NeuronThe Problem of Maps

Sensory cortical maps can be loosely defined as system-atic spatial distributions of sensory information within a cortical region or, in a more strict cartographic sense, as complete, point-to-point representations of peripheral receptor epithelia, stimulus parameters, sensory objects, or scenes of the external environment. What do sensory maps do in the brain? One view is that they are essential for perception and sensory-guided behavior. This propo-sition appears valid since there is a topographic represen-tation of the visual world in the retina (Woolsey, 1981b) whose retinotopic order is conserved in the visual thala-mus (Sanderson, 1971) and cortex (Tusa et al., 1978). The analogous somatotopic arrangements (Whitsel et al., 1978) in primary somatosensory cortex (SI) and of tono-topic order (Merzenich et al., 1975) in primary auditory cor