Paralimbic and medial prefrontal cortical involvement in neuroendocrine responses to traumatic stimuli

Identifying gray matter alterations in Cushing's disease using machine learning: An interpretable approach

BACKGROUND

Cushing's Disease (CD) is a rare clinical syndrome characterized by excessive secretion of adrenocorticotrophic hormone, leading to significant functional and structural brain alterations as observed in Magnetic Resonance Imaging (MRI). While traditional statistical analysis has been widely employed to investigate these MRI changes in CD, it has lacked the ability to predict individual-level outcomes.

PURPOSE

To address this problem, this paper has proposed an interpretable machine learning (ML) framework, including model-level assessment, feature-level assessment, and biology-level assessment to ensure a comprehensive analysis based on structural MRI of CD.

METHODS

The ML framework has effectively identified the changes in brain regions in the stage of model-level assessment, verified the effectiveness of these altered brain regions to predict CD from normal controls in the stage of feature-level assessment, and carried out a correlation analysis between altered brain regions and clinical symptoms in the stage of biology-level assessment.

RESULTS

The experimental results of this study have demonstrated that the Insula, Fusiform gyrus, Superior frontal gyrus, Precuneus, and the opercular portion of the Inferior frontal gyrus of CD showed significant alterations in brain regions. Furthermore, our study has revealed significant correlations between clinical symptoms and the frontotemporal lobes, insulin, and olfactory cortex, which also have been confirmed by previous studies.

CONCLUSIONS

The ML framework proposed in this study exhibits exceptional potential in uncovering the intricate pathophysiological mechanisms underlying CD, with potential applicability in diagnosing other diseases.

Central stress pathways in the development of cardiovascular disease

PURPOSE

Mental stress is of essential consideration when assessing cardiovascular pathophysiology in all patient populations. Substantial evidence indicates associations among stress, cardiovascular disease and aberrant brain-body communication. However, our understanding of the flow of stress information in humans, is limited, despite the crucial insights this area may offer into future therapeutic targets for clinical intervention.

METHODS

Key terms including mental stress, cardiovascular disease and central control, were searched in PubMed, ScienceDirect and Scopus databases. Articles indicative of heart rate and blood pressure regulation, or central control of cardiovascular disease through direct neural innervation of the cardiac, splanchnic and vascular regions were included. Focus on human neuroimaging research and the flow of stress information is described, before brain-body connectivity, via pre-motor brainstem intermediates is discussed. Lastly, we review current understandings of pathophysiological stress and cardiovascular disease aetiology.

RESULTS

Structural and functional changes to corticolimbic circuitry encode stress information, integrated by the hypothalamus and amygdala. Pre-autonomic brain-body relays to brainstem and spinal cord nuclei establish dysautonomia and lead to alterations in baroreflex functioning, firing of the sympathetic fibres, cellular reuptake of norepinephrine and withdrawal of the parasympathetic reflex. The combined result is profoundly adrenergic and increases the likelihood of cardiac myopathy, arrhythmogenesis, coronary ischaemia, hypertension and the overall risk of future sudden stress-induced heart failure.

CONCLUSIONS

There is undeniable support that mental stress contributes to the development of cardiovascular disease. The emerging accumulation of large-scale multimodal neuroimaging data analytics to assess this relationship promises exciting novel therapeutic targets for future cardiovascular disease detection and prevention.

[15O]H2O PET: Potential or Essential for Molecular Imaging?

Imaging water pathways in the human body provides an excellent way of measuring accurately the blood flow directed to different organs. This makes it a powerful diagnostic tool for a wide range of diseases that are related to perfusion and oxygenation. Although water PET has a long history, its true potential has not made it into regular clinical practice. The article highlights the potential of water PET in molecular imaging and suggests its prospective role in becoming an essential tool for the 21st century precision medicine in different domains ranging from preclinical to clinical research and practice. The recent technical advances in high-sensitivity PET imaging can play a key accelerating role in empowering this technique, though there are still several challenges to overcome.

The historical progression of positron emission tomography research in neuroendocrinology

The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission Tomography (PET) imaging of endocrine system actions in vivo in the human brain for several decades. PET radioligands have been developed to measure changes that are regulated by hormone action (e.g., glucose metabolism, cerebral blood flow, dopamine receptors) and actions within endocrine organs or glands such as steroids (e.g., glucocorticoids receptors), hormones (e.g., estrogen, insulin), and enzymes (e.g., aromatase). This systematic review is targeted to the neuroendocrinology community that may be interested in learning about positron emission tomography (PET) imaging for use in their research. Covering neuroendocrine PET research over the past half century, researchers and clinicians will be able to answer the question of where future research may benefit from the strengths of PET imaging.

