Teng-Shuo Zhang

Zi-Wen Li

Qiu Fang

Mario Barbatti
email: mario.barbatti@univ-amu.fr

Wei-Hai Fang

Ganglong Cui
email: ganglong.cui@bnu.edu.cn

Stereoselective Excited-State Isomerization and Decay Paths in cis-Cyclobiazobenzene

Herein we have employed OM2/MRCI-based full-dimensional nonadiabatic dynamics simulations to explore the photoisomerization and subsequent excited-state decay of a macrocyclic cyclobiazobenzene (CBA) molecule. Two S1/S0 conical intersection structures are found to be responsible for the excited-state decay. Related to these two conical intersections, we found two stereoselective photoisomerization and excited-state decay pathways, which correspond to the clockwise and counterclockwise rotation motions with respect to the N=N bond of the azo group.

In both pathways the excited-state isomerization is ultrafast and finishes within ca. 69 fs; but, the clockwise isomerization channel is much more favorable than the counterclockwise one with a ratio of 74% vs. 26%. Importantly, the present work demonstrates that stereoselective pathways exist not only in the photoisomerization of isolated azobenzene-like systems but also in macrocyclic systems with multiple azobenzenes (ABs). This finding could provide useful insights for understanding and controlling the photodynamics of macrocyclic nanostructures with AB units as the main building units.

INTRODUCTION

Azobenzene (AB), as one of the most studied photoswitchable compounds, has various potential applications ranging from photopharmacology via optochemical genetics to data storage because it is easily synthesized experimentally and highly stable, and presents high extinction coefficients and isomerization quantum yields. [START_REF] Beharry | Azobenzene Photoswitches for Biomolecules[END_REF][START_REF] Bandara | Photoisomerization in Different Classes of Azobenzene[END_REF][START_REF] Szymański | Reversible Photocontrol of Biological Systems by the Incorporation of Molecular Photoswitches[END_REF][START_REF] Velema | Photopharmacology: Beyond Proof of Principle[END_REF] Owing to its importance, in the past decade, many AB derivatives have been synthesized and applied in optical switches, reversible nanostructures, molecular machines, etc. [START_REF] Yurke | A DNA-Fuelled Molecular Machine Made of DNA[END_REF][START_REF] Norikane | Light-Driven Molecular Hinge: A New Molecular Machine Showing a Light-Intensity-Dependent Photoresponse That Utilizes the trans-cis Isomerization of Azobenzene[END_REF][START_REF] Henzl | Amino-Nitro-Azobenzene Dimers as a Prototype for a Molecular-Level Machine[END_REF][START_REF] Russew | Photoswitches: From Molecules to Materials[END_REF][START_REF] Bisoyi | Light-Directing Chiral Liquid Crystal Nanostructures: From 1D to 3D[END_REF][START_REF] Dong | Red-Shifting Azobenzene Photoswitches for in Vivo Use[END_REF][START_REF] Kuzyk | A Light-Driven Three-Dimensional Plasmonic Nanosystem That Translates Molecular Motion into Reversible Chiroptical Function[END_REF][START_REF] Iwaso | Fast Response Dry-Type Artificial Molecular Muscles with [c2] Daisy Chains[END_REF][START_REF] Weis | Light-Switchable Azobenzene-Containing Macromolecules: From UV to Near Infrared[END_REF][START_REF] Zhao | Near-Infrared Triggered Decomposition of Nanocapsules with High Tumor Accumulation and Stimuli Responsive Fast Elimination[END_REF] To get in-depth atomistic insights, computational studies have also been carried out, in companying with experimental studies, to explore photoinduced isomerization reactions and related dynamics of AB and its variants in the gas phase, in various solutions, and linked to peptides and nucleic acids. Nevertheless, most of previous experimental and computational studies are mainly focused on isolated AB and linearly linked ABs in complex surroundings. [START_REF] Dokic | Quantum Chemical Investigation of Thermal Cis-to-Trans Isomerization of Azobenzene Derivatives: Substituent Effects, Solvent Effects, and Comparison to Experimental Data[END_REF][START_REF] Bléger | Electronic Decoupling Approach to Quantitative Photoswitching in Linear Multiazobenzene Architectures[END_REF][START_REF] Floß | The Photoinduced E→Z Isomerization of Bisazobenzenes: A Surface Hopping Molecular Dynamics Study[END_REF][START_REF] Slavov | Connectivity Matters-Ultrafast Isomerization Dynamics of Bisazobenzene Photoswitches[END_REF] In recent years, photoswitchable macrocyclic systems with multiple ABs have been explored experimentally because of their potential applications in supramolecular chemistry, molecular machines, etc. [START_REF] Norikane | Light-Driven Molecular Hinge: A New Molecular Machine Showing a Light-Intensity-Dependent Photoresponse That Utilizes the trans-cis Isomerization of Azobenzene[END_REF][START_REF] Shen | Submolecular Observation of Photosensitive Macrocycles and Their Isomerization Effects on Host-Guest Network[END_REF][START_REF] Norikane | Photoinduced Isothermal Phase Transitions of Liquid-Crystalline Macrocyclic Azobenzenes[END_REF][START_REF] Reuter | Switchable 3D Networks by Light Controlled π-Stacking of Azobenzene Macrocycles[END_REF][START_REF] Wagner-Wysiecka | Azo Group(s) in Selected Macrocyclic Compounds[END_REF] These AB units are usually linked by chemical bonds, which thus leads to remarkable steric interaction and ring strain. Very recently, Slavov et al. have employed timeresolved absorption spectroscopy to explore the excited-state dynamics of a macrocyclic biazobenzene molecule (CBA) as shown in Figure 1. [START_REF] Slavov | Twist and Return-Induced Ring Strain Triggers Quick Relaxation of a (Z)-Stabilized Cyclobisazobenzene[END_REF] They found that upon continuous excitation on the most stable (Z,Z) isomer of CBA, it does not generate either (Z,E) or (E,E) isomers. This is ascribed to a very fast thermal back-isomerization of the (Z,E) isomer induced by large ring strain that is caused by the ultrafast excited-state photoisomerization process. This fast back reaction prevents the accumulation of both (Z,E) and (E,E) isomers. They have found that the individual AB unit still undergoes an ultrafast cis-trans photoisomerization in spite of the existence of strong steric hindrance. This interaction also breaks the molecular symmetry and finally gives rise to an enhanced adsorption intensity for the weak 1 nπ* singlet state. The experiments also indicate that both [START_REF] Beharry | Azobenzene Photoswitches for Biomolecules[END_REF] nπ* and 1 ππ* singlet states of the (Z,Z) isomer of CBA have similar kinetics, and the main photoisomerization is completed within about 200 fs, followed by a ground-state cooling process.

Although TD-DFT calculations have qualitatively rationalized some experimental phenomena, the photoisomerization and excited-state decay dynamics of this CBA molecule is far from a complete understanding, and it has not been explored by full-dimensional nonadiabatic dynamics simulations until now. In this work, we fill this knowledge gap and aim at exploring the CBA photoisomerization dynamics starting from its (Z,Z) conformer upon excitation to its weak 1 nπ* singlet state. Based on our "on-the-fly" dynamic simulations, we have identified the excited-state photoisomerization and excited-state decay mechanism. Moreover, our results reveal, for the first time, two stereoselective excited-state decay pathways in this macrocyclic CBA system.

