Brain-imaging studies of posttraumatic stress disorder

Reading the mind in the eyes in PTSD: Limited Moderation by the presence of a service dog

Persons with posttraumatic stress disorder (PTSD) frequently experience relationship failures in family and occupational domains resulting in loss of social supports. Prior research has implicated impairments in social cognition. The Reading the Mind in the Eyes Test (RMET) measures a key component of social cognition, the ability to infer the internal states of other persons based on features of the eyes region of the face; however, studies administering this popular test to persons with PTSD have yielded mixed results. This study assessed RMET performance in 47 male U.S. military Veterans with chronic, severe PTSD. Employing a within-subjects design that avoided selection biases, it aimed specifically to determine whether components of RMET performance, including accuracy, response latency, and stimulus dwell time, were improved by the company of a service dog, an intervention that has improved social function in other populations. RMET accuracies and response latencies in this PTSD sample were in the normal range. The presence of a familiar service dog did not improve RMET accuracy, reduce response latencies, or increase dwell times. Dog presence increased the speed of visual scanning perhaps consistent with reduced social fear.

The Molecular Relationship between Stress and Insomnia

The bi-directional relationship between sleep and stress has been actively researched as sleep disturbances and stress have become increasingly common in society. Interestingly, the brain and underlying neural circuits important for sleep regulation may respond uniquely to stress that leads to post-traumatic stress disorder (PTSD) and stress that does not. In stress that does not lead to PTSD, the hypothalamic-pituitary-adrenal axis (HPA) pathway is activated normally that results in sympathetic nervous system activation that allows the brain and body to return to baseline functioning. However, exposure to stress that leads to PTSD, causes enhanced negative feedback of this same pathway and results in long-term physiological and psychological changes. In this review, how stress regulates glucocorticoid signaling pathways in brain glial cells called astrocytes, and then mediates stress-induced insomnia are examined. Astrocytes are critical sleep regulatory cells and their connections to sleep and stress due to disturbed glucocorticoid signaling provide a novel mechanism to explain how stress leads to insomnia. This review will examine the interactions of stress neurobiology, astrocytes, sleep, and glucocorticoid signaling pathways and will examine the how stress that leads to PTSD and stress that does not impacts sleep-regulatory processes.

Neural function during emotion processing and modulation associated with treatment response in a randomized clinical trial for posttraumatic stress disorder

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with exaggerated threat processing and deficits in emotion modulation circuitry. It remains unknown how neural circuits are associated with response to evidence-based treatments for PTSD.

METHOD

We examined associations between PTSD symptoms and indicators of neural response in key emotion processing and modulation regions. Fifty-six military Veterans with PTSD were randomly assigned to one of three evidence-based treatments (prolonged exposure, sertraline, and PE plus sertraline) in a randomized clinical trial ("PROGrESS"; 2018, Contemp Clin Trials, 64, 128-138). Twenty-seven combat-exposed controls (CCs) served as a comparison group at pretreatment. Before and after PTSD treatment, functional magnetic resonance imaging was used to assess brain activation and connectivity during the validated Shifted Attention Emotion Appraisal Task (2003, J Neurosci, 23, 5627-5633; 2013, Biol Psychiatry, 73, 1045-1053).

RESULTS

Greater activation in emotion processing (anterior insula) and modulation (prefrontal cortex) regions and increased connectivity between attentional control (dorsolateral prefrontal cortex and superior parietal cortex) and emotion processing (amygdala) regions, at pretreatment, were associated with subsequent PTSD symptom improvement.

CONCLUSIONS

This study is one of the first to examine task-based activation and functional connectivity in a PTSD treatment trial, and provides evidence to suggest that activation in and connectivity between emotion processing and modulation regions are important predictors of treatment response.

Sexual function and pelvic floor activity in women: the role of traumatic events and PTSD symptoms

BACKGROUND

Traumatic sexual experiences can negatively affect sexual functioning and increase pelvic floor activity in women, especially when post-traumatic stress disorder (PTSD) is developed. However, little is known about the effect of other types of interpersonal and non-interpersonal, traumatic experiences on sexual function and pelvic floor overactivity.

OBJECTIVE

The aim of this study was to examine the effects of lifetime traumatic experiences and subsequent PTSD symptoms on sexual function and pelvic floor activity and to investigate whether the effects differ for interpersonal and non-interpersonal trauma.

METHODS

Women (N=82) with obesity and a history of infertility, participating in a follow-up study of an RCT investigating a lifestyle intervention programme, completed questionnaires on lifetime exposure to traumatic events (LEC-5), PTSD symptoms (PC-PTSD-5), sexual function (MFSQ) and pelvic floor activity (AOPFS-SV).

RESULTS

A large majority of women (85%) reported exposure to at least one traumatic event during their lifetime. Sexual function and pelvic floor activity did not differ between women who experienced non-interpersonal or interpersonal (including sexual) trauma and those who did not experience traumatic events during their lifetime. Women who had developed PTSD symptoms, however, did have higher pelvic floor activity, but sexual function was not affected. Women with a positive screen for PTSD had the highest pelvic floor activity score, and individual PTSD symptoms nightmares and hypervigilance were associated with significantly higher pelvic floor activity scores.

CONCLUSION

Trauma exposure is associated with pelvic floor overactivity in women with a positive screen for PTSD, such that pelvic floor overactivity is more severe with greater PTSD severity. These findings suggest that the development of PTSD after interpersonal trauma is pivotal in this association. Sexual function was unrelated to trauma exposure and pelvic floor function, perhaps related to the fact that the interpersonal trauma events reported in this study were mainly non-sexual.

