Functional properties of neurones in the posterior part of area 7 in awake monkey.

The posterolateral part of the parietal association cortex (area 7 of Brodmann) was investigated in three awake, behaving macaque monkeys using transdural microelectrode recording technique. Only one of the 114 cells isolated remained unidentified. Of the cells 79% responded to somesthetic (39%) or visual (23%) or both somesthetic and visual (17%) stimulation. The somesthetic receptive fields were large, covering, for instance, the whole arm or hand. Most receptive fields were on the upper extremities. Half of the somesthetically drivable cells had bilateral receptive fields. The visually drivable cells responded only to stimuli moving in a certain direction. The effective stimuli for most of the cells responding both to visual and somatosensory stimulation were: touching of the skin and visual stimuli moving towards the cutaneous receptive field. Of the cells 20% were active only during the monkey's own movements, most often during grasping and manipultion with fingers. The results indicate that the area studied is specialized in the control of hand movements, e. g. grasping, grooming and somesthetic recognition of the forms of objects.