Neurocircuitry models of posttraumatic stress disorder and beyond: a meta-analysis of functional neuroimaging studies

Neural circuitry changes associated with increasing self-efficacy in Posttraumatic Stress Disorder

Cognitive models suggest that posttraumtic stress disorder (PTSD) is maintained, in part, as a result of an individual's maladaptive beliefs about one's ability to cope with current and future stress. These models are consistent with considerable findings showing a link between low levels of self-efficacy and PTSD. A growing body of work has demonstrated that perceptions of self-efficacy can be enhanced experimentally in healthy subjects and participants with PTSD, and increasing levels of self-efficacy improves performance on cognitive, affective, and problem-solving tasks. This study aimed to determine whether increasing perceptions of self-efficacy in participants with PTSD would be associated with changes in neural processing. Combat veterans (N = 34) with PTSD were randomized to either a high self-efficacy (HSE) induction, in which they were asked to recall memories associated with successful coping, or a control condition before undergoing resting state fMRI scanning. Two global network measures in four neural circuits were examined. Participants in the HSE condition showed greater right-lateralized path length and decreased right-lateralized connectivity in the emotional regulation and executive function circuit. In addition, area under receiver operating characteristics curve (AUC) analyses found that average connectivity (.71) and path length (.70) moderately predicted HSE group membership. These findings provide further support for the importance of enhancing perceived control in PTSD, and doing so may engage neural targets that could guide the development of novel interventions.

Real-time fMRI amygdala neurofeedback positive emotional training normalized resting-state functional connectivity in combat veterans with and without PTSD: a connectome-wide investigation

Self-regulation of brain activation using real-time functional magnetic resonance imaging neurofeedback (rtfMRI-nf) is an emerging approach for treating mood and anxiety disorders. The effect of neurofeedback training on resting-state functional connectivity warrants investigation as changes in spontaneous brain activation could reflect the association between sustained symptom relief and brain alteration. We investigated the effect of amygdala-focused rtfMRI-nf training on resting-state functional connectivity in combat veterans with and without posttraumatic stress disorder (PTSD) who were trained to increase a feedback signal reflecting left amygdala activity while recalling positive autobiographical memories (Zotev et al., 2018). The analysis was performed in three stages: i) first, we investigated the connectivity in the left amygdala region; ii) next, we focused on the abnormal resting-state functional connectivity identified in our previous analysis of this data (Misaki et al., 2018); and iii) finally, we performed a novel data-driven longitudinal connectome-wide analysis. We introduced a longitudinal multivariate distance matrix regression (MDMR) analysis to comprehensively examine neurofeedback training effects beyond those associated with abnormal baseline connectivity.

These comprehensive exploratory analyses suggested that abnormal resting-state connectivity for combat veterans with PTSD was partly normalized after the training. This included hypoconnectivities between the left amygdala and the left ventrolateral prefrontal cortex (vlPFC) and between the supplementary motor area (SMA) and the dorsal anterior cingulate cortex (dACC). The increase of SMA-dACC connectivity was associated with PTSD symptom reduction. Longitudinal MDMR analysis found a connectivity change between the precuneus and the left superior frontal cortex. The connectivity increase was associated with a decrease in hyperarousal symptoms. The abnormal connectivity for combat veterans without PTSD - such as hypoconnectivity in the precuneus with a superior frontal region and hyperconnectivity in the posterior insula with several regions - could also be normalized after the training. These results suggested that the rtfMRI-nf training effect was not limited to a feedback target region and symptom relief could be mediated by brain modulation in several regions other than in a feedback target area. While further confirmatory research is needed, the results may provide valuable insight into treatment effects on the whole brain resting-state connectivity.

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fMRI neurofeedback training effect on resting-state connectivity was examined

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Left amygdala activity was trained to increase with positive memory

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Neurofeedback normalized altered connectivity in veterans with and without PTSD

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PTSD symptom reductions were significant but not specific to group (exp/ctrl)

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Connectivity-symptom association was seen in mPFC and precuneus

Reduced local segregation of single-subject gray matter networks in adult PTSD

To psychoradiologically investigate the topological organization of single-subject gray matter networks in patients with PTSD. Eighty-nine adult PTSD patients and 88 trauma-exposed controls (TEC) underwent a structural T1 magnetic resonance imaging scan. The single-subject brain structural networks were constructed based on gray matter similarity of 90 brain regions. The area under the curve (AUC) of each network metric was calculated and both global and nodal network properties were measured in graph theory analysis. We used nonparametric permutation tests to identify group differences in topological metrics. Relationships between brain network measures and clinical symptom severity were analyzed in the PTSD group. Compared with TEC, brain networks of PTSD patients were characterized by decreased clustering coefficient (C_p ) (p = .04) and local efficiency (E_loc ) (p = .04). Locally, patients with PTSD exhibited altered nodal centrality involving medial superior frontal (mSFG), inferior orbital frontal (iOFG), superior parietal (SPG), middle frontal (MFG), angular, and para-hippocampal gyri (p < .05, corrected). A negative correlation between the segregation (C_p ) of gray matter and functional networks was found in PTSD patients but not the TEC group. Analyses of topological brain gray matter networks indicate a more randomly organized brain network in PTSD. The reduced segregation in gray matter networks and its negative relation with increased segregation in the functional network indicate an inverse relation between gray matter and functional changes. The present psychoradiological findings may reflect a compensatory increase in functional network segregation following a loss of segregation in gray matter networks.

Resting-state pulvinar-posterior parietal decoupling in PTSD and its dissociative subtype

Key evidence points toward alterations in the neurocircuitry of large-scale networks among patients with posttraumatic stress disorder (PTSD). The pulvinar is a thalamic region displaying reciprocal connectivity with the cortex and has been shown to modulate alpha synchrony to facilitate network communication. During rest, the pulvinar displays functional connectivity with the posterior parietal cortex (PPC), a heteromodal network of brain areas underlying multisensory integration and socioaffective functions that are shown at deficit in PTSD. Accordingly, this study seeks to reveal the resting-state functional connectivity (rsFC) patterns of individuals with PTSD, its dissociative subtype (PTSD + DS) and healthy controls. A whole-brain rsFC analysis was conducted using SPM12 and PickAtlas. Connectivity was analyzed for the left and right pulvinar across groups of individuals with PTSD (n = 81), PTSD + DS (n = 49), and controls (n = 51). As compared to PTSD, controls displayed significantly greater pulvinar rsFC with the superior parietal lobule and precuneus. Moreover, as compared to PTSD + DS, controls showed increased pulvinar connectivity with the superior parietal lobule, inferior parietal lobule and the precuneus. PTSD groups did not display stronger connectivity with any region as compared to controls. Last, PTSD had greater rsFC in the supramarginal gyrus relative to PTSD + DS. Reduced connectivity between the pulvinar and PPC may explain impairments to autobiographical memory, self-referential processing, and socioaffective domains in PTSD and PTSD + DS even at "rest." Critically, these alterations appear to be exacerbated in individuals with PTSD + DS, which may have important implications for treatment.

The cerebellum after trauma: Resting-state functional connectivity of the cerebellum in posttraumatic stress disorder and its dissociative subtype

The cerebellum plays a key role not only in motor function but also in affect and cognition. Although several psychopathological disorders have been associated with overall cerebellar dysfunction, it remains unclear whether different regions of the cerebellum contribute uniquely to psychopathology. Accordingly, we compared seed-based resting-state functional connectivity of the anterior cerebellum (lobule IV-V), of the posterior cerebellum (Crus I), and of the anterior vermis across posttraumatic stress disorder (PTSD; n = 65), its dissociative subtype (PTSD + DS; n = 37), and non-trauma-exposed healthy controls (HC; n = 47). Here, we observed decreased functional connectivity of the anterior cerebellum and anterior vermis with brain regions involved in somatosensory processing, multisensory integration, and bodily self-consciousness (temporo-parietal junction, postcentral gyrus, and superior parietal lobule) in PTSD + DS as compared to PTSD and HC. Moreover, the PTSD + DS group showed increased functional connectivity of the posterior cerebellum with cortical areas related to emotion regulation (ventromedial prefrontal and orbito-frontal cortex, subgenual anterior cingulum) as compared to PTSD. By contrast, PTSD showed increased functional connectivity of the anterior cerebellum with cortical areas associated with visual processing (fusiform gyrus), interoceptive awareness (posterior insula), memory retrieval, and contextual processing (hippocampus) as compared to HC. Finally, we observed decreased functional connectivity between the posterior cerebellum and prefrontal regions involved in emotion regulation, in PTSD as compared to HC. These findings not only highlight the crucial role of each cerebellar region examined in the psychopathology of PTSD but also reveal unique alterations in functional connectivity distinguishing the dissociative subtype of PTSD versus PTSD.

