Special Features Of Motor Cortices

Rehabilitationists can begin to consider the contribution of the cortical nodes in the motor system to motor control, to anticipate how the activity of clusters of neurons may vary in relation to different tasks, to test for their dysfunction, and to adapt appropriate interventions. For example, patients with lesions that interrupt the corticocortical projections from somatosensory cortex to the primary motor cortex might have difficulty learning new motor skills, but they may be able to execute existing motor skills.67 The lateral premotor areas, especially BA 46 and 9, receive converging visual, auditory, and other sensory inputs that integrate planned motor acts. As discussed later in the section on working memory (see Working Memory and Executive Function Network, these regions have an important role in the temporal organization of behaviors, including motor sets and motor sequences.68 In the presence of a lesion that destroys or disconnects some motor areas, a portion of the distributed functional network for relearning a movement or learning a new compensatory skill may be activated best by a strategy that engages non-

primary and associative sensorimotor regions. Therapists may work around the disconnection of a stroke or traumatic brain injury with a strategy that is cued by vision or sound, self-paced or externally paced, proximal limb-directed, goal-based, mentally planned or practiced, or based on sequenced or unsequenced movements. Task-specific practice that utilizes diverse strategies may improve motor skills in part by engaging residual cortical, subcortical, and spinal networks involved in carrying out the desired motor function.69,70 Strategies that engage neuronal assemblies dedicated to imagery and hand functions are of immediate interest as rehabilitation approaches.

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