Plasticity of cortical projections after stroke.
Ischemic stroke produces cell death and disability, and a process of repair and partial recovery. Plasticity within cortical connections after stroke leads to partial recovery of function after the initial injury. Physiologically, cortical connections after stroke become hyperexcitable and more susceptible to the induction of LTP Stroke produces changes in the distribution and laterality of sensory, motor, and language representations within the brain that correlate with functional recovery. Anatomically, ischemic lesions induce axonal sprouting within local, intracortical projections and long distance, interhemispheric projections. This postischemic axonal sprouting establishes substantially new patterns of cortical connections with de-afferented or partially damaged brain areas. Axonal sprouting after ischemic lesions is induced by a transient pattern of synchronous, low-frequency neuronal activity in a network of cortical areas connected to the infarct. This pattern of neuronal activity that induces axonal sprouting in the adult after ischemic lesions resembles that seen in the developing brain during axonal elongation and synaptogenesis. Thus, stroke induces a process of remapping and reconnection within the adult brain through changes in neuronal activity that may involve a reactivation of developmental programs in areas connected to the infarct.
Carmichael
S Thomas
ST
Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA. scarmichael@mednet.ucla.edu
D000818:Animals; D001369:Axons / Q000378:metabolism; D002545:Brain Ischemia / Q000150:complications* / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D007839:Functional Laterality; D019922:GAP-43 Protein / Q000378:metabolism; D020439:Growth Cones / Q000378:metabolism; D006801:Humans; D017774:Long-Term Potentiation; D009434:Neural Pathways / Q000378:metabolism; D009473:Neuronal Plasticity; D020127:Recovery of Function; D020521:Stroke / Q000209:etiology / Q000378:metabolism*
D019922:GAP-43 Protein