COMPUTATIONAL DETAILS

Ground-state conformers of CBA are first optimized using the density functional theory (DFT) method1 with the globally hybrid B3LYP exchange-correlation functional. [START_REF] Parr | Density-Functional Theory of Atoms and Molecules[END_REF][START_REF] Vosko | Accurate Spin-Dependent Electron Liquid Correlation Energies for Local Spin Density Calculations: A Critical Analysis[END_REF][START_REF] Lee | Development of the Colle-Salvetti Correlation-Energy Formula into a Functional of the Electron Density[END_REF][START_REF] Becke | Density-Functional Exchange-Energy Approximation with Correct Asymptotic Behavior[END_REF][START_REF] Becke | A New Mixing of Hartree-Fock and Local Density-Functional Theories[END_REF] The 6-31G* basis set is employed for all DFT computations, [START_REF] Ditchfield | Self-Consistent Molecular-Orbital Methods. IX. An Extended Gaussian-Type Basis for Molecular-Orbital Studies of Organic Molecules[END_REF][START_REF] Francl | Self-Consistent Molecular Orbital Methods. XXIII. A Polarization-Type Basis Set for Second-Row Elements[END_REF] which are carried out using GAUSSIAN09. [START_REF] Parr | Density-Functional Theory of Atoms and Molecules[END_REF][START_REF] Frisch | Revision A.02[END_REF][START_REF] Marques | Timedependent Density Functional Theory[END_REF] Minima, conical intersections, and minimum-energy potential energy profiles in the S0 and S1 singlet states are optimized using the OM2/MRCI method, which has been extensively demonstrated to be very accurate for the description of the excited states of azobenzene and its variants. [START_REF] Weingart | Chiral Pathways and Periodic Decay in cis-Azobenzene Photodynamics[END_REF][START_REF] Gámez | Cooperating Dinitrogen and Phenyl Rotations in trans-Azobenzene Photoisomerization[END_REF][START_REF] Xia | How Photoisomerization Drives Peptide Folding and Unfolding: Insights from QM/MM and MM Dynamics Simulations[END_REF][START_REF] Gámez | Periodic Decay in the Photoisomerisation of p-Aminoazobenzene[END_REF][START_REF] Gámez | Enhanced E→Z Photoisomerisation in 2-Aminoazobenzene[END_REF][START_REF] Wu | MM Studies on Photoisomerization Dynamics of Azobenzene Chromophore Tethered to a DNA Duplex: Local Unpaired Nucleobase Plays a Crucial Role[END_REF] All semi-empirical calculations were performed using the MNDO99 code. [65][START_REF] Weber | Orthogonalization Corrections for Semiempirical Methods[END_REF][START_REF] Koslowski | Implementation of a General Multireference Configuration Interaction Procedure with Analytic Gradients in a Semiempirical Context Using the Graphical Unitary Group Approach[END_REF][START_REF] Thiel | MNDO99 program, version 6.1[END_REF] During geometry optimizations and dynamics simulations, all required energies, gradients, and nonadiabatic coupling elements were computed analytically. Minimum-energy conical intersections were optimized using the Lagrange-Newton approach. [START_REF] Yarkony | Nuclear Dynamics near Conical Intersections in the Adiabatic Representation: I. The Effects of Local Topography on Interstate Transitions[END_REF][START_REF] Keal | Comparison of Algorithms for Conical Intersection Optimisation Using Semiempirical Methods[END_REF] In the OM2/MRCI calculations, the restricted open-shell HF formalism is applied in the self-consistent field (SCF) treatment. The active space in the MRCI calculations includes 8 electrons in 6 orbitals (see Figure S1). In terms of the SCF configuration, it comprises the 4 highest doubly-occupied orbitals and the 2 lowest unoccupied orbitals. For the MRCI treatment, three configuration state functions are chosen as references, namely the SCF configuration and the two closed-shell configurations derived therefrom (i.e., all singlet configurations that can be generated from HOMO and LUMO of the closed-shell ground state). The MRCI wavefunction is built by allowing all single and double excitations from these three references.

The S1 nonadiabatic dynamics simulations are studied by performing 300 fs OM2/MRCI trajectory surface-hopping simulations. [START_REF] Tully | Trajectory Surface Hopping Approach to Nonadiabatic Molecular Collisions: Reaction of H with D2[END_REF][START_REF] Hammes-Schiffer | Proton Transfer in Solution: Molecular Dynamics with Quantum Transitions[END_REF][START_REF] Fabiano | Implementation of Surface Hopping Molecular Dynamics Using Semiempirical Methods[END_REF][START_REF] Virshup | Photodynamics in Complex Environments: ab initio Multiple Spawning Quantum Mechanical/Molecular Mechanical Dynamics[END_REF][START_REF] Tao | Ab Initio Multiple Spawning Dynamics Using Multi-State Second-Order Perturbation Theory[END_REF][START_REF] Barbatti | Relaxation mechanisms of UV-photoexcited DNA and RNA nucleobases[END_REF][START_REF] Nachtigallová | Does Stacking Restrain the Photodynamics of Individual Nucleobases?[END_REF][START_REF] Cui | Conical Intersection Is Responsible for the Fluorescence Disappearance Below 365 nm in Cyclopropanone[END_REF][START_REF] Cui | Ab Initio Based Surface-Hopping Dynamics Study on Ultrafast Internal Conversion in Cyclopropanone[END_REF][START_REF] Cui | Ab Initio Trajectory Surface-Hopping Study on Ultrafast Deactivation Process of Thiophene[END_REF][START_REF] Richter | Femtosecond Intersystem Crossing in the DNA Nucleobase Cytosine[END_REF][START_REF] Martínez-Fernández | Competing Ultrafast Intersystem Crossing and Internal Conversion: A Time Resolved Picture for the Deactivation of 6-Thioguanine[END_REF][START_REF] Cui | Generalized Trajectory Surface-Hopping Method for Internal Conversion and Intersystem Crossing[END_REF] The initial atomic coordinates and velocities for the S1 photodynamics simulations are randomly selected from a 10 ps canonical molecular dynamics trajectory in the ground state. The numbers of excited-state dynamics runs are then chosen according to the computed S0-S1 transition probabilities. A total of 425 surface-hopping trajectories are run for the S1 photodynamics, with all relevant energies, gradients, and nonadiabatic coupling vectors being computed on-the-fly as needed. For points with an energy gap of less than 10 kcal/mol, the fewest-switches criterion is applied to decide whether to hop. The time step is chosen to be 0.1 fs for the nuclear motion and 0.0005 fs for the electronic propagation.

The unitary propagator evaluated at mid-point is used to propagate the electronic motion. The translational and rotational motions are removed in each step. The empirical decoherence correction (0.1 au) by Granucci et al. is employed. [START_REF] Granucci | Including Quantum Decoherence in Surface Hopping[END_REF] The final evaluations are done for 417 trajectories that finish successfully in the photodynamics and that satisfies our energy continuity criterion and total energy conservation criterion (absolute energy difference less than 2 kcal/mol in 99.794% of time steps; see Figure S2-S4). The adapted time step by Thiel et al. will be used to treat the energy continuity issue in the future. [START_REF] Thiel | Adaptive Time Steps in Trajectory Surface Hopping Simulations[END_REF] Further technical details are given in previous publications. [START_REF] Cui | Intramolecular Hydrogen Bonding Plays a Crucial Role in the Photophysics and Photochemistry of the GFP Chromophore[END_REF][START_REF] Cui | Nonadiabatic Dynamics of a Truncated Indigo Model[END_REF][START_REF] Kazaryan | Surface Hopping Excited-State Dynamics Study of the Photoisomerization of a Light-Driven Fluorene Molecular Rotary Motor[END_REF][START_REF] Schönborn | Photochemical dynamics of E-iPrfurylfulgide[END_REF][START_REF] Cui | Photoinduced Ultrafast Wolff Rearrangement: A Non-Adiabatic Dynamics Perspective[END_REF][START_REF] Spöerkel | Photodynamics of Schiff Base Salicylideneaniline: Trajectory Surface-Hopping Simulations[END_REF][START_REF] Spöerkel | Nonequilibrium H/D Isotope Effects from Trajectory-Based Nonadiabatic Dynamics[END_REF][START_REF] Schönborn | Photochemical Dynamics of E-methylfurylfulgide-Kinematic Effects on Photorelaxation Dynamics of Furylfulgides[END_REF][START_REF] Shemesh | Photochemistry of Aldehyde Clusters: Cross-Molecular versus Unimolecular Reaction Dynamics[END_REF][START_REF] Xia | Excited-State Intramolecular Proton Transfer to Carbon Atoms: Nonadiabatic Surface-Hopping Dynamics Simulations[END_REF]

RESULTS AND DISCUSSION

In the S0 state, there are three main stable structures with respect to the trans and cis conformations of the two azo groups, which are referred to as S0-ZZ, S0-ZE, and S0-EE. Since we are mainly focused on exploring the photoinduced excited-state relaxation dynamics from the most stable S0-ZZ structure, only S0-ZZ and S0-ZE structures are heavily relevant and, therefore, optimized at the OM2/MRCI level, as shown in Figure 2. In S0-ZZ, both N3-N4 and N3'-N4' bond lengths are calculated to be 1.191 and 1.191 Å and the C2N3N4C5 and C2'N3'N4'C5' dihedral angles are 2.6° and 2.6° at the OM2/MRCI level, respectively. In S0-ZE, the bond length of the N3-N4 bond that is still in the cis conformation is estimated to be 1.192 Å; while, that of the N3'-N4' bond, which has already isomerized into the trans conformation, is increased to 1.214 Å.