Chemogenetic activation of an infralimbic cortex to basolateral amygdala projection promotes resistance to acute social defeat stress

Tremendous individual differences exist in stress responsivity and social defeat stress is a key approach for identifying cellular mechanisms of stress susceptibility and resilience. Syrian hamsters show reliable territorial aggression, but after social defeat they exhibit a conditioned defeat (CD) response characterized by increased submission and an absence of aggression in future social interactions. Hamsters that achieve social dominance prior to social defeat exhibit greater defeat-induced neural activity in infralimbic (IL) cortex neurons that project to the basolateral amygdala (BLA) and reduced CD response compared to subordinate hamsters. Here, we hypothesize that chemogenetic activation of an IL-to-BLA neural projection during acute social defeat will reduce the CD response in subordinate hamsters and thereby produce dominant-like behavior. We confirmed that clozapine-N-oxide (CNO) itself did not alter the CD response and validated a dual-virus, Cre-dependent, chemogenetic approach by showing that CNO treatment increased c-Fos expression in the IL and decreased it in the BLA. We found that CNO treatment during social defeat reduced the acquisition of CD in subordinate, but not dominant, hamsters. This project extends our understanding of the neural circuits underlying resistance to acute social stress, which is an important step toward delineating circuit-based approaches for the treatment of stress-related psychopathologies.

Current understanding of fear learning and memory in humans and animal models and the value of a linguistic approach for analyzing fear learning and memory in humans

Fear is an emotion that serves as a driving factor in how organisms move through the world. In this review, we discuss the current understandings of the subjective experience of fear and the related biological processes involved in fear learning and memory. We first provide an overview of fear learning and memory in humans and animal models, encompassing the neurocircuitry and molecular mechanisms, the influence of genetic and environmental factors, and how fear learning paradigms have contributed to treatments for fear-related disorders, such as posttraumatic stress disorder. Current treatments as well as novel strategies, such as targeting the perisynaptic environment and use of virtual reality, are addressed. We review research on the subjective experience of fear and the role of autobiographical memory in fear-related disorders. We also discuss the gaps in our understanding of fear learning and memory, and the degree of consensus in the field. Lastly, the development of linguistic tools for assessments and treatment of fear learning and memory disorders is discussed.

Persistent Stress-Induced Neuroplastic Changes in the Locus Coeruleus/Norepinephrine System

Neural plasticity plays a critical role in mediating short- and long-term brain responses to environmental stimuli. A major effector of plasticity throughout many regions of the brain is stress. Activation of the locus coeruleus (LC) is a critical step in mediating the neuroendocrine and behavioral limbs of the stress response. During stressor exposure, activation of the hypothalamic-pituitary-adrenal axis promotes release of corticotropin-releasing factor in LC, where its signaling promotes a number of physiological and cellular changes. While the acute effects of stress on LC physiology have been described, its long-term effects are less clear. This review will describe how stress changes LC neuronal physiology, function, and morphology from a genetic, cellular, and neuronal circuitry/transmission perspective. Specifically, we describe morphological changes of LC neurons in response to stressful stimuli and signal transduction pathways underlying them. Also, we will review changes in excitatory glutamatergic synaptic transmission in LC neurons and possible stress-induced modifications of AMPA receptors. This review will also address stress-related behavioral adaptations and specific noradrenergic receptors responsible for them. Finally, we summarize the results of several human studies which suggest a link between stress, altered LC function, and pathogenesis of posttraumatic stress disorder.

Nicotine exposure leads to deficits in differential cued fear conditioning in mice and humans: A potential role of the anterior cingulate cortex

Stress and anxiety disorders such as posttraumatic stress disorder (PTSD) are characterized by disrupted safety learning. Tobacco smoking has been strongly implicated in stress and anxiety disorder symptomatology, both as a contributing factor and as a vulnerability factor. Rodent studies from our lab have recently shown that acute and chronic nicotine exposure disrupts safety learning. However, it is unknown if these effects of nicotine translate to humans. The present studies addressed this gap by administering a translational differential cued fear conditioning paradigm to both mice and humans. In mice, we found that chronic nicotine exposure reduced discrimination between a conditioned stimulus (CS) that signals for danger (CS+) and another CS that signals for safety (CS-) during both acquisition and testing. We then employed a similar differential cued fear conditioning paradigm in human smokers and non-smokers undergoing functional magnetic resonance imaging (fMRI). Smokers showed reduced CS+/CS- discrimination during fear conditioning compared to non-smokers. Furthermore, using fMRI, we found that subgenual and dorsal anterior cingulate cortex activations were lower in smokers than in non-smokers during differential cued fear conditioning. These results suggest a potential biological mechanism underlying a dysregulated ability to discriminate between danger and safety cues. Our results indicate a clear parallel between the effects of nicotine exposure on safety learning in mice and humans and therefore suggest that smoking might represent a risk factor for inability to process information related to danger and safety related cues.

