Resting regional cerebral perfusion in recent posttraumatic stress disorder

Sex-based differences in brain morphometry under chronic stress: A pilot MRI study

Background

Sex-based differences are known to be a significant feature of chronic stress; however, the morphological mechanisms of the brain underlying these differences remain unclear. The present study aimed to use magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) to investigate the effects of sex on gray matter volume (GMV) changes under conditions of chronic stress.

Methods

A total of 32 subjects were included for analysis in the present study: 16 participants experiencing chronic stress and 16 healthy controls. T1-weighted (T1WI) images from a 3 T MRI scanner were extracted from the OpenfMRI database. Images were segmented into gray matter using VBM analysis. A two-way analysis of variance (ANOVA) with a 2 × 2 full factorial design was used to evaluate the main and interaction effects of chronic stress and sex on GMV changes, and then post hoc testing was used to verify each simple effect.

Results

Two-way ANOVA showed a chronic stress × sex interaction effect on GMV. Simple effects analysis indicated that the GMV of the bilateral pre- and post-central gyri, the right cuneus and superior occipital gyrus was decreased in males, whereas that of the bilateral pre- and post-central gyri, the right superior occipital gyrus and the left middle frontal gyrus and orbital middle frontal gyrus was increased in females, under chronic stress. Additionally, in the control group, the GMV of the bilateral pre- and post-central gyri, the right cuneus and superior occipital gyrus was greater in males than females. While in the chronic stress group, the above sex-based differences were no longer significant.

Conclusions

This study preliminarily shows that there are significant differences in gray matter volume changes between males and females under chronic stress. These findings provide a basis for future studies investigating the volumetric mechanisms of sex differences under chronic stress.

Effects of Low-Level Blast on Neurovascular Health and Cerebral Blood Flow: Current Findings and Future Opportunities in Neuroimaging

Low-level blast (LLB) exposure can lead to alterations in neurological health, cerebral vasculature, and cerebral blood flow (CBF). The development of cognitive issues and behavioral abnormalities after LLB, or subconcussive blast exposure, is insidious due to the lack of acute symptoms. One major hallmark of LLB exposure is the initiation of neurovascular damage followed by the development of neurovascular dysfunction. Preclinical studies of LLB exposure demonstrate impairment to cerebral vasculature and the blood-brain barrier (BBB) at both early and long-term stages following LLB. Neuroimaging techniques, such as arterial spin labeling (ASL) using magnetic resonance imaging (MRI), have been utilized in clinical investigations to understand brain perfusion and CBF changes in response to cumulative LLB exposure. In this review, we summarize neuroimaging techniques that can further our understanding of the underlying mechanisms of blast-related neurotrauma, specifically after LLB. Neuroimaging related to cerebrovascular function can contribute to improved diagnostic and therapeutic strategies for LLB. As these same imaging modalities can capture the effects of LLB exposure in animal models, neuroimaging can serve as a gap-bridging diagnostic tool that permits a more extensive exploration of potential relationships between blast-induced changes in CBF and neurovascular health. Future research directions are suggested, including investigating chronic LLB effects on cerebral perfusion, exploring mechanisms of dysautoregulation after LLB, and measuring cerebrovascular reactivity (CVR) in preclinical LLB models.

Pre-COVID resting-state brain activity in the fusiform gyrus prospectively predicts social anxiety alterations during the pandemic

BACKGROUND

Social anxiety (SA) has been linked to the coronavirus disease 2019 (COVID-19) pandemic, but the neurobiopsychological mechanisms underlying this relationship remain unclear. This study aimed to elucidate the neurofunctional markers for COVID-induced SA development and the potential role of COVID-related posttraumatic stress symptoms (PTSS) in the brain-SA alterations link.

METHODS

Before the COVID-19 pandemic (T1), 100 general college students underwent resting-state magnetic resonance imaging and behavioral tests. During the period of community-level outbreaks (T2), these students were re-contacted to undergo follow-up behavioral assessments.

RESULTS

Whole-brain correlation and prediction analyses found that pre-pandemic spontaneous neural activity (measured by fractional amplitude of low-frequency fluctuations) in the right fusiform gyrus (FG) was positively correlated to SA alterations (T2 - T1). Mediation analyses revealed that COVID-specific PTSS mediated the effects of right FG on SA alterations.

LIMITATIONS

The results should be interpreted carefully because only one-session neuroimaging data in a sample of normal adults were included.

CONCLUSIONS

The results provide evidence for neurofunctional markers of COVID-induced SA and may help develop targeted brain-based interventions that reduce SA.

The use of hyperbaric oxygen for veterans with PTSD: basic physiology and current available clinical data

Post-traumatic stress disorder (PTSD) affects up to 30% of veterans returning from the combat zone. Unfortunately, a substantial proportion of them do not remit with the current available treatments and thus continue to experience long-term social, behavioral, and occupational dysfunction. Accumulating data implies that the long-standing unremitting symptoms are related to changes in brain activity and structure, mainly disruption in the frontolimbic circuit. Hence, repair of brain structure and restoration of function could be a potential aim of effective treatment. Hyperbaric oxygen therapy (HBOT) has been effective in treating disruptions of brain structure and functions such as stroke, traumatic brain injury, and fibromyalgia even years after the acute insult. These favorable HBOT brain effects may be related to recent protocols that emphasize frequent fluctuations in oxygen concentrations, which in turn contribute to gene expression alterations and metabolic changes that induce neuronal stem cell proliferation, mitochondrial multiplication, angiogenesis, and regulation of the inflammatory cascade. Recently, clinical findings have also demonstrated the beneficial effect of HBOT on veterans with treatment-resistant PTSD. Moderation of intrusive symptoms, avoidance, mood and cognitive symptoms, and hyperarousal were correlated with improved brain function and with diffusion tensor imaging-defined structural changes. This article reviews the current data on the regenerative biological effects of HBOT, and the ongoing research of its use for veterans with PTSD.

Weaker situations: Uncertainty reveals individual differences in learning: Implications for PTSD

Few individuals who experience trauma develop posttraumatic stress disorder (PTSD). Therefore, the identification of individual differences that signal increased risk for PTSD is important. Lissek et al. (2006) proposed using a weak rather than a strong situation to identify individual differences. A weak situation involves less-salient cues as well as some degree of uncertainty, which reveal individual differences. A strong situation involves salient cues with little uncertainty, which produce consistently strong responses. Results from fear conditioning studies that support this hypothesis are discussed briefly. This review focuses on recent findings from three learning tasks: classical eyeblink conditioning, avoidance learning, and a computer-based task. These tasks are interpreted as weaker learning situations in that they involve some degree of uncertainty. Individual differences in learning based on behavioral inhibition, which is a risk factor for PTSD, are explored. Specifically, behaviorally inhibited individuals and rodents (i.e., Wistar Kyoto rats), as well as individuals expressing PTSD symptoms, exhibit enhanced eyeblink conditioning. Behaviorally inhibited rodents also demonstrate enhanced avoidance responding (i.e., lever pressing). Both enhanced eyeblink conditioning and avoidance are most evident with schedules of partial reinforcement. Behaviorally inhibited individuals also performed better on reward and punishment trials than noninhibited controls in a probabilistic category learning task. Overall, the use of weaker situations with uncertain relationships may be more ecologically valid than learning tasks in which the aversive event occurs on every trial and may provide more sensitivity for identifying individual differences in learning for those at risk for, or expressing, PTSD symptoms.

