| Popis: |
It is nowwell established that the functional organization of the cerebral cortex isplastic, that is, changes inorganizationoccur throughout life in response to normal as well as abnormal experience. The potential for reorganization hasbeendemonstrated inboth sensoryandmotor areasof adult cortex, either as a consequence of trauma, pathological changes, manipulation of sensory experience, or learning. These changes can only be evaluated with reference to an extensive experimental base that has identified a repeatable representation pattern (e.g. somatotopy, tonotopy, or retinotopy), for which change can be detected.While the scope of changes are often at the edge of our technical capabilities to assess, there are striking examples of significant and rapid change (for reviews, see SanesD Buonomano&Merzenich, 1998). There is an overwhelming belief that modifications in cortical organization emerge through changes in synaptic efficacy within the cortex and elsewhere in the nervous system. Further, these changes are have been closely linked to the phenomena called long-termpotentiation (LTP) and long-term depression (LTD). This review deals mainly with the changes that have been detected in themotor cortex and their link to synapticmodification. Some of the most convincing evidence that learning and practice influences cortical organization and that learning operates through LTP/D-mediated mechanisms has come through work in the motor cortex. This work is also of profound significance to the medical community because it implies that the impaired or damagedmotor cortex can be restructured through appropriate physical rehabilitation schemes or through pharmacologicalmeans that alter mechanisms accounting for LTP/D. |
