Grasping-related functional magnetic resonance imaging brain responses in the macaque monkey.

Research in recent decades has suggested the existence of a dedicated brain network devoted to the organization and execution of grasping, one of the most important and skilled movements of primates. Grasping an object requires the transformation of intrinsic object properties such as size, orientation, and shape into an appropriate motor scheme shaping the hand. Although electrophysiological recordings in the monkey model have proven invaluable for gaining insights into the neuronal substrate underlying this complex behavior, knowledge concerning the existence and organization of a similar system in the human brain is derived mainly from imaging studies. Here, we present for the first time functional magnetic resonance imaging (fMRI) of brain activity while macaque monkeys performed reaching and grasping movements in a 3 tesla MR scanner. Grasping in the dark (compared with reaching) yielded significant activations in anterior intraparietal area and ventral premotor area F5, in addition to area PFG in the rostral inferior parietal lobule, somatosensory areas (SI, SII, area 5), and the hand field of F1. Whole-brain macaque fMRI motor studies will be instrumental in establishing possible homologies concerning grasping organization in the human and monkey brains, bridging the gap between human imaging and monkey electrophysiology.