Remarkably, the C2N3N4C5 and C2'N3'N4'C5' dihedral angles are estimated to be 5.6° and 143.6°, respectively. The strong strain interaction makes these dihedral angles deviate from their typical values, 0° in the cis conformation and 180° in the trans one, observed in AB variants without external strain effects. At the Franck-Condon region, the first excited singlet state is of 1 nπ* character and is mainly composed of the HOMO-LUMO electronic configuration. The vertical excitation energy is 75.0 kcal/mol and the corresponding oscillator strength is 0.10 at the OM2/MRCI level. Compared with that of isolated AB molecule, the oscillator strength of the 1 nπ* singlet state in CBA is comparably enhanced, which is consistent with recent experimental observation. [START_REF] Slavov | Twist and Return-Induced Ring Strain Triggers Quick Relaxation of a (Z)-Stabilized Cyclobisazobenzene[END_REF] Two S1/S0 minimum-energy conical intersections (MECIs) relevant to the cis-trans photoisomerization of the N3'-N4' azo group of CBA are optimized at the OM2/MRCI level and are referred to as S1S0-1 and S1S0-2 in Figure 2. These two MECI structures are all related to the N3'-N4' azo group; however, they have different C2'N3'N4'C5' dihedral angles, which are 90.3° in S1S0-1 and -89.7° in S1S0-2. At the OM2/MRCI level, both of them have similar potential energies, 54.6 and 56.3 kcal/mol. Nevertheless, their dynamical roles in the excited-state relaxation dynamics are different (see below).

To gain insights into time-dependent excited-state properties, e.g., the S1 lifetime, the excitedstate deactivation channels, and the interplay of the competitive excited-state channels, we have performed hundreds of nonadiabatic surface-hopping dynamics runs (417 successful trajectories out 425 ones). Our simulations are carried out at the semi-empirical OM2/MRCI level, which has been demonstrated accurate enough to simulate the topological structures of the S0 and S1 potential energy surfaces of AB variants in many previous studies. [START_REF] Weingart | Chiral Pathways and Periodic Decay in cis-Azobenzene Photodynamics[END_REF][START_REF] Gámez | Cooperating Dinitrogen and Phenyl Rotations in trans-Azobenzene Photoisomerization[END_REF][START_REF] Xia | How Photoisomerization Drives Peptide Folding and Unfolding: Insights from QM/MM and MM Dynamics Simulations[END_REF][START_REF] Gámez | Periodic Decay in the Photoisomerisation of p-Aminoazobenzene[END_REF][START_REF] Gámez | Enhanced E→Z Photoisomerisation in 2-Aminoazobenzene[END_REF][START_REF] Wu | MM Studies on Photoisomerization Dynamics of Azobenzene Chromophore Tethered to a DNA Duplex: Local Unpaired Nucleobase Plays a Crucial Role[END_REF] In our simulations the S1 state is chosen as the initially populated excited singlet state.

The left panel of Figure 3 shows the distribution of the two dihedral angles relevant to the cistrans photoisomerization at all the S1→S0 hopping points as well as at the initial Franck-Condon region. All trajectories start from the S0-ZZ Franck-Condon region, where both C2N3N4C5 and C2'N3'N4'C5' dihedral angles are around 0°. Interestingly, one can see that there are four hopping regions (in red and blue in the left panel of Figure 3). It should be noted that the photoisomerization channel related to the N3N4 azo group is essentially the same as that related to the N3'N4' azo group due to the molecular symmetry, so these four hopping patterns actually correspond to two different hopping channels, which are separately related to the two S1/S0 conical intersection regions, namely S1S0-1 and S1S0-2 discussed above. It is a clockwise motion from S0-ZZ to S1S0-1 because the C2'N3'N4'C5' dihedral angle changes from 8.6° in S0-ZZ to 90.3° to S1S0-1; whereas, it is a counterclockwise from S0-ZZ to S1S0-2 because this dihedral angle changes from 8.6° in S0-ZZ to -89.7° to S1S0-2. It is natural to ask which channel plays a more important role in the excited-state relaxation process. This question is answered by the right panel of Figure 3, from which one can find that the clockwise excited-state deactivation channel via S1S0-1 is more favorable than that via S1S0-2, by 74% vs. 26% in terms of our nonadiabatic dynamics simulations. This ratio is close to that observed in AB molecule but smaller than our recently studied azobenzene-like molecule. [START_REF] Wang | Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited-State Relaxation[END_REF] It should be also noted that the photoinduced unidirectional motion has been observed in many recent works. [START_REF] Garcia-Iriepa | Chiral Hydrogen Bond Environment Providing Unidirectional Rotation in Photoactive Molecular Motors[END_REF][START_REF] Marchand | Directionality of Double-Bond Photoisomerization Dynamics Induced by a Single Stereogenic Center[END_REF][START_REF] Strambi | Anabaena Sensory Rhodopsin Is a Light-Driven Unidirectional Rotor[END_REF][100] To understand why the first channel via S1S0-1 is preferred dynamically, the S1 minimumenergy relaxation paths from S0-ZZ to either S1S0-1 or S1S0-2 are calculated at the OM2/MRCI level. As shown in Figure 4, it is apparent that the path from S0-ZZ to S1S0-2 has a small barrier trends about the preference of the S1→S0 hopping regions observed in our dynamical results. Figure S5 shows the time-dependent state populations of both S1 and S0 states on the basis of the nonadiabatic trajectories. It is clear that in the first 25 fs, there is no excited-state hopping occurring. This period corresponds to the S1 excited-state relaxation from the Franck-Condon to conical intersection regions. After that, the hopping takes place and the S1 state population starts to decrease gradually to zero at the end of 300 fs simulation time. Of course, in the same time, the S0 state population increases accordingly. Through fitting the S1 state population via a simple exponential function of y = exp( -(tt 0 ) / k) in which t0 = 22 fs, the S1 excited-state lifetime i.e. t 0 + k is estimated to be 69 fs, which is close to those of previously studied AB derivatives. [START_REF] Nägele | Femtosecond Photoisomerization of cis-Azobenzene[END_REF][START_REF] Weingart | Chiral Pathways and Periodic Decay in cis-Azobenzene Photodynamics[END_REF][START_REF] Pederzoli | Nonadiabatic Molecular Dynamics Study of the cis-trans Photoisomerization of Azobenzene Excited to the S1 State[END_REF][START_REF] Quick | Photoisomerization Dynamics and Pathways of trans-and cis-Azobenzene in Solution from Broadband Femtosecond Spectroscopies and Calculations[END_REF] The distribution of final products at the end of 300 fs simulation time is shown in Figure S6. It is clear that there are three main product regions: 41% of trajectories stay in the region near S0-ZZ; 43% stop in the region near S0-ZE with the clockwise C2'N3'N4'C5' dihedral angle; and 16% are in the region near S0-ZE with the counterclockwise C2'N3'N4'C5' dihedral angle. This final product yield is consistent with our electronic structure calculations. As discussed above, for S0-ZZ, only one conformer exists as demonstrated in Figure 4; but, for S0-ZE, there are two isoenergetic conformers with the clockwise and counterclockwise dihedral angles. Remembering that the ratio of the S1→S0 hoppings via the clockwise S1/S0 conical intersection S1S0-1 and the counterclockwise S1/S0 conical intersection S1S0-2 is about 74% vs. 26%, one can deduce that 10%

[31%] trajectories that hop to the S0 state via the counterclockwise [clockwise] S1/S0 conical intersection S1S0-2 [S1S0-1] return to the S0-ZZ region; the remaining 43% and 16% trajectories go to the corresponding S0-ZE regions, respectively. Certainly, one should be noted that the above analysis is based merely on the final product distribution of 300 fs nonadiabatic dynamics simulation, which could only provide some qualitative insights.

