Mesoscale functional architecture in medial posterior parietal cortex

The posterior parietal cortex (PPC) in mice has various functions, including multisensory integration, vision-guided behaviors, working memory, and posture control. However, an integrated understanding of these functions and their cortical localizations in and around the PPC and higher visual areas (HVAs) has not been completely elucidated. Here, we simultaneously imaged the activity of thousands of neurons within a 3 × 3 mm 2 field of view, including eight cortical areas around the PPC, during behavior with a two-photon mesoscope. Mice performed both a vision-guided task and a choice history-dependent task, and the imaging results revealed distinct, localized, and behavior-related functions of two medial PPC areas. Neurons in the anteromedial (AM) HVA responded to both vision and choice information, and thus AM is a locus of association between these channels. By contrast, the anterior ( A ) HVA stores choice history with sequential dynamics and represents posture. Mesoscale correlation analysis on the intertrial variability of neuronal activity demonstrated that neurons in AM exhibited diverse, area-dependent interactions, while neurons in area A shared fluctuations with the primary somatosensory area. Pairwise interareal interactions among neurons were precisely predicted by the anatomical input correlations, with the exception of some global interactions. Thus, the medial PPC has two distinct modules, areas AM and A, with each having distinctive modes of cortical communication. These medial PPC modules can serve separate higher-order functions: area AM for multisensory and cognitive integration with locally processed signals and area A for transmission of information including posture, movement, and working memory.