Central nervous system lesions: sprouting and unmasking in rehabilitation.

Recovery of function following a central nervous system lesion can continue for months or years following the injury. Considerable experimental evidence supports the conclusion that the plasticity of the brain is of importance to the functional recovery. A number of neural mechanisms may be involved in the functional recovery. Two of the mechanisms of neuroplasticity considered particularly likely to play a role, are the following: 1) Collateral sprouting from intact cells to a denervated region after some or all of its normal input has been destroyed, and 2) The unmasking of neural pathways and synapses which are not normally used for the particular function under study but which can be called upon when the ordinarily of dominant system fails. The process of unmasking is extensively discussed in the context of the role of rehabilitation in obtaining maximum recovery of function.