Cannabidiol as a Therapeutic Alternative for Post-traumatic Stress Disorder: From Bench Research to Confirmation in Human Trials

Post-traumatic stress disorder (PTSD) is characterized by poor adaptation to a traumatic experience. This disorder affects approximately 10% of people at some point in life. Current pharmacological therapies for PTSD have been shown to be inefficient and produce considerable side effects. Since the discovery of the involvement of the endocannabinoid (eCB) system in emotional memory processing, pharmacological manipulation of eCB signaling has become a therapeutic possibility for the treatment of PTSD. Cannabidiol (CBD), a phytocannabinoid constituent of Cannabis sativa without the psychoactive effects of Δ⁹-tetrahydrocannabinol, has gained particular attention. Preclinical studies in different rodent behavioral models have shown that CBD can both facilitate the extinction of aversive memories and block their reconsolidation, possibly through potentialization of the eCB system. These results, combined with the currently available pharmacological treatments for PTSD being limited, necessitated testing CBD use with the same therapeutic purpose in humans as well. Indeed, as observed in rodents, recent studies have confirmed the ability of CBD to alter important aspects of aversive memories in humans and promote significant improvements in the symptomatology of PTSD. The goal of this review was to highlight the potential of CBD as a treatment for disorders related to inappropriate retention of aversive memories, by assessing evidence from preclinical to human experimental studies.

Intrinsic connectivity network dynamics in PTSD during amygdala downregulation using real-time fMRI neurofeedback: A preliminary analysis

Posttraumatic stress disorder (PTSD) has been associated with a disturbance in neural intrinsic connectivity networks (ICN), including the central executive network (CEN), default mode network (DMN), and salience network (SN). Here, we conducted a preliminary investigation examining potential changes in ICN recruitment as a function of real-time fMRI neurofeedback (rt-fMRI-NFB) during symptom provocation where we targeted the downregulation of neural response within the amygdala-a key region-of-interest in PTSD neuropathophysiology. Patients with PTSD (n = 14) completed three sessions of rt-fMRI-NFB with the following conditions: (a) regulate: decrease activation in the amygdala while processing personalized trauma words; (b) view: process trauma words while not attempting to regulate the amygdala; and (c) neutral: process neutral words. We found that recruitment of the left CEN increased over neurofeedback runs during the regulate condition, a finding supported by increased dlPFC activation during the regulate as compared to the view condition. In contrast, DMN task-negative recruitment was stable during neurofeedback runs, albeit was the highest during view conditions and increased (normalized) during rest periods. Critically, SN recruitment was high for both the regulate and the view conditions, a finding potentially indicative of CEN modality switching, adaptive learning, and increasing threat/defense processing in PTSD. In conclusion, this study provides provocative, preliminary evidence that downregulation of the amygdala using rt-fMRI-NFB in PTSD is associated with dynamic changes in ICN, an effect similar to those observed using EEG modalities of neurofeedback.

Post-traumatic stress influences local and remote functional connectivity: a resting-state functional magnetic resonance imaging study

Post-traumatic stress disorder (PTSD) is associated with alterations in regional brain activation and remote functional connectivity (FC) in limbic and prefrontal cortex. However, little is known about local FC changes following a traumatic event. Resting-state functional magnetic resonance images were collected for typhoon survivors with (n = 27) and without PTSD (n = 33), and healthy controls (n = 30). Local FC was examined by calculating regional homogeneity (ReHo), and remote FC was investigated between regions showing significant ReHo group differences. The PTSD group showed ReHo changes in multiple regions, including the amygdala, parahippocampal gyrus, and prefrontal cortex relative to both control groups. Compared with healthy controls, typhoon survivors had increased ReHo in the insula/inferior frontal gyrus, middle and dorsal anterior cingulate cortex (MCC/dACC), as well as enhanced negative FC between the MCC/dACC and posterior cingulate cortex (PCC)/precuneus. The typhoon-exposed control group exhibited higher ReHo in the PCC/precuneus than the PTSD and healthy control groups. Furthermore, positive correlations were found between PTSD symptom severity and ReHo in several regions. Post-traumatic stress can influence local and remote FC, irrespective of PTSD diagnosis. Future studies are needed to validate the findings and to determine whether the alterations represent pre-existing or acquired deficits.

Plastic change of prefrontal cortex mediates anxiety-like behaviors associated with chronic pain in neuropathic rats

Clinical studies show that anxiety and chronic pain are concomitant. The neural basis for the comorbidity is unclear. The prefrontal cortex (PFC) has been recognized as a critical area for affective disorders and chronic pain modulation. In this study, we examined the role of the PFC in the pathogenesis of anxiety associated with chronic pain in a rat model of neuropathic pain with spare nerve injury (SNI). The SNI rats showed apparent anxiety-like behaviors in both open field (OF) test and elevated-plus maze (EPM) test eight weeks after surgery. Thus, the number of entries to the central area in the OF decreased to 45% (±5%, n = 15) of sham control (n = 17), while the overall motor activity (i.e., total distance) was unaffected. In the EPM, the percentage of entries into the open arms significantly (p < 0.001) decreased in SNI rats (SNI: 12.58 ± 2.7%, n = 15; sham: 30.75 ± 2.82%, n = 17), so did the time spent in the open arms (SNI: 4.35 ± 1.45%, n = 15; Sham: 11.65 ± 2.18%, n = 17). To explore the neural basis for the association between anxiety and chronic pain, local field potentials (LFPs) were recorded from the medial PFC (mPFC) and ventral hippocampus. In SNI rats, there were significantly greater increases in both theta-frequency power in the mPFC and theta-frequency synchronization between the mPFC and ventral hippocampus, when animals were displaying elevated anxiety-like behaviors in avoiding anxiogenic regions in EPM and OF chamber. Western blot analyses showed a significant elevation of serotonin transporter expression in the anxious SNI rats. Inhibition of serotonin transporter effectively alleviated anxiety-like behaviors following sub-chronic (15 days) treatment with systemic citalopram (10 mg/kg/day, intraperitoneally). Moreover, the anxiety-like behaviors in the SNI rats were also suppressed by direct mPFC application of serotonin. Taken together, we conclude that the plasticity of serotonin transmission in the mPFC likely contribute to the promotion of anxiety state associated with neuropathic pain.

Functional connectivity of hippocampal subregions in PTSD: relations with symptoms

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with abnormal hippocampal activity; however, the functional connectivity (FC) of the hippocampus with other brain regions in PTSD and its relations with symptoms warrants further attention. We investigated subregional hippocampal FC in PTSD during a resting state compared with a trauma-exposed control (TEC) group. Based on extant research, we targeted the FCs of the anterior and posterior hippocampal subregions with the amygdala, medial prefrontal cortex (mPFC), and the posterior cingulate (PCC).

METHODS

Resting-state functional magnetic resonance images were acquired from 11 individuals with PTSD and 13 trauma-exposed controls. Anterior and posterior hippocampal FC was compared between groups. Within the PTSD and TEC groups, subregional hippocampal FC was correlated with scores on the Clinician-Administered PTSD Scale (CAPS) at time of scan and 4 months post-scan.

RESULTS

Those with PTSD had significantly greater FC compared with the TEC group between the left posterior hippocampus and the bilateral PCC (g's > .96). Direct contrasts of the Fisher z-transformed coefficients indicated that the correlations between CAPS scores 4 months post scan and the FC between the left hippocampal head and the right PCC (z = - 2.07, p = .039) as well as the FC between the right hippocampal tail and the right mPFC (z = - 2.19, p = .029) were significantly greater in the PTSD group compared to the TEC group.

CONCLUSIONS

These results support between-group differences in posterior hippocampal FC and different relations with PTSD future symptoms, underscoring associations with the anterior and posterior hippocampus. These findings enrich our understanding of PTSD pathophysiology and provide support for future investigations of imaging biomarkers predictive of disease progression.

Default mode network abnormalities in posttraumatic stress disorder: A novel network-restricted topology approach

Disruption in the default mode network (DMN) has been implicated in numerous neuropsychiatric disorders, including posttraumatic stress disorder (PTSD). However, studies have largely been limited to seed-based methods and involved inconsistent definitions of the DMN. Recent advances in neuroimaging and graph theory now permit the systematic exploration of intrinsic brain networks. In this study, we used resting-state functional magnetic resonance imaging (fMRI), diffusion MRI, and graph theoretical analyses to systematically examine the DMN connectivity and its relationship with PTSD symptom severity in a cohort of 65 combat-exposed US Veterans. We employed metrics that index overall connectivity strength, network integration (global efficiency), and network segregation (clustering coefficient). Then, we conducted a modularity and network-based statistical analysis to identify DMN regions of particular importance in PTSD. Finally, structural connectivity analyses were used to probe whether white matter abnormalities are associated with the identified functional DMN changes. We found decreased DMN functional connectivity strength to be associated with increased PTSD symptom severity. Further topological characterization suggests decreased functional integration and increased segregation in subjects with severe PTSD. Modularity analyses suggest a spared connectivity in the posterior DMN community (posterior cingulate, precuneus, angular gyrus) despite overall DMN weakened connections with increasing PTSD severity. Edge-wise network-based statistical analyses revealed a prefrontal dysconnectivity. Analysis of the diffusion networks revealed no alterations in overall strength or prefrontal structural connectivity. DMN abnormalities in patients with severe PTSD symptoms are characterized by decreased overall interconnections. On a finer scale, we found a pattern of prefrontal dysconnectivity, but increased cohesiveness in the posterior DMN community and relative sparing of connectivity in this region. The DMN measures established in this study may serve as a biomarker of disease severity and could have potential utility in developing circuit-based therapeutics.