To illustrate the clockwise and counterclockwise excited-state isomerization channels, we have plotted the time-dependent changes of the C2N3N4C5 and C2'N3'N4'C5' dihedral angles in two representative trajectories in which the cis-trans photoisomerization takes place to produce S0-ZE products, as shown in Figure S7. The left panel shows a trajectory that decays to the S0 state at 53 fs via the clockwise photoisomerization channel, in which the reaction coordinates, i.e., the C2'N3'N4'C5' dihedral angle, increases from ca. 0° at the beginning, via ca. 90° at the hopping time, to ca. 180° at the end; while the C2N3N4C5 dihedral angle just oscillates slightly. On the other hand, in the right panel, the C2'N3'N4'C5' dihedral angle decreases from ca. 0° at the beginning, via ca. -90° at the hopping time, to ca. -180° at the end. Figure S8 shows two the S0-ZZ reactant is repopulated. Figure 5 summarizes the photoinduced isomerization and subsequent excited-state decay channels for the cis CBA molecule. Considering that both AB units in CBA are chemically equivalent, there are two different photoisomerization pathways with respect to the clockwise and counterclockwise rotation of the central N=N bond of each AB unit. However, the roles of these two pathways differ in the excited-state decay of CBA. In terms of our nonadiabatic dynamics simulations, it can be found that the clockwise photoisomerization via S1S0-1 is more favorable dynamically than its counterclockwise one via S1S0-2. The yield of trajectories via S1S0-1 versus S1S0-2 is estimated to be 74% vs. 26%. The preference of the excited-state decay channel via S1S0-1 is essentially from its barrierless photoisomerization path from the Franck-Condon point to the S1/S0 minimum-energy conical intersection S1S0-1. Differing from S1S0-1, there is a subtle barrier for the excited-state decay path to S1S0-2, which is calculated to be 3.7 kcal/mol at the OM2/MRCI level. This small barrier leads to comparably distinct dynamical outcomes.

Our present OM2/MRCI calculations complement recent electronic structure calculations by Slavov et al. where the S1 and S0 potential energy surfaces, only relevant to the clockwise photoisomerization, are explored using the TD-DFT. [START_REF] Slavov | Twist and Return-Induced Ring Strain Triggers Quick Relaxation of a (Z)-Stabilized Cyclobisazobenzene[END_REF] The topological structures of potential energy surfaces relevant to the cis-trans photoisomerization from the (Z,Z) to (Z,E) conformers are nearly the same as those calculated by us with the OM2/MRCI method. It is an almost barrierless process in both TD-DFT and OM2/MRCI levels for the clockwise pathway. Different from the clockwise situation, there is a small barrier of ca. 3.7 kcal/mol associated with the counterclockwise photoisomerization channel. Nevertheless, this excited-state decay pathway cannot be excluded because it contributes about 23% for the excited-state decay of CBA.

Previously combined experimental and theoretical work believe that the individual AB unit in CBA still undergoes the ultrafast Z-E photoisomerization in spite of the associated large steric hindrance and internal strain. [START_REF] Slavov | Twist and Return-Induced Ring Strain Triggers Quick Relaxation of a (Z)-Stabilized Cyclobisazobenzene[END_REF] Our current nonadiabatic dynamics simulations support such viewpoint from dynamical perspective. In terms of our trajectories, the excited-state decay time is estimated to be ca. 69 fs, which is close previously reported values for isolated AB and its variants in different surroundings. This kind of stereoselectivity for the excited-state decay has been previously found in isolated AB by Weingart et al., in which a ratio of ca. 77% vs. 23% is observed between the clockwise and counterclockwise photoisomerization pathways. [START_REF] Weingart | Chiral Pathways and Periodic Decay in cis-Azobenzene Photodynamics[END_REF] Later, one of the authors has found that in arylazopyrazole, a similar azo system, this stereoselectivity can be increased to ca. 97% vs. 3%. [START_REF] Wang | Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited-State Relaxation[END_REF] Motivated by this work, Pang and coworkers have recently this ratio can reach to ca. 99.7% vs. 0.3% in azoheteroarene systems. 101 All these path selectivity are caused by the fact that there are two different extent barriers associated with the clockwise and counterclockwise photoisomerization channels. Nevertheless, it should be stressed that to our best knowledge, this kind of stereoselectivity of excited-state decay is not reported for cyclic multiple AB systems. Our work demonstrates that this interesting phenomenon could be available in the complex cyclic system in which the AB units are linked by covalent bonds.

CONCLUSION

In summary, we have employed OM2/MRCI-based full-dimensional nonadiabatic dynamics simulation method to explore the S1 photoisomerization mechanism and subsequent S1→S0 excited-state decay dynamics of a macrocyclic biazobenzene (CBA) molecule in which the two AB units are linked by covalent bonds. In terms of our electronic structure calculations, two relevant S1/S0 minimum-energy conical intersection structures are determined, which are responsible for the excited-state decay. Importantly, these two different conical intersections lead to two comparably important stereoselective photoisomerization and excited-state decay pathways, which separately correspond to the clockwise and counterclockwise photoisomerization motions with respect to the rotation of the N=N double bond of the central azo group. In both excited-state decay pathways, the excited-state isomerization and decay are found to be ultrafast and finished within ca. 69 fs, as estimated from on our dynamical trajectories. The most important finding is that our dynamics simulations reveal that the clockwise isomerization channel is much more favorable than the counterclockwise one with a ratio of 74% vs. 26%. Considering recent works, this ratio could be further enhanced to produce nearly exclusive stereoselective excited-state decay channel, which is very important for the realization of photoinduced molecular motors in which the unidirectional motion is necessary. In one word, we have computationally demonstrated that stereoselective pathways not only exist in the photoisomerization of isolated azobenzene-like systems but also could be available in some macrocyclic systems with multiple AB units with strong steric hindrance and internal strain. This finding could pay the way for controlling the photodynamics of photoswitchable macrocyclic systems.

Figure 1 .

 1 Figure 1. Our studied cyclobiazobenzene molecule in which two azobenzene units are linked by the covalent bonds.

Figure 2 .

 2 Figure 2. (Top panel) Stable (Z, Z) and (Z, E) conformers referred to as S0-ZZ and S0-ZE; (bottom panel) minimum-energy S1/S0 conical intersections referred to as S1S0-1 and S1S0-2. Also shown are selected geometric parameters optimized at the OM2/MRCI level.

Figure 3 .

 3 Figure 3. Distributions of (left) the selected geometric parameters at the S1→S0 hopping points and (right) the corresponding hopping times. See text for discussion.

Figure 4 .

 4 Figure 4. OM2/MRCI optimized (S1) minimum-energy paths along the clockwise (red) and counterclockwise (blue) isomerization directions.

Figure 5 .

 5 Figure 5. Suggested photoisomerization mechanism of the studied CBA molecule. See text for discussion.

Acknowledgments

This work is supported by National Natural Science Foundation of China (NSFC-21421003); G.C. is also grateful for financial supports from "Fundamental Research Funds for Central Universities". M. B. thanks the support of the Excellence Initiative of Aix-Marseille University (A*MIDEX) and the project Equip@Meso (ANR-10-EQPX-29-01), both funded by the French Government "Investissements d'Avenir" program.

Supporting Information

Active orbitals in OM2/MRCI calculations, additional figures and tables, and Cartesian coordinates of all optimized structures.


