Stimuli In Posttraumatic Stress Disorder Research Articles

Exaggerated amygdala activation to ambiguous facial expressions is a familial vulnerability factor for posttraumatic stress disorder

ObjectivePrevious research has reported hyperresponsivity in the amygdala and hyporesponsivity in ventral portions of the medial prefrontal cortex to threat-related stimuli in posttraumatic stress disorder (PTSD). Whether such findings generalize to more ambiguous stimuli and whether such brain activation abnormalities reflect familial vulnerabilities, trauma-exposure, or acquired characteristics of PTSD remain unclear. In this study, we measured brain responses to emotionally ambiguous stimuli (i.e., surprised facial expressions) in identical twin pairs discordant for trauma exposure to elucidate the origin of brain activation abnormalities. MethodsParticipants with PTSD (n = 12) and their trauma-unexposed identical cotwins (n = 12), as well as trauma-exposed participants without PTSD (n = 15) and their trauma-unexposed identical cotwins (n = 15), passively viewed surprised and neutral facial expressions during functional magnetic resonance imaging (fMRI). Afterward, participants labeled and rated each facial expression on valence and arousal. ResultsAmygdala activation to Surprised and Neutral facial expressions (versus Fixation) was greater in the participants with PTSD and their trauma-unexposed identical cotwins without PTSD, compared to the control twin pairs. In contrast, medial frontal gyrus (MFG) activation to Surprised facial expressions (versus Fixation) was diminished in the PTSD group relative to the other three groups. ConclusionsAmygdala hyperresponsivity to emotionally ambiguous facial expressions may be a familial vulnerability factor that increases the likelihood of developing PTSD after experiencing a traumatic event. In contrast, MFG hyporesponsivity may be an acquired characteristic of the disorder.

Attentional bias toward negative stimuli in PTSD: an eye-tracking study.

Research on biased processing of aversive stimuli in posttraumatic stress disorder (PTSD) has produced inconsistent results between response time (RT) and eye-tracking studies. Recent RT-based results of dot-probe studies showed no attentional bias (AB) for threat while eye-tracking research suggested heightened sustained attention for this information. Here, we used both RT-based and eye-tracking measures to explore the dynamics of AB to negative stimuli in PTSD. Twenty-three individuals diagnosed with PTSD, 23 trauma-exposed healthy controls, and 23 healthy controls performed an emotional dot-probe task with pairs of negative and neutral scenes presented for either 1 or 2 s. Analyses included eye movements during the presentation of the scenes and RT associated with target localization. There was no evidence for an AB toward negative stimuli in PTSD from RT measures. However, the main eye-tracking results revealed that all three groups showed longer dwell times on negative pictures than neutral pictures at 1 s and that this AB was stronger for individuals with PTSD. Moreover, although AB disappeared for the two groups of healthy controls with prolonged exposure, it persisted for individuals with PTSD. PTSD is associated with an AB toward negative stimuli, characterized by heightened sustained attention toward negative scenes once detected. This study sheds light on the dynamics of AB to negative stimuli in PTSD and encourages us to consider optimized therapeutic interventions targeting abnormal AB patterns.

Attention allocation to negatively-valenced stimuli in PTSD is associated with reward-related neural pathways.

