Review ■: Multiple Representations of Space in the Brain

Lesions of the posterior parietal cortex have long been known to produce visuospatial deficits in both humans and monkeys. Yet there is no known map of space in the parietal cortex. The posterior parietal cortex projects to a number of other areas that are involved in specialized spatial functions. In these areas, space is represented at the level of single neurons and, in many of them, there is a topographically organized map of space. These extraparietal areas include the premotor cortex and the putamen, involved in visuomotor space, the frontal eye fields and the superior colliculus, involved in oculomotor space, the hippocampus, involved in environmental space, and the dorsolateral prefrontal cortex, involved in mnemonic space. In many of these areas, space is represented by means of a coordinate system that is fixed to a particular body part. Thus, the processing of space is not unitary but is divided among several brain areas and several coordinate systems, in addition to those in the posterior parietal cortex.