Cortical cartography revisited: A frequency perspective on the functional architecture of visual cortex.
Viewed in the plane of the cortical surface, the visual cortex is composed of overlapping functional maps that represent stimulus features such as edge orientation, direction of motion, and spatial frequency. Spatial relationships between these maps are thought to ensure that all combinations of stimulus features are represented uniformly across the visual field. Implicit in this view is the assumption that feature combinations are represented in the form of a place code such that a given pattern of activity uniquely signifies a specific combination of stimulus features. Here we review results of experiments that challenge the place code model for the representation of feature combinations. Rather than overlapping maps of stimulus features, we suggest that patterns of activity evoked by complex stimuli are best understood in the context of a single map of spatiotemporal energy.