TOB is an effector of the hippocampus-mediated acute stress response

Stress affects behavior and involves critical dynamic changes at multiple levels ranging from molecular pathways to neural circuits and behavior. Abnormalities at any of these levels lead to decreased stress resilience and pathological behavior. However, temporal modulation of molecular pathways underlying stress response remains poorly understood. Transducer of ErbB2.1, known as TOB, is involved in different physiological functions, including cellular stress and immediate response to stimulation. In this study, we investigated the role of TOB in psychological stress machinery at molecular, neural circuit, and behavioral levels. Interestingly, TOB protein levels increased after mice were exposed to acute stress. At the neural circuit level, functional magnetic resonance imaging (fMRI) suggested that intra-hippocampal and hippocampal-prefrontal connectivity were dysregulated in Tob knockout (Tob-KO) mice. Electrophysiological recordings in hippocampal slices showed increased postsynaptic AMPAR-mediated neurotransmission, accompanied by decreased GABA neurotransmission and subsequently altered Excitatory/Inhibitory balance after Tob deletion. At the behavioral level, Tob-KO mice show abnormal, hippocampus-dependent, contextual fear conditioning and extinction, and depression-like behaviors. On the other hand, increased anxiety observed in Tob-KO mice is hippocampus-independent. At the molecular level, we observed changes in factors involved in stress response like decreased stress-induced LCN2 expression and ERK phosphorylation, as well as increased MKP-1 expression. This study introduces TOB as an important modulator in the hippocampal stress signaling machinery. In summary, we reveal a molecular pathway and neural circuit mechanism by which Tob deletion contributes to expression of pathological stress-related behavior.

Pathways from early adversity to later adjustment: Tests of the additive and bidirectional effects of executive control and diurnal cortisol in early childhood

Additive and bidirectional effects of executive control and hypothalamic-pituitary-adrenal (HPA) axis regulation on children's adjustment were examined, along with the effects of low income and cumulative risk on executive control and the HPA axis. The study utilized longitudinal data from a community sample of preschool age children (N = 306, 36-39 months at Time 1) whose families were recruited to overrepresent low-income contexts. We tested the effects of low income and cumulative risk on levels and growth of executive control and HPA axis regulation (diurnal cortisol level), the bidirectional effects of executive control and the HPA axis on each other, and their additive effects on children's adjustment problems, social competence and academic readiness. Low income predicted lower Time 4 executive control, and cumulative risk predicted lower Time 4 diurnal cortisol level. There was little evidence of bidirectional effects of executive control and diurnal cortisol. However, both executive control and diurnal cortisol predicted Time 4 adjustment, suggesting additive effects. There were indirect effects of income on all three adjustment outcomes through executive control, and of cumulative risk on adjustment problems and social competence through diurnal cortisol. The results provide evidence that executive control and diurnal cortisol additively predict children's adjustment and partially account for the effects of income and cumulative risk on adjustment.

The Fragile Brain: Stress Vulnerability, Negative Affect and GABAergic Neurocircuits in Psychosis

Persons with schizophrenia exhibit sensitivity to stress and negative affect (NA), both strongly correlated with poor functional outcome. This theoretical review suggests that NA reflects a "fragile brain," ie, vulnerable to stress, including events not experienced as stressful by healthy individuals. Based on postmortem evidence of altered gamma-aminobutyric acid (GABA) function in parvalbumin positive interneurons (PVI), animal models of PVI abnormalities and neuroimaging data with GABAergic challenge, it is suggested that GABAergic disruptions weaken cortical regions, which leads to stress vulnerability and excessive NA. Neurocircuits that respond to stressful and salient environmental stimuli, such as the hypothalamic-pituitary-adrenal axis and the amygdala, are highly dysregulated in schizophrenia, exhibiting hypo- and hyper-activity. PVI abnormalities in lateral prefrontal cortex and hippocampus have been hypothesized to affect cognitive function and positive symptoms, respectively; in the medial frontal cortex (dorsal anterior cingulate cortex and dorsal medial prefrontal cortex), these abnormalities may lead to vulnerability to stress, NA and dysregulation of stress responsive systems. Given that postmortem PVI disruptions have been identified in other conditions, such as bipolar disorder and autism, stress vulnerability may reflect a transdiagnostic dimension of psychopathology.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Comprehensive Review

