Neural Correlates of Sense of Effort in Active Duty Military Members with Mild Traumatic Brain Injury

OBJECTIVE: Active duty military members who had and had not sustained one or more mild traumatic brain injuries (mTBI) were compared on an objective measure of sense of effort during functional MRI.BACKGROUND: Since the year 2000, over 333,000 military members have sustained traumatic brain injuries (TBI) [1]. Of these, 82.4[percnt] were mild. Mild traumatic brain injury (mTBI) refers to any injury to the brain resulting from external force that can cause confusion, loss of consciousness for up to 30 minutes, memory loss of up to 24 hours, and diffuse neuronal injury, which can result in cognitive problems [1]. Specifically, TBI often compromises the normal allocation of resources for attention and determination of effort. As service members who sustained brain injuries return from Iraq and Afghanistan, it is increasingly important to determine the relationship between effort and cognitive complaint in this population.DESIGN/METHODS: Active duty soldiers deployed to OIF/OEF/Endura with and without mTBI were recruited (n=140). fMRI scans were collected during a constant effort task (measuring rate of fatigue) [2] and an estimated effort task (measuring perception of effort) [3]. BOLD activation contrasted each task condition with rest. Associations between performance on the task and fMRI data are analyzed with MANOVA.RESULTS: Participants with mTBI are expected to perceive increased sense of effort, particularly in conditions of heightened task demands, compared to those without mTBI. Brain function measured by fMRI is also expected to differ between groups, particularly in frontal and parietal regions of the attention network involved in allocation.CONCLUSIONS: Sense of effort is impaired in military members who have sustained mTBI. Participants successful in a cognitive rehabilitation program will demonstrate within-subject changes in sense of effort, and its correlates in brain function, at multiple time points before, midway, and after treatment.Supported by: Department of Defense W81XWH-13-2-0025 Disclosure: Dr. New has nothing to disclose. Dr. Ramage has nothing to disclose. Dr. Robin has nothing to disclose. Dr. Tate has nothing to disclose.