Beauprez Sophie-Anne

Laroche Betty

Perret Cyril

Bidet-Ildei Christel

Christel Bidet
email: christel.bidet@univ-poitiers.fr

How action context modulates the action-language relationship: a topographic ERP analysis

Keywords: evoked potential, spatiotemporal segmentation, action perception, action verb processing, context

The aim of the present study was to investigate how the context in which an action is presented could modulate the effect of action observation on language processing, an effect that is classically observed in the literature. To address this question, we recorded both behavioral (reaction times) and electrophysiological measures (event-related potentials) of participants performing a semantic decision task involving a verb describing an action that was congruent or incongruent with the action presented in a prime picture that had been observed. The prime picture presented an action performed in a usual or an unusual context.

The results revealed different behavioral and topographical pattern responses according to the context in which an action is presented. Importantly, only in the usual context, the congruency between the prime picture and the verb stimulus facilitated the semantic processes, leading to shorter response times in this condition compared to the others. Moreover, the topographic analysis revealed that this facilitation was related to reduced processing times for the semantic access to the verb and for the motor preparation for the answer. Taken together, these findings demonstrate that the context of an action is crucial in the link between action and language.

Introduction

Many behavioral and brain studies have investigated the relationship that exists between language and action and have revealed a strong link between them (see [START_REF] Fischer | Embodied language: a review of the role of the motor system in language comprehension[END_REF][START_REF] Jirak | Grasping language--a short story on embodiment[END_REF]. Thus, action and the language influence each other (e.g., [START_REF] Liepelt | Bidirectional semantic interference between action and speech[END_REF] and activate the same neural network (e.g., [START_REF] Hauk | Somatotopic representation of action words in human motor and premotor cortex[END_REF], revealing a clear crosstalk between both processes [START_REF] Pulvermüller | Brain mechanisms linking language and action[END_REF]. Interestingly, this effect of action word processing is not limited to action execution but is also present when actions are simply simulated [START_REF] Khader | Neural correlates of generating visual nouns and motor verbs in a minimal phrase context[END_REF] or observed [START_REF] Beauprez | Perceiving a Biological Human Movement Facilitates Action Verb Processing[END_REF][START_REF] Bidet-Ildei | Reading action word affects the visual perception of biological motion[END_REF], suggesting that the link between action and language depends on the activation of common sensorimotor representations (Aziz-Zadeh, Wilson, [START_REF] Aziz-Zadeh | Congruent embodied representations for visually presented actions and linguistic phrases describing actions[END_REF][START_REF] Bidet-Ildei | Are judgments for action verbs and point-light human actions equivalent?[END_REF].

An issue to be addressed is to determine what features of an action affect the activation of these sensorimotor representations (e.g., [START_REF] Beauprez | When context modulates the influence of action observation on language processing[END_REF]. In the present study, we propose to investigate the role of context in which the action is embedded.

In our everyday life, people perceive others performing actions in a context, and this context is critical since it provides much information that allows an understanding of the intention of the other [START_REF] Iacoboni | Grasping the intentions of others with one's own mirror neuron system[END_REF]. Recently, some researchers have studied how action context can influence action perception. To investigate this question, researchers were interested in unusual actions. Actions can be defined as "usual" when they are presented in a typical and expected context, whereas actions that do not fit a given context are considered "unusual" [START_REF] Ampe | Unusual actions do not always trigger the mentalizing network[END_REF]. Unusual actions and usual actions are processed differently and do not activate the same cerebral networks [START_REF] Brass | Investigating action understanding: inferential processes versus action simulation[END_REF][START_REF] Liepelt | How do we infer others' goals from non-stereotypic actions? The outcome of context-sensitive inferential processing in right inferior parietal and posterior temporal cortex[END_REF][START_REF] Van Overwalle | Understanding others' actions and goals by mirror and mentalizing systems: a meta-analysis[END_REF]. On the one hand, usual actions could be supported by the activation of the mirror neuron system [START_REF] Rizzolatti | Neurophysiological mechanisms underlying the understanding and imitation of action[END_REF]. On the other hand, the understanding of unusual actions would necessitate the intervention of another system, the mentalizing system, a system involved in rationalization processes [START_REF] Amodio | Meeting of minds: the medial frontal cortex and social cognition[END_REF]. Thus, the mirror neuron network appears to be insufficient for understanding unusual actions. Since it is known that the mirror neuron network plays a key role in the action-language relationship [START_REF] Aziz-Zadeh | Congruent embodied representations for visually presented actions and linguistic phrases describing actions[END_REF][START_REF] Rizzolatti | The mirror-neuron system[END_REF], we hypothesized that the context of action presentation could play a role in this relationship and could modulate the effect of action observation on language processing.

In a previous behavioral study [START_REF] Beauprez | When context modulates the influence of action observation on language processing[END_REF], we conducted an experiment to assess this question by observing how action context can affect the subsequent judgments of congruent or incongruent action verbs. The results showed that the semantic processing of action verbs was facilitated when the participants had previously seen that particular action. However, this effect was only obtained when the action observed was in a usual context. For example, the verb "to water" was judged faster after the presentation of a picture representing the action of someone watering a plant (usual context), whereas this effect disappeared when the same action was unusual, as someone watering a computer for example. We interpreted our results as reflecting the activation of different brain systems for usual and unusual actions. More specifically, we suggested that the usual pictures presented to the participants could have activated the mirror system [START_REF] Rizzolatti | Neurophysiological mechanisms underlying the understanding and imitation of action[END_REF], thereby activating the sensorimotor representation related to this action. In contrast, the unusual pictures presented to the participants could have activated the mentalizing system and less activated the mirror neuron system; consequently, the sensorimotor representation would be reduced or not activated, which would have led to the absence of effect in the unusual context.

To assess this hypothesis, we proposed to replicate this first study while adding ERP measures. Thus, the objective of the present study was to precisely characterize the temporal sequence of the cognitive processes involved when our participants performed a semantic decision task after being primed by usual or unusual action observations. We used spatiotemporal segmentation analyses to obtain detailed information on the time-windows corresponding to stable configurations of the spatial properties of the electric field and their temporal dynamics across conditions. This analysis will inform about which time-window is affected by the context of production of an action. More precisely, if our hypothesis is true, we should observed different topography when the participants are observing an action in a usual context or in an unusual context. Indeed, the spatiotemporal segmentation technique allows us to observe topographies (or microstates, namely period of coherent synchronized activation of a large scale neuronal network) reflecting that the brain is in a certain information processing step [START_REF] Brunet | Spatiotemporal Analysis of Multichannel EEG: CARTOOL[END_REF]. Thus, across condition, when the same cerebral sources are activated, the same microstates should be observed. On the contrary, different cerebral sources should lead to different microstates.

Assuming the involvement of the mirror system for usual pictures and of the mentalizing system for unusual pictures, we hypothesized that the spatiotemporal segmentation should revealed different topographies according of the picture nature.

Moreover, we expected to observe differences during the verb processing. In our previous experiment, we proposed that perceiving an action lead to the activation of the sensorimotor representation of this action. Subsequently, the activation of this sensorimotor representation would facilitate the access to the meaning of the verb [START_REF] Beauprez | When context modulates the influence of action observation on language processing[END_REF]. Thereby, differences should be observed during the semantic processing of the verbs. One of the most common index of semantic processing is the N400 component [START_REF] Curran | Topography of the N400: brain electrical activity reflecting semantic expectancy[END_REF][START_REF] Kutas | Reading senseless sentences: brain potentials reflect semantic incongruity[END_REF], a negative deflexion in the ERP wave at about 400ms, which is known to be greater when there is semantic incongruency. Thus, at this time period (around 400ms), we hypothesized that differences in the spatiotemporal segmentation would be observed. More precisely, we assumed that the semantic processing step would be shorter when the action of the verb has been previously perceived.

Method

Participants

Twenty-five French-speaking, 19-to 25-year-old (M = 21 years old, SD = 1.59), undergraduate students (15 males) participated in this experiment. All participants were righthanded as determined by the Edinburgh Handedness Scales [START_REF] Oldfield | The assessment and analysis of handedness: The Edinburgh inventory[END_REF]; mean quotient of laterality = 95%, max = 100%, min = 83%). They had normal or corrected-to-normal vision and reported no history of motor, perceptual or neurological disorders. All participants provided their written informed consent prior to their inclusion in the experiment and were paid for their participation. They were also unaware of the purpose of the study.

