Motor training induces experience-specific patterns of plasticity across motor cortex and spinal cord

Abstract

The motor cortex and spinal cord possess the remarkable ability to alter structure and function in response to differential motor training. Here we review the evidence that the corticospinal system is not only plastic but that the nature and locus of this plasticity is dictated by the specifics of the motor experience. Skill training induces synaptogenesis, synaptic potentiation, and reorganization of movement representations within motor cortex. Endurance training induces angiogenesis in motor cortex, but it does not alter motor map organization or synapse number. Strength training alters spinal motoneuron excitability and induces synaptogenesis within spinal cord, but it does not alter motor map organization. All three training experiences induce changes in spinal reflexes that are dependent on the specific behavioral demands of the task. These results demonstrate that the acquisition of skilled movement induces a reorganization of neural circuitry within motor cortex that supports the production and refinement of skilled movement sequences. We present data that suggest increases in strength may be mediated by an increased capacity for activation and/or recruitment of spinal motoneurons while the increased metabolic demands associated with endurance training induce cortical angiogenesis. Together these results show the robust pattern of anatomic and physiological plasticity that occurs within the corticospinal system in response to differential motor experience. The consequences of such distributed, experience-specific plasticity for the encoding of motor experience by the motor system are discussed.

Thinning, movement, and volume loss of residual cortical tissue occurs after stroke in the adult rat as identified by histological and magnetic resonance imaging analysis

“…Firstly, the activation of previously latent neural networks in residual tissue may take on the function of the lost tissue (Sigler et al, 2009); alternatively, enhanced axonal sprouting, synaptogenesis, and dendritic spine turnover (Biernaskie and Corbett, 2001;Brown et al, 2007Gonzalez and Kolb, 2003;Stroemer et al, 1995;Winship and Murphy, 2009) may support reorganization of residual tissue such that it can support the function of the lost tissue. Again, the application of plasticity promoting factors such as environmental enrichment (Williams et al, 2006), behavioural therapy (Adkins et al, 2006;Kleim et al, 2004), pharmacological treatments (MacDonald et al, 2007), and neurotrophic factor application (Monfils et al, 2005) have been shown to facilitate reorganization of cortical maps.…”

“…The size and organization of the "motor map" is altered in response to, and is thus indicative of, cortical injury (Gharbawie et al, 2005;Nudo, 1997;Williams et al, 2006), corticofugal fiber function (Kartje-Tillotson et al, 1987), and motor experience/learning (Adkins et al, 2006;Jacobs and Donoghue, 1991;Kleim et al, 1998Kleim et al, , 2002. Changes in ICMS motor map organization are also often used as a measure of peri-infarct tissue function after focal cortical stroke (Gharbawie et al, 2005).…”

Awareness of Hormesis Will Enhance Future Research in Basic and Applied Neuroscience

“…The latter effects of exercise on cells in the hippocampus may be due, in part, to imposition of a mild stress on the nerve cell during exercise, because levels of several molecular markers of mild stress are increased in response to exercise, including BDNF and vascular endothelial cell growth factor (Cotman et al, 2007). Of course, motor neurons and neurons in the motor cortex, striatum, and cerebellum that effect and control exercise are themselves highly active (and therefore energetically, ionically, and oxidatively stressed) during exercise (Adkins et al, 2006). Neurons in many regions of the brain are "exercised" during cognitive processing of information and are therefore subjected to the same kinds of stress that motor neurons experience during physical exercise.…”

Dynamic Properties of Human Brain Structure: Learning-Related Changes in Cortical Areas and Associated Fiber Connections

“…The adult brain shows a remarkable capacity for morphological alterations during learning or adaption to a changing environment (Markham and Greenough, 2004;Adkins et al, 2006;Draganski and May, 2008). In human subjects, gray and white matter changes can be observed after intensive long-term motor skill learning for several months (Draganski et al, 2004;Scholz et al, 2009).…”