Functional Neuroanatomy of Emotion and Its Regulation in PTSD

Posttraumatic stress disorder (PTSD) is a devastating disorder, linked to profound mental, physical, occupational, and functional impairment. In addition, it is a highly complex disorder, characterized by symptom heterogeneity across multiple domains. Nevertheless, emotion dysregulation arising from the exaggerated response to threat or from the inability to regulate negative emotional states plays a defining role in the pathophysiology of PTSD. In order to improve our understanding of how emotion dysregulation manifests in this illness, functional neuroimaging research over the past 20 years provides great insight into underlying neuroanatomy of each component of emotion dysregulation in the context of PTSD. While prior reviews exist on the topic of neuroimaging findings in PTSD, the present review synthesizes that work through the lens of emotion and its regulation. Studies that employed tasks of emotional responding and symptom provocation, implicit regulation (e.g., emotional Stroop and interference), explicit regulation (e.g., cognitive reappraisal), and fear conditioning/extinction were reviewed. Findings demonstrate that emotion dysregulation in PTSD arises from complications within a large neurocircuitry involving the amygdala, insula, hippocampus, anterior cingulate cortex, and prefrontal cortex. Although an exaggerated response in the amygdala and insula to negative emotional triggers is pervasive, PTSD is also marked by deficient appraisal, resolution, and management of negative emotional states subserved by the anterior cingulate cortex and prefrontal cortex during regulation. These findings further support the importance of studying emotion-regulation deficits in tandem with exaggerated symptom provocation in order to better understand the constellation of symptoms present in those with PTSD.

Abnormal fear circuitry in Attention Deficit Hyperactivity Disorder: A controlled magnetic resonance imaging study

We examined whether non-traumatized subjects with Attention Deficit Hyperactivity Disorder (ADHD) have dysfunctional activation in brain structures mediating fear extinction, possibly explaining the statistical association between ADHD and other disorders characterized by aberrant fear processing such as PTSD. Medication naïve, non-traumatized young adult subjects with (N=27) and without (N=20) ADHD underwent a 2-day fear conditioning and extinction protocol in a 3T functional magnetic resonance imaging (fMRI) scanner. Skin conductance response (SCR) was recorded as a measure of conditioned response. Compared to healthy controls, ADHD subjects had significantly greater insular cortex activation during early extinction, lesser dorsal anterior cingulate cortex (dACC) activation during late extinction, lesser ventromedial prefrontal cortex (vmPFC) activation during late extinction learning and extinction recall, and greater hippocampal activation during extinction recall. Hippocampal and vmPFC deficits were similar to those documented in PTSD subjects compared to traumatized controls without PTSD. Non-traumatized, medication naive adults with ADHD had abnormalities in fear circuits during extinction learning and extinction recall, and some findings were consistent with those previously documented in subjects with PTSD compared to traumatized controls without PTSD. These findings could explain the significant association between ADHD and PTSD as well as impaired emotion regulation in ADHD.

The Association Between Genetic Variants in the Dopaminergic System and Posttraumatic Stress Disorder: A Meta-Analysis

Posttraumatic stress disorder (PTSD) is a complex mental disorder and can severely interfere with the normal life of the affected people. Previous studies have examined the association of PTSD with genetic variants in multiple dopaminergic genes with inconsistent results. To perform a systematic literature search and conduct meta-analysis to examine whether genetic variants in the dopaminergic system is associated with PTSD. Data Sources: PubMed, Cochrane Library, Embase, Google Scholar, and HuGE. Study eligibility criteria and participants: The studies included subjects who had been screened for the presence of PTSD; the studies provided data for genetic variants of genes involved in the dopaminergic system; the outcomes of interest included diagnosis status of PTSD; and the studies were case-control studies. Study appraisal and synthesis methods: Odds ratio was used as a measure of association. We used random-effects model in all the meta-analyses. Between-study heterogeneity was assessed using I², and publication bias was evaluated using Egger test. Findings from meta-analyses were confirmed using random-effects meta-analyses under the framework of generalized linear model (GLM). A total of 19 studies met the eligibility criteria and were included in our analyses. We found that rs1800497 in DRD2 was significantly associated with PTSD (OR = 1.96, 95% CI: 1.15-3.33; P = 0.014). The 3'-UTR variable number tandem repeat (VNTR) in SLC6A3 also showed significant association with PTSD (OR = 1.62, 95% CI: 1.12-2.35; P = 0.010), but there was no association of rs4680 in COMT with PTSD (P = 0.595). Sample size is limited for some studies; type and severity of traumatic events varied across studies; we could not control for potential confounding factors, such as age at traumatic events and gender; and we could not examine gene-environment interaction due to lack of data. We found that rs1800497 in DRD2 and the VNTR in SLC6A3 showed significant association with PTSD. Future studies controlling for confounding factors, with large sample sizes and more homogeneous traumatic exposure, are needed to validate the findings from this study.

Impaired Functional Connectivity in the Prefrontal Cortex: A Mechanism for Chronic Stress-Induced Neuropsychiatric Disorders

Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC) is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders.

Muscle fatigability and control of force in men with posttraumatic stress disorder

INTRODUCTION

Acute stress can increase fatigability and decrease steadiness of sustained low-force contractions that are required for functional tasks in upper limb muscles. Whether motor performance is more impaired in people with a chronic stress disorder is not known.

PURPOSE

This study compared the fatigability and steadiness (force fluctuations) of handgrip muscles in veterans with posttraumatic stress disorder (PTSD) and civilian controls in the presence and absence of varying levels of cognitive demand.

METHODS

Eighteen veterans with PTSD and 21 healthy controls (33 ± 9 yr) attended three randomized experimental sessions to perform an isometric fatiguing contraction (20% of maximal strength) with the handgrip muscles. Two sessions involved performing a cognitive task during the fatiguing contraction: 1) difficult mental math task (stressor) and 2) a simple mental math task (mental attentiveness). A third session involved a fatiguing contraction with no mental task (control).

RESULTS

Stress elevated heart rate, blood pressure, and levels of anxiety in veterans with PTSD (P < 0.05) but blunted cortisol levels (P < 0.05). Time to failure was briefer (7.2 ± 2.5 vs 9.3 ± 5.2 min, P = 0.03), and force fluctuations increased at a greater rate for veterans with PTSD than for controls (P < 0.05). Cognitive stress did not influence time to failure or force fluctuations for either group (P > 0.05).