2.2.Materials

Prime Picture:

One hundred different pictures depicting an actor performing an action were used. These pictures were color photographs with a size of 75% of the computer screen (17 in).

Fifty different actions were represented in these pictures. Each action was presented both in a usual and unusual context, leading to a set of 100 pictures (see appendix 1 for examples and appendix 2 for a description of the 100 pictures of the experiment). Thus, a same action (e.g., "to water") had a usual picture (someone watering a plant) and an unusual picture (someone watering a computer).

The choice of these pictures was determined by a pilot study. A questionnaire containing a set of 134 pictures was completed by 15 people. They had to answer three questions for each picture. First, they had to spontaneously name the action represented in the picture by giving one or several verbs corresponding to it (i.e., What is the verb corresponding to this action?).

The picture obtained a score of 1 when the answer provided by the participant corresponded to the action, namely, when the participants gave the exact verb of the action or a semantically close verb (e.g., "to lunch" instead of "to eat"). The picture obtained a score of 0 when the answer provided by the participant differed semantically from the one expected (e.g., "to play" instead of "to shoot"). From this score, a percentage of recognition was calculated for each picture. Then, they had to judge whether the verb we chose to label the picture was adequate for characterizing this action (e.g., "Do you think the verb "drink" corresponds to this action?") using a 5-point scale ranging from "does not fit at all" to "fit perfectly". Finally, they had to judge the plausibility of the action ("Do you think it is probable that someone would perform this action in this context?") using a 5-point scale ranging from "very improbable" to "very probable". The 100 pictures we kept had a mean plausibility score that was high when the action was performed in a usual context (4.8) and low for the unusual context (1.6). Moreover, the actions of these pictures were spontaneously recognized by more than 90% of the participants in the usual and unusual context. Finally, the mean score of adequacy with the label we chose was high for these pictures (4.8).

Stimuli:

One hundred verbs were used. Half of them were "action verbs" corresponding to the 50 actions represented in the pictures, the other half were "non-action verbs", namely, stative verbs that do not depict a movement of the body (e.g., "to want"; see appendix 3 for the complete list of verbs). All verbs were presented in French and in the infinitive form.

2.3.Procedure

The participants were tested individually in a soundproof dark room. The presentation of the trials was controlled by the software E-Prime.

The experimental session included 300 trials: presentation of the 100 prime pictures (50 actions in two contexts) that could be followed by three different verbs (congruent action verb, incongruent action verb, and non-action verb). Therefore, in a third of the trials, the prime was followed by a congruent action verb (for example, seeing the picture of someone skiing before seeing the word "to ski"), in another third of the trials, the prime was followed by an incongruent action verb (for example, seeing the picture of someone skiing before seeing the word "to drink") and in the last third, the prime was followed by a non-action verb (for example, seeing the picture of someone skiing before seeing the word "to think"). This last kind of trial was considered a filler, and these trials were not analyzed. They were included only to propose a task for the participants. Thus, in the end, we analyzed 4 different types of trials (usual picture-congruent action verb; usual picture-incongruent action verb; unusual picture-congruent action verb; and unusual picture-incongruent action verb).

Each trial involved the following procedure: a fixation cross appeared (500 ms), and then the prime picture (2000 ms) was presented. Following another fixation cross (500 ms), the verb stimulus appeared. It remained on the screen until the participant entered a response. The participant's task was to judge, as quickly and as accurately as possible, whether the verb depicted an action. Participants answered by pressing the left button on the mouse for "yes" (for an action verb as "to water") the right button on the mouse for "no" (for a non-action verb as "to want"). Thus, the participant had to perform a semantic decision task on the verb regardless of the picture previously observed.

After the experimental task, the participants had to answer a questionnaire which served as a control measure. The aim of this questionnaire was to check whether each action in the primes had been recognized by the participants and assess whether the actions in the pictures appeared to be relatively probable according to their context. Each picture of the task was presented and the participants had to answer two questions. The first question asked the participants to say what action they thought was depicted. The picture obtained a score of 1 when the answer provided by the participant corresponded to the action (i.e., the participants gave the exact verb of the action or a semantically close verb) and obtained a score of 0 when the answer provided by the participant differed semantically from the one expected. A percentage of recognition per participant was calculated from these scores. The second question asked them to assess the plausibility of each picture using a 5-point scale ranging from "very probable" to "very improbable". We expected the participants to be able to recognize the action whatever the context (i.e., the percentage of recognition would be similar for the usual pictures and unusual pictures), but we expected them to consider the usual picture more probable than the unusual pictures (i.e., have a score of probability higher for the usual pictures).

2.2.RT analysis

Participants' response times were analyzed after trials with errors and with response time outliers (± 2.5 standard deviations) were excluded from the analysis (less than 10% of the data). We used the lmer function of the lmerTest package [START_REF] Kuznetsova | lmerTest Package: Tests in Linear Mixed Effects Models[END_REF] in the R environment (R version 3.3.0, R Core Team © 2016) to build linear mixed-effects models. Participants and words items were specified as random-effects factors. Two fixed-effects factors were used and included the following: the picture context (usual action x unusual action) and the congruency of the verb according to the prime (congruent x incongruent), as well as their interaction. The p values were obtained for the reported F values (Type III ANOVA) with the error degrees of freedom calculated based on Satterthwaite's approximation. The responses of the recognition questionnaire were assessed with a Wilcoxon signed-rank test. The significance level was set at p < 0.05.

2.3.EEG acquisition and preanalyses

EEG was recorded continuously using the Active-Two Biosemi EEG system (Biosemi V.O.F Amsterdam, Netherlands) with 128 channels covering the entire scalp. Signals were sampled at 512 Hz.

First, each trial was visually inspected in order to reject trials contaminated by eye blinking, movements or other noise (20% of the data). ERPs were then bandpass-filtered to 0.16-30 Hz and recalculated against the average reference. After rejection of errors and of contaminated epochs, the remaining epochs were averaged per subject for each of the conditions.

For the prime presentation, epochs of 2000 ms were averaged for each subject according to the context condition (usual x unusual). Therefore, the individual averaged data, as well as the group grand-average, covered the time from the appearance of the prime picture until its disappearance.

For the verb presentation, two averaging procedures, concerning two time periods, were combined: one was performed on stimulus-aligned epochs (forward) of 668 ms starting at the moment the stimulus appeared on the screen and one on response-aligned epochs (backward) of 668 ms starting at the production latency of each individual trial. In other words, stimulus-aligned epochs started at the moment the verb appeared on screen. Response-aligned epochs started at the moment the participant pressed the mouse to answer. Stimulus-aligned epochs and response-aligned epochs were averaged for each subject according to the context condition (usual x unusual) and the congruency of the verb (congruent x incongruent). This method that combines stimulus-and response-aligned data was introduced by Laganaro and [START_REF] Laganaro | Comparing electrophysiological correlates of word production in immediate and delayed naming through the analysis of word age of acquisition effects[END_REF] and allows a full matching between stimulus-aligned and response-aligned ERPs. For the spatiotemporal segmentation analysis (section 2.5), the forward and backward data of each participant were merged according to each participant's RT in each condition.

Therefore, the individual averaged data, as well as the group grand-average, covered the time from the appearance of the verb until the response of the participant. In a last step, electrode artifacts were interpolated using 3D spline interpolation [START_REF] Perrin | Mapping of scalp potentials by surface spline interpolation[END_REF].

2.4.Global field power analysis

The ERPs were first analyzed to determine the time periods at which the ERPs of the two conditions for prime presentation and of the four conditions for verbs presentation started to differ significantly from one another. In order to avoid influence of reference choice [START_REF] Murray | Topographic ERP Analyses: A Step-by-Step Tutorial Review[END_REF], we compared the standard deviation of all electrodes at a given time and at each time points over the entire analyzed periods [START_REF] Lehmann | Spatial analysis of evoked potentials in mana review[END_REF]. Paired t-tests were computed on this global field power between conditions at each time-frame, with alpha criterion of 0.05 and a time-window of 24 ms of consecutive significant difference.

