Heteromodal Motion Coding in the Associative Parietal Cortex in Rats

Motion perception is facilitated by the interplay of various sensory channels. In rodents, the cortical areas involved in multisensory motion coding remains to be identified. Using voltage-sensitive-dye imaging, we revealed a visuo-tactile convergent region which anatomically corresponds to the associative parietal cortex (APC). Our electrophysiological unit recordings provide the first single-unit evidence of direction and speed tuning of APC visual neurons during moving visual gratings which suggest the APC as a motion processing area. Strikingly, using whisker deflections, we also found somatosensory neurons exhibiting selectivity to motion characteristics. Using a classification procedure, we revealed that APC population carries information about motion features in both sensory modalities. The presence of a large proportion of bimodal neurons underpins potential integrative functions of APC and suggests its role in the elaboration of a multimodal motion percept.