Specific amygdala response to masked fearful faces in post-traumatic stress relative to other anxiety disorders

BACKGROUND

Altered amygdala activation to fear-related stimuli has been proposed to be a potential neural correlate of heightened threat sensitivity in anxiety- and stress-related disorders. However, the role of stimulus awareness and disorder specificity remains widely unclear. Here we investigated amygdala responses to conscious and unconscious fearful faces in patients suffering from panic disorder (PD), generalized anxiety disorder (GAD), or post-traumatic stress disorder (PTSD) and in a large sample of healthy controls (HC).

METHODS

During event-related functional magnetic resonance imaging participants (n = 120; 20 PD, 20 GAD, 20 PTSD, 60 HC) were confronted with briefly presented fearful faces, neutral faces, and non-faces in a backward masking paradigm. The design allowed for the analysis of trial-by-trial face detection performance and amygdala responses to fearful v. neutral faces.

RESULTS

All participants exhibited increased amygdala activation to fearful v. neutral faces during conscious trials. Specifically during unconscious face processing, the PTSD, compared with all other groups, showed higher right basolateral (BLA) amygdala activity to fearful v. neutral faces.

CONCLUSIONS

The present study shows that BLA amygdala hyperactivity during unconscious, but not conscious, processing of fearful faces differentiates PTSD from the investigated disorders. This finding suggests an automatic and specific neural hyper-responsivity to general fear cues in PTSD and supports the idea of categorical differences between PTSD and other anxiety-related disorders.

Alterations in the Three Components of Selfhood in Persons with Post-Traumatic Stress Disorder Symptoms: A Pilot qEEG Neuroimaging Study

Background and Objective:

Understanding how trauma impacts the self-structure of individuals suffering from the Post-Traumatic Stress Disorder (PTSD) symptoms is a complex matter and despite several attempts to explain the relationship between trauma and the “Self”, this issue still lacks clarity. Therefore, adopting a new theoretical perspective may help understand PTSD deeper and to shed light on the underlying psychophysiological mechanisms.

Methods:

In this study, we employed the “three-dimensional construct model of the experiential selfhood” where three major components of selfhood (phenomenal first-person agency, embodiment, and reflection/narration) are related to three Operational Modules (OMs) of the self-referential brain network. These modules can be reliably estimated through operational synchrony analysis of the Electroencephalogram (EEG). Six individuals with PTSD symptoms and twenty-nine sex-, age- and demographic- (race, education, marital status) matched healthy controls underwent resting state EEG signal acquisition with the following estimation of the synchrony strength within every OM.

Results:

Our results indicate that subjects with PTSD symptoms had significantly stronger EEG operational synchrony within anterior and right posterior OMs as well as significantly weaker EEG operational synchrony within left posterior OM compared to healthy controls. Moreover, increased the functional integrity of the anterior OM was positively associated with hyperactivity symptoms, reduced synchrony of the left posterior OM was associated with greater avoidance, and increased right posterior OM integrity was positively correlated with intrusion and mood symptoms.

Conclusion:

The results are interpreted in light of the triad model of selfhood and its theoretical and clinical implications (including a new treatment approach) are discussed.

Real-time fMRI neurofeedback training of the amygdala activity with simultaneous EEG in veterans with combat-related PTSD

Posttraumatic stress disorder (PTSD) is a chronic and disabling neuropsychiatric disorder characterized by insufficient top-down modulation of the amygdala activity by the prefrontal cortex. Real-time fMRI neurofeedback (rtfMRI-nf) is an emerging method with potential for modifying the amygdala-prefrontal interactions. We report the first controlled emotion self-regulation study in veterans with combat-related PTSD utilizing rtfMRI-nf of the amygdala activity. PTSD patients in the experimental group (EG, n = 20) learned to upregulate blood‑oxygenation-level-dependent (BOLD) activity of the left amygdala (LA) using the rtfMRI-nf during a happy emotion induction task. PTSD patients in the control group (CG, n = 11) were provided with a sham rtfMRI-nf. The study included three rtfMRI-nf training sessions, and EEG recordings were performed simultaneously with fMRI. PTSD severity was assessed before and after the training using the Clinician-Administered PTSD Scale (CAPS). The EG participants who completed the study showed a significant reduction in total CAPS ratings, including significant reductions in avoidance and hyperarousal symptoms. They also exhibited a significant reduction in comorbid depression severity. Overall, 80% of the EG participants demonstrated clinically meaningful reductions in CAPS ratings, compared to 38% in the CG. No significant difference in the CAPS rating changes was observed between the groups. During the first rtfMRI-nf session, functional connectivity of the LA with the orbitofrontal cortex (OFC) and the dorsolateral prefrontal cortex (DLPFC) was progressively enhanced, and this enhancement significantly and positively correlated with the initial CAPS ratings. Left-lateralized enhancement in upper alpha EEG coherence also exhibited a significant positive correlation with the initial CAPS. Reduction in PTSD severity between the first and last rtfMRI-nf sessions significantly correlated with enhancement in functional connectivity between the LA and the left DLPFC. Our results demonstrate that the rtfMRI-nf of the amygdala activity has the potential to correct the amygdala-prefrontal functional connectivity deficiencies specific to PTSD.

Disrupted grey matter network morphology in pediatric posttraumatic stress disorder

Introduction

Disrupted topological organization of brain functional networks has been widely observed in posttraumatic stress disorder (PTSD). However, the topological organization of the brain grey matter (GM) network has not yet been investigated in pediatric PTSD who was more vulnerable to develop PTSD when exposed to stress.

Materials and methods

Twenty two pediatric PTSD patients and 22 matched trauma-exposed controls who survived a massive earthquake (8.0 magnitude on Richter scale) in Sichuan Province of western China in 2008 underwent structural brain imaging with MRI 8–15 months after the earthquake. Brain networks were constructed based on the morphological similarity of GM across regions, and analyzed using graph theory approaches. Nonparametric permutation testing was performed to assess group differences in each topological metric.

Results

Compared with controls, brain networks of PTSD patients were characterized by decreased characteristic path length (P = 0.0060) and increased clustering coefficient (P = 0.0227), global efficiency (P = 0.0085) and local efficiency (P = 0.0024). Locally, patients with PTSD exhibited increased centrality in nodes of the default-mode (DMN), central executive (CEN) and salience networks (SN), involving medial prefrontal (mPFC), parietal, anterior cingulate (ACC), occipital and olfactory cortex and hippocampus.

Conclusions

Our analyses of topological brain networks in children with PTSD indicate a significantly more segregated and integrated organization. The associations and disassociations between these grey matter findings and white matter (WM) and functional changes previously reported in this sample may be important for diagnostic purposes and understanding the brain maturational effects of pediatric PTSD.

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Brain networks of children with PTSD were psychoradiologically characterized by more segregated and integrated organization.

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Locally, pediatric PTSD patients exhibited increased centrality in nodes of three core neocortical networks.

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There are associations and disassociations among multimodal MRI findings in the same population of pediatric PTSD.

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Increased local efficiency relative to controls was greater in 13-16 year old than 10-12 year old PTSD patients.

Normalization and the Cholinergic Microcircuit: A Unified Basis for Attention

Attention alters three key properties of population neural activity - firing rate, rate variability, and shared variability between neurons. All three properties are well explained by a single canonical computation - normalization - that acts across hierarchically integrated brain systems. Combining data from rodents and nonhuman primates, we argue that cortical cholinergic modulation originating from the basal forebrain closely mimics the effects of directed attention on these three properties of population neural activity. Cholinergic modulation of the cortical microcircuit underlying normalization may represent a key biological basis for the rapid and flexible changes in population neuronal coding that are required by directed attention.