In a recent eye-tracking study we found a differential dwell time pattern for negatively-valenced and neutral faces among patients with posttraumatic stress disorder (PTSD), trauma-exposed healthy control (TEHCs), and healthy control (HC) participants. Here, we explored whether these group differences relate to resting-state functional connectivity (rsFC) patterns of brain areas previously linked to both attention processes and PTSD. These encompass the amygdala, dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (dlPFC), ventrolateral prefrontal cortex (vlPFC), and nucleus accumbens (NAcc). Ten minutes magnetic resonance imaging rsFC scans were recorded in 17 PTSD patients, 21 TEHCs, and 16 HCs. Participants then completed a free-viewing eye-tracking task assessing attention allocation outside the scanner. Dwell time on negatively-valenced stimuli (DT%) were assessed relative to functional connectivity in the aforementioned seed regions of interest (amygdala, dACC, dlPFC, vlPFC, and NAcc) to whole-brain voxel-wise rsFC. As previously reported, group differences occurred in attention allocation to negative-valence stimuli, with longer dwell time on negatively valence stimuli in the PTSD and TEHC groups than the HC group. Higher DT% correlated with weaker NAcc-orbitofrontal cortex (OFC) connectivity in patients with PTSD. Conversely, a positive association emerged in the HC group between DT% and NAcc-OFC connectivity. While exploratory in nature, present findings may suggest that reward-related brain areas are involved in disengaging attention from negative-valenced stimuli, and possibly in regulating ensuing negative emotions.

The Effect of Blue Light Therapy on Functional Brain Responses to Masked Fearful Stimuli in Post-Traumatic Stress Disorder

Post-Traumatic Stress Disorder (PTSD) is often associated with an increased emotional response to aversive stimuli. Blue Light Therapy (BLT) is effective for improving sleep and mood in a number of psychological disorders but has not yet been evaluated as a treatment for PTSD. We hypothesized that 6 weeks of daily morning BLT, in comparison to Amber (placebo) Light Therapy (ALT), would lead to significant improvements in PTSD severity as well as reduced functional brain responses to subliminal presentation of threat.

Dwelling on verbal but not pictorial threat cues: An eye-tracking study with adult survivors of childhood interpersonal violence.

Previous studies have found evidence of an attentional bias for trauma-related stimuli in posttraumatic stress disorder (PTSD) using eye-tracking (ET) technlogy. However, it is unclear whether findings for PTSD after traumatic events in adulthood can be transferred to PTSD after interpersonal trauma in childhood. The latter is often accompanied by more complex symptom features, including, for example, affective dysregulation and has not yet been studied using ET. The aim of this study was to explore which components of attention are biased in adult victims of childhood trauma with PTSD compared to those without PTSD. Female participants with (n = 27) or without (n = 27) PTSD who had experienced interpersonal violence in childhood or adolescence watched different trauma-related stimuli (Experiment 1: words, Experiment 2: facial expressions). We analyzed whether trauma-related stimuli were primarily detected (vigilance bias) and/or dwelled on longer (maintenance bias) compared to stimuli of other emotional qualities. For trauma-related words, there was evidence of a maintenance bias but not of a vigilance bias. For trauma-related facial expressions, there was no evidence of any bias. At present, an attentional bias to trauma-related stimuli cannot be considered as robust in PTSD following trauma in childhood compared to that of PTSD following trauma in adulthood. The findings are discussed with respect to difficulties attributing effects specifically to PTSD in this highly comorbid though understudied population. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Posttraumatic stress disorder and the social brain: Affect-related disruption of the default and mirror networks.

Social cognitive impairments, specifically in mentalizing and emotion recognition, are common and debilitating symptoms of posttraumatic stress disorder (PTSD). Despite this, little is known about the neurobiology of these impairments, as there are currently no published neuroimaging investigations of social inference in PTSD. Trauma-exposed veterans with and without PTSD (n = 20 each) performed the Why/How social inference task during functional magnetic resonance imaging (fMRI). Patients with PTSD had two fMRI sessions, between which they underwent affect labeling training. We probed the primary networks of the "social brain"-the default mode network (DMN) and mirror neuron system (MNS)-by examining neural activity evoked by mentalizing and action identification prompts, which were paired with emotional and nonemotional targets. Hyperactivation to emotional stimuli differentiated PTSD patients from controls, correlated with symptom severity, and predicted training outcomes. Critically, these effects were nonsignificant or marginal for nonemotional stimuli. Results were generally consistent throughout DMN and MNS. Unexpectedly, effects were nonsignificant in core affect regions, but robust in regions that overlap with the dorsal attention, ventral attention, and frontoparietal control networks. The array of social cognitive processes subserved by DMN and MNS appear to be inordinately selective for emotional stimuli in PTSD. However, core affective processes do not appear to be the primary instigators of such selectivity. Instead, we propose that affective attentional biases may instigate widespread affect-selectivity throughout the social brain. Affect labeling training may inhibit such biases. These accounts align with numerous reports of affect-biased attentional processes in PTSD.