The cerebellum and anxiety

Although the cerebellum is traditionally known for its role in motor functions, recent evidence points toward the additional involvement of the cerebellum in an array of non-motor functions. One such non-motor function is anxiety behavior: a series of recent studies now implicate the cerebellum in anxiety. Here, we review evidence regarding the possible role of the cerebellum in anxiety-ranging from clinical studies to experimental manipulation of neural activity-that collectively points toward a role for the cerebellum, and possibly a specific topographical locus within the cerebellum, as one of the orchestrators of anxiety responses.

Transcranial Magnetic Stimulation and its Imaging Features in Patients With Depression, Post-traumatic Stress Disorder, and Traumatic Brain Injury

Transcranial magnetic stimulation (TMS) is a type of noninvasive neurostimulation used increasingly often in clinical medicine. While most studies to date have focused on TMS's ability to treat major depressive disorder, it has shown promise in several other conditions including post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI). As different treatment protocols are often used across studies, the ability to predict patient outcomes and evaluate immediate and long-term changes using imaging becomes increasingly important. Several imaging features, such as thickness, connectedness, and baseline activity of a variety of cortical and subcortical areas, have been found to be correlated with a greater response to TMS therapy. Intrastimulation imaging can reveal in real time how TMS applied to superficial areas activates or inhibits activity in deeper brain regions. Functional imaging performed weeks to months after treatment can offer an understanding of how long-term effects on brain activity relate to clinical improvement. Further work should be done to expand our knowledge of imaging features relevant to TMS therapy and how they vary across patients with different neurological and psychiatric conditions.

The cerebellum and psychological trauma: A systematic review of neuroimaging studies

Psychological trauma is highly prevalent among psychiatric disorders, however, the relationship between trauma, neurobiology and psychopathology is not yet fully understood. The cerebellum has been recognized as a crucial structure for cognition and emotion, however, it has been relatively ignored in the literature of psychological trauma, as it is not considered as part of the traditional fear neuro-circuitry. The aim of this review is to investigate how psychological trauma affects the cerebellum and to make conclusive remarks on whether the cerebellum forms part of the trauma-affected brain circuitry. A total of 267 unique records were screened and 39 studies were included in the review. Structural cerebellar alterations and aberrant cerebellar activity and connectivity in trauma-exposed individuals were consistently reported across studies. Early-onset of adverse experiences was associated with cerebellar alterations in trauma-exposed individuals. Several studies reported alterations in connectivity between the cerebellum and nodes of large-brain networks, which are implicated in several psychiatric disorders, including the default mode network, the salience network and the central executive network. Also, trauma-exposed individuals showed altered resting state and task based cerebellar connectivity with cortical and subcortical structures that are involved in emotion and fear regulation. Our preferred interpretation of the results is through the lens of the Universal Cerebellar Transform, the hypothesis that the cerebellum, given its homogeneous cytoarchitecture, performs a common computation for motor, cognitive and emotional functions. Therefore, trauma-induced alterations in this computation might set the ground for a variety of psychiatric symptoms.

Classification of posttraumatic stress disorder and related outcomes in women veterans using magnetoencephalography

Women veterans represent a unique population whose experiences and neurobiology differ from that of their male counterparts. Thus, while previous research has demonstrated the utility of synchronous neural interactions (SNI) as a biomarker of posttraumatic stress disorder (PTSD) in male veterans, the utility of SNI as a biomarker of PTSD in women veterans is unclear. Here we extend that line of research to evaluate classification of women veterans with and without PTSD and other trauma-related outcomes based on functional connectivity using magnetoencephalography (MEG). A total of 121 U.S. women veterans completed diagnostic interviews and underwent a task-free MEG scan from which SNI was computed. Linear discriminant analysis was used to classify PTSD and control groups according to SNI. That discriminant function was then used to classify each individual in the partial recovery and full recovery diagnostic groups as PTSD or control. All individuals were classified correctly (100% accuracy) according to their SNI in their PTSD and control groups. Seventy-seven percent of the full recovery group and 69% of the partial recovery group were classified as control. Individual staging in PTSD recovery was captured by the Mahalanobis D² distances from the center of the control and PTSD centroid clusters. These findings provide compelling evidence supporting the utility of task-free SNI as a biomarker of PTSD and related outcomes in women veterans.

Structural and functional deficits and couplings in the cortico-striato-thalamo-cerebellar circuitry in social anxiety disorder

Although functional and structural abnormalities in brain regions involved in the neurobiology of fear and anxiety have been observed in patients with social anxiety disorder (SAD), the findings have been heterogeneous due to small sample sizes, demographic confounders, and methodological differences. Besides, multimodal neuroimaging studies on structural-functional deficits and couplings are rather scarce. Herein, we aimed to explore functional network anomalies in brain regions with structural deficits and the effects of structure-function couplings on the SAD diagnosis. High-resolution structural magnetic resonance imaging (MRI) and resting-state functional MRI images were obtained from 49 non-comorbid patients with SAD and 53 demography-matched healthy controls. Whole-brain voxel-based morphometry analysis was conducted to investigate structural alterations, which were subsequently used as seeds for the resting-state functional connectivity analysis. In addition, correlation and mediation analyses were performed to probe the potential roles of structural-functional deficits in SAD diagnosis. SAD patients had significant gray matter volume reductions in the bilateral putamen, right thalamus, and left parahippocampus. Besides, patients with SAD demonstrated widespread resting-state dysconnectivity in cortico-striato-thalamo-cerebellar circuitry. Moreover, dysconnectivity of the putamen with the cerebellum and the right thalamus with the middle temporal gyrus/supplementary motor area partially mediated the effects of putamen/thalamus atrophy on the SAD diagnosis. Our findings provide preliminary evidence for the involvement of structural and functional deficits in cortico-striato-thalamo-cerebellar circuitry in SAD, and may contribute to clarifying the underlying mechanisms of structure-function couplings for SAD. Therefore, they could offer insights into the neurobiological substrates of SAD.

Cortical thickness abnormalities in patients with post-traumatic stress disorder: A vertex-based meta-analysis

Neuroimaging studies report altered cortical thickness in patients with post-traumatic stress disorder (PTSD), but the results are inconsistent. Using anisotropic effect-size seed-based d mapping (AES-SDM) software with its recently-developed meta-analytic thickness mask, we conducted a meta-analysis of published studies which used whole-brain surface-based morphometry, in order to define consistent cortical thickness alterations in PTSD patients. Eleven studies with 438 patients and 396 controls were included. Compared with all controls, patients with PTSD showed increased cortical thickness in right superior temporal gyrus, and in left and right superior frontal gyrus; the former survived in subgroup analysis of adult patients, and in subgroup comparison with only non-PTSD trauma-exposed controls, the latter in subgroup comparison with only non-trauma-exposed healthy controls. Cortical thickness in right superior frontal gyrus was positively associated with percentage of female patients, and cortical thickness in left superior frontal gyrus was positively associated with symptom severity measured by the clinician-administered PTSD scale. These robust results may help to elucidate the pathophysiology of PTSD.

Shandhi M, Gazi AH, Shah AJ, Pearce BD, Murrah N, Ko YA, Shallenberger LH, Vaccarino V, Inan OT, Bremner JD. Noninvasive Cervical Vagal Nerve Stimulation Alters Brain Activity During Traumatic Stress in Individuals With Posttraumatic Stress Disorder

OBJECTIVE

Posttraumatic stress disorder (PTSD) is a disabling condition affecting a large segment of the population; however, current treatment options have limitations. New interventions that target the neurobiological alterations underlying symptoms of PTSD could be highly beneficial. Transcutaneous cervical (neck) vagal nerve stimulation (tcVNS) has the potential to represent such an intervention. The goal of this study was to determine the effects of tcVNS on neural responses to reminders of traumatic stress in PTSD.

