Activity- and use-dependent plasticity of the developing corticospinal system.

Publication Type	Review
Authors	Martin J, Friel K, Salimi I, Chakrabarty S
Journal	Neurosci Biobehav Rev
Volume	31
Issue	8
Pagination	1125-35
Date Published	05/17/2007
ISSN	0149-7634
Keywords	Neuronal Plasticity, Neurons, Pyramidal Tracts, Spinal Cord
Abstract	The corticospinal (CS) system, critical for controlling skilled movements, develops during the late prenatal and early postnatal periods in all species examined. In the cat, there is a sequence of development of the mature pattern of terminations of CS tract axons in the spinal gray matter, followed by motor map development of the primary motor cortex. Skilled limb movements begin to be expressed as the map develops. Development of the proper connections between CS axons and spinal neurons in cats depends on CS neural activity and motor behavioral experience during a critical postnatal period. Reversible CS inactivation or preventing limb use produces an aberrant distribution of CS axon terminations and impairs visually guided movements. This altered pattern of CS connections after inactivation in cats resembles the aberrant pattern of motor responses evoked by transcranial magnetic stimulation in hemiplegic cerebral palsy patients. Left untreated in the cat, these impairments do not resolve. We have found that activity-dependent processes can be harnessed in cats to reestablish normal CS connections and function. This finding suggests that aspects of normal CS connectivity and function might some day be restored in hemiplegic cerebral palsy.
DOI	10.1016/j.neubiorev.2007.04.017
PubMed ID	17599407
PubMed Central ID	PMC2769920