Characterizing emotional Stroop interference in posttraumatic stress disorder, major depression and anxiety disorders: A systematic review and meta-analysis.

BackgroundPosttraumatic stress disorder is a debilitating psychiatric disorder characterized by symptoms of intrusive re-experiencing of trauma, avoidance and hyper-arousal. Diagnosis and treatment of PTSD is further complicated by concurrently occurring disorders, the most frequent being major depressive disorder and anxiety disorders. Previous research highlights that attentional processing in posttraumatic stress disorder is associated with substantial interference by emotional stimuli, a phenomenon also observed in these concurrently occurring psychiatric disorders. However, the diagnosis-relevance of this interference remains elusive. Here, we investigated the emotional Stroop interference for diagnosis-related stimuli, generally negative stimuli, and generally positive stimuli in posttraumatic stress disorder, major depressive disorder and anxiety disorders.MethodsWe performed a systematic database search in PubMed (Medline), Cochrane Library and PsycINFO on emotional Stroop performance in individuals with a diagnosis of posttraumatic stress disorder, major depressive disorder or anxiety disorders separately. Mean effect sizes, standard errors and confidence intervals were estimated for each clinical group and healthy control group comparison using random effect models.ResultsAs compared to healthy control group, the posttraumatic stress disorder group displayed greater interference by diagnosis-related stimuli and positive stimuli but not for generally negative stimuli. The major depressive disorder and anxiety disorders groups showed greater interference by diagnosis-related and negative stimuli, but not by positive stimuli. The age and sex had no significant impact on interference.ConclusionsThese findings highlight the importance of diagnosis-relevant information on attentional processing in all three clinical populations, posttraumatic stress disorder, major depressive disorder and anxiety disorders. Further, the impact of generally negative stimuli but not generally positive stimuli in major depressive disorder and anxiety disorders indicate impaired attentional bias for mood-congruent stimuli but not for general stimuli. Finally, it remains to be studied whether the influence of generally positive stimuli in posttraumatic stress disorder indicate that positive stimuli are perceived as PTSD related.

Associability-modulated loss learning is increased in posttraumatic stress disorder.

Disproportionate reactions to unexpected stimuli in the environment are a cardinal symptom of posttraumatic stress disorder (PTSD). Here, we test whether these heightened responses are associated with disruptions in distinct components of reinforcement learning. Specifically, using functional neuroimaging, a loss-learning task, and a computational model-based approach, we assessed the mechanistic hypothesis that overreactions to stimuli in PTSD arise from anomalous gating of attention during learning (i.e., associability). Behavioral choices of combat-deployed veterans with and without PTSD were fit to a reinforcement learning model, generating trial-by-trial prediction errors (signaling unexpected outcomes) and associability values (signaling attention allocation to the unexpected outcomes). Neural substrates of associability value and behavioral parameter estimates of associability updating, but not prediction error, increased with PTSD during loss learning. Moreover, the interaction of PTSD severity with neural markers of associability value predicted behavioral choices. These results indicate that increased attention-based learning may underlie aspects of PTSD and suggest potential neuromechanistic treatment targets.

Is autonoetic recollection of threat in PTSD related to impaired inhibitory skills?