CONCLUSIONS

Veterans with PTSD demonstrated greater fatigability and loss of steadiness (greater force fluctuations) of the handgrip muscles compared with healthy controls.

SIGNIFICANCE

Male veterans with PTSD demonstrated altered neuromuscular function of arm muscles that potentially affects functional tasks during daily, ergonomic, and military activities.

Anxiety-like behaviour and c-fos expression in rats that inhaled vetiver essential oil

Vetiver essential oil (VEO) has been used in aromatherapy for relaxation. This study aimed to investigate the effects of VEO on an anxiety-related behavioural model (the elevated plus-maze, EPM) and immediate-early gene c-fos in amygdala, known to be involved in anxiety. Male Wistar rats were administered diazepam (1 mg/kg i.p.) for 30 min or inhalated with VEO (1%, 2.5% or 5% w/w) for 7 min prior to exposure to the EPM. Then, the effects of 2.5% VEO, the anxiolytic dose, on c-fos expression in amygdala were investigated. The rats given either 2.5% VEO or diazepam exhibited an anxiolytic-like profile in the EPM. VEO and diazepam significantly increased c-fos expression in the lateral division of the central amygdaloid nucleus (CeL). Therefore, the anxiolytic properties of VEO might be associated with altering neuronal activation in CeL. However, future studies are needed to investigate the precise mechanism of action of VEO.

Abnormalities in whole-brain functional connectivity observed in treatment-naive post-traumatic stress disorder patients following an earthquake

BACKGROUND

Convergent studies have highlighted the dysfunction of the amygdala, prefrontal cortex and hippocampus in post-traumatic stress disorder (PTSD). However, only a few studies have investigated the functional connectivity between brain regions in PTSD patients during the resting state, which may improve our understanding of the neuropathophysiology of PTSD. The aim of this study was to investigate patterns of whole-brain functional connectivity in treatment-naive PTSD patients without co-morbid conditions who experienced the 8.0-magnitude earthquake in the Sichuan province of China.

METHOD

A total of 72 PTSD patients and 86 trauma-exposed non-PTSD controls participated in the resting-state functional magnetic resonance imaging study. All these subjects were recruited from the disaster zone of the 2008 Sichuan earthquake. Functional connectivities between 90 paired brain regions in PTSD patients were compared with those in trauma-exposed non-PTSD controls. Furthermore, Pearson correlation analysis was performed between significantly abnormal connectivities in PTSD patients and their clinician-administered PTSD scale (CAPS) scores.

RESULTS

Compared with non-PTSD controls, PTSD patients showed weaker positive connectivities between the middle prefrontal cortex (mPFC) and the amygdala, hippocampus, parahippocampal gyrus and rectus, as well as between the inferior orbitofrontal cortex and the hippocampus. In addition, PTSD patients showed stronger negative connectivity between the posterior cingulate cortex (PCC) and the insula. The CAPS scores in PTSD patients correlated negatively with the connectivity between the amygdala and the mPFC.

CONCLUSIONS

PTSD patients showed abnormalities in whole-brain functional connectivity, primarily affecting the connectivities between the mPFC and limbic system, and connectivity between the PCC and insula.

Device-based brain stimulation to augment fear extinction: implications for PTSD treatment and beyond

Conditioned fear acquisition and extinction paradigms have been widely used both in animals and humans to examine the neurobiology of emotional memory. Studies have also shown that patients suffering from posttraumatic stress disorder (PTSD) exhibit deficient extinction recall along with dysfunctional activation of the fear extinction network, including the ventromedial prefrontal cortex, amygdala, and hippocampus. A great deal of overlap exists between this fear extinction network and brain regions associated with symptom severity in PTSD. This suggests that the neural nodes of fear extinction could be targeted to reduce behavioral deficits that may subsequently translate into symptom improvement. In this article, we discuss potential applications of brain stimulation and neuromodulation methods, which, combined with a mechanistic understanding of the neurobiology of fear extinction, could be used to further our understanding of the pathophysiology of anxiety disorders and develop novel therapeutic tools. To this end, we discuss the following stimulation approaches: deep-brain stimulation, vagus nerve stimulation, transcranial direct current stimulation, and transcranial magnetic stimulation. We propose new translational research avenues that, from a systems neuroscience perspective, aim to expand our understanding of circuit dynamics and fear processing toward the practical development of clinical tools, to be used alone or in combination with behavioral therapies.

Remodeling of axo-spinous synapses in the pathophysiology and treatment of depression

Dendritic spines provide a compartment for assembly and functional organization of synaptic machinery that plays a fundamental role in neuronal communication and neuroplasticity. Studies in humans as well as in animal models have demonstrated abnormal spine architecture in several psychiatric disorders, including depression and other stress-related illnesses. The negative impact of stress on the density and organization of spines is thought to contribute to the behavioral deficits caused by stress exposure. Moreover, there is now evidence that medication-induced recovery involves changes in synaptic plasticity and dendrite morphology, including increased expression of pre- and postsynaptic plasticity-related proteins, as well as the density and function of axo-spinous synapses. Here we review the evidence from brain imaging and postmortem studies demonstrating that depression is accompanied by structural and functional alterations of cortical and limbic brain regions, including the prefrontal cortex, hippocampus and amygdala. In addition, we present more direct evidence from basic research studies that exposure to stress alters spine morphology, function and plasticity and that antidepressants, particularly new rapid acting agents, reverse these effects. Elucidation of the signaling pathways and molecular mechanisms that control spine synapse assembly and plasticity will contribute to a better understanding of the pathophysiology of depression and development of novel, more effective therapeutic agents.