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown aetiology that is recognized by the World Health Organization (WHO) and the United States Center for Disease Control and Prevention (US CDC) as a disorder of the brain. The disease predominantly affects adults, with a peak age of onset of between 20 and 45 years with a female to male ratio of 3:1. Although the clinical features of the disease have been well established within diagnostic criteria, the diagnosis of ME/CFS is still of exclusion, meaning that other medical conditions must be ruled out. The pathophysiological mechanisms are unclear but the neuro-immuno-endocrinological pattern of CFS patients gleaned from various studies indicates that these three pillars may be the key point to understand the complexity of the disease. At the moment, there are no specific pharmacological therapies to treat the disease, but several studies' aims and therapeutic approaches have been described in order to benefit patients' prognosis, symptomatology relief, and the recovery of pre-existing function. This review presents a pathophysiological approach to understanding the essential concepts of ME/CFS, with an emphasis on the population, clinical, and genetic concepts associated with ME/CFS.

Sex differences in major depression and comorbidity of cardiometabolic disorders: impact of prenatal stress and immune exposures

Major depressive disorder topped ischemic heart disease as the number one cause of disability worldwide in 2012, and women have twice the risk of men. Further, the comorbidity of depression and cardiometabolic disorders will be one of the primary causes of disability worldwide by 2020, with women at twice the risk. Thus, understanding the sex-dependent comorbidities has public health consequences worldwide. We propose here that sex differences in MDD-cardiometabolic comorbidity originate, in part, from pathogenic processes initiated in fetal development that involve sex differences in shared pathophysiology between the brain, the vascular system, the CNS control of the heart and associated hormonal, immune, and metabolic physiology. Pathways implicate neurotrophic and angiogenic growth factors, gonadal hormone receptors, and neurotransmitters such as gamma amino butyric acid (GABA) on neuronal and vascular development of HPA axis regions, such as the paraventricular nucleus (PVN), in addition to blood pressure, in part through the renin-angiotensin system, and insulin and glucose metabolism. We show that the same prenatal exposures have consequences for sex differences across multiple organ systems that, in part, share common pathophysiology. Thus, we believe that applying a sex differences lens to understanding shared biologic substrates underlying these comorbidities will provide novel insights into the development of sex-dependent therapeutics. Further, taking a lifespan perspective beginning in fetal development provides the opportunity to target abnormalities early in the natural history of these disorders in a sex-dependent way.

Brain activity and connectivity in response to negative affective stimuli: Impact of dysphoric mood and sex across diagnoses

Negative affective stimuli elicit behavioral and neural responses which vary on a continuum from adaptive to maladaptive, yet are typically investigated in a dichotomous manner (healthy controls vs. psychiatric diagnoses). This practice may limit our ability to fully capture variance from acute responses to negative affective stimuli to psychopathology at the extreme end. To address this, we conducted a functional magnetic resonance imaging study to examine the neural responses to negative valence/high arousal and neutral valence/low arousal images as a function of dysphoric mood and sex across individuals (n = 99) who represented traditional categories of healthy controls, major depressive disorder, bipolar psychosis, and schizophrenia. Observation of negative (vs. neutral) stimuli elicited blood oxygen-level dependent responses in the following circuitry: periaqueductal gray, hypothalamus (HYPO), amygdala (AMYG), hippocampus (HIPP), orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and greater connectivity between AMYG and mPFC. Across all subjects, severity of dysphoric mood was associated with hyperactivity of HYPO, and, among females, right (R) AMYG. Females also demonstrated inverse relationships between severity of dysphoric mood and connectivity between HYPO - R OFC, R AMYG - R OFC, and R AMYG - R HIPP. Overall, our findings demonstrated sex-dependent deficits in response to negative affective stimuli increasing as a function of dysphoric mood state. Females demonstrated greater inability to regulate arousal as mood became more dysphoric. These findings contribute to elucidating biosignatures associated with response to negative stimuli across disorders and suggest the importance of a sex-dependent lens in determining these biosignatures. Hum Brain Mapp 37:3733-3744, 2016. © 2016 Wiley Periodicals, Inc.

Neural - hormonal responses to negative affective stimuli: Impact of dysphoric mood and sex

BACKGROUND

Maladaptive responses to negative affective stimuli are pervasive, including clinically ill and healthy people, and men and women respond differently at neural and hormonal levels. Inspired by the Research Domain Criteria initiative, we used a transdiagnostic approach to investigate the impact of sex and dysphoric mood on neural-hormonal responses to negative affective stimuli.