IntroductionIntrusive traumatic reminiscences are among the most distressing and salient characteristics of post-traumatic stress disorder (PTSD). Associated with involuntary onsets, emotional disturbances and consciousness-related impairments, such symptoms suggest that memory functioning could be impaired in PTSD. While there is a growing body of research on experimental assessments of memory in patients with PTSD, inconsistent results remain.ObjectiveUsing an experimental methodology, this study aims to measure memory in PTSD in consideration of central features of intrusive symptoms, especially emotional, inhibitory and consciousness-related memory impairments.Method34 patients diagnosed with PTSD were compared with 37 non-PTSD controls on an item-cued directed forgetting paradigm for emotional words combined with a remember/know recognition procedure.ResultsResults confirmed prior findings of an increased and peculiarly conscious recognition of trauma-related words in PTSD. Interestingly, our results showed that, despite general memory inhibitory deficits, PTSD patients, if requested, presented a preserved ability to inhibit this improved recollection of trauma-related words.ConclusionWhile our findings highlight a biased memory functioning in favour of threatening stimuli in PTSD, inhibitory deficits for such information was not reported to play a role on this effect. Conversely, it seems that instead of inhibitory deficits, patients presented a preferential treatment of threat concordant with vigilant-avoidant models of information processing. Focusing on memory impairment in treatment for PTSD appears of prime importance. Our findings regarding preserved inhibitory skills for threat memories in the disorder could be an interesting clue for therapeutic interventions on intrusive symptoms.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Dissociation between amygdala and bed nucleus of the stria terminalis during threat anticipation in female post-traumatic stress disorder patients.

Feelings of uncontrollability and anxiety regarding possibly harmful events are key features of post-traumatic stress disorder (PTSD) symptomatology. Due to a lack of studies, the neural correlates of anticipatory anxiety in PTSD are still poorly understood. During functional magnetic resonance imaging, female PTSD patients with interpersonal violence trauma and healthy controls (HC) anticipated the temporally unpredictable presentation of aversive (human scream) or neutral sounds. Based on separate analysis models, we investigated phasic and sustained brain activations. PTSD patients reported increased anxiety during anticipation of aversive versus neutral sounds. Furthermore, we found both increased initial, phasic amygdala activation and increased sustained activation of the bed nucleus of the stria terminalis (BNST) during anticipation of aversive versus neutral sounds in PTSD patients in comparison to HC. PTSD patients as compared with HC also showed increased phasic responses in mid-cingulate cortex (MCC), posterior cingulate cortex (PCC), mid-insula and lateral prefrontal cortex (PFC) as well as increased sustained responses in MCC, PCC, anterior insula and lateral and medial PFC. Our results demonstrate a relationship between anticipatory anxiety in PTSD patients and hyperresponsiveness of brain regions that have previously been associated with PTSD symptomatology. Additionally, the dissociation between amygdala and BNST indicates distinct temporal and functional characteristics and suggests that phasic fear and sustained anxiety responses are enhanced during unpredictable anticipation of aversive stimuli in PTSD. Hum Brain Mapp 38:2190-2205, 2017. © 2017 Wiley Periodicals, Inc.

Reduced amygdala responsivity during conditioning to trauma-related stimuli in posttraumatic stress disorder.

Exaggerated conditioned fear responses and impaired extinction along with amygdala overactivation have been observed in posttraumatic stress disorder (PTSD). These fear responses might be triggered by cues related to the trauma through higher-order conditioning, where reminders of the trauma may serve as unconditioned stimuli (US) and could maintain the fear response. We compared arousal, valence, and US expectancy ratings and BOLD brain responses using fMRI in 14 traumatized persons with PTSD and 14 without PTSD (NPTSD) and 13 matched healthy controls (HC) in a differential aversive conditioning paradigm. The US were trauma-specific pictures for the PTSD and NPTSD group and equally aversive and arousing for the HC; the conditioned stimuli (CS) were graphic displays. During conditioning, the PTSD patients compared to the NPTSD and HC indicated higher arousal to the conditioned stimulus that was paired with the trauma picture (CS+) compared to the unpaired (CS-), increased dissociation during acquisition and extinction, and failure to extinguish the CS/US-association compared to NPTSD. During early and late acquisition, the PTSD patients showed a significantly lower amygdala activation to CS+ versus CS- and a negative interaction between activation in the amygdala and dorsolateral prefrontal cortex (PFC), while NPTSD and HC displayed a negative interaction between amygdala and medial PFC. These findings suggest maladaptive anticipatory coping with trauma-related stimuli in patients with PTSD, indicated by enhanced conditioning, with related abnormal amygdala reactivity and connectivity, and delayed extinction.

