Impaired Motor Learning & Diffuse Axonal Damage In Traumatic Brain Injury

Cognitive-motor functioning or motor skill learning is impaired in humans following traumatic brain injury. A more complete understanding of the mechanisms involved in the disorders is essential for any effective rehabilitation. The specific goals of this study are to examine motor learning disorders, and their relationship to pathological changes in adult rats with closed head injury. Motor learning deficits can be determined by comparing the ability to complete a series of complex motor learning tasks with simple motor activity. In our previous study, extent of neuronal damage was determined using silver impregnation. At all post-injury time points (day 1 to day 14), statistically significant deficits were observed in parallel bar traversing, foot placing, ladder climbing, and rope climbing. Performance improved with time, but never reached control levels.

In contrast, no deficits were found in simple motor activity tested with beam balance and runway traverse. Histologically, axonal degeneration was widely distributed in several brain areas that relate to motor learning, including the white matter of sensorimotor cortex, corpus callosum, striatum, thalamus, and cerebellum. Additionally, severely damaged axons were observed in the primary visual pathway, including the optic chiasm, optic tract, lateral geniculate nuclei, and superior colliculus.

Recent Publications in Peer-reviewed Journal:

Ding, Y-C, Yao , B., Lai, Q., McAllister J.P. (2001) Impaired motor learning and diffuse axonal damage in motor and visual systems of the rat following traumatic brain injury. Neurological Research , Special issue on Neurotrauma. 23:193-202.