Diffuse axonal injury (DAI) is defined as damage to axons in the white matter of the brain. DAI can be difficult to detect using traditional imaging techniques, such as CT or MRI scans. However, diffusion tensor imaging (DTI) is a type of MRI scan that traces water movement in white matter. DTI can therefore illustrate damage to white matter tracts that occurs from DAI.
A recent study found that damage to specific white matter tracts in the brain, as seen through DTI, was associated with specific memory impairments. Working memory, which is responsible for remembering things in the very short-term, was impaired when there was damage to the superior longitudinal fasciculus. The superior longitudinal fasciculus is a long bundle of axons that extends from the frontal lobe through to the back of the brain at the occipital lobe.
Declarative memory, which is a long-term memory of specific experiences or knowledge, was impaired with there was damage to the fornix. The fornix is a relatively small area of white matter tracts related to the hippocampus.
The results of this study not only contribute to the understanding of how memory processes are distributed in the brain, but also how specific memory impairments can be linked to specifically damaged areas.
Palacios EM, Fernandez-Espejo D, Junque C, et al. Diffusion tensor imaging differences related to memory deficits in diffuse traumatic brain injury. BMC Neurology. (March 2011).