N-back Performance with Trauma-Relevant Visual Distractors: Associations with Posttraumatic Stress Symptomatology
2018-09
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N-back Performance with Trauma-Relevant Visual Distractors: Associations with Posttraumatic Stress Symptomatology
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2018-09
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Responses to psychological trauma can range widely from resiliency to psychiatric disability. Posttraumatic stress disorder (PTSD) is one possible outcome following trauma composed of specific symptoms such as intrusive re-experiencing of trauma reminders, avoidance of trauma-related cues, dysphoric mood, and hyperarousal. The existence of PTSD-related cognitive impairments is well documented, but the contributory factors behind these effects are less understood. Questions about cognitive functioning are relevant for recently returning military service members who commonly report past neurological sequelae consistent with mild traumatic brain injury (mTBI) from explosive blasts. There is interest in using laboratory paradigms to tease apart the relative effects of PTSD and mTBI. The attentional control theory proposes misallocations of attentional resources are responsible for cognitive alterations among individuals with anxiety-related disorders. Elevated anxiety may lead to perceptual engagement with task-irrelevant threat, which would require goal-directed attentional resources to inhibit and shift back towards primary task goals. In this way, task effectiveness can be maintained at the cost of inefficiently slowed responding. A cross-sectional sample of veterans from Operations Enduring/Iraqi Freedom (OEF/OIF) were recruited (n = 128) to complete a sequential-letter N-back task superimposed over task-irrelevant neutral images or affectively aversive combat scenes. Consistent with the attentional control theory, individuals with elevated symptoms of PTSD were more inefficient while task efficacy was largely preserved. Response time (RT) variability indices assessing the relative prominence of goal-directed decisional processes failed to produce associations with PTSD. Instead, inefficient cognition was best explained by general psychopathology effects and prolonged engagement with threat by non-decisional mental processes. Event-related potentials (ERPs) to the onset of the task stimuli supported the RT findings. Specific alterations in early engagement with stimulus-driven attentional processing were observed among individuals with elevated PTSD symptomatology. Two-step temporal-spatial decompositions of the ERPs did not reveal any PTSD effects specific to an identified central spatial component. Instead, effects of PTSD were best explained as alterations in perceptual processing most clearly observed within neural activity at a posterior spatial component. Effects of mTBI were isolated to the behavioral indices and resulted in more rather than less efficient engagement with the task. Several key aspects of the attentional control theory were not supported by the results. Alterations in goal-directed attentional systems may not be strictly necessary to produce PTSD-related cognitive inefficiencies. Study findings have implications for alternative models of PTSD using dimensional symptom severity scores.
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University of Minnesota Ph.D. dissertation. September 2018. Major: Psychology. Advisors: Scott Sponheim, Shmuel Lissek. 1 computer file (PDF); viii, 166 pages.
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Marquardt, Craig. (2018). N-back Performance with Trauma-Relevant Visual Distractors: Associations with Posttraumatic Stress Symptomatology. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/201681.
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