METHODS

Twenty-two participants were randomized to receive either sham (n = 11) or active (n = 11) tcVNS stimulation in conjunction with exposure to neutral and personalized traumatic stress scripts with high-resolution positron emission tomography scanning with radiolabeled water for brain blood flow measurements.

RESULTS

Compared with sham, tcVNS increased brain activations during trauma scripts (p < .005) within the bilateral frontal and temporal lobes, left hippocampus, posterior cingulate, and anterior cingulate (dorsal and pregenual), and right postcentral gyrus. Greater deactivations (p < .005) with tcVNS were observed within the bilateral frontal and parietal lobes and left thalamus. Compared with tcVNS, sham elicited greater activations (p < .005) in the bilateral frontal lobe, left precentral gyrus, precuneus, and thalamus, and right temporal and parietal lobes, hippocampus, insula, and posterior cingulate. Greater (p < .005) deactivations were observed with sham in the right temporal lobe, posterior cingulate, hippocampus, left anterior cingulate, and bilateral cerebellum.

CONCLUSIONS

tcVNS increased anterior cingulate and hippocampus activation during trauma scripts, potentially indicating a reversal of neurobiological changes with PTSD consistent with improved autonomic control.Trial Registration: No. NCT02992899.

Transcriptomic organization of the human brain in post-traumatic stress disorder

Despite extensive study of the neurobiological correlates of post-traumatic stress disorder (PTSD), little is known about its molecular determinants. Here, differential gene expression and network analyses of four prefrontal cortex subregions from postmortem tissue of people with PTSD demonstrate extensive remodeling of the transcriptomic landscape. A highly connected downregulated set of interneuron transcripts is present in the most significant gene network associated with PTSD. Integration of this dataset with genotype data from the largest PTSD genome-wide association study identified the interneuron synaptic gene ELFN1 as conferring significant genetic liability for PTSD. We also identified marked transcriptomic sexual dimorphism that could contribute to higher rates of PTSD in women. Comparison with a matched major depressive disorder cohort revealed significant divergence between the molecular profiles of individuals with PTSD and major depressive disorder despite their high comorbidity. Our analysis provides convergent systems-level evidence of genomic networks within the prefrontal cortex that contribute to the pathophysiology of PTSD in humans.

Individualized Prediction of PTSD Symptom Severity in Trauma Survivors From Whole-Brain Resting-State Functional Connectivity

Previous studies have demonstrated relations between spontaneous neural activity evaluated by resting-state functional magnetic resonance imaging (fMRI) and symptom severity in post-traumatic stress disorder. However, few studies have used brain-based measures to identify imaging associations with illness severity at the level of individual patients. This study applied connectome-based predictive modeling (CPM), a recently developed data-driven and subject-level method, to identify brain function features that are related to symptom severity of trauma survivors. Resting-state fMRI scans and clinical ratings were obtained 10-15 months after the earthquake from 122 earthquake survivors. Symptom severity of post-traumatic stress disorder features for each survivor was evaluated using the Clinician Administered Post-traumatic Stress Disorder Scale (CAPS-IV). A functionally pre-defined atlas was applied to divide the human brain into 268 regions. Each individual's functional connectivity 268 × 268 matrix was created to reflect correlations of functional time series data across each pair of nodes. The relationship between CAPS-IV scores and brain functional connectivity was explored in a CPM linear model. Using a leave-one-out cross-validation (LOOCV) procedure, findings showed that the positive network model predicted the left-out individual's CAPS-IV scores from resting-state functional connectivity. CPM predicted CAPS-IV scores, as indicated by a significant correspondence between predicted and actual values (r = 0.30, P = 0.001) utilizing primarily functional connectivity between visual cortex, subcortical-cerebellum, limbic, and motor systems. The current study provides data-driven evidence regarding the functional brain features that predict symptom severity based on the organization of intrinsic brain networks and highlights its potential application in making clinical evaluation of symptom severity at the individual level.

Peripersonal Space and Bodily Self-Consciousness: Implications for Psychological Trauma-Related Disorders

Peripersonal space (PPS) is defined as the space surrounding the body where we can reach or be reached by external entities, including objects or other individuals. PPS is an essential component of bodily self-consciousness that allows us to perform actions in the world (e.g., grasping and manipulating objects) and protect our body while interacting with the surrounding environment. Multisensory processing plays a critical role in PPS representation, facilitating not only to situate ourselves in space but also assisting in the localization of external entities at a close distance from our bodies. Such abilities appear especially crucial when an external entity (a sound, an object, or a person) is approaching us, thereby allowing the assessment of the salience of a potential incoming threat. Accordingly, PPS represents a key aspect of social cognitive processes operational when we interact with other people (for example, in a dynamic dyad). The underpinnings of PPS have been investigated largely in human models and in animals and include the operation of dedicated multimodal neurons (neurons that respond specifically to co-occurring stimuli from different perceptive modalities, e.g., auditory and tactile stimuli) within brain regions involved in sensorimotor processing (ventral intraparietal sulcus, ventral premotor cortex), interoception (insula), and visual recognition (lateral occipital cortex). Although the defensive role of the PPS has been observed in psychopathology (e.g., in phobias) the relation between PPS and altered states of bodily consciousness remains largely unexplored. Specifically, PPS representation in trauma-related disorders, where altered states of consciousness can involve dissociation from the body and its surroundings, have not been investigated. Accordingly, we review here: (1) the behavioral and neurobiological literature surrounding trauma-related disorders and its relevance to PPS; and (2) outline future research directions aimed at examining altered states of bodily self-consciousness in trauma related-disorders.

Interpersonal early life trauma is associated with increased cerebral perfusion and poorer memory performance in post-9/11 veterans

•

IP-ELT is associated with greater cerebral perfusion in the right inferior/middle temporal gyrus.

•

Cerebral perfusion mediates the relationship between IP-ELT and memory, not attention or executive function.

•

PTSD diagnosis and severity were not significantly associated with cerebral perfusion.

•

Other factors relevant to perfusion did not influence the relationship between IP-ELT and cerebral perfusion.