High-Fidelity Measures of Whole-Brain Functional Connectivity and White Matter Integrity Mediate Relationships between Traumatic Brain Injury and Post-Traumatic Stress Disorder Symptoms

Traumatic brain injury (TBI) disrupts brain communication and increases risk for post-traumatic stress disorder (PTSD). However, mechanisms by which TBI-related disruption of brain communication confers PTSD risk have not been successfully elucidated in humans. This may be in part because functional MRI (fMRI), the most common technique for measuring functional brain communication, is unreliable for characterizing individual patients. However, this unreliability can be overcome with sufficient within-individual data. Here, we examined whether relationships could be observed among TBI, structural and functional brain connectivity, and PTSD severity by collecting ∼3.5 hours of resting-state fMRI and diffusion tensor imaging (DTI) data in each of 26 United States military veterans. We observed that a TBI history was associated with decreased whole-brain resting-state functional connectivity (RSFC), while the number of lifetime TBIs was associated with reduced whole-brain fractional anisotropy (FA). Both RSFC and FA explained independent variance in PTSD severity, with RSFC mediating the TBI-PTSD relationship. Finally, we showed that large amounts of per-individual data produced highly reliable RSFC measures, and that relationships among TBI, RSFC/FA, and PTSD could not be observed with typical data quantities. These results demonstrate links among TBI, brain connectivity, and PTSD severity, and illustrate the need for precise characterization of individual patients using high-data fMRI scanning.

Longitudinal Associations Between Family Aggression, Externalizing Behavior, and the Structure and Function of the Amygdala

Using longitudinal data from 21 adolescents, we assessed family aggression (via mother, father, and youth report) in early adolescence, externalizing behavior in mid-adolescence, and magnetic resonance imaging (MRI) data in late adolescence. Amygdalae were manually traced, and used as seed regions for resting state analyses. Both family aggression and subsequent externalizing behavior predicted larger right amygdala volumes and stronger amygdala-frontolimbic/salience network connectivity and weaker amygdala-posterior cingulate connectivity. Externalizing behavior in mid-adolescence mediated associations between family aggression in early adolescence and resting state connectivity between the amygdala and the subgenual anterior cingulate cortex, medial prefrontal cortex, orbitofrontal cortex, and posterior cingulate cortex in late adolescence. Family adversity and adolescent behavior problems may share common neural correlates.

PERK signalling pathway mediates single prolonged stress-induced dysfunction of medial prefrontal cortex neurons

Post-traumatic stress disorder (PTSD) is characterized with abnormal learning and memory. Impairments in learning and memory are closely associated with apoptosis in the medial prefrontal cortex (mPFC). We previously examined the endoplasmic reticulum (ER) stress was involved in the apoptosis in the mPFC of PTSD. The PERK pathway plays the important role in the ER stress-induced apoptosis. The aim of the present study was to explore the role of PERK pathway in neuronal apoptosis in the mPFC of rat models of PTSD. We used the single prolonged stress (SPS) to mimic PTSD in rats and studied the effects of the PERK pathway in mPFC. Learning and memory behavior were examined by Morris water maze and novel object recognition tests. Apoptosis in mPFC was detected by TUNEL staining. Our results showed decreased learning memory and increased apoptosis of mPFC neurons in rats exposed to SPS. SPS exposure upregulate mRNA expressions of PERK, p-PERK, eIF2α, p-eIF2α, nuclear ATF4 and C/EBP-homologous protein (CHOP) in mPFC neurons, but the protein levels of these molecules showed difference in magnitude and time course. GSK2606414 (an antagonist of PERK) treatment successfully reversed the above changes. These results suggested that the PERK pathway mediated SPS-induced neural apoptosis in the mPFC. These findings will be helpful in understanding mPFC-related pathogenesis of PTSD.

The effects of theta burst stimulation (TBS) targeting the prefrontal cortex on executive functioning: A systematic review and meta-analysis

Theta burst stimulation (TBS) is a highly efficient repetitive transcranial magnetic stimulation (rTMS) variant employed in experimental and clinical treatment paradigms. Despite widespread usage of TBS targeting the prefrontal cortex (PFC), there has been no systematic review of the evidence linking TBS protocols to changes in task performance on common measures of prefrontal function in general, and executive functions specifically. A systematic review of the literature was conducted using PsycINFO, PubMed, Web of Science and Scopus databases to identify articles examining the effects of TBS targeting the PFC on executive function task performance. Both the up-regulating (intermittent theta burst stimulation; iTBS) and down-regulating (continuous theta burst stimulation; cTBS) variants of TBS were considered. 32 (29 cTBS; 8 iTBS) studies met the inclusion criteria. Participants (n = 759; 51.41% female) were primarily young adults (M_age = 26), with one study examining the effects of cTBS and iTBS in older adults. Results from individual studies were converted to Hedge's g and random-effects models were used to estimate the overall effect size for each protocol. Age, biological sex, and control methodology were examined as potential moderators of the cTBS effect on executive function test performance. Findings indicated a- reliable attentuating effect of cTBS on executive function task performance (g = -.244, Z = -5.920, p < .001); this effect was relatively uniform across included studies (Q= 24.178, p = .838, I² = 0). Although no significant moderators of the cTBS effect were identified, laterality sub analyses indicated that the magnitude of the effect was significantly higher (M_diff = .213, Z_diff = 2.546, p = .011) for left-sided (g = -.358, Z = -5.816, p < .001) relative to right-sided (g = -.145, Z = -2.552, p = .011) PFC stimulation. A systematic review of iTBS studies revealed variability in reliability of effects though most were in the theorized direction. TBS protocols appear to be effective in modulating prefrontal cortical excitability in previously theorized directions.

Spontaneous neural activity differences in posttraumatic stress disorder: A quantitative resting-state meta-analysis and fMRI validation

Identifying the pathophysiology of posttraumatic stress disorder (PTSD) is a critical step toward reducing its debilitating impact. Spontaneous neural activity, measured at rest using various neuroimaging techniques (e.g., regional homogeneity [ReHo], amplitude of low frequency fluctuations [ALFF]), can provide insight about baseline neurobiological factors influencing sensory, cognitive, or behavioral processes associated with PTSD. The present study used activation likelihood estimation (ALE) to conduct the largest-to-date quantitative meta-analysis of spontaneous neural activity in PTSD, including 457 PTSD cases, 292 trauma-exposed controls (TECs), and 293 non-traumatized controls (NTCs) across 22 published studies. Five regions-of-interest (ROIs) were identified where activity differed between PTSD cases and controls: one when compared to all controls (left globus pallidus), two when compared to TECs (left inferior parietal lobule [IPL] and right lingual gyrus), and two when compared to NTCs (left amygdala and right caudate head). To corroborate these results, a second analysis was conducted using resting-state functional magnetic resonance imaging on an independent sample of 205 previously-deployed US military veterans. In this analysis, converging evidence from ReHo and ALFF showed that spontaneous neural activity in the left IPL alone was positively correlated with PTSD symptom severity. This result is consistent with theoretical accounts that link left IPL activity with PTSD-relevant processes such as processing of emotional stimuli (e.g., fearful faces) and the extent that attention is captured by salient autobiographical memories. By modeling the neurobiological correlates of PTSD, we can increase our understanding of this debilitating disorder and guide the development of future clinical innovations.

Network Mechanisms of Clinical Response to Transcranial Magnetic Stimulation in Posttraumatic Stress Disorder and Major Depressive Disorder

BACKGROUND

Repetitive transcranial magnetic stimulation (TMS) therapy can modulate pathological neural network functional connectivity in major depressive disorder (MDD). Posttraumatic stress disorder is often comorbid with MDD, and symptoms of both disorders can be alleviated with TMS therapy. This is the first study to evaluate TMS-associated changes in connectivity in patients with comorbid posttraumatic stress disorder and MDD.

METHODS

Resting-state functional connectivity magnetic resonance imaging was acquired before and after TMS therapy in 33 adult outpatients in a prospective open trial. TMS at 5 Hz was delivered, in up to 40 daily sessions, to the left dorsolateral prefrontal cortex. Analyses used a priori seeds relevant to TMS, posttraumatic stress disorder, or MDD (subgenual anterior cingulate cortex [sgACC], left dorsolateral prefrontal cortex, hippocampus, and basolateral amygdala) to identify imaging predictors of response and to evaluate clinically relevant changes in connectivity after TMS, followed by leave-one-out cross-validation. Imaging results were explored using data-driven multivoxel pattern activation.

RESULTS

More negative pretreatment connectivity between the sgACC and the default mode network predicted clinical improvement, as did more positive amygdala-to-ventromedial prefrontal cortex connectivity. After TMS, symptom reduction was associated with reduced connectivity between the sgACC and the default mode network, left dorsolateral prefrontal cortex, and insula, and reduced connectivity between the hippocampus and the salience network. Multivoxel pattern activation confirmed seed-based predictors and correlates of treatment outcomes.

CONCLUSIONS

These results highlight the central role of the sgACC, default mode network, and salience network as predictors of TMS response and suggest their involvement in mechanisms of action. Furthermore, this work indicates that there may be network-based biomarkers of clinical response relevant to these commonly comorbid disorders.

