The sources of visual information to the primate frontal lobe: a novel role for the superior parietal lobule.

Reaching movements are performed in order to bring the hand to targets of interest. It is widely believed that the distributed cortical network underlying visual reaching transforms the information concerning the spatial location of the target into an appropriate motor command. Modern views decompose this process into sequences of coordinate transformations between informational domains. The set of cortical areas and pathways by which the information on target location is relayed from the visual areas of the occipital lobe to the motor areas of the frontal lobe have, so far, been poorly understood. Recent data from different fields of neuroscience offer the basis for a new definition of the cortical system subserving reaching and, at the same time, for a reconsideration of the nature of the underlying visuo-to-motor transformation.