Altered amygdala activation during face processing in Iraqi and Afghanistani war veterans

Background

Exposure to combat can have a significant impact across a wide array of domains, and may manifest as post-traumatic stress disorder (PTSD), a debilitating mental illness that is associated with neural and affective sequelae. This study tested the hypothesis that combat-exposed individuals with and without PTSD, relative to healthy control subjects with no history of PTSD or combat exposure, would show amygdala hyperactivity during performance of a well-validated face processing task. We further hypothesized that differences in the prefrontal cortex would best differentiate the combat-exposed groups with and without PTSD.

Methods

Twelve men with PTSD related to combat in Operations Enduring Freedom and/or Iraqi Freedom, 12 male combat-exposed control patients with a history of Operations Enduring Freedom and/or Iraqi Freedom combat exposure but no history of PTSD, and 12 healthy control male patients with no history of combat exposure or PTSD completed a face-matching task during functional magnetic resonance imaging.

Results

The PTSD group showed greater amygdala activation to fearful versus happy faces than both the combat-exposed control and healthy control groups. Both the PTSD and the combat-exposed control groups showed greater amygdala activation to all faces versus shapes relative to the healthy control group. However, the combat-exposed control group relative to the PTSD group showed greater prefrontal/parietal connectivity with the amygdala, while the PTSD group showed greater connectivity with the subgenual cingulate. The strength of connectivity in the PTSD group was inversely related to avoidance scores.

Conclusions

These observations are consistent with the hypothesis that PTSD is associated with a deficiency in top-down modulation of amygdala activation by the prefrontal cortex and shows specific sensitivity to fearful faces.

Posttraumatic stress disorders in civilian orthopaedics

Posttraumatic stress disorder (PTSD) is a well-characterized anxiety disorder that may occur after exposure to a traumatic event. Research is ongoing to document neuroanatomic, neuroendocrine, and genetic correlates to the behavioral phenotype. PTSD occurs in 20% to 51% of patients with musculoskeletal injury. Orthopaedic outcomes, including return to work, activities of daily living, patient perception of physical recovery, and objective physical parameters, suffer considerably in patients with PTSD. There are several ways by which treating orthopaedic surgeons can recognize at-risk patients and help prevent the development of PTSD. Should prevention prove unsuccessful, effective treatment strategies exist, as well. Research is needed to investigate whether a correlation exists between successful management of the psychiatric manifestations of PTSD and improved physical outcomes.

Altered amygdala resting-state functional connectivity in post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is often characterized by aberrant amygdala activation and functional abnormalities in corticolimbic circuitry, as elucidated by functional neuroimaging. These "activation" studies have primarily relied on tasks designed to induce region-specific, and task-dependent brain responses in limbic (e.g., amygdala) and paralimbic brain areas through the use of aversive evocative probes. It remains unknown if these corticolimbic circuit abnormalities exist at baseline or "at rest," in the absence of fear/anxiety-related provocation and outside the context of task demands. Therefore the primary aim of the present experiment was to investigate aberrant amygdala functional connectivity patterns in combat-related PTSD patients during resting-state. Seventeen Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans with combat-related PTSD (PTSD group) and 17 combat-exposed OEF/OIF veterans without PTSD [combat-exposed control (CEC) group] underwent an 8-min resting-state functional magnetic resonance imaging scan. Using an anatomically derived amygdala "seed" region we observed stronger functional coupling between the amygdala and insula in the PTSD group compared to the CEC group, but did not find group differences in amygdala-prefrontal connectivity. These findings suggest that the aberrant amygdala and insula activation to fear-evocative probes previously characterized in PTSD may be driven by an underlying enhanced connectivity between the amygdala, a region known for perceiving threat and generating fear responses, and the insula, a region known for processing the meaning and prediction of aversive bodily states. This enhanced amygdala-insula connectivity may reflect an exaggerated, pervasive state of arousal that exists outside the presence of an overt actual threat/danger. Studying amygdala functional connectivity "at rest" extends our understanding of the pathophysiology of PTSD.

Neuropathic pain: mind-body considerations

Emerging research in neuroscience is bridging the gap between mind and body. Thought is brain based and influences brain function. The continuum and bidirectionality of mind and body, thought and brain, emotions and physiology forms the basis of understanding neuropathic pain, a neuropsychiatric condition with myriad clinical manifestations.

Gray matter density in limbic and paralimbic cortices is associated with trauma load and EMDR outcome in PTSD patients

There is converging evidence of gray matter (GM) structural alterations in different limbic structures in Post-Traumatic Stress Disorder (PTSD) patients. The aim of this study was to evaluate GM density in PTSD in relation to trauma load, and to assess the GM differences between responders (R) and non-responders (NR) to EMDR therapy. Magnetic Resonance Imaging (MRI) scans of 21 subjects exposed to occupational trauma, who developed PTSD (S), and of 22 who did not (NS), were compared by means of an optimized Voxel-Based Morphometry (VBM) analysis as implemented in SPM. Within S, further comparisons were made between 10 R and 5 NR. A regression analysis between GM density and the Traumatic Antecedents Questionnaire (TAQ) was also performed on all 43 subjects. Results showed a significantly lower GM density in S as compared to NS in the left posterior cingulate and the left posterior parahippocampal gyrus. Moreover, NR showed a significantly lower GM density as compared to R in bilateral posterior cingulate, as well as anterior insula, anterior parahippocampal gyrus and amygdala in the right hemisphere. Regression analysis showed that GM density negatively correlated with trauma load in bilateral posterior cingulate, left anterior insula, and right anterior parahippocampal gyrus. In conclusion, a GM lower density in limbic and paralimbic cortices were found to be associated with PTSD diagnosis, trauma load, and EMDR treatment outcome, suggesting a view of PTSD characterized by memory and dissociative disturbances.

