Neural activity is spatially clustered in motor and dorsal premotor cortex

Abstract

Motor (M1) and dorsal premotor (PMd) cortex are central to arm and hand control in primates. Motor outputs in both areas confer somatotopically organized arm and hand zones. Here, we investigate the spatial mapping between those motor zones and movement-related neural activity to gain insight about functional organization in M1 and PMd. Two macaques reached and grasped while cortical activity was measured with intrinsic signal optical imaging. Activity maps were quantified in relation to microstimulation motor maps from the same hemispheres. Each activity map was comprised of many patches and overlapped surprisingly small portions of the motor map. Functional differences between the patches were inferred from their activity time courses and location within the motor map. We propose that M1 and PMd contain subzones that are preferentially tuned for specific actions. Thus, the spatial dimension of neural activity in frontal motor areas is an important organizing principle of the neural code for movement control.