Crossmodal action representations 1 2 Surface-based information mapping reveals crossmodal vision-action 3 representations in human parietal and occipitotemporal cortex 4 5 6

27 Many lines of evidence point to a tight linkage between the perceptual and 28 motoric representations of actions. Numerous demonstrations show how the visual 29 perception of an action engages compatible activity in the observer’s motor system. 30 This is seen for both intransitive actions (e.g. in the case of unconscious postural 31 imitation) and for transitive actions (e.g. grasping an object). While the discovery of 32 “mirror neurons” in macaques has inspired explanations of these processes in human 33 action behaviours, the evidence for areas in the human brain that similarly form a 34 crossmodal visual/motor representation of actions remains incomplete. To address 35 this, in the present study, participants performed and observed hand actions while 36 being scanned with fMRI. We took a data-driven approach by applying whole-brain 37 information mapping using a multi-voxel pattern analysis (MVPA) classifier, 38 performed on reconstructed representations of the cortical surface. The aim was to 39 identify regions in which local voxel-wise patterns of activity can distinguish among 40 different actions, across the visual and motor domains. Experiment 1 tested 41 intransitive, meaningless hand movements, while Experiment 2 tested object-directed 42 actions (all right-handed). Our analyses of both experiments revealed crossmodal 43 action regions in the lateral occipitotemporal cortex (bilaterally) and in the left 44 postcentral gyrus/anterior parietal cortex. Furthermore, in Experiment 2 we identified 45 a gradient of bias in the patterns of information in the left hemisphere postcentral / 46 parietal region. The postcentral gyrus carried more information about the effectors 47 used to carry out the action (fingers vs whole hand), while anterior parietal regions 48 carried more information about the goal of the action (lift vs punch). Taken together, 49 these results provide evidence for common neural coding in these areas of the visual 50 and motor aspects of actions, and demonstrate further how MVPA can contribute to 51 our understanding of the nature of distributed neural representations. 52 53 Introduction 54 There is increasing evidence for a direct link between perception and action: 55 perceiving another person’s action activates the same representations as does the 56 actual performance of the action. Such common codes between perceiving and 57 producing actions enable humans to embody the behavior of others and to infer the 58 internal states driving it (e.g., Barsalou et al. 2003). That is, by creating common 59 representations between ourselves and another person, we have a deeper 60 understanding of their current states, and are better able to predict their future 61 behaviour, facilitating complex social interactions. However, the basis of the brain’s 62 crucial ability to relate one’s own actions to those of others remains poorly 63