562 Parietal cortex: from sight to action Giacomo Rizzolatti, Leonardo Fogassi and Vittorio Gallese Recent findings have altered radically our thinking about the functional role of the parietal cortex. According to this view, the parietal lobe consists of a multiplicity of areas with specific connections to the frontal lobe. These areas, together with the frontal areas to which they are connected, mediate distinct sensorimotor transformations related to the control of hand, arm, eye or head movements. Space perception is not unitary, but derives from the joint activity of the fronto-parietal circuits that control actions requiring space computation. Addresses lstituto di Fisiologia Umana, Universita di Parma, Via Gramsci 14, 43100 Parma, Italy; e-mail: Fisioum@Symbolic.Pr.It Current Opinion in Neurobiology 1997, 7:562-567 http://biomednet.com/elecref~0959436800700562 0 Current Biology Ltd ISSN 0959-4388 Abbreviations 3D AIP IPL IPS LIP MDP MIP MST MT PIP PO RF SPL VIP three-dimensional anterior intraparietal (area) inferior parietal lobule intraparietal sulcus lateral intraparietal (area) medial dorsal parietal (area) medial intraparietal (area) medial superior temporal (area) middle temporal visual (area) posterior intraparietal (area) parieto-occipital (area) receptive field superior parietal lobule ventral intraparietal (area) Introduction The parietal lobe of primates consists of three main sectors: the postcentral gyrus, the superior parietal lobule (SPL) and the inferior parietal lobule (IPL). Together, the two lobules (SPL and IPL) form the posterior parietal lobe, classically seen as a large association region in which different types of sensory information converged to provide space perception and a general schema of the body [1,2]. At the time, space perception was seen as unitary and independent of action systems. Modern data have challenged this view. The posterior parietal lobe is now thought to consist of a mosaic of areas, each receiving specific sensory information and transforming it into information appropriate for action [3,4], with no identifiable ‘space area’. Rather, space perception appears to be a secondary result of the activity of a series of sensorimotor circuits, each of which encodes the spatial location of an object according to its own motor purposes and transforms it into a potential action [4,.5,6’]. The main aim of the present review is to focus on recent data concerning the functional properties of ‘visual’ parietal areas related to the organization of hand, arm and head movements. Oculomotor circuits will not be considered. Inferior parietal lobule Figure 1 depicts the main areas of the parietal lobe and agranular frontal cortex. Among the inferior parietal areas, two areas have recently attracted particular attention: areas AIP (anterior intraparietal) and VIP (ventral intraparietal). We will discuss their properties in particular detail. Fiaure zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHG 1 V6A V6/PO I , zyxwvutsrqponmlkjihgfedcbaZY 0 1997 Current Opinion in Neurobiology Lateral and dorsal view of macaque monkey cerebral cortex, highlighting the main areas of the parietal lobe and of the agranular frontal cortex. (a) Frontal and parietal areas of the macaque monkey. The intraparietal sulcus is opened (shaded gray) to show areas located in its medial and lateral banks. Frontal agranular cortical areas are classified according to Matelli ef a/. [51]. (b) Occipital and posterior parietal areas. Lunate, intraparietal and parieto-occipital sulci are opened (shaded gray) to show the location of different areas within the sulcal cortex, including areas V6/PO and V6A. Modified from Colby et al. (411. Area AIP and related areas Neurons that discharge in response to the presentation of specific three-dimensional (3D) objects and/or during