HUMAN ANTERIOR INTRAPARIETAL AREA SUBSERVES PREHENSION - A COMBINED LESION AND FUNCTIONAL MRI ACTIVATION STUDY

It has been shown in nonhuman primates that the posterior parietal cor tex is involved in coordination of arm and eye movements in space, whe reas the anterior intraparietal area in the anterior lateral bank of t he intraparietal sulcus plays a crucial role in fine finger movements, such as grasping. In this study we show by optoelectronic movement re cordings that patients with cortical lesions involving the anterior la teral bank of the intraparietal sulcus have selective deficits in the coordination of finger movements required for object grasping, whereas reaching is much less disturbed. Patients with parietal lesions spari ng the cortex lining the anterior intraparietal sulcus showed intact g rasping behavior. Complementary evidence was obtained from functional MRI in normal control subjects showing a specific activation of the an terior lateral bank of the intraparietal sulcus during grasping. In co nclusion, this combined lesion and activation study suggests that the anterior lateral bank of the intraparietal sulcus, possibly including the human homologue of the anterior intraparietal area, mediates the p rocessing of sensorimotor integration of precisely tuned finger moveme nts in humans.