2.5.Topographic pattern analyses

Significant variations of the global filed power can be the consequence of modulation in the strength of the electric field, of topographical changes in the electric field (revealing distinguishable brain generators), or of latency shifts in similar brain processes. To differentiate these effects, we applied topographic analyses (spatiotemporal segmentation, [START_REF] Brunet | Spatiotemporal Analysis of Multichannel EEG: CARTOOL[END_REF] to summarize the ERP data into a limited number of topographical map configurations (stable electrophysiological period, [START_REF] Lehmann | Spatial analysis of evoked potentials in mana review[END_REF]. A map configuration is a period during which the topography of the electrophysiological activity on the scalp remains stable for several tens of milliseconds. Any change of the spatial configuration of the electric field on the scalp was interpreted as revealing a difference in the distribution of the underlying intracranial sources [START_REF] Brunet | Spatiotemporal Analysis of Multichannel EEG: CARTOOL[END_REF]. This method is insensitive to pure amplitude modulations across conditions (i.e., the topographies of normalized maps are compared) and independent of the reference electrode [START_REF] Michel | EEG source imaging[END_REF]. To determine the most dominant configurations of the electric field at the scalp (i.e., topographic maps), we used a modified hierarchical clustering analysis [START_REF] Murray | Topographic ERP Analyses: A Step-by-Step Tutorial Review[END_REF]. A given topography had to be present for at least 20 time frames (40 ms) and had to be correlated above 95%. To determine the optimal number of maps, a modified cross-validation criterion was used. The procedure is described in detail in [START_REF] Pascual-Marqui | Segmentation of brain electrical activity into microstates: model estimation and validation[END_REF].

We applied these spatiotemporal segmentations on the two grand-average data sets of the prime picture presentation and on the four grand average datasets of the verb presentation.

Then, the pattern of the map templates observed in the averaged data was statistically tested by comparing each of these map templates with the moment-by-moment scalp topography of individual subjects' ERPs from each condition. Each time point was labeled according to the map with which it best correlated spatially, yielding a measure of map presence. This procedure, referred to as "fitting", allowed a determination how well a cluster map explained individual patterns of activity (GEV: global explained variance) and its duration. GEV and duration measures observed in each subject's data were analyzed to determine whether one map was more representative of one condition or lasted longer in one condition. For the prime picture presentation, we used paired t-tests to compare the maps of the usual and unusual pictures. For the verb presentation, ANOVAs were performed to compare the maps of the different conditions. The map, the congruency (congruent action x incongruent action) and context (usual x unusual) were set as within-subject factors. When the interaction was significant, comparisons were performed with paired t-tests. This procedure has been regularly used with language data (e.g., [START_REF] Laganaro | Inter-study and inter-Individual consistency and variability of EEG/ERP microstate sequences in referential word production[END_REF]Laganaro, Valente, & Perret, 2012;[START_REF] Perret | Exploring the multiple-level hypothesis of AoA effects in spoken and written picture naming using a topographic ERP analysis[END_REF]Perret & Laganaro, 2012;[START_REF] Python | ERP evidence of distinct processes underlying semantic facilitation and interference in word production[END_REF] and the procedure has been described in detail by Murray and his colleagues (2008).

Results

Behavioral results: response times and recognition questionnaire

The analyses (see Fig. 1) showed that response time varied according to the context (F(1,3918) = 13.47, p < 0.001) and varied according to the congruency of the verbs (F(1,3913) = 53.41, p < 0.001). Moreover, a significant interaction between the congruency of the verb and context was found (F(1,3922) = 13.56, p < 0.001). Student's t-tests revealed that in the usual context, response times for congruent verbs were significantly shorter than the response times for incongruent verbs (t(24) = 7.54, p < 0.001). However, in the unusual context, there was no significant difference between the congruent and incongruent verbs (t(24) = 1.22, p = 0.24). Concerning the recognition questionnaire, a Wilcoxon signed-rank test revealed that usual action recognition rate (98%) was not significantly different than the unusual action recognition rate (97%, Z = 0.75, p = 0.49). Moreover, the usual actions were rated as more probable (4.87) than the unusual actions (1.62, Z = 4.37, p < 0.01).

Electrophysiological Data

Prime Picture -Global field power analysis and Spatiotemporal segmentation

The global field power analysis revealed differences between the prime conditions around 1100 ms (see Fig. 2 -A). This result was confirmed by the spatiotemporal segmentation.

This spatiotemporal segmentation, applied to the averaged data of usual and unusual pictures, revealed 4 different electrophysiological periods of stability accounting for 95.39% of the variance. These four maps were labelled respectively map 0, 1, 2 and 3 according to their order of apparition (see Fig. 2 -C).

The same sequence of topographical maps appeared in both prime conditions (see Fig. 2 -B).

The stable maps labelled "0" and "1" seemed to have the same durations across the two prime presentations. The stable map labelled "2" was shorter for usual than for unusual pictures, and shifted the first onset of the next stable map "3" (see appendix 4 for the precise timing of beginning and end of the different maps). Prime Picture -Fitting procedure Then, the fitting procedure was applied. The results of the fitting procedure applied to the individual data supported the results of the global field power analysis and of the spatiotemporal segmentation. The maps "0" and "1" were not different whereas the map labeled as "2" was significantly different for both map duration (p < 0.002) and GEV (p = 0.01). More precisely, this map lasted longer when the picture was unusual (279 ms, SD = 88ms) than when the picture was usual (201 ms, SD = 91.82ms). Finally, the same duration and GEV were observed for the map "3".

Verb -Global field power analysis and Spatiotemporal segmentation

In the usual context (when comparing congruent and incongruent conditions) different GFPs were reported, for stimulus-aligned ERPs around 550-600ms. Moreover, different GFPs were also reported around 700 ms for response-aligned ERPs. The analyses of the spatiotemporal segmentation confirmed these periods of difference. In the unusual context, no different GFP was reported (Fig. 3 -A).

The spatiotemporal segmentation applied to the four grand-averaged ERPs (usual congruent, usual incongruent, unusual congruent and unusual incongruent condition) revealed 5 different electrophysiological period of stability accounting for 91.03% of the variance (see Fig. 3). These five maps were labelled respectively map 0, 1, 2, 3 and 4 according to their order of apparition. The same sequence of topographical maps appeared in all conditions (Fig. 3 -B).

The stable maps labelled "0", "1", and "2" seemed to have the same durations whatever the experimental conditions. However, the stable maps labelled "3" and "4" appeared to be shorter when the participant is processing congruent verbs than incongruent verbs, but only in the usual condition (see appendix 4 for the precise timing of beginning and end of the different maps).

Verb -Fitting procedure

Then, the fitting procedure was applied. Before performing the analyses on each map separately, we tested the interaction between the context, the congruency and the map (0, 1, 2, 3, 4). The results of this global ANOVA are summarized in Table 1.

Table 1. Results of the ANOVA concerning the durations with the context (usual and unusual), the congruency (congruent and incongruent) and the map (1, 2, 3, and 4) as factors. Thus, the interaction context*congruency*map was significant (p = 0.009), revealing that the interaction between the context and the congruency was dependent on the map. Taking this into account, the following analyses were performed on each map separately.

The global field power and spatiotemporal segmentation analyses were supported by the results of the fitting procedure applied to individual ERPs data in three time-windows: from 0 to 250 ms, from 250 ms to 500 ms and from 500 ms to the participant response.

In the first time window, the same durations and GEV of the stable maps "0", "1" and "2"

were observed in each condition. The results of the fitting procedure applied in the time window from 250 to 500 ms revealed a difference concerning the electrophysiological map labeled "3". For the map duration, a significant interaction between context and congruency was found (F(1,24) = 10.98, p = 0.003). In the usual context, Student's t-test revealed that the duration of this map was shorter for the congruent condition (77.11 ms) than the incongruent condition (149.65 ms, p = 0.004). In the unusual context however, the map duration was not different in the congruent (131,65 ms) and the incongruent conditions (131.84 ms, p = 0.99).

The results of the GEV concerning this interaction was close to significance (F(1,24) = 1.27, p = 0.05). Finally, the results of a fitting procedure applied in a time window from 500 ms to the end of trial revealed a difference concerning the electrophysiological map labeled "4".

