Spectacular developments in non-invasive imaging and brain stimulation techniques have recently led to significant advances in understanding the reorganisation of motor and sensory cortical maps in adults following lesions or with learning . This review addresses specific questions about the capacity of motor maps to change in adult primates, including humans, in response to behaviourally relevant experience or central or peripheral nervous system lesions.

The first part deals with the role of primary motor cortex (M1) in motor control and cognition. The organization and function of the multiple ‘non-primary’ motor areas located rostrally to M1 and in the cingulate cortex are also discussed. A second part of this review focuses on advances in understanding motor cortex plasticity in various pathological conditions. Since representations in M1 have been shown to change after motor learning a contribution of M1 to motor learning has been proposed; arguments for and against this hypothesis are discussed. In addition, data suggesting that the sub-cortical circuitry of M1 may play a role in map re-organization following learning are evaluated.

The second part of the paper reviews a large body of evidence from animal and human observations which confirm that M1 representations can also be altered as a result of changes in the availability of effectors or following sensory deprivation. The mechanisms underlying the plasticity of cortical maps following peripheral lesions are becoming increasingly well understood.

A third section discusses data which show that a cortico-spinal system lesion can lead to a complete reorganization of the area allocated to the hand representation in M1 or to reorganization of the whole network of motor areas responsible for voluntary movement.

In conclusion, therapeutic perspectives arising from improved understanding of the various mechanisms that result in plasticity of motor maps are proposed and discussed.

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