuropsychology Task Force[END_REF]. Attention is divided into several dimensions: alertness, selective attention, divided attention and sustained attention [START_REF] Cohen | The neuropsychology of attention[END_REF]. Some AEDs may have a direct positive effect on cognitive performance by improving alertness and cognitive abilities in epilepsy [START_REF] Helmstaedter | Differential effects of temporal pole resection with amygdalohippocampectomy versus selective amygdalohippocampectomy on material-specific memory in patients with mesial temporal lobe epilepsy[END_REF]. Negative effects of AEDs on attention could depend on used posology and could therefore be improved by pre and posttreatment introduction. Improvement of attention was described after surgery [START_REF] Helmstaedter | Differential effects of temporal pole resection with amygdalohippocampectomy versus selective amygdalohippocampectomy on material-specific memory in patients with mesial temporal lobe epilepsy[END_REF] and interpreted as the result of a general cognitive improvement [START_REF] Helmstaedter | Chronic epilepsy and cognition: a longitudinal study in temporal lobe epilepsy[END_REF]. Therefore, we recommend assessing three attentional processes among those described.

Impairment in executive functions is observed in epilepsy regardless of the location of epileptogenic zone [START_REF] Helmstaedter | Neuropsychological consequences of epilepsy surgery in frontal lobe epilepsy[END_REF][START_REF] Witt | Adverse cognitive effects of antiepileptic pharmacotherapy: each additional drug matters[END_REF] and postoperative improvement can be reported [START_REF] Sherman | Neuropsychological outcomes after epilepsy surgery: systematic review and pooled estimates[END_REF]. Executive functions as defined by GREFEX group (French executive functions task force providing French normative data) [START_REF] Roussel | La batterie GREFEX: données normatives[END_REF] include shifting, inhibition, verbal initiation, deduction, planning, and memory retrieval. A large assessment is therefore recommended with at least three functions.

Language is characterized by a complex brain network, depending mainly on dominant hemisphere functions, which can vary significantly between individuals. In epilepsy, there is a higher percentage of atypical language representations [START_REF] Möddel | Atypical language lateralization in epilepsy patients[END_REF]. Furthermore, language functions can be affected by epilepsy, and their assessment is crucial before surgery [START_REF] Hermann | The effects of localization-related epilepsy on language lateralization and networks[END_REF]. Language has a localizing, lateralizing, and even physiopathological value, to maximize surgical success [START_REF] Drane | Interictal epileptiform discharge effects on neuropsychological assessment and epilepsy surgical planning[END_REF][START_REF] Drane | Knowledge of language function and underlying neural networks gained from focal seizures and epilepsy surgery[END_REF]. The most frequently observed deficit is naming deficit [START_REF] Bartha-Doering | The interictal language profile in adult epilepsy[END_REF]. Language disorders are more frequently observed in left temporal lobe epilepsy (TLE), but a significant proportion of patients with right TLE shows deficits too [START_REF] Bartha-Doering | The interictal language profile in adult epilepsy[END_REF]. Language assessment should include receptive and productive verbal tasks, as well as oral and written modalities. A comprehensive language assessment by a speech-therapist is also useful for documentation. As appropriate, functional MRI with specific language paradigms could be added.

Concerning visual processing, a perceptual reasoning index is assessed in WAIS-IV. Optional visuoperceptual and visuospatial tests (visual field, orientation judgment, gnosis, face processing) may be added, especially in posterior epilepsy [START_REF] Drane | Famous face identification in temporal lobe epilepsy: support for a multimodal integration model of semantic memory[END_REF].

Finally, NAP must include psychobehavioral dimension, because increased rates of psychiatric disturbances are observed in patients with epilepsy, with respect to the general population [START_REF] Josephson | Psychiatric comorbidities in epilepsy[END_REF]. In surgery, a specific assessment is necessary to interpret the overall clinical profile. Depression, apathy, anxiety, and quality of life should be explored using scales and interviews with a psychiatrist and/or psychologist. A high prevalence of depression [START_REF] Josephson | Psychiatric comorbidities in epilepsy[END_REF] or more generally emotional dysregulation [START_REF] Blumer | The interictal dysphoric disorder: recognition, pathogenesis, and treatment of the major psychiatric disorder of epilepsy[END_REF] has been reported, which can interfere with postoperative outcome. Confounding factors, such as sleep disturbances, fatigue, AEDs effects, need to be considered. Similarly, the impact of social cognition impairment on the psychosocial functioning and quality of life of patients is often suspected but remains to be clarified. Some research studies point to the presence of social cognition disorders in patients with epilepsy [START_REF] Bora | Social cognition in temporal lobe epilepsy: a systematic review and meta-analysis[END_REF][START_REF] Edwards | Facial emotion perception in patients with epilepsy: a systematic review with meta-analysis[END_REF][START_REF] Giovagnoli | Expanding the spectrum of cognitive outcomes after temporal lobe epilepsy surgery: a prospective study of theory of mind[END_REF]. In clinical practice, social cognition abilities remain insufficiently explored in patients with epilepsy, and no consensual assessment of social cognition skills is defined. Further investigations appear necessary to determine the characteristics, the prevalence, as well as the impact of epilepsy surgery. In this context, an assessment of social cognition abilities is encouraged, including emotional processing and theory of mind.