Both GEV (F(1,24) = 4.67, p = 0.04) and map duration (F(1,24) = 8.19, p < 0.001) showed a significant interaction between context and congruency. In the usual context, Student's t-test revealed that this map was shorter in the congruent condition (95.39 ms) compared to the incongruent condition (162.38 ms, p < 0.001). In the unusual context, the duration of the map was not different in the congruent condition (183.3 ms) and the incongruent condition (179.84 ms, p = 0.88).

Discussion

The first aim of this study was to replicate the findings of our previous study [START_REF] Beauprez | When context modulates the influence of action observation on language processing[END_REF], namely, to demonstrate that the context of an observed action can affect the relationship between the sensorimotor system and language processing. The behavioral results

in the present study confirmed these findings. Indeed, in the usual condition, a facilitation effect was obtained, demonstrated by the fact that the participants were faster to answer when the action verbs were congruent rather than when they were incongruent with the action they had previously seen. In contrast, no difference was obtained between congruent and incongruent action verbs when perceiving an action in an unusual context.

It is worth noting that in our previous study, we used pictures of a cartoon character, whereas in the present study, we used pictures of a real person. We could have expected different results in the present study, since it could be easier to resonate with real human beings rather than with cartoon characters. Indeed, it is known that sensorimotor representations are involved when an observed action matches the perceiver's motor repertoire [START_REF] Calvo-Merino | Action observation and acquired motor skills: an FMRI study with expert dancers[END_REF] and that the closer an action is to our motor repertoire, the stronger the motor resonance will be. However, we found that, even if it should be easier to resonate with a real human being, no effect was obtained in the unusual context. These results seem to indicate a strong involvement of the context in the influence of action perception on semantic activation during word processing.

The second aim of this study was to investigate the temporal course of the cognitive processes involved in this effect. During the picture presentation, we observed that the same maps, but with different duration, were involved in the usual and unusual pictures (see Fig. 2).

Assuming that different maps reflect different underlying neurophysiological mechanisms, and that the same map is more likely to reflect the same mechanism, our results suggest that the same process was involved when the participants saw usual or unusual action. However, the process duration was shorter in the usual condition than in the unusual condition. This result appears to be in contradiction to the studies demonstrating that usual and unusual actions do not activate the same cerebral networks [START_REF] Brass | Investigating action understanding: inferential processes versus action simulation[END_REF][START_REF] Van Overwalle | Understanding others' actions and goals by mirror and mentalizing systems: a meta-analysis[END_REF].

One possibility could be that in both the usual and unusual condition, sensorimotor representations were activated. Indeed, it is recognized that the perception of actions is associated to motor areas activation [START_REF] Calvo-Merino | Action observation and acquired motor skills: an FMRI study with expert dancers[END_REF][START_REF] Nishitani | Temporal dynamics of cortical representation for action[END_REF], thus, we could reasonably assumed that the perception of usual actions led to motor activation. And since the same maps (reflecting the same processing levels) were observed during usual and unusual actions perception, we could assume that motor areas were also activated for unusual actions. However, the difference in the duration of map 2 could reflect the necessary time to relate the action with motor experience. In the usual context, it would be easier to resonate with the action perceived while this step would be more difficult in the unusual context. This idea agrees with our behavioral results; since the activation of the sensorimotor representation would require more time in the unusual context, the processing of the verbs would not be facilitated, which would explain the absence of facilitation in the unusual condition.

On the other hand, during processing of the verb, the global field power analysis and spatiotemporal segmentation revealed topographical differences in the ERPs latencies. More precisely, the EEG data revealed 5 different maps (see Fig. 3). It appears that the context of the action influenced maps 3 and 4. In contrast, the two first maps were not affected by the context. These results are in agreement with the literature, since we know that the first map could be more related to visual processing of the word and that the second map could be related to orthographic and phonological processes associated with the word. Indeed, map 1 occurred at approximately 150 -200 ms, a time period which is known to be associated with visual processes (i.e., visual feature analysis and general analysis of complex graphical features; [START_REF] Kuriki | Neural processing of words in the human extrastriate visual cortex[END_REF]Hirata, 1998, Dien, 2009). Map 2 occurred approximately 200 -300 ms which corresponds to the time period during which a word is recognized. It has been suggested that orthographic and phonological processes occur in this time period [START_REF] Bentin | ERP manifestations of processing printed words at different psycholinguistic levels: time course and scalp distribution[END_REF][START_REF] Simon | Chronometry of visual word recognition during passive and lexical decision tasks: an ERP investigation[END_REF].

One of the main differences between our conditions is map 3. This map occurred after 300 ms and we propose that it could reflect semantic processing. More precisely, this processing would be related to the task; that is, to decide if the word is an action word involving a movement of the body. Indeed, using ERP analyses, Mari-Beffa and her colleagues (2005) proposed a dissociation between an initial stage of semantic processing that is automatic and related to semantic priming (≈200 ms), and a later stage of semantic processing controlled by the task goal (≈400 ms). They proposed that this second semantic step could reflect the necessary processing to convert the activation of a word's meaning into a conscious judgement about this word. Thus, it seems that in the usual condition, the semantic processing of the verbs was facilitated when there was a correspondence between the action of the picture and the action of the verb (congruent trials).

The second difference between our conditions concerned map 4, which occurs after 550 ms and could reflect response preparation in the motor cortex. Indeed, studies involving responses times requiring a button press measured the lateralized readiness potential. This component is considered a reflection of specific motor preparation and generally occurred 100 ms before the response [START_REF] Killikelly | Asymmetry in stimulus and response conflict processing across the adult lifespan: ERP and EMG evidence[END_REF]. For example, [START_REF] Müller | Access to lexical information in language comprehension: semantics before syntax[END_REF] recorded this lateralized readiness potential between 500 and 800 ms, which is in accordance with our map 4.

Thus, it seems that the perception of an action in a congruent context facilitated both the semantic access to the verb and the preparation of the motor response, since these two processes appeared to be significantly faster in this condition. We suggest that the more the action of a verb and the action of a picture correspond the faster these processes could be.

Note that an alternative interpretation could be propose to our results. Since the participants had 500 ms (fixation cross) before the apparition of the verb, they could have used this time to silently name the action after the picture presentation and to prepare the matching motor response. This would explained why the response times were faster when the predicted verb actually appeared. However, we can rule out this possibility because of the results of the recognition questionnaire. Indeed, it indicates that participants recognized the actions of the picture both in the usual and unusual context. So, if the participants strategically repeated the verb of the action, they should have done it with both usual and unusual actions.

Thus, this interpretation does not explained why the congruency effect is not present in the unusual condition. We think it is more probable that the absence of effect in association with congruent unusual actions is related to decrease in sensorimotor activation.

In brief, our results confirm that the context of the presentation of an action is crucial in the link between action and language. More particularly, we show that the semantic of the word and the motor preparation of the answer were influenced. We propose that the context could modulate the motor resonance, and so, the action-language relationship would be related to the strength of the sensorimotor activations produced during the action perception.

Future brain imaging and behavioral studies will have to confirm this point.

Fig. 1

 1 Fig. 1 Mean response times (ms) according to context of the prime picture (usual and

Fig. 2

 2 Fig. 2 A. Results of the statistical analysis (1-p-values) of the global field power (GFP). B.

Fig. 3

 3 Fig. 3 A. Results of the statistical analysis (1-p-values) of the global field power (GFP). B.

Acknowledgment

We would like to thank Yves Almécija for his help in the creation of the pictures of the study and Paul-Alexis Beauprez for the creation of the figures used in this paper. We also thank the Maison des Sciences de l'Homme et de la Société for providing the EEG material necessary for carrying out this study.

The Cartool software (http://brainmapping.unige.ch/Cartool.php) was used for all the EEG analysis.

Ethical approval

The experiments were conducted in accordance with the ethical standards of the institution and with the 1964 Helsinki Declaration.

This study was approved by the ethical committee of the University of Poitiers (CERNI Poitiers -Tours, 2016-10-02).