Role of adaptive plasticity in recovery of function after damage to motor cortex

Abstract

Based upon neurophysiologic, neuroanatomic, and neuroimaging studies conducted over the past two decades, the cerebral cortex can now be viewed as functionally and structurally dynamic. More specifically, the functional topography of the motor cortex (commonly called the motor homunculus or motor map), can be modified by a variety of experimental manipulations, including peripheral or central injury, electrical stimulation, pharmacologic treatment, and behavioral experience. The specific types of behavioral experiences that induce long-term plasticity in motor maps appear to be limited to those that entail the development of new motor skills. Moreover, 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. These findings have strong clinical relevance as it has recently been shown that after injury to the motor cortex, as might occur in stroke, post-injury behavioral experience may play an adaptive role in modifying the functional organization of the remaining, intact cortical tissue.

Probability of Regaining Dexterity in the Flaccid Upper Limb

“…Better understanding of the different time frames for mechanisms that contribute to functional recovery such as plasticity, a gradual reversal of diaschisis, 24 and behavioral mechanisms that allow compensation strategies 25 may have a significant impact on rehabilitation management of patients.…”

Neurorestorative treatment of stroke: Cell and pharmacological approaches

“…4 Increasing dendritic arborization and spine density are potential morphological strategies for enabling the brain to reorganize its neuronal circuits. 5 Functional alterations in motor cortex organization are accompanied by changes in dendritic and synaptic structure, as well as by alterations in the regulation of cortical neurotransmitter systems. 5,6 After a stroke, synaptic activity is increased in the ischemic boundary zone, as evidenced by increased expression of synaptic proteins such as synaptophysin and growthassociated protein 43.…”

“…5 Functional alterations in motor cortex organization are accompanied by changes in dendritic and synaptic structure, as well as by alterations in the regulation of cortical neurotransmitter systems. 5,6 After a stroke, synaptic activity is increased in the ischemic boundary zone, as evidenced by increased expression of synaptic proteins such as synaptophysin and growthassociated protein 43. These proteins are amplified with successful neurorestorative treatments.…”

Neurophysiological assessment of lower-limb voluntary control in incomplete spinal cord injury

“…9 The promise of new treatment approaches and their likely incremental effects on voluntary control demands objective measures with greater sensitivity be employed to assess their effectiveness. The attempted therapeutic manipulation of neuroplasticity [10][11][12] to modify neural circuitry through neural implantation 13 and molecular manipulation of surviving neural structures 14 will require objective quantification methods to reach clinical practice.…”