Dynamic spatial coding in parietal cortex mediates tactile-motor transformation

Movements towards touch on the body require integrating tactile location and body posture information. Tactile processing and movement planning both rely on posterior parietal cortex (PPC) but their interplay is not understood. Here, human participants pointed towards or away from memorized tactile stimuli on their feet, dissociating sensory and motor locations. Participants crossed or uncrossed their feet to dissociate stimulus location relative to anatomy versus in external space. Multi-voxel pattern analysis of concurrently recorded fMRI signals revealed that tactile location was coded anatomically in anterior PPC but spatially in posterior PPC during sensory processing. After movement instructions were specified, PPC exclusively represented the movement goal in space, in regions closely matching those that mediate visuomotor planning and with regional overlap for sensory, rule-related, and movement coding. Thus, PPC flexibly updates its spatial codes to accommodate rule-based transformation of arbitrary sensory input to generate movement to environment and own body alike.