Neuropsychological assessment is essential and systematically required in epilepsy surgery [START_REF] Baxendale | Neuropsychological assessment in epilepsy[END_REF][START_REF] Jones-Gotman | The contribution of neuropsychology to diagnostic assessment in epilepsy[END_REF]. The main goal of NAP is to estimate cognitive outcome relative to the functional adequacy model and mental reserve capacities, and to determine risks and benefits in regard to surgery. With this in mind, the first French neuropsychological procedure consensus has been established and includes a comprehensive procedure with structured longitudinal steps. Pre-and postoperative assessments are systematically required to anticipate neuropsychological outcome following surgery. Preoperative evaluation delay is within one year before surgery, and postoperative is from 6 months to 1 year, 2 years and 5 years of follow-up, because several longitudinal studies show cognitive improvement in the long term, depending on seizure's control [START_REF] Helmstaedter | Cognitive outcomes more than 5 years after temporal lobe epilepsy surgery: remarkable functional recovery when seizures are controlled[END_REF][START_REF] Giovagnoli | The course of language functions after temporal lobe epilepsy surgery: a prospective study[END_REF]. NAP requires trained professionals, appropriate and recent psychometric tools, and time constraints (6 to 8 h for each NAP) in order to fully document the overall profile and improve patient care in epilepsy units.

These French neuropsychological procedures reflect a current consensus, in relation to the availability of French tests, and they may of course be perfectible in the future. The psychometric qualities (sensitivity and specificity) of these tests are not all perfect, and some tests have not been validated for patients with epilepsy especially, that's why neuropsychological researches should therefore be encouraged and financially supported to develop appropriate tests for patients with epilepsy, specific to each country, in particular regarding long-term memory and social cognition. This work highlights a significant willing to improve neuropsychological evaluation of French patients with epilepsy who are candidates to surgery.

Conclusion

A common procedure for assessing cognitive and psychobehavioral function for patients with epilepsy undergoing surgical evaluation is now available and has been established, which may help to improve the quality of care and the patient experience. This work highlights the need of further investigations and the necessity to develop specific tools with normative data.

Ethical publication statement

We confirm that we have read the journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Fig. 1 .

 1 Fig. 1. Flowchart of the study.

Table 1

 1 French neuropsychological procedure consensus.

	COGNITIVE DIMENSIONS	REQUIRED TESTS	OPTIONAL TESTS
		ANAMNESIS
	INTELLECTUAL EFFICIENCY
	Intellectual efficiency	Wechsler Adult Intelligence Test-Fourth edition (WAIS-IV) 1	-
		Parallel form : no
	LONG TERM MEMORY
		High socio-educational level
		Selective Reminding Test 2
		Parallel form : yes (2)
		Low socio-educational level
	Verbal memory	16-item Free and Cued Recall 3

Mahieux-Laurent et al., 2009 -17 Colombo & Assal, 1992 // Roussel & Godefroy, 2016 -18 Tran & Godefroy, 2011 -19 Bézy et al., 2016 -20 De Renzi & Faglioni, 1978 -21 Warrington & James, 1991 -22 Agniel et al., 1993 -23 Benton et al., 1983 -24 Beck, 1998 -25 Lecrubier et al., 1998 -26 Gauthier & Bouchard, 1993 -27 Marin et al., 1991 -28 Sockeel et al., 2006 -29 Delbeuck et al., 2010 -30 Desgranges et al., 2012-31 Biervoye et al., 2018 -32 Picot et al., 2004 -33 Cramer et al., 1998 -NR: no recommendation.

Acknowledgments

The authors would like to thank French League Against Epilepsy -Ligue Française Contre l'Epilepsie (LFCE) for its financial support which allowed the establishment of the Neuropsychology Task force.

Declaration of competing interest

NF reports personal fees from UCB Pharma. The remaining authors have no financial disclosures to make.

Appendix A. Supplementary data

Supplementary data (Appendix A to D) to this article can be found online at https://doi.org/10.1016/j.yebeh.2019.106522.