Estrogen promotes stress sensitivity in a prefrontal cortex-amygdala pathway

We have recently reported in male rats that medial prefrontal cortex (mPFC) neurons that project to the basolateral nucleus of the amygdala (BLA) are resilient to stress-induced dendritic remodeling. The present study investigated whether this also occurs in female rats. This pathway was identified using the retrograde tracer Fast Blue injected into the BLA of ovariectomized female rats with estrogen replacement (OVX + E) and without (OVX + veh). Animals were exposed for 10 days either to 2-h immobilization stress or to home cage rest, after which layer III mPFC neurons that were either retrogradely labeled by Fast Blue or unlabeled were filled with Lucifer Yellow and analyzed for apical dendritic length and spine density. No dendritic remodeling occurred in unlabeled neurons from OVX + veh or OVX + E animals. In BLA-projecting neurons, however, stress had no effect on length in OVX + veh animals, but stressed OVX + E females showed greater dendritic length than controls at intermediate branches. Stress also caused an increase in spine density in all neurons in OVX + veh animals and a spine density increase in BLA-projecting neurons in OVX + E females. Estrogen also increased spine density on BLA-projecting neurons in unstressed animals. These data demonstrate both independent effects of estrogen on pyramidal cell morphology and effects that are interactive with stress, with the BLA-projecting neurons being sensitive to both kinds of effects.

Stress-induced dendritic remodeling in the prefrontal cortex is circuit specific

Chronic stress exposure has been reported to induce dendritic remodeling in several brain regions, but it is not known whether individual neural circuits show distinct patterns of remodeling. The current study tested the hypothesis that the projections from the infralimbic (IL) area of the medial prefrontal cortex (mPFC) to the basolateral nucleus of the amygdala (BLA), a pathway relevant to stress-related mental illnesses like depression and post-traumatic stress disorder, would have a unique pattern of remodeling in response to chronic stress. The retrograde tracer FastBlue was injected into male rats' BLA or entorhinal cortex (EC) 1 week prior to 10 days of immobilization stress. After cessation of stress, FastBlue-labeled and unlabeled IL pyaramidal neurons were loaded with fluorescent dye Lucifer Yellow to visualize dendritic arborization and spine density. As has been previously reported, randomly selected (non-FastBlue-labeled) neurons showed stress-induced dendritic retraction in apical dendrites, an effect also seen in EC-projecting neurons. In contrast, BLA-projecting neurons showed no remodeling with stress, suggesting that this pathway may be particularly resilient against the effects of stress. No neurons showed stress-related changes in spine density, contrasting with reports that more dorsal areas of the mPFC show stress-induced decreases in spine density. Such region- and circuit-specificity in response to stress could contribute to the development of stress-related mental illnesses.

Stress-induced dendritic remodeling in the medial prefrontal cortex: effects of circuit, hormones and rest

The medial prefrontal cortex (mPFC) has been implicated as a site of dysfunction and abnormal morphology in major depressive disorder and post-traumatic stress disorder, two illnesses that can be brought on by exposure to stress. In animal models, stress has long been shown to induce impairments in tasks known to be mediated by the mPFC, and recent work has demonstrated that chronic stress can lead to morphological changes in mPFC pyramidal cells. This review explores the current literature on stress-induced dendritic remodeling in the mPFC, with particular focus on new findings that illuminate modulators of these effects.

Functional activation and neural networks in women with posttraumatic stress disorder related to intimate partner violence

BACKGROUND

Intimate partner violence (IPV) is one of the most common causes of posttraumatic stress disorder (PTSD) in women. Victims of IPV are often preoccupied by the anticipation of impending harm. This investigation tested the hypothesis that IPV-related PTSD individuals show exaggerated insula reactivity to the anticipation of aversive stimuli.

METHODS

Fifteen women with a history of IPV and consequent PTSD (IPV-PTSD) and 15 non-traumatized control (NTC) women performed a task involving cued anticipation to images of positive and negative events during functional magnetic resonance imaging.

RESULTS

Both groups showed increased activation of bilateral anterior insula during anticipation of negative images minus anticipation of positive images. Activation in right anterior/middle insula was significantly greater in the IPV-PTSD relative to the NTC group. Functional connectivity analysis revealed that changes in activation in right middle insula and bilateral anterior insula were more strongly associated with amygdala activation changes in NTC than in IPV-PTSD subjects.

CONCLUSIONS

This study revealed increased activation in the anterior/middle insula during negative anticipation in women with IPV-related PTSD. These findings in women with IPV could be a consequence of the IPV exposure, reflect pre-existing differences in insular function, or be due to the development of PTSD. Thus, future longitudinal studies need to examine these possibilities.

Neurophysiological responses to traumatic reminders in the acute aftermath of serious motor vehicle collisions using [15O]-H2O positron emission tomography

BACKGROUND

Neuroimaging studies report that individuals with posttraumatic stress disorder show abnormal responses in the amygdala and medial prefrontal cortex (mPFC)/anterior cingulate cortex (ACC) during exposure to traumatic reminders. However, neural responses arising in the early aftermath of a traumatic event have not been studied.

METHODS

Twenty-two motor vehicle collision survivors and 12 nontraumatized control subjects participated. Regional cerebral blood flow (rCBF) was measured using [(15)O]-H(2)O positron emission tomography (PET) at rest and as subjects listened to scripts of traumatic and neutral events. Self-report measures rated emotional responses to the scripts; standardized assessments (Impact of Events--Revised) evaluated acute stress symptoms at scanning and at 3-month follow-up. Most subjects improved symptomatically.