Threat modulation of visual search efficiency in PTSD: A comparison of distinct stimulus categories

Although an attentional bias for threat has been implicated in posttraumatic stress disorder (PTSD), the cues that best facilitate this bias are unclear. Some studies utilize images and others utilize facial expressions that communicate threat. However, the comparability of these two types of stimuli in PTSD is unclear. The present study contrasted the effects of images and expressions with the same valence on visual search among veterans with PTSD and controls. Overall, PTSD patients had slower visual search speed than controls. Images caused greater disruption in visual search than expressions, and emotional content modulated this effect with larger differences between images and expressions arising for more negatively valenced stimuli. However, this effect was not observed with the maximum number of items in the search array. Differences in visual search speed by images and expressions significantly varied between PTSD patients and controls for only anger and at the moderate level of task difficulty. Specifically, visual search speed did not significantly differ between PTSD patients and controls when exposed to angry expressions. However, PTSD patients displayed significantly slower visual search than controls when exposed to anger images. The implications of these findings for better understanding emotion modulated attention in PTSD are discussed.

Altered processing of visual emotional stimuli in posttraumatic stress disorder: an event-related potential study

Patients with posttraumatic stress disorder (PTSD) display abnormal emotional processing and bias towards emotional content. Most neurophysiological studies in PTSD found higher amplitudes of event-related potentials (ERPs) in response to trauma-related visual content. Here we aimed to characterize brain electrical activity in PTSD subjects in response to non-trauma-related emotion-laden pictures (positive, neutral and negative). A combined behavioral-ERP study was conducted in 14 severe PTSD patients and 14 controls. Response time in PTSD patients was slower compared with that in controls, irrespective to emotional valence. In both PTSD and controls, response time to negative pictures was slower compared with that to neutral or positive pictures. Upon ranking, both control and PTSD subjects similarly discriminated between pictures with different emotional valences. ERP analysis revealed three distinctive components (at ~300, ~600 and ~1000ms post-stimulus onset) for emotional valence in control subjects. In contrast, PTSD patients displayed a similar brain response across all emotional categories, resembling the response of controls to negative stimuli. We interpret these findings as a brain-circuit response tendency towards negative overgeneralization in PTSD.

Heightened attentional capture by threat in veterans with PTSD.

Although an attentional bias for threat-relevant cues has been theorized in posttraumatic stress disorder (PTSD), to date empirical demonstration of this phenomenon has been at best inconsistent. Furthermore, the nature of this bias in PTSD has not been clearly delineated. In the present study, veterans with PTSD (n = 20), trauma-exposed veterans without PTSD (n = 16), and healthy nonveteran controls (n = 22) completed an emotional attentional blink task that measures the extent to which emotional stimuli capture and hold attention. Participants searched for a target embedded within a series of rapidly presented images. Critically, a combat-related, disgust, positive, or neutral distracter image appeared 200 ms, 400 ms, 600 ms, or 800 ms before the target. Impaired target detection was observed among veterans with PTSD relative to both veterans without PTSD and healthy nonveteran controls after only combat-related threat distracters when presented 200 ms, 400 ms, or 600 ms before the target, indicating increased attentional capture by cues of war and difficulty disengaging from such cues for an extended period. Veterans without PTSD and healthy nonveteran controls did not significantly differ from each other in target detection accuracy after combat-related threat distracters. These data support the presence of an attentional bias toward combat related stimuli in PTSD that should be a focus of treatment efforts.

