Monthly Archives: September 2010
The specific brain areas related to memory impairment in mTBI
Two main areas of the brain associated with memory are the medial temporal lobe, which houses the hippocampus and is thought to be responsible for consolidating new information into long-term memory, and the pre-frontal cortex, which has been found to be related to attention and short-term memory.
In mild traumatic brain injury, one of the most common complaints is memory impairment. A recent functional MRI (fMRI) study that compared mTBI patients to healthy individuals found that mTBI patients showed reduced activation in the medial temporal lobe when performing a memory task. Surprisingly, there was no difference in activation in the pre-frontal cortex between mTBI patients and healthy individuals. The reduction in medial temporal lobe activation was correlated with a reduction in task score.
This implies that the memory impairment may be directly related to medial temporal lobe damage. However, why the medial temporal lobe seems to be more vulnerable in mTBI or how rehabilitation can address these deficits are questions that still remain.
Sulemeijer M, Vos PE, Ven Der Werf S, et al. How mild traumatic brain injury may affect declarative memory performance in the post-acute stage. Journal of Neurotrauma. (July 2010).
Degeneration of Peripheral Motor Axons After Spinal Cord Injury
Peripheral motor axons are the long neural tracts that connect the spinal cord to muscle. When the spinal cord is traumatized, these tracts can degenerate from lack of input and activation, leading them to become weak and inactive.
Using compound muscle action potentials, a tool that (in simple terms) measures the ability of the motor axon to activate when stimulated, a research team found significant decreases in remote peripheral nerves in spinal cord injury patients. These peripheral nerves included the abductor digiti minimi and the abductor hallucis. This decrease, however, could be significantly recovered within 5-12 months after injury.
Since recovery was associated with increased muscle strength, spinal cord injury rehabilitation efforts should focus on these specific peripheral nerves.
Van De Meent H, Hosman AJF, Hendriks J, Zwarts M, & Schubert M. Severe degeneration of peripheral motor axons after spinal cord injury: A European multicenter study. Neurorehabilitation and Neural Repair. (May 2010).
