Inferior parietal somatosensory neurons coding face-hand coordination in Japanese macaques

Neuronal activities of the anterior part of the inferior parietal lobule (area 7b or PF) were investigated in five awake Japanese monkeys. There were neurons which had specific combinations of receptive field (RF) locations, most typically in both the face and hand; we refer to these as Face-Hand neurons. The most interesting property of the Face-Hand neurons is that some of these neurons responded to specific behavior executed with synergism between the face (especially the mouth) and hand movements; namely, face-hand coordinated behavior (e.g., eating behavior). We call these cells Face-Hand coordination neurons (52% of all the Face-Hand neurons). These neurons discharged more strongly when the animal executed face-hand coordinated behavior, especially eating behavior, than when somatosensory stimuli were given to RFs passively, or when face movements and hand movements were executed separately. We thus propose that the neuronal activities of area 7b are related to the representation of face-hand coordination.