Movement representations in motor, somatosensory, and posterior parietal cortex of the greater galago

Previous studies suggest that anterior parietal cortical areas including S1 (3b) play a central role in motor control that is distinct from traditionally defined motor areas of the neocortex (eg M1). The role of anterior parietal areas in generating movement has never been described in any prosimian primate, a lineage thought to reflect the last common ancestor of all living primates. This study describes movements elicited from long-train intracortical microstimulation in the greater galago (Otolemur garnettii) in area 3b and adjacent frontal and parietal cortical fields. We found that the representation of forelimb digits was exceptionally small relative to other primate species, while tongue representations were enlarged-possibly an adaptation for frugivory. We discuss these findings in relation to primate behavioral variation, and highlight features of movement representations in 3b and M1 that are common to all mammals studied using similar methods.