Activation of parieto-frontal stream during reaching and grasping studied by positron emission tomography in monkeys

The whole brain activation during visually guided reaching and grasping behaviors was investigated in three macaque monkeys using positron emission tomography (PET) scanning with [15O]H2O. Activation was consistently observed in the parietal regions such as PO, MIP, VIP, LIP and AIP, frontal regions such as PMd, M1 and S1 on the contralateral hemisphere and in the ipsilateral intermediate and lateral deep cerebellar nuclei. Activation was also observed in the areas representing the central and peripheral visual field in the early visual cortices. Thus, the visuo-motor processing, including parieto-frontal stream, involved in the control of visually guided reaching and grasping behaviors could be visualized for the first time in macaque monkeys.