Cerebral blood flow (CBF) is critically important in the overall maintenance of brain health, and disruptions in normal flow have been linked to the degradation of the brain’s structural integrity and function. Recent studies have highlighted the potential role of CBF as a link between psychiatric disorders and brain integrity. Although interpersonal early life trauma (IP-ELT) is a risk factor for the development of psychiatric disorders and has been linked to disruptions in brain structure and function, the mechanisms through which IP-ELT alters brain integrity and development remain unclear. The goal of this study was to understand whether IP-ELT was associated with alterations in CBF assessed during adulthood. Further, because the cognitive implications of perfusion disruptions in IP-ELT are also unclear, this study sought to investigate the relationship between IP-ELT, perfusion, and cognition. Methods: 179 Operations Enduring Freedom/Iraqi Freedom/New Dawn (OEF/OIF/OND) Veterans and military personnel completed pseudo-continuous arterial spin labeling (pCASL) imaging, clinical interviews, the Traumatic Life Events Questionnaire (TLEQ), and a battery of neuropsychological tests that were used to derive attention, memory, and executive function cognitive composite scores. To determine whether individuals were exposed to an IP-ELT, events on the TLEQ that specifically queried interpersonal trauma before the age of 18 were tallied for each individual. Analyses compared individuals who reported an interpersonal IP-ELT (IP-ELT+, n = 48) with those who did not (IP-ELT-, n = 131). Results: Whole brain analyses revealed that IP-ELT+ individuals had significantly greater CBF in the right inferior/middle temporal gyrus compared to those in the IP-ELT- group, even after controlling for age, sex, and posttraumatic stress disorder (PTSD). Further, perfusion in the right inferior/middle temporal gyrus significantly mediated the relationship between IP-ELT and memory, not attention or executive function, such that those with an IP-ELT had greater perfusion, which, in turn, was associated with poorer memory. Examination of other clinical variables such as current PTSD diagnosis and severity as well as the interaction between IP-ELT and PTSD yielded no significant effects. Conclusions: These results extend prior work demonstrating an association between ELT and cerebral perfusion by suggesting that increased CBF may be an important neural marker with cognitive implications in populations at risk for psychiatric disorders.

Involvement of the cerebellum in EMDR efficiency: a metabolic connectivity PET study in PTSD

BACKGROUND

We recently reported an improvement of precuneus PET metabolism after EMDR therapy in military participants suffering from PTSD.

OBJECTIVE

The aim of the present study was to investigate the metabolic changes of precuneus connectivity in these participants after such treatment.

METHOD

Fifteen participants with PTSD performed a brain 18F-FDG-PET sensitized by virtual reality exposure to war scenes, before and after EMDR treatment. Inter-regional correlation analysis was performed to study metabolic changes of precuneus connectivity through SPMT maps at whole-brain level (p < 0.005 for the voxel, p < 0.05 for the cluster).

RESULTS

A decrease of connectivity was observed after EMDR between the precuneus and two significant bilateral clusters of the cerebellum (bilateral Crus I and VI cerebellar lobules, Tmax voxel of 5.8 and 5.3, and cluster size of 343 and 314 voxels, respectively). Moreover, higher cerebellar metabolism before treatment was associated with reduced clinical PTSD scores after EMDR (p = 0.03).

CONCLUSIONS

The posterior cerebellum and its metabolic connectivity with the precuneus are involved in the clinical efficiency of EMDR in PTSD.

The cerebellum under stress

Stress-related psychiatric conditions are one of the main causes of disability in developed countries. They account for a large portion of resource investment in stress-related disorders, become chronic, and remain difficult to treat. Research on the neurobehavioral effects of stress reveals how changes in certain brain areas, mediated by a number of neurochemical messengers, markedly alter behavior. The cerebellum is connected with stress-related brain areas and expresses the machinery required to process stress-related neurochemical mediators. Surprisingly, it is not regarded as a substrate of stress-related behavioral alterations, despite numerous studies that show cerebellar responsivity to stress. Therefore, this review compiles those studies and proposes a hypothesis for cerebellar function in stressful conditions, relating it to stress-induced psychopathologies. It aims to provide a clearer picture of stress-related neural circuitry and stimulate cerebellum-stress research. Consequently, it might contribute to the development of improved treatment strategies for stress-related disorders.

Dissociation between Cerebellar and Cerebral Neural Activities in Humans with Long-Term Bilateral Sensorineural Hearing Loss

Abnormal neural activity in the cerebellum has been implicated in hearing impairments, but the effects of long-term hearing loss on cerebellar function are poorly understood. To further explore the role of long-term bilateral sensorineural hearing loss on cerebellar function, we investigated hearing loss-induced changes among neural networks within cerebellar subregions and the changes in cerebellar-cerebral connectivity patterns using resting-state functional MRI. Twenty-one subjects with long-term bilateral moderate-to-severe sensorineural hearing loss and 21 matched controls with clinically normal hearing underwent MRI scanning and a series of neuropsychological tests targeting cognition and emotion. Voxel-wise functional connectivity (FC) analysis demonstrated decreased couplings between the cerebellum and other cerebral areas, including the temporal pole (TP), insula, supramarginal gyrus, inferior frontal gyrus (IFG), medial frontal gyrus, and thalamus, in long-term bilateral sensorineural hearing loss patients. An ROI-wise FC analysis found weakened interregional connections within cerebellar subdivisions. Moreover, there was a negative correlation between anxiety and FC between the left cerebellar lobe VI and left insula. Hearing ability and anxiety scores were also correlated with FC between the left cerebellar lobe VI and left TP, as well as the right cerebellar lobule VI and left IFG. Our results suggest that sensorineural hearing loss disrupts cerebellar-cerebral circuits, some potentially linked to anxiety, and interregional cerebellar connectivity. The findings contribute to a growing body showing that auditory deprivation caused by cochlear hearing loss disrupts not only activity with the classical auditory pathway but also portions of the cerebellum that communicates with other cortical networks.

Inhibited Personality Temperaments Translated Through Enhanced Avoidance and Associative Learning Increase Vulnerability for PTSD

Although many individuals who experience a trauma go on to develop post-traumatic stress disorder (PTSD), the rate of PTSD following trauma is only about 15-24%. There must be some pre-existing conditions that impart increased vulnerability to some individuals and not others. Diathesis models of PTSD theorize that pre-existing vulnerabilities interact with traumatic experiences to produce psychopathology. Recent work has indicated that personality factors such as behavioral inhibition (BI), harm avoidance (HA), and distressed (Type D) personality are vulnerability factors for the development of PTSD and anxiety disorders. These personality temperaments produce enhanced acquisition or maintenance of associations, especially avoidance, which is a criterion symptom of PTSD. In this review, we highlight the evidence for a relationship between these personality types and enhanced avoidance and associative learning, which may increase risk for the development of PTSD. First, we provide the evidence confirming a relationship among BI, HA, distressed (Type D) personality, and PTSD. Second, we present recent findings that BI is associated with enhanced avoidance learning in both humans and animal models. Third, we will review evidence that BI is also associated with enhanced eyeblink conditioning in both humans and animal models. Overall, data from both humans and animals suggest that these personality traits promote enhanced avoidance and associative learning, as well as slowing of extinction in some training protocols, which all support the learning diathesis model. These findings of enhanced learning in vulnerable individuals can be used to develop objective behavioral measures to pre-identify individuals who are more at risk for development of PTSD following traumatic events, allowing for early (possibly preventative) intervention, as well as suggesting possible therapies for PTSD targeted on remediating avoidance or associative learning. Future work should explore the neural substrates of enhanced avoidance and associative learning for behaviorally inhibited individuals in both the animal model and human participants.

Neuroimaging research in posttraumatic stress disorder - Focus on amygdala, hippocampus and prefrontal cortex

Neuroimaging research reflects the complexity of post-traumatic stress disorder and shares some common difficulties of post-traumatic stress disorder research, such as the different classifications of the disorder over time, changes in diagnostic criteria, and extensive comorbidities, as well as precisely delineated and prevailing genetic and environmental determinants in the development of the disorder and its clinical manifestations. Synthesis of neuroimaging findings in an effort to clarify causes, clinical manifestations, and consequences of the disorder is complicated by a variety of applied technical approaches in different brain regions, differences in symptom dimensions in a study population, and typically small sample sizes, with the interplay of all of these consequently bringing about divergent results. Furthermore, combinations of the aforementioned issues serve to weaken any comprehensive meta-analytic approach. In this review, we focus on recent neuroimaging studies and those performed on larger samples, with particular emphasis on research concerning the amygdala, hippocampus, and prefrontal cortex, as these are the brain regions postulated by the core research to play a prominent role in the pathophysiology of post-traumatic stress disorder. Additionally, we review the guidelines for future research and list a number of new intersectional and cross-sectional approaches in the area of neuroimaging. We conclude that future neuroimaging research in post-traumatic stress disorder will certainly benefit from a higher integration with genetic research, better profiling of control groups, and a greater involvement of the neuroimaging genetics approach and from larger collaborative studies.

