Neuroimaging in Posttraumatic Stress Disorder and Other Stress-Related Disorders

Abstract

SynopsisTraumatic stress has a broad range of effects on the brain. Brain areas implicated in the stress response include the amygdala, hippocampus, and prefrontal cortex. Studies in patients with posttraumatic stress disorder (PTSD) and other psychiatric disorders related to stress have replicated findings in animal studies by finding alterations in these brain areas. Brain regions implicated in PTSD also play an important role in memory function, highlighting the important interplay between memory and the traumatic stress response. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders. EFFECTS OF TRAUMATIC STRESS ON THE INDIVIDUALTraumatic stressors including childhood abuse can lead to posttraumatic stress disorder (PTSD), as well as depression [1,2], substance abuse [3,4], dissociative disorders [5], personality disorders [6,7], and health problems [8]. For many trauma victims, PTSD, which affects about 8% of Americans at some time in their lives [3], may be a life-long problem [9]. However, the development of effective treatments is limited by gaps in knowledge about the underlying neurobiological mechanisms that mediate symptoms of trauma related disorders like PTSD. Until twelve years ago, no brain imaging studies had been performed in patients with PTSD or other stress-related psychiatric disorders. The past decade has seen an explosion of research using brain imaging to assess the effects of traumatic stress on the brain [10]. These studies have implicated the amygdala, hippocampus, and medial prefrontal cortex (including anterior cingulate) in PTSD and other stress related psychiatric disorders. This chapter reviews brain imaging studies looking at the effects of traumatic stress on the brain, and integrates them with basic science findings on the neuroscience of stress. NEURAL CIRCUITS OF PTSDPTSD is characterized by specific symptoms, including intrusive thoughts, hyperarousal, flashbacks, nightmares, and sleep disturbances, changes in memory and concentration, and startle responses. Symptoms of PTSD are hypothesized to represent the behavioral manifestation of stress-induced changes in brain structure and function. Stress results in acute and chronic changes in neurochemical systems and specific brain regions, which result in longterm changes in brain "circuits" involved in the stress response [11][12][13][14]. Brain regions that are

Altered behavior and neural activity in conspecific cagemates co-housed with mouse models of brain disorders

“…Neural activity in the mPFC is important to regulate both social behavior and emotional expression, and optogenetic elevation of an excitation/inhibition balance in mPFC leads social dysfunction [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] Cagemate mice were subjected to behavioral tasks 4 weeks following the cessation of 6-week cohousing. …”

“…Disruption of the anatomical and functional interconnections between these areas is consistently implicated as a key mediating factor of brain disorders such as depression, bipolar disorder, post-traumatic stress disorder, and schizophrenia [37][38][39][40][41][42][43][44][45][46][47]. The PFC specifically is a key brain region for social recognition, interaction, and regulation of emotion [48][49][50][51][52], and it performs complicated functions by forming reciprocal neural connections with the amygdala (emotion) and the hippocampus (memory) [22,[31][32][33][34]36].…”

Smaller grey matter volumes in the anterior cingulate cortex and greater cerebellar volumes in patients with long-term remission of Cushing's disease: a case–control study

“…The amygdala and hippocampus are connected to the anterior regions of the ACC and constitute a neural circuitry for stress reactivity and modulation (37). Dysfunction of this circuitry is implicated in mood and anxiety disorders (38). In addition, patients with stress-related psychopathology show a reduced volume of the ACC (39,40).…”

Assessment of cognitive functions in individuals with post-traumatic symptoms after work-related accidents

“…Hyperactivation of emotional representations would determine increased interference by emotional distracters, because emotional representations would compete more strongly with task-relevant representations causing greater disruption of task performance (Buckley et al, 2000;McNally, 2006;Vythilingam et al, 2007). Alternatively, failure of top-down inhibition of the amygdala by the medial prefrontal cortex might determine inadequate priming of taskrelevant representations such that emotional distractors cause excessive interference (Bremner, 2007;Vythilingam et al, 2007). More generally, the prefrontal cortex plays a critical role in the ability to sustain attention, inhibit inappropriate responses, monitor performance, evaluate action outcomes, and encode and retrieve information from memory (Ridderinkhof, van den Wildenberg, Segalowitz, & Carter, 2004), so that reduced activity in this brain structure would affect cognitive functioning well beyond that related with the processing of trauma-related stimuli.…”