Poster C45, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Effects of emotion, load, distraction, and dopamine tone on working memory and associated neural function in veterans with mTBI and/or PTSD
Michael Ballard1,2, Taylor Vega1,2, Andrew Kayser1,2; 1Weill Institute for Neurosciences, University of California, San Francisco, 2VA Northern California Health Care System
Individuals with a history of mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) often report persistent memory deficits, increased distractibility, and feeling overwhelmed in emotional situations. Studies of working memory in these populations typically employ tasks that don’t include emotional arousal or distraction, potentially leading to equivocal results. We administered an emotional working memory task with distraction to veterans with mTBI and/or PTSD in the context of a pharmacological intervention, tolcapone, thought to selectively enhance cortical dopamine tone and thereby to improve task performance. Seventeen (40 planned) veterans have received a single dose of tolcapone and placebo in counterbalanced fashion while fMRI images were obtained. Memory was worse for fearful versus neutral faces, and after distraction by congruent (faces) relative to incongruent (places) stimuli. Response times were also slower following arousing versus neutral distractors, consistent with greater activation in ventral visual areas, lateral temporoparietal regions, and the posterior cingulate during presentation of arousing versus neutral distractors. On high load trials, subjects’ memory accuracy was lower and response times higher than on low load trials, but neural activation was not greater. However, a main effect of drug condition was found in multiple regions including the fronto-parietal attention network and striatum during encoding in the high-minus-low load conditions. Our task thus demonstrates potential effects of emotion, load, distraction, and dopamine tone on working memory in individuals with mTBI and/or PTSD, and once sufficiently powered, will be used to investigate individual differences in behavioral and neural responses to tolcapone.
Topic Area: EXECUTIVE PROCESSES: Working memory