Current and future functional imaging techniques for post-traumatic stress disorder

Posttraumatic stress disorder (PTSD) is a trauma and stressor related psychiatric disorder associated with structural, metabolic, and molecular alternations in several brain regions including diverse cortical areas, neuroendocrine regions, the striatum, dopaminergic, adrenergic and serotonergic pathways, and the limbic system. We are in critical need of novel therapeutics and biomarkers for PTSD and a deep understanding of cutting edge imaging and spectroscopy methods is necessary for the development of promising new approaches to better diagnose and treat the disorder. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criterion, all forms of traumatic stress-induced disorder are considered acute stress disorder for the first month following the stressor. Only after symptoms do not remit for one month can the disorder be deemed PTSD. It would be particularly useful to differentiate between acute stress disorder and PTSD during the one month waiting period so that more intensive treatments can be applied early on to patients with a high likelihood of developing PTSD. This would potentially enhance treatment outcomes and/or prevent the development of PTSD. Comprehension of the qualities and limitations of currently applied methods as well as the novel emerging techniques provide invaluable knowledge for fast paced development. Conventional methods of studying PTSD have proven to be insufficient for diagnosis, measurement of treatment efficacy, and monitoring disease progression. As the field currently stands, there is no diagnostic biomarker available for any psychiatric disease, PTSD included. Currently, emerging and available technologies are not utilized to their full capacity and in appropriate experimental designs for the most fruitful possible studies in this area. Therefore, there is an apparent need for improved methods in PTSD research. This review demonstrates the current state of the literature in PTSD, including molecular, cellular, and behavioral indicators, possible biomarkers and clinical and pre-clinical imaging techniques relevant to PTSD, and through this, elucidate the void of current practical imaging and spectroscopy methods that provide true biomarkers for the disorder and the significance of devising new techniques for future investigations. We are unlikely to develop a single biomarker for any psychiatric disorder however. As psychiatric disorders are incomparably complex compared to other medical diagnoses, its most likely that transcriptomic, metabolomic and structural and connectomic imaging data will have to be analyzed in concert in order to produce a dependable non-behavioral marker of PTSD. This can explain the necessity of bridging conventional approaches to novel technologies in order to create a framework for further discoveries in the treatment of PTSD.

Conventional methods of studying posttraumatic stress disorder (PTSD) have proven to be insufficient for diagnosis. We have reviewed clinical and preclinical imaging techniques as well as molecular, cellular, and behavioral indicators for PTSD.

The potential of calibrated fMRI in the understanding of stress in eating disorders

Eating disorders (ED), including Anorexia Nervosa (AN), Bulimia Nervosa (BN), and Binge Eating Disorder (BED), are medically dangerous psychiatric disorders of unknown etiology. Accumulating evidence supports a biopsychosocial model that includes genetic heritability, neurobiological vulnerability, and psychosocial factors, such as stress, in the development and maintenance of ED. Notably, stress hormones influence appetite and eating, and dysfunction of the physiological stress response has been implicated in ED pathophysiology. Stress signals also appear associated with food reward neurocircuitry response in ED, providing a possible mechanism for the role of stress in appetite dysregulation. This paper provides a review of some of the interacting psychological, behavioral, physiological, and neurobiological mechanisms involved in the stress response among individuals with ED, and discusses novel neuroimaging techniques to address potential physiological confounds of studying neural correlates of stress in ED, such as calibrated fMRI.

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.

The cerebellum in fear and anxiety-related disorders

Fear and anxiety-related disorders are highly prevalent psychiatric conditions characterized by avoidant and fearful reactions towards specific stimuli or situations, which are disproportionate given the real threat such stimuli entail. These conditions comprise the most common mental disorder group. There are a high proportion of patients who fail to achieve remission and the presence of high relapse rates indicate the therapeutic options available are far from being fully efficient. Despite an increased understanding the neural circuits underlying fear and anxiety-related behaviors in the last decades, a factor that could be partially contributing to the lack of adequate therapies may be an insufficient understanding of the core features of the disorders and their associated neurobiology. Interestingly, the cerebellum shows connections with fear and anxiety-related brain areas and functional involvement in such processes, but explanations for its role in anxiety disorders are lacking. Therefore, the aims of this review are to provide an overview of the neural circuitry of fear and anxiety and its connections to the cerebellum, and of the animal studies that directly assess an involvement of the cerebellum in these processes. Then, the studies performed in patients suffering from anxiety disorders that explore the cerebellum will be discussed. Finally, we'll propose a function for the cerebellum in these disorders, which could guide future experimental approaches to the topic and lead to a better understanding of the neurobiology of anxiety-related disorders, ultimately helping to develop more effective treatments for these conditions.

Metabolic and Electrophysiological Changes Associated to Clinical Improvement in Two Severely Traumatized Subjects Treated With EMDR-A Pilot Study

Neuroimaging represents a powerful tool to investigate the neurobiological correlates of Eye Movements Desensitization and Reprocessing (EMDR). The impact of EMDR on cortical and sub-cortical brain regions has been proven by several investigations demonstrating a clear association between symptoms disappearance and changes in cortical structure and functionality. The aim of this study was to assess by electroencephalography (EEG) and for the first time by positron emission tomography (PET) the changes occurring after EMDR therapy in two cases of psychological trauma following brain concussion and comatose state due to traffic accident. A 28 and a 29 years old men underwent extensive neuropsychological examination, which investigated: (i) categorical and phonological verbal fluency; (ii) episodic verbal memory; (iii) executive functions; (iv) visuospatial abilities; (v) attention and working memory as well as clinical assessment by means of psychopathological tests (CAPS, IES, BDI, SCL90R, and DES). They were then treated by eight sessions of EMDR. During the first session EEG monitoring was continuously performed and ¹⁸F-FDG PET scans, depicting brain metabolism, were acquired at rest within a week (T0). After the last session, in which the two clients were considered to be symptoms-free, neuropsychological, clinical, and PET assessment were repeated (T1). PET data were semi-quantitatively compared to a group of 18 normal controls, as for EEG the preferential cortical activations were disclosed by thresholding the individual z-score to a p < 0.05. There was a significant improvement in clinical condition for both clients associated with a significant decrease in CAPS scores. IES and BDI were found to be pathological at T0 and improved at T1 in only one subject. Visuo-constructive abilities and abstract reasoning improved after EMDR in both subjects. As for EEG, the most striking changes occurred in fronto-temporal-parietal cortex in subject 1 while subject 2 showed only minor changes. PET showed more pronounced metabolism in orbito-frontal and prefrontal cortex at T1 as compared to T0 in both subjects. In conclusion both clients had a clear clinical improvement in PTSD symptoms associated with metabolic and electrophysiological changes in limbic and associative cortex, respectively, highlighting the value of EMDR also in such extreme pathological conditions.

