Neural correlates of attention bias in posttraumatic stress disorder

Violence Exposure Is Associated With Atypical Appraisal of Threat Among Women: An EEG Study

Introduction

The present study investigates the association of lifetime interpersonal violence (IPV) exposure, related posttraumatic stress disorder (IPV-PTSD), and appraisal of the degree of threat posed by facial avatars.

Methods

We recorded self-rated responses and high-density electroencephalography (HD-EEG) among women, 16 of whom with lifetime IPV-PTSD and 14 with no PTSD, during a face-evaluation task that displayed male face avatars varying in their degree of threat as rated along dimensions of dominance and trustworthiness.

Results

The study found a significant association between lifetime IPV exposure, under-estimation of dominance, and over-estimation of trustworthiness. Characterization of EEG microstates supported that lifetime IPV-PTSD modulates emotional appraisal, specifically in encoding and decoding processing associated with N170 and LPP evoked potentials. EEG source localization demonstrated an overactivation of the limbic system, in particular the parahippocampal gyrus, in response to non-threatening avatars. Additionally, dysfunctional involvement of attention-related processing anterior prefrontal cortex (aPFC) was found in response to relatively trustworthy avatars in IPV-PTSD individuals compared with non-PTSD controls.

Discussion

This study showed that IPV exposure and related PTSD modulate individuals' evaluation of facial characteristics suggesting threat. Atypical processing of these avatar characteristics was marked by group differences in brain regions linked to facial processing, emotion regulation, and memory.

Sexual trauma history is associated with reduced orbitofrontal network strength in substance-dependent women

AIM

Substance use disorders (SUDs) are highly comorbid with post-traumatic stress disorder (PTSD). PTSD-SUD comorbidity is associated with greater functional impairments and relapse risk. Women with SUDs experience markedly higher rates of trauma and PTSD compared to men with SUDs, particularly due to sexual and domestic abuse. Despite the strong association between trauma exposure and SUDs, the neurobiological correlates are understudied, particularly among females with SUDs. However, there is indication of abnormal somatic and interoceptive processing in women with PTSD. The present study examines interoception-linked differences in intrinsic brain networks in a group of women with SUDs and varying histories of trauma exposure, some of whom have a current PTSD diagnosis.

METHODS

Pre-intervention data were analyzed from a subset (N = 43) of women in SUD residential treatment recruited for a mindfulness-based intervention efficacy clinical trial. Participants diagnosed with PTSD (n = 14) or not (n = 29) performed a task which involved attending to the somatic and visceral sensations of the breathing cycle (interoception) while undergoing a functional MRI (fMRI) scan. FMRI analysis employed independent components analysis and dual regression. First, we assessed differences in functional connectivity of interoception-modulated functional networks among those with and without PTSD. Second, we tested associations between network strength and lifetime sexual violence exposure across all participants on networks that showed significant group differences.

RESULTS

PTSD diagnosis was associated with reduced functional connectivity of an orbitofrontal network with the precuneus, mid-posterior insula, lateral prefrontal cortex and angular gyrus. OFC network strength was inversely associated with sexual violence exposure over-and-above the contribution of PTSD status alone.

CONCLUSIONS

Our findings provide a novel network-level account of brain activity associated with PTSD among women with SUDs, which may inform treatment response in this subpopulation.

Abnormal target detection and novelty processing neural response in posttraumatic stress disorder

Attention impairments are common symptoms of posttraumatic stress disorder (PTSD); however, the nature of these impairments remains elusive. Attention impairment may arise as the result of either excessive response to task-irrelevant stimuli or reduced response to task-relevant information. To test the association between PTSD and response to task-relevant and task-irrelevant stimuli, we used a 3-tone novelty auditory oddball task (AOD). We hypothesized that participants with PTSD relative to trauma controls would have less response during novelty processing in the dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate cortex, as well as less response in the dlPFC and the orbitofrontal cortex during target detection. Thirty-one male veterans completed a 3-tone novelty AOD task during functional magnetic resonance imaging. Compared to trauma controls, the PTSD group had reduced response during novelty processing in ventromedial prefrontal cortex, superior/middle frontal gyrus (dlPFC), supplementary motor area/caudate, and in posterior regions including bilateral posterior cingulate cortex. The current results suggest PTSD is associated with a pattern of reduced response to novel stimuli. A disturbed orienting response in these brain regions could theoretically underlie PTSD attention-related symptoms.

Uncensored EEG: The role of DC potentials in neurobiology of the brain

Brain direct current (DC) potentials denote sustained shifts and slow deflections of cerebral potentials superimposed with conventional electroencephalography (EEG) waves and reflect alterations in the excitation level of the cerebral cortex and subcortical structures. Using galvanometers, such sustained displacement of the EEG baseline was recorded in the early days of EEG recordings. To stabilize the EEG baseline and eliminate artefacts, EEG was performed later by voltage amplifiers with high-pass filters that dismiss slow DC potentials. This left slow DC potential recordings as a neglected diagnostic source in the routine clinical setting over the last few decades. Brain DC waves may arise from physiological processes or pathological phenomena. Recordings of DC potentials are fundamental electro-clinical signatures of some neurological and psychological disorders and may serve as diagnostic, prognostic, and treatment monitoring tools. We here review the utility of both physiological and pathological brain DC potentials in different aspects of neurological and psychological disorders. This may enhance our understanding of the role of brain DC potentials and improve our fundamental clinical and research strategies for brain disorders.

Superior colliculus resting state networks in post-traumatic stress disorder and its dissociative subtype

OBJECTIVES

The innate alarm system (IAS) models the neurocircuitry involved in threat processing in posttraumatic stress disorder (PTSD). Here, we investigate a primary subcortical structure of the IAS model, the superior colliculus (SC), where the SC is thought to contribute to the mechanisms underlying threat-detection in PTSD. Critically, the functional connectivity between the SC and other nodes of the IAS remains unexplored.

EXPERIMENTAL DESIGN

We conducted a resting-state fMRI study to investigate the functional architecture of the IAS, focusing on connectivity of the SC in PTSD (n = 67), its dissociative subtype (n = 41), and healthy controls (n = 50) using region-of-interest seed-based analysis.

PRINCIPAL OBSERVATIONS

We observed group-specific resting state functional connectivity between the SC for both PTSD and its dissociative subtype, indicative of dedicated IAS collicular pathways in each group of patients. When comparing PTSD to its dissociative subtype, we observed increased resting state functional connectivity between the left SC and the right dorsolateral prefrontal cortex (DLPFC) in PTSD. The DLPFC is involved in modulation of emotional processes associated with active defensive responses characterising PTSD. Moreover, when comparing PTSD to its dissociative subtype, increased resting state functional connectivity was observed between the right SC and the right temporoparietal junction in the dissociative subtype. The temporoparietal junction is involved in depersonalization responses associated with passive defensive responses typical of the dissociative subtype.

CONCLUSIONS

Our findings suggest that unique resting state functional connectivity of the SC parallels the unique symptom profile and defensive responses observed in PTSD and its dissociative subtype. Hum Brain Mapp 39:563-574, 2018. © 2017 Wiley Periodicals, Inc.