Veterans with PTSD demonstrate amygdala hyperactivity while viewing threatening faces: A MEG study

Posttraumatic stress disorder (PTSD) is a major psychiatric disorder that is prevalent in combat veterans. Previous neuroimaging studies have found elevated amygdala activity in PTSD in response to threatening stimuli, but previous work has lacked the temporal specificity to study fast bottom-up fear responses involving the amygdala. Forty-four combat veterans, 28 with PTSD and 16 without, completed psychological testing and then a face-processing task during magnetoencephalography (MEG). The resulting MEG data were pre-processed, transformed into the time-frequency domain, and then imaged using a beamforming approach. We found that veterans with PTSD exhibited significantly stronger oscillatory activity from 50 to 450 ms in the left amygdala compared to veterans without PTSD while processing threatening faces. This group difference was not present while viewing neutral faces. The current study shows that amygdala hyperactivity in response to threatening cues begins quickly in PTSD, which makes theoretical sense as an adaptive bottom-up fear response.

Mindfulness-based treatments for posttraumatic stress disorder: a review of the treatment literature and neurobiological evidence

Mindfulness-based treatments for posttraumatic stress disorder (PTSD) have emerged as promising adjunctive or alternative intervention approaches. A scoping review of the literature on PTSD treatment studies, including approaches such as mindfulness-based stress reduction, mindfulness-based cognitive therapy and metta mindfulness, reveals low attrition with medium to large effect sizes. We review the convergence between neurobiological models of PTSD and neuroimaging findings in the mindfulness literature, where mindfulness interventions may target emotional under- and overmodulation, both of which are critical features of PTSD symptomatology. Recent emerging work indicates that mindfulness-based treatments may also be effective in restoring connectivity between large-scale brain networks among individuals with PTSD, including connectivity between the default mode network and the central executive and salience networks. Future directions, including further identification of the neurobiological mechanisms of mindfulness interventions in patients with PTSD and direct comparison of these interventions to first-line treatments for PTSD are discussed.

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.

Single-Prolonged Stress: A Review of Two Decades of Progress in a Rodent Model of Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a common, costly, and often debilitating psychiatric condition. However, the biological mechanisms underlying this disease are still largely unknown or poorly understood. Considerable evidence indicates that PTSD results from dysfunction in highly-conserved brain systems involved in stress, anxiety, fear, and reward. Pre-clinical models of traumatic stress exposure are critical in defining the neurobiological mechanisms of PTSD, which will ultimately aid in the development of new treatments for PTSD. Single prolonged stress (SPS) is a pre-clinical model that displays behavioral, molecular, and physiological alterations that recapitulate many of the same alterations observed in PTSD, illustrating its validity and giving it utility as a model for investigating post-traumatic adaptations and pre-trauma risk and protective factors. In this manuscript, we review the present state of research using the SPS model, with the goals of (1) describing the utility of the SPS model as a tool for investigating post-trauma adaptations, (2) relating findings using the SPS model to findings in patients with PTSD, and (3) indicating research gaps and strategies to address them in order to improve our understanding of the pathophysiology of PTSD.

Increased Inhibition of the Amygdala by the mPFC may Reflect a Resilience Factor in Post-traumatic Stress Disorder: A Resting-State fMRI Granger Causality Analysis

Purpose: To determine whether effective connectivity of the amygdala is altered in traumatized subjects with and without post-traumatic stress disorder (PTSD). Materials and Methods: Resting-state functional MRI data were obtained for 27 patients with typhoon-related PTSD, 33 trauma-exposed controls (TEC), and 30 healthy controls (HC). Effective connectivity of the bilateral amygdala was examined with Granger causality analysis and then compared between groups by conducting an analysis of variance. Results: Compared to the HC group, both the PTSD group and the TEC group showed increased effective connectivity from the amygdala to the medial prefrontal cortex (mPFC). The TEC group showed increased effective connectivity from the mPFC to the amygdala relative to the HC group. Compared to the TEC group, the PTSD group showed increased effective connectivity from the amygdala to the supplementary motor area (SMA), whereas decreased effective connectivity was detected from the SMA to the amygdala. Both the PTSD group and the TEC group showed decreased effective connectivity from the superior temporal gyrus (STG) to the amygdala relative to the HC group. Compared to the HC group, the TEC group showed increased effective connectivity from the amygdala to the dorsolateral prefrontal cortex (dlPFC), while both the PTSD group and the TEC group showed decreased effective connectivity from the dlPFC to the amygdala. The PTSD group showed decreased effective connectivity from the precuneus to the amygdala relative to both control groups, but increased effective connectivity from the amygdala to the precuneus relative to the HC group. Conclusion: Trauma leads to an increased down-top excitation from the amygdala to the mPFC and less regulation of the amygdala by the dlPFC. The results suggest that increased inhibition of the amygdala by the mPFC may reflect a resilience factor, and altered amygdala-SMA and amygdala-STG effective connectivity may reflect compensatory mechanisms of brain function. These data raise the possibility that insufficient inhibition of the amygdala by the mPFC might lead to PTSD in those who have been exposed to traumatic incidents, and may inform future therapeutic interventions.

Cerebellar and prefrontal cortical alterations in PTSD: structural and functional evidence

BACKGROUND

Neuroimaging studies have revealed that disturbances in network organization of key brain regions may underlie cognitive and emotional dysfunction in posttraumatic stress disorder (PTSD). Examining both brain structure and function in the same population may further our understanding of network alterations in PTSD.

METHODS

We used tensor-based morphometry (TBM) and intrinsic connectivity distribution (ICD) to identify regions of altered volume and functional connectivity in unmedicated individuals with PTSD (n=21) and healthy comparison (HC) participants (n=18). These regions were then used as seeds for follow-up anatomical covariance and functional connectivity analyses.

RESULTS

Smaller volume in the cerebellum and weaker structural covariance between the cerebellum seed and middle temporal gyrus were observed in the PTSD group. Individuals with PTSD also exhibited lower whole-brain connectivity in the cerebellum, dorsolateral prefrontal cortex (dlPFC) and medial prefrontal cortex (mPFC). Functional connectivity in the cerebellum and grey matter volume in the dlPFC were negatively correlated with PTSD severity as measured by the DSM-5 PTSD checklist (PCL-5; r= -.0.77, r=-0.79). Finally, seed connectivity revealed weaker connectivity within nodes of the central executive network (right and left dlPFC), and between nodes of the default mode network (mPFC and cerebellum) and the supramarginal gyrus, in the PTSD group.

CONCLUSION

We demonstrate structural and functional alterations in PTSD converging on the PFC and cerebellum. Whilst PFC alterations are relatively well established in PTSD, the cerebellum has not generally been considered a key region in PTSD. Our findings add to a growing evidence base implicating cerebellar involvement in the pathophysiology of PTSD.

Impaired Voluntary Control in PTSD: Probing Self-Regulation of the ACC With Real-Time fMRI

Background: Post-traumatic stress disorder (PTSD) is characterized by deficits in the self-regulation of cognitions and emotions. Neural networks of emotion regulation may exhibit reduced control mediated by the anterior cingulate cortex (ACC), contributing to aberrant limbic responses in PTSD. Methods: Real-time fMRI neurofeedback (rt-fMRI NF) assessed self-regulation of the ACC in nine patients with PTSD after single trauma exposure and nine matched healthy controls. All participants were instructed to train ACC upregulation on three training days. Results: Both groups achieved regulation, which was associated with wide-spread brain activation encompassing the ACC. Compared to the controls, regulation amplitude and learning rate was lower in patients, correlating with symptom severity. In addition, a frontopolar activation cluster was associated with self-regulation efforts in patients. Conclusions: For the first time, we tested self-regulation of the ACC in patients with PTSD. The observed impairment supports models of ACC-mediated regulation deficits that may contribute to the psychopathology of PTSD. Controlled trials in a larger sample are needed to confirm our findings and to directly investigate whether training of central regulation mechanisms improves emotion regulation in PTSD.

Tracing the Neural Carryover Effects of Interpersonal Anger on Resting-State fMRI in Men and Their Relation to Traumatic Stress Symptoms in a Subsample of Soldiers

Uncontrolled anger may lead to aggression and is common in various clinical conditions, including post traumatic stress disorder. Emotion regulation strategies may vary with some more adaptive and efficient than others in reducing angry feelings. However, such feelings tend to linger after anger provocation, extending the challenge of coping with anger beyond provocation. Task-independent resting-state (rs) fMRI may be a particularly useful paradigm to reveal neural processes of spontaneous recovery from a preceding negative emotional experience. We aimed to trace the carryover effects of anger on endogenous neural dynamics by applying a data-driven examination of changes in functional connectivity (FC) during rs-fMRI between before and after an interpersonal anger induction (N = 44 men). Anger was induced based on unfair monetary offers in a previously validated decision-making task. We calculated a common measure of global FC (gFC) which captures the level of FC between each region and all other regions in the brain, and examined which brain regions manifested changes in this measure following anger. We next examined the changes in all functional connections of each individuated brain region with all other brain regions to reveal which connections underlie the differences found in the gFC analysis of the previous step. We subsequently examined the relation of the identified neural modulations in the aftermath of anger with state- and trait- like measures associated with anger, including brain structure, and in a subsample of designated infantry soldiers (N = 21), with levels of traumatic stress symptoms (TSS) measured 1 year later following combat-training. The analysis pipeline revealed an increase in right amygdala gFC in the aftermath of anger and specifically with the right inferior frontal gyrus (IFG).We found that the increase in FC between the right amygdala and right IFG following anger was positively associated with smaller right IFG volume, higher trait-anger level and among soldiers with more TSS. Moreover, higher levels of right amygdala gFC at baseline predicted less reported anger during the subsequent anger provocation. The results suggest that increased amygdala-IFG connectivity following anger is associated with maladaptive recovery, and relates to long-term development of stress symptomatology in a subsample of soldiers.