Abnormal brain functional connectivity leads to impaired mood and cognition in hyperthyroidism: a resting-state functional MRI study

Patients with hyperthyroidism frequently have neuropsychiatric complaints such as lack of concentration, poor memory, depression, anxiety, nervousness, and irritability, suggesting brain dysfunction. However, the underlying process of these symptoms remains unclear. Using resting-state functional magnetic resonance imaging (rs-fMRI), we depicted the altered graph theoretical metric degree centrality (DC) and seed-based resting-state functional connectivity (FC) in 33 hyperthyroid patients relative to 33 healthy controls. The peak points of significantly altered DC between the two groups were defined as the seed regions to calculate FC to the whole brain. Then, partial correlation analyses were performed between abnormal DC, FC and neuropsychological performances, as well as some clinical indexes. The decreased intrinsic functional connectivity in the posterior lobe of cerebellum (PLC) and medial frontal gyrus (MeFG), as well as the abnormal seed-based FC anchored in default mode network (DMN), attention network, visual network and cognitive network in this study, possibly constitutes the latent mechanism for emotional and cognitive changes in hyperthyroidism, including anxiety and impaired processing speed.

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.

The verbal nature of worry in generalized anxiety: Insights from the brain

Background

The Cognitive Avoidance Theory of Worry argues that worry is a cognitive strategy adopted to control the physiological arousal associated with anxiety. According to this theory, pathological worry, as in Generalized Anxiety Disorder (GAD), is verbal in nature, negative and abstract, rather than concrete. Neuroimaging studies link the expression of worry to characteristic modes of brain functional connectivity, especially in relation to the amygdala. However, the distinctive features of worry (verbal, abstract, negative), and their relationship to physiological arousal, have not so far been mapped to brain function.

Methods

We addressed this omission by undertaking a resting-state functional magnetic resonance neuroimaging study of 19 patients with GAD and 21 controls, before and after induction of perseverative cognitions, while measuring emotional bodily arousal from heart rate (HR). Seed-based analyses quantified brain changes in whole brain functional connectivity from the amygdala.

Results

In GAD, the induction increased negative thoughts and their verbal content. In line with predictions, the verbal expression of worry in GAD was associated with higher HR at baseline and attenuated HR increases after induction of perseverative cognitions. Within brain, the increased use of words during worry, and the associated dampening of HR after induction were mediated by the strength of functional connectivity between the amygdala and default mode network ‘hubs’ and the opercular cortex. The negative content of worry was further related to functional communication between amygdala and cingulo-opercular and temporal cortices.

Conclusions

Findings provide a neurobiological basis for the impact of verbal worry on HR in GAD.

•

More negative worrisome thoughts have more words in GAD and more images in controls.

•

Thinking in words is associated with reduced cardiac reactivity during worry.

•

Verbal, abstract, and negative features of worry have unique neural correlates.

•

Amygdala functional connectivity mediates use of words and HR decrease during worry.

•

A neurobiological basis for the impact of verbal worry on HR in GAD is provided.

Eye Movement Desensitization and Reprocessing and Slow Wave Sleep: A Putative Mechanism of Action

Eye Movement Desensitization and Reprocessing (EMDR) is considered highly efficacious for the treatment of Post-traumatic Stress Disorder and has proved to be a valid treatment approach with a wide range of applications. However, EMDR’s mechanisms of action is not yet fully understood. This is an active area of clinical and neurophysiological research, and several different hypotheses have been proposed. This paper discusses a conjecture which focuses on the similarity between the delta waves recorded by electroencephalography during Slow Wave Sleep (SWS) and those registered upon typical EMDR bilateral stimulation (eye movements or alternate tapping) during recurrent distressing memories of an emotionally traumatic event. SWS appears to have a key role in memory consolidation and in the reorganization of distant functional networks, as well as Eye Movements seem to reduce traumatic episodic memory and favor the reconsolidation of new associated information. The SWS hypothesis may put forward an explanation of how EMDR works, and is discussed also in light of other theories and neurobiological findings.

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.

An Effective Method to Identify Adolescent Generalized Anxiety Disorder by Temporal Features of Dynamic Functional Connectivity

Generalized anxiety disorder (GAD) is one of common anxiety disorders in adolescents. Although adolescents with GAD are thought to be at high risk for other mental diseases, the disease-specific alterations have not been adequately explored. Recent studies have revealed the abnormal functional connectivity (FC) in adolescents with GAD. Most previous researches have investigated the static FC which ignores the fluctuations of FC over time and focused on the structures of “fear circuit”. To figure out the alterations of dynamic FC caused by GAD and the possibilities of dynamic FC as biomarkers, we propose an effective approach to identify adolescent GAD using temporal features derived from dynamic FC. In our study, the instantaneous synchronization of pairwise signals was estimated as dynamic FC. The Hurst exponent (H) and variance, indicating regularity and variable degree of a time series respectively, were calculated as temporal features of dynamic FC. By leave-one-out cross-validation (LOOCV), a relatively high accuracy of 88.46% could be achieved when H and variance of dynamic FC were combined as features. In addition, we identified the disease-related regions, including regions belonging to default mode (DM) and cerebellar networks. The results suggest that temporal features of dynamic FC could achieve a clinically acceptable diagnostic power and serve as biomarkers of adolescent GAD. Furthermore, our work could be helpful in understanding the pathophysiological mechanism of adolescent GAD.

Electrical Stimulation Normalizes c-Fos Expression in the Deep Cerebellar Nuclei of Depressive-like Rats: Implication of Antidepressant Activity

The electrical stimulation of specific brain targets has been shown to induce striking antidepressant effects. Despite that recent data have indicated that cerebellum is involved in emotional regulation, the mechanisms by which stimulation improved mood-related behaviors in the cerebellum remained largely obscure. Here, we investigated the stimulation effects of the ventromedial prefrontal cortex (vmPFC), nucleus accumbens (NAc), and lateral habenular nucleus on the c-Fos neuronal activity in various deep cerebellar and vestibular nuclei using the unpredictable chronic mild stress (CMS) animal model of depression. Our results showed that stressed animals had increased number of c-Fos cells in the cerebellar dentate and fastigial nuclei, as well as in the spinal vestibular nucleus. To examine the stimulation effects, we found that vmPFC stimulation significantly decreased the c-Fos activity within the cerebellar fastigial nucleus as compared to the CMS sham. Similarly, there was also a reduction of c-Fos expression in the magnocellular part of the medial vestibular nucleus in vmPFC- and NAc core-stimulated animals when compared to the CMS sham. Correlational analyses showed that the anxiety measure of home-cage emergence escape latency was positively correlated with the c-Fos neuronal activity of the cerebellar fastigial and magnocellular and parvicellular parts of the interposed nuclei in CMS vmPFC-stimulated animals. Interestingly, there was a strong correlation among activation in these cerebellar nuclei, indicating that the antidepressant-like behaviors were possibly mediated by the vmPFC stimulation-induced remodeling within the forebrain-cerebellar neurocircuitry.