RESULTS

At rest, trauma subjects showed hyperperfusion in right mPFC/ACC and hypoperfusion in right amygdala compared with control subjects. In trauma subjects, listening to trauma scripts versus neutral scripts resulted in decreased flow in the right amygdala and left amygdala/perirhinal cortex, and symptom scores correlated negatively with right hippocampal flow changes. Symptom improvement at 3 months correlated negatively with rCBF changes in right perirhinal cortex and hippocampus during the trauma versus neutral script contrast. Subjective disturbance during the trauma versus neutral contrast correlated positively with rCBF changes in right amygdala and left mPFC. Functional connectivity analyses of rCBF changes during trauma versus neutral scripts demonstrated left amygdala coupling with right ACC and bilateral anterior insula, as well as coupling between the amygdala and contralateral hippocampus.

CONCLUSIONS

In recently traumatized subjects functional interactions between the amygdala, perirhinal cortex and ACC/mPFC that occur during exposure to traumatic reminders may underlie adaptive/recuperative processes.

Neural correlates of speeded as compared with delayed responses in a stop signal task: an indirect analog of risk taking and association with an anxiety trait

The stop signal task (SST) is widely used to explore neural processes involved in cognitive control. By randomly intermixing stop and go trials and imposing on participants to respond quickly to the go but not the stop signal, the SST also introduces an indirect element of risk, which participants may avert by slowing down or ignore by responding "as usual," during go trials. This "risk-taking" component of the SST has to our knowledge never been investigated. The current study took advantage of variability of go trial reaction time (RT) and compared the post-go go trials that showed a decrease in RT (risk-taking decision) and those post-go go trials that showed an increase in RT ("risk-aversive" decision) in 33 healthy individuals who underwent functional magnetic resonance imaging during the SST. This contrast revealed robust activation in bilateral visual cortices as well as left inferior parietal and posterior cingulate cortices, amygdala, and middle frontal gyrus (P < 0.05, family-wise error [FWE] corrected). Furthermore, we observed that the magnitude of amygdala activity is positively correlated with trait anxiety of the participants. These results thus delineated, for the first time, a neural analog of risk taking during stop signal performance, highlighting a novel aspect and broadening the utility of this behavioral paradigm.

Diminished rostral anterior cingulate activity in response to threat-related events in posttraumatic stress disorder

BACKGROUND

Previous brain imaging studies have reported hyperactivation of the amygdala and hypoactivation of the anterior cingulate in posttraumatic stress disorder (PTSD) patients, which is believed to be an underlying neural mechanism of the PTSD symptoms. The current study specifically focuses on the abnormal activity of the rostral anterior cingulate, using a paradigm which elicits an unexpected processing conflict caused by salient emotional stimuli.

METHODS

Twelve survivors (seven men and five women) of the Taegu subway fire in 2003, who later developed PTSD, agreed to participate in this study. Twelve healthy volunteers (seven men and five women) were recruited for comparison. Functional brain images of all participants were acquired using functional magnetic resonance imaging while performing a same-different judgment task, which was modified to elicit an unexpected emotional processing conflict.

RESULTS

PTSD patients, compared to comparison subjects, showed a decreased rostral anterior cingulate functioning when exposed to situations which induce an unexpected emotional processing conflict. Moreover, PTSD symptom severity was negatively correlated to the level of decrease in the rostral anterior cingulate activity.

CONCLUSIONS

The results of this study provide evidence that the rostral anterior cingulate functioning is impaired in PTSD patients during response-conflict situations that involve emotional stimuli.

Neuroimaging in posttraumatic stress disorder and other stress-related disorders

Traumatic stress has a broad range of effects on the brain. Brain areas implicated in the stress response include the amygdala, the hippocampus, and the prefrontal cortex. Studies in patients who have 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.

Inhibitory control and emotional stress regulation: neuroimaging evidence for frontal-limbic dysfunction in psycho-stimulant addiction

This review focuses on neuroimaging studies that examined stress processing and regulation and cognitive inhibitory control in patients with psycho-stimulant addiction. We provide an overview of these studies, summarizing converging evidence and discrepancies as they occur in the literature. We also adopt an analytic perspective and dissect these psychological processes into their sub-components, to identify the neural pathways specific to each component process and those that are more specifically involved in psycho-stimulant addiction. To this aim we refer frequently to studies conducted in healthy individuals. Despite the separate treatment of stress/affect regulation, stress-related craving or compulsive drug seeking, and inhibitory control, neural underpinnings of these processes overlap significantly. In particular, the ventromedial prefrontal regions including the anterior cingulate cortex, amygdala and the striatum are implicated in psychostimulant dependence. Our overarching thesis is that prefrontal activity ensures intact emotional stress regulation and inhibitory control. Altered prefrontal activity along with heightened striatal responses to addicted drug and drug-related salient stimuli perpetuates habitual drug seeking. Further studies that examine the functional relationships of these neural systems will likely provide the key to understanding the mechanisms underlying compulsive drug use behaviors in psycho-stimulant dependence.

