The posterior parietal cortex (the portion of parietal neocortex posterior to the primary somatosensory cortex) plays an important role in producing planned movements. Before an effective movement can be initiated, the nervous system must know the original positions of the body parts that are to be moved, and the positions of any external objects with which the body is going to interact. The posterior parietal cortex receives input from the three sensory systems that play roles in the localization of the body and external objects in space: the visual system, the auditory system, and the somatosensory system. In turn, much of the output of the posterior parietal cortex goes to areas of frontal motor cortex: the dorsolateral prefrontal cortex, various areas of the secondary motor cortex, and the frontal eye field. fMRI studies in monkeys and TMS studies in humans indicate that the posterior parietal cortex comprises a mosaic of small areas, each specialized for guiding particular movements of eyes, head, arms or hands.