Attentional bias for affective visual stimuli in posttraumatic stress disorder and the role of depression

An attentional bias for trauma-related verbal cues was frequently demonstrated in posttraumatic stress disorder (PTSD) using variants of the emotional Stroop task (EST). However, the mechanisms underlying the Stroop-effect are ill-defined and it is yet unclear how the findings apply to different paradigms and stimulus modalities. To address these open questions, for the first time a spatial-cuing task with pictorial cues of different emotional valence was administered to trauma-exposed individuals with and without PTSD, and non-trauma-exposed controls. Groups did not show different response profiles across affective conditions. However, a group effect was evident when comparing depressed with non-depressed individuals: Those with depression showed delayed attending towards trauma-related cues and faster attending away from negative cues. In correlational analyses, attentional avoidance was associated with both depression and PTSD symptom severity. These findings highlight the need for research on trauma populations and anxiety in general to pay closer attention to depression as an important confound in the study of emotional information processing.

P-987 - Investigation of autonomic response changes to traumatic stimuli in posttraumatic stress disorder using neurovisceral integral model

Studies support the view that the balance of autonomic nervous system shifts to sympathetic direction and that there is a suppression on the parasympathetic system in Posttraumatic Stres Disorder(PTSD). Basal and post-traumatic-stimulus measurements were made with HRV (Heart Rate Variability) on soldiers diagnosed with PTSD. The data were compared with control group. The sample of this study consisted of 27 patients diagnosed with PTSB according to the DSM-IV criteria and 23 healthy control. Holter recording device was installed in all subjects for 2 hours. Then a slide show was shown with a total of 120 pieces of traumatic experience photographes about six minutes in duration. And Holter recording was continued for another 2 hours. After exposing to the photographes, in control group: RMSSD, NN 50 Count and pNN 50 parameters of HRV increased as an indicator of parasympathetic activation; SDANN and SDNN decreased as an indicator of dominance of parasympathetic system to sympathetic system. But in patient group after exposing to the photographes; SDNN and SDANN increased as an indicator of sympathetic activation and RMSSD and pNN 50 decreased as an indicator of dominance of sympathetic system to parasympathetic system. Patient group results indicate parasympathetic failure. This was thought to be related to insufficiant prefrontal inhibition. HRV is thought to be used for detection of short-and long-term change of the sympathovagal balance. It is evaluated that the severity of autonomic symptoms may have predictive about the development of the disease and may be a guide for treatment.

An fMRI study of unconditioned responses in post-traumatic stress disorder

BackgroundBoth fear and pain processing are altered in post-traumatic stress disorder (PTSD), as evidenced by functional neuroimaging studies showing increased amygdala responses to threats, and increased insula, putamen and caudate activity in response to heat pain. Using psychophysiology and functional magnetic resonance imaging, we studied conditioned and unconditioned autonomic and neuronal responses in subjects with PTSD versus trauma-exposed non-PTSD control (TENC) subjects. A design using an electric shock selected by subjects to be 'highly annoying but not painful' as an unconditioned stimulus (US) with partially reinforced cues allowed us to partly disentangle the expectancy- and prediction-error components from sensory components of the unconditioned response.ResultsWhereas responses to the conditioned stimulus (CS) were similar in PTSD and TENC, the former displayed higher putamen, insula, caudate and amygdala responses to the US. Reactivity to the US in the anterior insula correlated with PTSD symptom severity. Functional connectivity analyses using the putamen as a seed region indicated that TENC subjects had increased amygdala-putamen connectivity during US delivery; this connection was disengaged in PTSD.ConclusionsOur results indicate that although neural processing of fear learning in people with PTSD seems to be comparable with controls, neural responses to unconditioned aversive stimuli in PTSD seem to be increased.

