Ethologically relevant movements mapped on the motor cortex
Electrical stimulation of the motor cortex of monkeys elicits complex movements that combine many muscles and joints and that resemble fragments of the animal’s normal movement repertoire. Hand-to-mouth movements, reaching movements, defensive movements, and other ethologically relevant actions can be evoked. Different movements are evoked from different locations in motor cortex. The movement repertoire of the monkey appears to be mapped on the cortical sheet in a manner that preserves local continuity. Simple map schemes that have been proposed in the past, such as a map of the body, or a segregation of the motor cortex into separate areas that process different aspects of movement, explain only some aspects of motor cortex organization. More of the subtlety and complexity of the motor cortex topography can be explained by the principle of a highly dimensional movement repertoire that is flattened onto the cortical surface.