Intensity-Dependent Auditory Evoked Potential Defines Subgroups of Patients with PTSD: A Multimodality Imaging Study

Post Traumatic Stress Disorder (PTSD) is a complex and heterogeneous psychiatric disorder. Patients with chronic PTSD present with significant psychiatric co-morbidities. Current treatment guidelines recommend the use of selective serotonin reuptake inhibitors in PTSD patients, but only 50–60% of these patients respond favorably. To improve the response rate, understanding the underlying pathophysiology is necessary. Serotonergic transmission has been implicated in PTSD and the intensity-dependent auditory evoked potential (IDAEP) is presumed to reflect central serotonergic activity, thereby providing an opportunity to more precisely characterize PTSD patient populations and possibly predict response to treatment. We studied nineteen patients diagnosed with PTSD, matched for age and medications. Based on the stimulus intensity relationship, the patients were divided into two groups: augmenters and reducers. These groups were further evaluated using resting state quantitative EEG and HMPAO-based SPECT brain perfusion acquired simultaneously. The imaging data were correlated with behavioral measures characterizing symptoms of PTSD and measurements of mood state. The augmenters differed from the reducers in the resting state quantitative EEG and SPECT perfusion measures. The differences were primarily localized to the right hemisphere. There were significant differences in measures of PTSD symptoms, but not in overall measures of depression. Item analysis of depression measures showed a significant difference between the augmenters and the reducers in reported sleep difficulties, which correlated with the reported anxiety measures. Objective separation of patients into subgroups based on the IDAEP contributes to the understanding of PTSD biological substrate and can potentially lead to more effective treatment strategies.

Molecular Neuroimaging in Posttraumatic Stress Disorder

Over the past decade, an increasing number of neuroimaging studies have provided insight into the neurobiological mechanisms of posttraumatic stress disorder (PSTD). In particular, molecular neuroimaging techniques have been employed in examining metabolic and neurochemical processes in PTSD. This article reviews molecular neuroimaging studies in PTSD and focuses on findings using three imaging modalities including positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance spectroscopy (MRS). Although there were some inconsistences in the findings, patients with PTSD showed altered cerebral metabolism and perfusion, receptor bindings, and metabolite profiles in the limbic regions, medial prefrontal cortex, and temporal cortex. Studies that have investigated brain correlates of treatment response are also reviewed. Lastly, the limitations of the molecular neuroimaging studies and potential future research directions are discussed.

Decreased Regional Cerebral Perfusion at Resting State in Acute Posttraumatic Stress Disorder Resulting From a Single, Prolonged Stress Event

RATIONALE AND OBJECTIVES

This study evaluated the altered regional cerebral blood flow (rCBF) in resting state in patients with acute posttraumatic stress disorder (PTSD) 3 months after trauma.

MATERIALS AND METHODS

The rCBF was measured in 30 patients with acute PTSD and 36 healthy controls.

RESULTS

Survivors with acute PTSD showed decreased rCBF, the Clinician-Administered PTSD Scale score correlated negatively with the rCBF, and rCBF at resting state decreased in acute PTSD.

CONCLUSIONS

PTSD symptom severity was associated with diminished cerebral blood flow in the right insular cortex and right orbital medial frontal gyrus. The rCBF may predict PTSD symptom severity.

Effects of antipsychotics on cortisol, interleukin-6 and hippocampal perfusion in healthy volunteers

This randomized within-subject, double blind study aimed to compare the effects of a single dose of two different antipsychotics (haloperidol and aripiprazole) on cortisol, interleukin (IL)-6 and hippocampal regional Cerebral Blood Flow (rCBF) in the same 17 healthy male individuals. Subjects received a single dose of haloperidol (3mg), aripiprazole (10mg) and placebo, in a randomized order on three study appointments. We measured salivary cortisol levels at multiple time points, IL-6 levels from plasma samples, and resting cerebral blood flow (rCBF), using a pulsed continuous arterial spin labeling (pCASL) sequence (1.5T). We found significantly lower cortisol levels in the haloperidol condition (F(2,32)=5.78, p=0.007), than in either placebo (p=0.013; CI=0.45, 0.406) or aripiprazole (p=0.037; CI=-0.520, -0.014). Interleukin-6 levels were also lower following haloperidol (F(2,22)=4.19, p=0.048) in comparison with placebo (p=0.02; CI=0.14, 1.8), but not with aripiprazole. Finally, we found a greater rCBF in the right (peak voxel: T=6.47, p<0.0001) and left (peak voxel T=5.17, p<0.01) hippocampus following haloperidol compared with placebo, and at trend level also in the left hippocampus following aripiprazole compared with placebo (T=4.07, p=0.057). These differences in hippocampal rCBF after both antipsychotics were no longer evident (haloperidol) or present at trend level (aripiprazole), after controlling for cortisol and IL-6 levels. Our findings suggest that haloperidol can directly regulate the hypothalamic-pituitary-adrenal (HPA) axis and immune system through a pharmacological action via D2 receptor antagonism. Finally, our data suggest that the increased hippocampal rCBF is a manifestation of the reduction in IL-6 and cortisol which follows the administration of haloperidol.

ABERRANT RESTING-STATE BRAIN ACTIVITY IN POSTTRAUMATIC STRESS DISORDER: A META-ANALYSIS AND SYSTEMATIC REVIEW

BACKGROUND

About 10% of trauma-exposed individuals develop PTSD. Although a growing number of studies have investigated resting-state abnormalities in PTSD, inconsistent results suggest a need for a meta-analysis and a systematic review.

METHODS

We conducted a systematic literature search in four online databases using keywords for PTSD, functional neuroimaging, and resting-state. In total, 23 studies matched our eligibility criteria. For the meta-analysis, we included 14 whole-brain resting-state studies, reporting data on 663 participants (298 PTSD patients and 365 controls). We used the activation likelihood estimation approach to identify concurrence of whole-brain hypo- and hyperactivations in PTSD patients during rest. Seed-based studies could not be included in the quantitative meta-analysis. Therefore, a separate qualitative systematic review was conducted on nine seed-based functional connectivity studies.

RESULTS

The meta-analysis showed consistent hyperactivity in the ventral anterior cingulate cortex and the parahippocampus/amygdala, but hypoactivity in the (posterior) insula, cerebellar pyramis and middle frontal gyrus in PTSD patients, compared to healthy controls. Partly concordant with these findings, the systematic review on seed-based functional connectivity studies showed enhanced salience network (SN) connectivity, but decreased default mode network (DMN) connectivity in PTSD.

CONCLUSIONS

Combined, these altered resting-state connectivity and activity patterns could represent neurobiological correlates of increased salience processing and hypervigilance (SN), at the cost of awareness of internal thoughts and autobiographical memory (DMN) in PTSD. However, several discrepancies between findings of the meta-analysis and systematic review were observed, stressing the need for future studies on resting-state abnormalities in PTSD patients.

Altered resting-state functional activity in posttraumatic stress disorder: A quantitative meta-analysis

Many functional neuroimaging studies have reported differential patterns of spontaneous brain activity in posttraumatic stress disorder (PTSD), but the findings are inconsistent and have not so far been quantitatively reviewed. The present study set out to determine consistent, specific regional brain activity alterations in PTSD, using the Effect Size Signed Differential Mapping technique to conduct a quantitative meta-analysis of resting-state functional neuroimaging studies of PTSD that used either a non-trauma (NTC) or a trauma-exposed (TEC) comparison control group. Fifteen functional neuroimaging studies were included, comparing 286 PTSDs, 203 TECs and 155 NTCs. Compared with NTC, PTSD patients showed hyperactivity in the right anterior insula and bilateral cerebellum, and hypoactivity in the dorsal medial prefrontal cortex (mPFC); compared with TEC, PTSD showed hyperactivity in the ventral mPFC. The pooled meta-analysis showed hypoactivity in the posterior insula, superior temporal, and Heschl’s gyrus in PTSD. Additionally, subgroup meta-analysis (non-medicated subjects vs. NTC) identified abnormal activation in the prefrontal-limbic system. In meta-regression analyses, mean illness duration was positively associated with activity in the right cerebellum (PTSD vs. NTC), and illness severity was negatively associated with activity in the right lingual gyrus (PTSD vs. TEC).