Large-scale brain organization during facial emotion processing as a function of early life trauma among adolescent girls

Background

A wealth of research has investigated the impact of early life trauma exposure on functional brain activation during facial emotion processing and has often demonstrated amygdala hyperactivity and weakened connectivity between amygdala and medial PFC (mPFC). There have been notably limited investigations linking these previous node-specific findings into larger-scale network models of brain organization.

Method

To address these gaps, we applied graph theoretical analyses to fMRI data collected during a facial emotion processing task among 88 adolescent girls (n = 59 exposed to direct physical or sexual assault; n = 29 healthy controls), aged 11-17, during fMRI. Large-scale organization indices of modularity, assortativity, and global efficiency were calculated for stimulus-specific functional connectivity using an 883 region-of-interest parcellation.

Results

Among the entire sample, more severe early life trauma was associated with more modular and assortative, but less globally efficient, network organization across all stimulus categories. Among the assaulted girls, severity of early life trauma and PTSD diagnoses were both simultaneously related to increased modular brain organization. We also found that more modularized network organization was related both to amygdala hyperactivation and weakened connectivity between amygdala and medial PFC.

Conclusions

These results demonstrate that early life trauma is associated with enhanced brain organization during facial emotion processing and that this pattern of brain organization might explain the commonly observed association between childhood trauma and amygdala hyperactivity and weakened connectivity with mPFC. Implications of these results for neurocircuitry models are discussed.

Neural differences underlying face processing in veterans with TBI and co-occurring TBI and PTSD

BACKGROUND

Traumatic brain injury (TBI) is common in military personnel and associated with high rates of posttraumatic stress disorder (PTSD). TBI impacts widely-distributed neural patterns, some of which influence affective processing. Better understanding how TBI and PTSD/TBI alters affective neural activity may improve our understanding of comorbidity mechanisms, but to date the neural correlates of emotional processing in these groups has been relatively understudied.

METHODS

Military controls, military personnel with a history of TBI, and military personnel with both TBI and PTSD (N = 53) completed an emotional face processing task during fMRI. Whole-brain activation and functional connectivity during task conditions were compared between groups.

RESULTS

Few whole-brain group differences emerged in planned pairwise contrasts, though the TBI group showed some areas of hypoactivation relative to other groups during processing of faces versus shapes. The PTSD/TBI group compared to the control and TBI groups demonstrated greater connectivity between the amygdala and insula seed regions and a number of prefrontal and posterior cingulate regions.

LIMITATIONS

Generalizability to other patient groups, including those with only PTSD, has not yet been established.

CONCLUSION

TBI alone was associated with hypoactivation during a condition processing faces versus shapes, but PTSD with TBI was associated altered functional connectivity between amygdala and insula regions and cingulate and prefrontal areas. Altered connectivity patterns across groups suggests that individuals with PTSD/TBI may need to increase frontal connectivity with the insulae in order to achieve similar task-based activity.

Selective Effects of Psychotherapy on Frontopolar Cortical Function in PTSD

OBJECTIVE

Exposure therapy is an effective treatment for posttraumatic stress disorder (PTSD), but a comprehensive, emotion-focused perspective on how psychotherapy affects brain function is lacking. The authors assessed changes in brain function after prolonged exposure therapy across three emotional reactivity and regulation paradigms.

METHOD

Individuals with PTSD underwent functional MRI (fMRI) at rest and while completing three tasks assessing emotional reactivity and regulation. Individuals were then randomly assigned to immediate prolonged exposure treatment (N=36) or a waiting list condition (N=30) and underwent a second scan approximately 4 weeks after the last treatment session or a comparable waiting period, respectively.

RESULTS

Treatment-specific changes were observed only during cognitive reappraisal of negative images. Psychotherapy increased lateral frontopolar cortex activity and connectivity with the ventromedial prefrontal cortex/ventral striatum. Greater increases in frontopolar activation were associated with improvement in hyperarousal symptoms and psychological well-being. The frontopolar cortex also displayed a greater variety of temporal resting-state signal pattern changes after treatment. Concurrent transcranial magnetic stimulation and fMRI in healthy participants demonstrated that the lateral frontopolar cortex exerts downstream influence on the ventromedial prefrontal cortex/ventral striatum.

CONCLUSIONS

Changes in frontopolar function during deliberate regulation of negative affect is one key mechanism of adaptive psychotherapeutic change in PTSD. Given that frontopolar connectivity with ventromedial regions during emotion regulation is enhanced by psychotherapy and that the frontopolar cortex exerts downstream influence on ventromedial regions in healthy individuals, these findings inform a novel conceptualization of how psychotherapy works, and they identify a promising target for stimulation-based therapeutics.

Smaller amygdala volume and increased neuroticism predict anxiety symptoms in healthy subjects: A volumetric approach using manual tracing

Volume reductions in the amygdala (AMY) have been found in patients with anxiety disorders, but findings are mixed in subclinical participants with high trait anxiety scores, in whom both reductions and increases in AMY volume have been identified. One potential reason for such discrepancies could be the employment of different methods to determine the AMY volume (i.e., manual tracing in psychiatric research vs. automated methods), in non-patient research. In addition to trait anxiety, smaller AMY volume has also been linked to neuroticism, a personality trait consistently linked to increased vulnerability to anxiety. However, it is not clear how AMY volume and neuroticism together may contribute to anxiety symptoms in healthy functioning. These issues were investigated in a sample of 46 healthy participants who underwent anatomical MRI scanning and completed questionnaires measuring trait anxiety and neuroticism. AMY volume was assessed using manual tracing, based on anatomical landmarks identified in each participant's anatomical image. First, smaller left AMY volume was linked to higher levels of neuroticism (p = .013) and trait anxiety (p = .024), which in turn were positively correlated with each other. Moreover, AMY volume had a significant indirect effect on trait anxiety through neuroticism (ab = - .009, 95% CI [- .019, - .002]). This effect was not bidirectional, as trait anxiety did not predict AMY volume through neuroticism. Collectively, these findings provide support for a brain-personality-symptom framework of understanding affective dysregulation, which may help inform the development of prevention and intervention paradigms targeting preservation of AMY volume and reduction of neuroticism, to protect against anxiety symptoms.

Hippocampal GABA enables inhibitory control over unwanted thoughts

Intrusive memories, images, and hallucinations are hallmark symptoms of psychiatric disorders. Although often attributed to deficient inhibitory control by the prefrontal cortex, difficulty in controlling intrusive thoughts is also associated with hippocampal hyperactivity, arising from dysfunctional GABAergic interneurons. How hippocampal GABA contributes to stopping unwanted thoughts is unknown. Here we show that GABAergic inhibition of hippocampal retrieval activity forms a key link in a fronto-hippocampal inhibitory control pathway underlying thought suppression. Subjects viewed reminders of unwanted thoughts and tried to suppress retrieval while being scanned with functional magnetic resonance imaging. Suppression reduced hippocampal activity and memory for suppressed content. ¹H magnetic resonance spectroscopy revealed that greater resting concentrations of hippocampal GABA predicted better mnemonic control. Higher hippocampal, but not prefrontal GABA, predicted stronger fronto-hippocampal coupling during suppression, suggesting that interneurons local to the hippocampus implement control over intrusive thoughts. Stopping actions did not engage this pathway. These findings specify a multi-level mechanistic model of how the content of awareness is voluntarily controlled.

It is not fully understood how intrusive or unwanted memories are regulated. Here the authors show that hippocampal GABA concentrations, and coupling between the dorsolateral prefrontal cortex and hippocampus, predict how well subjects can suppress unwanted memories when presented with a reminder.