Glucocorticoid receptor activation is involved in producing abnormal phenotypes of single-prolonged stress rats: a putative post-traumatic stress disorder model

Post-traumatic stress disorder (PTSD) is a stress-related mental disorder caused by traumatic experience, and presents with characteristic symptoms, such as intrusive memories, a state of hyperarousal, and avoidance, that endure for years. Single-prolonged stress (SPS) is one of the animal models proposed for PTSD. Rats exposed to SPS showed enhanced inhibition of the hypothalamo-pituitary-adrenal (HPA) axis, which has been reliably reproduced in patients with PTSD, and increased expression of glucocorticoid receptor (GR) in the hippocampus. In this study, we characterized further neuroendocrinologic, behavioral and electrophysiological alterations in SPS rats. Plasma corticosterone recovered from an initial increase within a week, and gross histological changes and neuronal cell death were not observed in the hippocampus of the SPS rats. Behavioral analyses revealed that the SPS rats presented enhanced acoustic startle and impaired spatial memory that paralleled the deficits in hippocampal long-term potentiation (LTP) and depression. Contextual fear memory was enhanced in the rats 1 week after SPS exposure, whereas LTP in the amygdala was blunted. Interestingly, blockade of GR activation by administering 17-beta-hydroxy-11-beta-/4-/[methyl]-[1-methylethyl]aminophenyl/-17-alpha-[prop-1-ynyl]estra-4-9-diene-3-one (RU40555), a GR antagonist, prior to SPS exposure prevented potentiation of fear conditioning and impairment of LTP in the CA1 region. Altogether, SPS caused a number of behavioral changes similar to those described in PTSD, which marks SPS as a putative PTSD model. The preventive effects of a GR antagonist suggested that GR activation might play a critical role in producing the altered behavior and neuronal function of SPS rats.

Functional neuroimaging in post-traumatic stress disorder

Traumatic stress has a broad range of effects on brain function. Brain areas implicated in the stress response include the amygdala, hippocampus, and prefrontal cortex. Brain studies in patients with post-traumatic stress disorder replicated findings in animal studies by finding alterations in these brain areas. Brain areas implicated in post-traumatic stress disorder play an important role in the stress response as well as memory, highlighting the important interplay between memory and the traumatic stress response. Future studies are required to assess the relationship between recovery from traumatic stress and changes in brain function.

Trauma and Posttraumatic Stress Disorder in Women With Chronic Pelvic Pain

OBJECTIVE

To examine the effect of abuse history, other major trauma, and posttraumatic stress disorder (PTSD) on medical symptoms and health-related daily functioning in women with chronic pelvic pain.

METHODS

We administered a questionnaire to 713 consecutive women seen in a referral-based pelvic pain clinic.

RESULTS

We found that 46.8% reported having either a sexual or physical abuse history. A total of 31.3% had a positive screen for PTSD. Using regression and path analysis, controlling for demographic variables, we found that a trauma history was associated with worse daily physical functioning due to poor health (P<.001), more medical symptoms (P<.001), more lifetime surgeries (P<.001), more days spent in bed (P<.001), and more dysfunction due to pain (P<.001). Furthermore, a positive screen for PTSD was highly related to most measures of poor health status (P<.001) and somewhat explained the trauma-related poor health status.

CONCLUSION

The association of trauma with poor health may be due in part to the development of PTSD resulting from trauma. These findings demonstrate the importance of screening for trauma and PTSD in women with chronic pelvic pain.

LEVEL OF EVIDENCE

II.

Anxiety, respiration, and cerebral blood flow: implications for functional brain imaging

Brain functional imaging methods, such as fMRI, are sensitive to changes in cerebral blood flow (CBF) that are normally associated with changes in regional neural activation. However, other endogenous and exogenous factors can alter CBF independently of brain neural activity, thus complicating the interpretation of functional imaging data. The presence of an anxiety disorder, as well as change in state anxiety, is often accompanied by respiratory alterations that affect arterial CO(2) tensions and produce significant changes in CBF that are independent of task-related neural activation. Therefore, the effects of trait and state anxiety need to be given close consideration in interpreting functional imaging findings. In this paper, we review the dependence of most brain functional imaging methods on localized changes in CBF and the potentially confounding effects of anxiety-related alterations of respiration on interpreting patterns of functional activation. Approaches for addressing these effects are discussed.

A review of neuroimaging studies in PTSD: heterogeneity of response to symptom provocation

Different experiential, psychophysiological, and neurobiological responses to traumatic symptom provocation in posttraumatic stress disorder (PTSD) have been reported in the literature. Two subtypes of trauma response have been hypothesized, one characterized predominantly by hyperarousal and the other primarily dissociative, each one representing unique pathways to chronic stress-related psychopathology. Recent PTSD neuroimaging findings in our own laboratory support this notion and are consistent with the view that grouping all PTSD subjects, regardless of their different symptom patterns, in the same diagnostic category may interfere with our understanding of posttrauma psychopathology. This review will integrate findings of different experiential, psychophysiological, and neurobiological responses to traumatic symptom provocation with the clinical symptomatology and the neurobiology of PTSD.

Neuroimaging studies of emotional responses in PTSD

Neuroimaging research offers a powerful and noninvasive means to understand healthy as well as dysregulated emotional processing in healthy subjects and PTSD patients. Functional neuroimaging findings suggest specific roles for subregions of the medial prefrontal (mPFC), orbito frontal (OFC), anterior cingulate (ACC), and insular cortices as well as the sublenticular extended amygdala (SLEA) and hippocampus in various components of emotional processing. Some of the same regions appear to be associated with emotional response to trauma, and with symptom formation in PTSD. Neuroimaging findings of emotional processing in healthy subjects and PTSD patients are discussed, addressing the specific roles of cortical regions like mPFC, ACC, and insula, and their potential contribution to PTSD pathophysiology. Processes of cognitive-emotional interactions and social emotions are discussed in an attempt to synthesize the prefrontal findings in healthy subjects and PTSD patients. Further links between functional neuroanatomy of emotional responses and neuroendocrine stress regulation are proposed.