Cortical frames of reference for eye-hand coordination.

To reach for an object the brain must transform visual input from the eye into motor output of the arm. Recent neurophysiological experiments have shown that this transformation maps onto a network of brain areas including the posterior parietal (PPC) and premotor (PMC) cortices. In this chapter, we review evidence from our own experiments which demonstrate that this network can only partially complete the transformation when the eye and limb movement amplitudes are dissociated. We also discuss the effects of disrupting either the PPC or PMC using transcranial magnetic stimulation (TMS) on the ability to carry out the transformation successfully.