PTSD symptoms are associated with visual retrieval performance in OEF/OIF/OND veterans

Posttraumatic stress disorder (PTSD) is associated with poorer performance on neuropsychological tests in veterans. However, prior studies have generally compared individuals with PTSD to control groups, often excluding individuals with moderate symptoms. The present study evaluated neuropsychological performance among OEF/OIF/OND veterans as a function of overall PTSD severity, while also exploring potential associations between cognitive performance and PTSD symptom clusters. Using a brief neuropsychological battery, clinical interviews, and self-report instruments, we evaluated neuropsychological and psychiatric functioning in 90 OEF/OIF/OND veterans. When controlling for the effects of premorbid intellectual functioning and combat exposure, higher PTSD severity predicted worse visual retrieval performance, but not attention, verbal retrieval, visual learning, or executive functioning performance. A trend was observed where higher PTSD symptoms predicted worse verbal learning performance. All PTSD symptom clusters were associated with visual retrieval performance within the full sample. Avoidance and numbing symptoms were associated with verbal learning in the full sample. Findings suggest that among OEF/OIF/OND veterans with a range of PTSD symptoms, the assessment of visual memory may have implications for clinical practice.

Resting-state functional connectivity of anterior and posterior hippocampus in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) has been associated with altered resting-state functional connectivity (rs-FC) of several brain regions within the salience (SN) and default-mode (DMN) networks, including the hippocampus. However, most rs-FC studies have not focused primarily on the hippocampus, nor have they appreciated its structural heterogeneity, despite clear evidence for a dissociation between posterior and anterior hippocampal connectivity. Here, we examine rs-FC of anterior and posterior hippocampus with key regions in the SN (amygdala, insula, and dorsal anterior cingulate cortex/pre-supplementary motor area) and DMN (ventromedial prefrontal cortex, posterior cingulate cortex, and precuneus) previously implicated in PTSD, using a seed-based approach. Resting-state magnetic resonance images were obtained from 48 PTSD patients and 34 trauma-exposed healthy participants (TEHC). Results indicated no group differences when examining the hippocampus as a whole. However, examining the anterior and posterior hippocampus revealed a loss of anterior to posterior connectivity differentiation in PTSD patients. The PTSD group also demonstrated lower negative connectivity of the posterior hippocampus-precuneus pathway compared with the TEHC group. Finally, as differences in anterior and posterior hippocampus connectivity have been also related to age, we performed a secondary analysis exploring the association between age and posterior- and anterior-hippocampus connectivity in both groups. Results showed that among PTSD patients, increased age had the effect of normalizing posterior hippocampus-precuneus and hippocampus-posterior cingulate cortex connectivity, whereas no such effect was noted for the control group. These findings highlight the need for PTSD connectivity research to consider sub-parts of the hippocampus and to account for age-related connectivity differences.

Unseen scars: Cocaine patients with prior trauma evidence heightened resting state functional connectivity (RSFC) between the amygdala and limbic-striatal regions

BACKGROUND

Substance use disorder (SUD) patients with a history of trauma exhibit poorer treatment outcome, greater functional impairment and higher risk for relapse. Endorsement of prior trauma has, in several SUD populations, been linked to abnormal functional connectivity (FC) during task-based studies. We examined amygdala FC in the resting state (RS), testing for differences between cocaine patients with and without prior trauma.

METHODS

Patients with cocaine use disorder (CUD; n=34) were stabilized in an inpatient setting prior to a BOLD fMRI scan. Responses to Addiction Severity Index and the Mini-International Neuropsychiatric Interview were used to characterize the No-Trauma (n=16) and Trauma (n=18) groups. Seed-based RSFC was conducted using the right and left amygdala as regions of interest. Examination of amygdala RSFC was restricted to an a priori anatomical mask that incorporated nodes of the limbic-striatal motivational network.

RESULTS

RSFC was compared for the Trauma versus No-Trauma groups. The Trauma group evidenced greater connectivity between the amygdala and the a priori limbic-striatal mask. Peaks within the statistically significant limbic-striatal mask included the amygdala, putamen, pallidum, caudate, thalamus, insula, hippocampus/parahippocampus, and brain stem.

CONCLUSIONS

Results suggest that cocaine patients with prior trauma (versus without) have heightened communication within nodes of the motivational network, even at rest. To our knowledge, this is the first fMRI study to examine amygdala RSFC among those with CUD and trauma history. Heightened RSFC intralimbic connectivity for the Trauma group may reflect a relapse-relevant brain vulnerability and a novel treatment target for this clinically-challenging population.

Connectome-wide investigation of altered resting-state functional connectivity in war veterans with and without posttraumatic stress disorder

Altered resting-state functional connectivity in posttraumatic stress disorder (PTSD) suggests neuropathology of the disorder. While seed-based fMRI connectivity analysis is often used for the studies, such analysis requires defining a seed location a priori, which restricts search scope and could bias findings toward presupposed areas. Recently, a comprehensive exploratory voxel-wise connectivity analysis, the connectome-wide association approach, has been introduced using multivariate distance matrix regression (MDMR) for resting-state functional connectivity analysis. The current study performed a connectome-wide investigation of resting-state functional connectivity for war veterans with and without PTSD compared to non-trauma-exposed healthy controls using MDMR. Thirty-five male combat veterans with PTSD (unmedicated), 18 male combat veterans without PTSD (veterans control, VC), and 28 age-matched non-trauma-exposed healthy males (NC) participated in a resting-state fMRI scan. MDMR analysis was used to identify between-groups differences in regions with altered connectivity. The identified regions were used as a seed for post-hoc functional connectivity analysis. The analysis revealed that PTSD patients had hypoconnectivity between the left lateral prefrontal regions and the salience network regions as well as hypoconnectivity between the parahippocampal gyrus and the visual cortex areas. Connectivity between the ventromedial prefrontal cortex and the middle frontal gyrus and between the parahippocampal gyrus and the anterior insula were negatively correlated with PTSD symptom severity. VC subjects also had altered functional connectivity compared to NC, including increased connectivity between the posterior insula and several brain regions and decreased connectivity between the precuneus region and several other brain areas. The decreased connectivity between the lateral prefrontal regions and the salience network regions in PTSD was consistent with previous reports that indicated lowered emotion-regulation function in these regions. The decreased connectivity between the parahippocampal gyrus and visual cortex supported the dual representation theory of PTSD, which suggests dissociation between sensory and contextual memory representations in PTSD. The theory also supposes that the precuneus is a region that triggers retrieval of sensory memory of traumatic events. The decreased connectivity at the precuneus for VC might be associated with suppressing such a process.

Altered Insula Connectivity under MDMA

Recent work with noninvasive human brain imaging has started to investigate the effects of 3,4-methylenedioxymethamphetamine (MDMA) on large-scale patterns of brain activity. MDMA, a potent monoamine-releaser with particularly pronounced serotonin- releasing properties, has unique subjective effects that include: marked positive mood, pleasant/unusual bodily sensations and pro-social, empathic feelings. However, the neurobiological basis for these effects is not properly understood, and the present analysis sought to address this knowledge gap. To do this, we administered MDMA-HCl (100 mg p.o.) and, separately, placebo (ascorbic acid) in a randomized, double-blind, repeated-measures design with twenty-five healthy volunteers undergoing fMRI scanning. We then employed a measure of global resting-state functional brain connectivity and follow-up seed-to-voxel analysis to the fMRI data we acquired. Results revealed decreased right insula/salience network functional connectivity under MDMA. Furthermore, these decreases in right insula/salience network connectivity correlated with baseline trait anxiety and acute experiences of altered bodily sensations under MDMA. The present findings highlight insular disintegration (ie, compromised salience network membership) as a neurobiological signature of the MDMA experience, and relate this brain effect to trait anxiety and acutely altered bodily sensations-both of which are known to be associated with insular functioning.

A Network-Based Neurobiological Model of PTSD: Evidence From Structural and Functional Neuroimaging Studies

PURPOSE OF REVIEW

Although a fine-grained understanding of the neurobiology of posttraumatic stress disorder (PTSD) is yet to be elucidated, the last two decades have seen a rapid growth in the study of PTSD using neuroimaging techniques. The current review summarizes important findings from functional and structural neuroimaging studies of PTSD, by primarily focusing on their relevance towards an emerging network-based neurobiological model of the disorder.

RECENT FINDINGS

PTSD may be characterized by a weakly connected and hypoactive default mode network (DMN) and central executive network (CEN) that are putatively destabilized by an overactive and hyperconnected salience network (SN), which appears to have a low threshold for perceived saliency, and inefficient DMN-CEN modulation. There is considerable evidence for large-scale functional and structural network dysfunction in PTSD. Nevertheless, several limitations and gaps in the literature need to be addressed in future research.

