Neurophysiologic, neuroanatomic and neuroimaging studies conducted over the past two decades reveal that the cerebral cortex is functionally and structurally dynamic. The functional topography of the motor cortex can be modified by a variety of experimental manipulations, including peripheral or central injury, electrical stimulation, pharmocologic treatment or behavioral experience. Recent evidence demonstrates that functional alterations in motor cortex organization are accompanied by changes in dendritic and synaptic structure, as well as alterations in the regulation of cortical neurotransmitter systems. This article describes the state of the science regarding the main mechanisms implicated in the motor cortex plasticity, the main tools used for its investigation and the consequence of the recent discoveries on the therapeutic and rehabilitation procedures for the brain-injured persons.