Decreased regional cerebral blood flow in medial prefrontal cortex during trauma-unrelated stressful imagery in Vietnam veterans with post-traumatic stress disorder

Neuroimaging research has demonstrated medial prefrontal cortex (mPFC) hyporesponsivity and amygdala hyperresponsivity to trauma-related or emotional stimuli in post-traumatic stress disorder (PTSD). Relatively few studies have examined brain responses to the recollection of stressful, but trauma-unrelated, personal events in PTSD. In the current study, we sought to determine whether regional cerebral blood flow (rCBF) abnormalities in mPFC and amygdala in PTSD could be observed during the recollection of trauma-unrelated stressful personal events. Participants were 35 right-handed male combat veterans (MCVs) and female nurse veterans (FNVs) who served in Vietnam: 17 (seven male, 10 female) with current military-related PTSD and 18 (nine male, nine female) with no current or lifetime PTSD. We used positron emission tomography (PET) and script-driven imagery to study rCBF during the recollection of trauma-unrelated stressful versus neutral and traumatic events. Voxelwise tests revealed significant between-group differences for the trauma-unrelated stressful versus neutral comparison in mPFC, specifically in the anterior cingulate cortex (ACC). Functional region of interest (ROI) analyses demonstrated that this interaction in mPFC represented greater rCBF decreases in the PTSD group during trauma-unrelated stressful imagery relative to neutral imagery compared to the non-PTSD group. No differential amygdala activation was observed between groups or in either group separately. Veterans with PTSD, compared to those without PTSD, exhibited decreased rCBF in mPFC during mental imagery of trauma-unrelated stressful personal experiences. Functional neuroanatomical models of PTSD must account for diminished mPFC responses that extend to emotional stimuli, including stressful personal experiences that are not directly related to PTSD.

Eye tracking and physiological reactivity to threatening stimuli in posttraumatic stress disorder

This study tested the vigilance-avoidance model of anxiety and attention bias in posttraumatic stress disorder (PTSD). This study used eye tracking technology to record initial fixations, pupil dilation, fixation time and concurrent skin conductance response to examine initial orienting towards threat stimuli and subsequent fixations. Twenty-one traumatized participants (11 diagnosed with PTSD and 10 trauma-exposed participants without PTSD) viewed 32 stimuli (with four words in each quadrant). Sixteen trials contained a trauma-relevant word in one quadrant and 16 had four neutral words. PTSD patients reported significantly greater number of initial fixations to trauma words, and a greater number of skin conductance responses to initial threat fixations. There were no significant differences in subsequent fixations to trauma words between groups. Although this study provides evidence of attentional bias towards threat that is accompanied by specific autonomic arousal, it does not indicate subsequent avoidance of threat stimuli in PTSD.

The Neurocircuitry of Fear, Stress, and Anxiety Disorders

Anxiety disorders are a significant problem in the community, and recent neuroimaging research has focused on determining the brain circuits that underlie them. Research on the neurocircuitry of anxiety disorders has its roots in the study of fear circuits in animal models and the study of brain responses to emotional stimuli in healthy humans. We review this research, as well as neuroimaging studies of anxiety disorders. In general, these studies have reported relatively heightened amygdala activation in response to disorder-relevant stimuli in post-traumatic stress disorder, social phobia, and specific phobia. Activation in the insular cortex appears to be heightened in many of the anxiety disorders. Unlike other anxiety disorders, post-traumatic stress disorder is associated with diminished responsivity in the rostral anterior cingulate cortex and adjacent ventral medial prefrontal cortex. Additional research will be needed to (1) clarify the exact role of each component of the fear circuitry in the anxiety disorders, (2) determine whether functional abnormalities identified in the anxiety disorders represent acquired signs of the disorders or vulnerability factors that increase the risk of developing them, (3) link the findings of functional neuroimaging studies with those of neurochemistry studies, and (4) use functional neuroimaging to predict treatment response and assess treatment-related changes in brain function. (Reprinted with permission from Neuropsychopharmacology Reviews 2010; 35:169–191)