Abstract
Background and ObjectiveThe medial forebrain bundle (MFB) contains ascending catecholamine fibers that project to the prefrontal cortex (PFC). Damage to these fibers following traumatic brain injury (TBI) may alter extracellular catecholamine levels in the PFC and impede attention and working memory ability. This study investigated white matter microstructure of the medial MFB, specifically the supero‐lateral branch (slMFB), following TBI, and its association with performance on attention and working memory tasks.MethodNeuropsychological measures of attention and working memory were administered to 20 moderate‐severe participants with TBI (posttraumatic amnesia M = 40.05 ± 37.10 days, median time since injury 10.48 months, range 3.72–87.49) and 20 healthy controls. Probabilistic tractography was used to obtain fractional anisotropy (FA) and mean diffusivity (MD) values for 17 participants with TBI and 20 healthy controls.ResultsWhen compared to controls, participants with TBI were found to have significantly lower FA (p < .001) and higher MD (p < .001) slMFB values, and they were slower to complete tasks including Trail Making Task‐A, Hayling, selective attention task, n‐back, and Symbol Digit Modalities Test.ConclusionThis study was the first to demonstrate microstructural white matter damage within the slMFB following TBI. However, no evidence was found for an association of alterations to this tract and performance on attentional tasks.
Highlights
Attention and working memory deficits are prevalent cognitive impairments following moderate to severe traumatic brain injury (TBI; Ponsford & Willmott, 2004; Willmott, Ponsford, Hocking, & Schonberger, 2009)
Elucidating TBI-induced disruptions to the DA system and whether they are associated with attention deficits may assist in identifying those most likely to benefit from pharmacological interventions
Using a well-matched sample, TBI participants were found to have reduced fractional anisotropy (FA) and higher mean diffusivity (MD) within the slMFB when compared to controls, indicating microstructural white matter damage caused by diffuse axonal injury (DAI)
Summary
Attention and working memory deficits are prevalent cognitive impairments following moderate to severe traumatic brain injury (TBI; Ponsford & Willmott, 2004; Willmott, Ponsford, Hocking, & Schonberger, 2009). These deficits adversely affect individuals’ ability to work, socialize and function in everyday life The medial forebrain bundle (MFB) contains ascending catecholamine fibers that project to the prefrontal cortex (PFC) Damage to these fibers following traumatic brain injury (TBI) may alter extracellular catecholamine levels in the PFC and impede attention and working memory ability. This study investigated white matter microstructure of the medial MFB, the supero-lateral branch (slMFB), following TBI, and its association with performance on attention and working memory tasks. No evidence was found for an association of alterations to this tract and performance on attentional tasks
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