Attention training improves aberrant neural dynamics during working memory processing in veterans with PTSD

Posttraumatic stress disorder (PTSD) is associated with executive functioning deficits, including disruptions in working memory (WM). Recent studies suggest that attention training reduces PTSD symptomatology, but the underlying neural mechanisms are unknown. We used high-density magnetoencephalography (MEG) to evaluate whether attention training modulates brain regions serving WM processing in PTSD. Fourteen veterans with PTSD completed a WM task during a 306-sensor MEG recording before and after 8 sessions of attention training treatment. A matched comparison sample of 12 combat-exposed veterans without PTSD completed the same WM task during a single MEG session. To identify the spatiotemporal dynamics, each group's data were transformed into the time-frequency domain, and significant oscillatory brain responses were imaged using a beamforming approach. All participants exhibited activity in left hemispheric language areas consistent with a verbal WM task. Additionally, veterans with PTSD and combat-exposed healthy controls each exhibited oscillatory responses in right hemispheric homologue regions (e.g., right Broca's area); however, these responses were in opposite directions. Group differences in oscillatory activity emerged in the theta band (4-8 Hz) during encoding and in the alpha band (9-12 Hz) during maintenance and were significant in right prefrontal and right supramarginal and inferior parietal regions. Importantly, following attention training, these significant group differences were reduced or eliminated. This study provides initial evidence that attention training improves aberrant neural activity in brain networks serving WM processing.

Posterior and prefrontal contributions to the development posttraumatic stress disorder symptom severity: an fMRI study of symptom provocation in acute stress disorder

Acute stress disorder (ASD) is predictive of the development of posttraumatic stress disorder (PTSD). In response to symptom provocation, the exposure to trauma-related pictures, ASD patients showed increased activation of the medial posterior areas of precuneus and posterior cingulate cortex as well as of superior prefrontal cortex in a previous study. The current study aimed at investigating which activated areas are predictive of the development of PTSD. Nineteen ASD patients took part in an fMRI study in which they were shown personalized trauma-related and neutral pictures within 4 weeks of the traumatic event. They were assessed for severity of PTSD 4 weeks later. Activation contrasts between trauma-related and neutral pictures were correlated with subsequent PTSD symptom severity. Greater activation in, among others, right medial precuneus, left retrosplenial cortex, precentral and right superior temporal gyrus as well as less activation in lateral, superior prefrontal and left fusiform gyrus was related to subsequently increased PTSD severity. The results are broadly in line with neural areas related to etiological models of PTSD, namely multisensory associative learning recruiting posterior regions on the one hand and failure to reappraise maladaptive cognitions, thought to involve prefrontal areas, on the other.

Cognitive profiles of Post-traumatic Stress Disorder and depression in children and adolescents

Background/Objective: Several diagnostic criteria of Post-traumatic Stress Disorder (PTSD) are remarkably similar to symptoms reported by individuals with depression, particularly as they manifest as cognitive processing deficits in children. Because of this overlap in profile and the high rate of comorbidity of PTSD and depression (48% to 69%), pinpointing similarities/differences in cognitive processes related to each of these disorders is essential to accurate diagnosis. This study aims to examine cognitive performance profiles of 23 children who have been victims of PTSD and to compare their results with 23 children with depression and 24 controls. Method: Empirical study, observational and descriptive methodologies were performed using several neuropsychological tests to assess IQ, attention, memory and executive function. Statistical comparisons between groups were made using the non-parametric Kruskall-Wallis test and post-hoc analyses were conducted using a Mann Whitney U test, as well as Quade's co-variance analysis. Results: Data show different profiles of cognitive performance in those with PTSD compared to those with depression and controls. Conclusions: The findings suggests that PTSD and depressed children differ somewhat in their cognitive profiles, and the differences in IQ found between those with PTSD and those without are not necessarily a confounding variable, but may rather be a consequence of their traumatic experience.

Grey matter density changes of structures involved in Posttraumatic Stress Disorder (PTSD) after recovery following Eye Movement Desensitization and Reprocessing (EMDR) therapy

Recovery of stress-induced structural alterations in Posttraumatic Stress Disorder (PTSD) remains largely unexplored. This study aimed to determine whether symptoms improvement is associated with grey matter (GM) density changes of brain structures involved in PTSD. Two groups of PTSD patients were involved in this study. The first group was treated with Eye Movement Desensitization and Reprocessing (EMDR) therapy and recovered from their symptoms (recovery group) (n = 11); Patients were scanned prior to therapy (T1), one week (T2) and five months after the end of therapy (T3). The second group included patients which followed a supportive therapy and remained symptomatic (wait-list group) (n = 7). They were scanned at three time-steps mimicking the same inter-scan intervals. Voxel-based morphometry (VBM) was used to characterize GM density evolution. GM density values showed a significant group-by-time interaction effect between T1 and T3 in prefrontal cortex areas. These interaction effects were driven by a GM density increase in the recovery group with respect to the wait-list group. Symptoms removal goes hand-in-hand with GM density enhancement of structures involved in emotional regulation.

Restless 'rest': intrinsic sensory hyperactivity and disinhibition in post-traumatic stress disorder

Post-traumatic stress disorder is characterized by exaggerated threat response, and theoretical accounts to date have focused on impaired threat processing and dysregulated prefrontal-cortex-amygdala circuitry. Nevertheless, evidence is accruing for broad, threat-neutral sensory hyperactivity in post-traumatic stress disorder. As low-level, sensory processing impacts higher-order operations, such sensory anomalies can contribute to widespread dysfunctions, presenting an additional aetiological mechanism for post-traumatic stress disorder. To elucidate a sensory pathology of post-traumatic stress disorder, we examined intrinsic visual cortical activity (based on posterior alpha oscillations) and bottom-up sensory-driven causal connectivity (Granger causality in the alpha band) during a resting state (eyes open) and a passive, serial picture viewing state. Compared to patients with generalized anxiety disorder (n = 24) and healthy control subjects (n = 20), patients with post-traumatic stress disorder (n = 25) demonstrated intrinsic sensory hyperactivity (suppressed posterior alpha power, source-localized to the visual cortex-cuneus and precuneus) and bottom-up inhibition deficits (reduced posterior→frontal Granger causality). As sensory input increased from resting to passive picture viewing, patients with post-traumatic stress disorder failed to demonstrate alpha adaptation, highlighting a rigid, set mode of sensory hyperactivity. Interestingly, patients with post-traumatic stress disorder also showed heightened frontal processing (augmented frontal gamma power, source-localized to the superior frontal gyrus and dorsal cingulate cortex), accompanied by attenuated top-down inhibition (reduced frontal→posterior causality). Importantly, not only did suppressed alpha power and bottom-up causality correlate with heightened frontal gamma power, they also correlated with increased severity of sensory and executive dysfunctions (i.e. hypervigilance and impulse control deficits, respectively). Therefore, sensory aberrations help construct a vicious cycle in post-traumatic stress disorder that is in action even at rest, implicating dysregulated triangular sensory-prefrontal-cortex-amygdala circuitry: intrinsic sensory hyperactivity and disinhibition give rise to frontal overload and disrupt executive control, fuelling and perpetuating post-traumatic stress disorder symptoms. Absent in generalized anxiety disorder, these aberrations highlight a unique sensory pathology of post-traumatic stress disorder (ruling out effects merely reflecting anxious hyperarousal), motivating new interventions targeting sensory processing and the sensory brain in these patients.

Trauma, PTSD, and the Developing Brain

PURPOSE OF REVIEW

PTSD in youth is common and debilitating. In contrast to adult PTSD, relatively little is known about the neurobiology of pediatric PTSD, nor how neurodevelopment may be altered. This review summarizes recent neuroimaging studies in pediatric PTSD and discusses implications for future study.

RECENT FINDINGS

Pediatric PTSD is characterized by abnormal structure and function in neural circuitry supporting threat processing and emotion regulation. Furthermore, cross-sectional studies suggest that youth with PTSD have abnormal frontolimbic development compared to typically developing youth. Examples include declining hippocampal volume, increasing amygdala reactivity, and declining amygdala-prefrontal coupling with age. Pediatric PTSD is characterized by both overt and developmental abnormalities in frontolimbic circuitry. Notably, abnormal frontolimbic development may contribute to increasing threat reactivity and weaker emotion regulation as youth age. Longitudinal studies of pediatric PTSD are needed to characterize individual outcomes and determine whether current treatments are capable of restoring healthy neurodevelopment.

Literature review of trauma-informed care: Implications for mental health nurses working in acute inpatient settings in Australia

Trauma-informed care (TIC) is increasingly recognized as an approach to improving consumers' experience of, and outcomes from, mental health services. Deriving consensus on the definition, successful approaches, and consumer experiences of TIC is yet to be attained. In the present study, we sought to clarify the challenges experienced by mental health nurses in embedding TIC into acute inpatient settings within Australia. A systematic search of electronic databases was undertaken to identify primary research conducted on the topic of TIC. A narrative review and synthesis of the 11 manuscripts retained from the search was performed. The main findings from the review indicate that there are very few studies focussing on TIC in the Australian context of acute mental health care. The review demonstrates that TIC can support a positive organizational culture and improve consumer experiences of care. The present review highlights that there is an urgency for mental health nurses to identify their role in delivering and evaluating TIC, inclusive of undertaking training and clinical supervision, and to engage in systemic efforts to change service cultures.