Plasticity of cortical sensorimotor output maps during recovery from cervical spinal cord injury

The literature suggests that sensorimotor areas of adult brain are capable of adaptive change in response to various experiences. The anatomical and functional consequences of SCI on the human cerebral cortex were examined to determine the relationship between these changes and the recovery of movement post injury.; In the initial experiment, MRI was used to acquire structural images of human cortex to identify grey and white matter atrophy post SCI. No significant difference in either the location or grey matter area of the hand region of M1 was found between a group of individuals with SCI and a group of neurologically healthy control subjects. Voxel-based morphometric analysis of both grey and white matter density found no significant difference across the motor areas of the cortex between the two groups.; The absence of corticomotor neuronal atrophy prompted investigation of the functional organization of M1. FMRI was used to acquire functional activation maps of M1 during wrist and tongue movements. No significant difference in the size and location of wrist movement-related activation was found between the SCI and control groups. Tongue movement-related activation was located significantly more medial, posterior, and superior in the SCI group, reflecting an enlarged volume of activation. This displacement, and expansion, was related to the level of injury, the higher the injury, the greater the displacement.; The final experiment was designed to elucidate the temporal progression of cortical reorganization and determine the relationship with recovery of movement. FMRI was used to acquire functional activation maps of the cortical sensorimotor network at 3--4 time points during the first year post SCI. Shortly after the injury, movement-related M1 activation was decreased and activation in higher-order sensorimotor areas was increased compared to controls. If movement recovered, M1 activation progressively increased while higher-order activation decreased to a level similar to that found in control subjects. If movement did not return, a progressive decrease to almost no activation was seen across the entire network.; These experiments demonstrate that sensorimotor regions of the adult cerebral cortex undergo plastic changes following cervical SCI which may be related to sensorimotor function post injury.