Tracking down the footprints of bad paternal relationships in dissociative disorders: A diffusion tensor imaging study

Preclinical studies indicate that stress early in life can cause long-term alterations in brain development. Studies have shown alterations in the brain functions of patients after experiencing trauma. Our aim is to examine whether the integrity of white matter tracts might be affected in dissociative disorder (DD) patients. A total of 15 DD patients and 15 healthy controls were studied, with the groups matched by age and gender. Diffusion-weighted echoplanar brain images were obtained using a 1.5 Tesla magnetic resonance imaging scanner. Regions of interest were manually placed on directional maps based on principal anisotropy. Apparent diffusion coefficient and fractional anisotropy (FA) values of white matter were measured bilaterally in the anterior corona radiata (ACR) and by diffusion tensor imaging in the genu and splenium of the corpus callosum. Significantly lower FA values were observed in the right ACR of DD patients versus healthy individuals. We also found an association between bad paternal relationships and lower FA in the genu of the corpus callosum in female patients. Alterations in the right ACR suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for DD. Paternal relationships may also affect the brain's microstructure in women with DD.

The innate alarm circuit in post-traumatic stress disorder: Conscious and subconscious processing of fear- and trauma-related cues

Fast defensive responses to salient threatening stimuli are an important clinical feature of post-traumatic stress disorder (PTSD). We investigated the neural correlates of subliminal and supraliminal processing of fearful faces and individualized trauma-related words in individuals with PTSD (n=26) compared with healthy controls (n=20) using functional magnetic resonance imaging. Increased activity in the right cerebellum and the posterior cingulum was observed in individuals with PTSD during subliminal processing of trauma-related words, whereas increased activity of the basal forebrain was found within the PTSD group when processing supraliminal trauma-related words. Moreover, significant positive correlations were found between re-experiencing symptoms and response within the amygdala, and between hyper-arousal symptoms and response within the periaqueductal gray matter, during subliminal processing of trauma-related words and during supraliminal processing of fearful faces, respectively. These findings further our understanding of rapid threat processing and defensive responses, highlighting the role of the cerebellum and periaqueductal gray matter as part of an 'innate alarm system' in PTSD.

Viewing the Personality Traits Through a Cerebellar Lens: a Focus on the Constructs of Novelty Seeking, Harm Avoidance, and Alexithymia

The variance in the range of personality trait expression appears to be linked to structural variance in specific brain regions. In evidencing associations between personality factors and neurobiological measures, it seems evident that the cerebellum has not been up to now thought as having a key role in personality. This paper will review the most recent structural and functional neuroimaging literature that engages the cerebellum in personality traits, as novelty seeking and harm avoidance, and it will discuss the findings in the context of contemporary theories of affective and cognitive cerebellar function. By using region of interest (ROI)- and voxel-based approaches, we recently evidenced that the cerebellar volumes correlate positively with novelty seeking scores and negatively with harm avoidance scores. Subjects who search for new situations as a novelty seeker does (and a harm avoiding does not do) show a different engagement of their cerebellar circuitries in order to rapidly adapt to changing environments. The emerging model of cerebellar functionality may explain how the cerebellar abilities in planning, controlling, and putting into action the behavior are associated to normal or abnormal personality constructs. In this framework, it is worth reporting that increased cerebellar volumes are even associated with high scores in alexithymia, construct of personality characterized by impairment in cognitive, emotional, and affective processing. On such a basis, it seems necessary to go over the traditional cortico-centric view of personality constructs and to address the function of the cerebellar system in sustaining aspects of motivational network that characterizes the different temperamental traits.

Functional Neuroimaging Distinguishes Posttraumatic Stress Disorder from Traumatic Brain Injury in Focused and Large Community Datasets

BACKGROUND

Traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) are highly heterogeneous and often present with overlapping symptomology, providing challenges in reliable classification and treatment. Single photon emission computed tomography (SPECT) may be advantageous in the diagnostic separation of these disorders when comorbid or clinically indistinct.

METHODS

Subjects were selected from a multisite database, where rest and on-task SPECT scans were obtained on a large group of neuropsychiatric patients. Two groups were analyzed: Group 1 with TBI (n=104), PTSD (n=104) or both (n=73) closely matched for demographics and comorbidity, compared to each other and healthy controls (N=116); Group 2 with TBI (n=7,505), PTSD (n=1,077) or both (n=1,017) compared to n=11,147 without either. ROIs and visual readings (VRs) were analyzed using a binary logistic regression model with predicted probabilities inputted into a Receiver Operating Characteristic analysis to identify sensitivity, specificity, and accuracy. One-way ANOVA identified the most diagnostically significant regions of increased perfusion in PTSD compared to TBI. Analysis included a 10-fold cross validation of the protocol in the larger community sample (Group 2).

RESULTS

For Group 1, baseline and on-task ROIs and VRs showed a high level of accuracy in differentiating PTSD, TBI and PTSD+TBI conditions. This carefully matched group separated with 100% sensitivity, specificity and accuracy for the ROI analysis and at 89% or above for VRs. Group 2 had lower sensitivity, specificity and accuracy, but still in a clinically relevant range. Compared to subjects with TBI, PTSD showed increases in the limbic regions, cingulum, basal ganglia, insula, thalamus, prefrontal cortex and temporal lobes.

CONCLUSIONS

This study demonstrates the ability to separate PTSD and TBI from healthy controls, from each other, and detect their co-occurrence, even in highly comorbid samples, using SPECT. This modality may offer a clinical option for aiding diagnosis and treatment of these conditions.

The cerebellum and psychiatric disorders

The cerebellum has been considered for a long time to play a role solely in motor coordination. However, studies over the past two decades have shown that the cerebellum also plays a key role in many motor, cognitive, and emotional processes. In addition, studies have also shown that the cerebellum is implicated in many psychiatric disorders including attention deficit hyperactivity disorder, autism spectrum disorders, schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorders. In this review, we discuss existing studies reporting cerebellar dysfunction in various psychiatric disorders. We will also discuss future directions for studies linking the cerebellum to psychiatric disorders.

Brain metabolic changes in Hodgkin disease patients following diagnosis and during the disease course: An 18F-FDG PET/CT study

The aim of the present study was to investigate brain glucose metabolism in patients with Hodgkin disease (HD) after diagnosis and during chemotherapy treatment. Following the administration of first-line doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy, 74 HD patients underwent ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography brain scans, both baseline (PET0) and interim (PET2) at the Department of Biomedicine and Prevention, University of Rome Tor Vergata (Rome, Italy). Fifty-seven patients were further evaluated 15±6 days after four additional cycles (PET6). Furthermore, a control group (CG) of 40 chemotherapy-naïve subjects was enrolled. Differences in brain ¹⁸F-FDG uptake between the CG, PET0, PET2 and PET6 scans were analyzed using statistical parametric mapping. Compared with the PET0 and CG scans, the PET2 scan demonstrated a higher metabolic activity in Brodmann area (BA) 39, and a metabolic reduction in BA 11 bilaterally and in left BA 32. All of these changes disappeared at PET6. The results of the present study indicate that ABVD chemotherapy has a limited impact on brain metabolism.