METHODS

Participants included 99 individuals with major depressive disorder, psychosis and healthy controls. Functional magnetic resonance imaging (fMRI) was complemented with real-time acquisition of hypothalamo-pituitary-adrenal (HPA) and -gonadal (HPG) hormones. fMRI data were analyzed in SPM8 and task-related connectivity was assessed using generalized psychophysiological interaction.

RESULTS

Across all participants, elevated cortisol response predicted lower brain activity in orbitofrontal cortex and hypothalamus-amygdala connectivity. In those with worse dysphoric mood, elevated cortisol response predicted lower activity in hypothalamus and hippocampus. In women, elevated cortisol response was associated with lower activity in medial prefrontal cortex and low hypothalamo-hippocampal connectivity. In women with high dysphoric mood, elevated cortisol response was associated with low hypothalamo-hippocampal connectivity. There were no interactions with diagnosis or medication.

LIMITATIONS

There was limited power to correct for multiple comparisons across total number of ROIs and connectivity targets; cortisol responses were relatively low.

CONCLUSIONS

We conclude that the pathophysiology in neural-hormonal responses to negative affective stimuli is shared across healthy and clinical populations and varies as a function of sex and dysphoric mood. Our findings may contribute to the development of hormonal adjunctive therapeutics that are sex-dependent, underscoring the importance of one's sex to precision medicine.

The burden of conscientiousness? Examining brain activation and cortisol response during social evaluative stress

Although conscientiousness has for a long time been considered generally adaptive, there are findings challenging this view, suggesting that conscientiousness might be less advantageous during uncontrollable stress. We here examined the impact of conscientiousness on brain activation during and the cortisol response following an uncontrollable social evaluative stress task in order to test this hypothesis. Brain activation and cortisol levels were measured during an fMRI stress task, where subjects (n=86) performed cognitive tasks containing preprogrammed failure under time pressure, while being monitored by a panel of experts inducing social-evaluative threat. The degree of conscientiousness was measured using the NEO-FFI. We observed a positive correlation between conscientiousness and salivary cortisol levels in response to the stressful task in male subjects only. In male subjects conscientiousness correlated positively with activation in right amygdala and left insula, and, moreover, mediated the influence of amygdala and insula activation on cortisol output. This pattern of brain activation can be interpreted as a disadvantageous response to uncontrollable stress to which highly conscientious individuals might be predisposed. This is the first study showing the effect of conscientiousness on physiology and brain activation to an uncontrollable psychosocial stressor. Our results provide neurobiological evidence for the hypothesis that conscientiousness should not just be seen as beneficial, but rather as a trait associated with either costs or benefits depending on the extent to which one is in control of the situation.

Prednisolone increases neural reactivity to negative socio-emotional stimuli in healthy young men

Exogenous glucocorticoids are known to trigger affective changes, but these are highly variable across individuals. A better understanding of how synthetic glucocorticoids impact the processing of negative emotions in the human brain might help to predict such changes. In the present functional magnetic resonance imaging (fMRI) study, we sought to uncover the slow effects of a synthetic glucocorticoid infusion on the neural response to socio-emotional scenes using a within-participant, double-blind, placebo-controlled design. In two separate sessions, 20 young males were given either an intravenous prednisolone dose (250mg) or placebo in a cross-over, randomized order. Four hours later, they were scanned while viewing drawings of persons in a neutral or negative emotional situation. On the next morning participants provided a blood sample for serum cortisol measurement, which served as a manipulation check. Prednisolone strongly suppressed morning cortisol, and heightened brain reactivity to emotional stimuli in left amygdala, left caudate head, right inferior frontal gyrus, bilateral supplementary motor area, and right somatosensory cortex. Amygdala reactivity was related to lower self-reported fatigue and higher irritability in the prednisolone condition. Moreover, prednisolone blunted inferior frontal and amygdala connectivity with other regions of the emotion-processing neural circuitry. Our results suggest specific brain pathways through which exogenous glucocorticoids may labilize affect.

Maternal depression across the first years of life compromises child psychosocial adjustment; relations to child HPA-axis functioning

Maternal depression across the first years of life negatively impacts children's development. One pathway of vulnerability may involve functioning of the hypothalamic-pituitary-adrenal (HPA) axis. We utilize a community cohort of 1983 women with no comorbid risk repeatedly assessed for depression from birth to six years to form two groups; chronically depressed (N=40) and non-depressed (N=91) women. At six years, mother and child underwent psychiatric diagnosis, child salivary cortisol (CT) was assessed three times during a home-visit, mother-child interaction was videotaped, and child empathy was coded from behavioral paradigms. Latent Growth curve Model using Structural Equation Modeling (SEM) estimated the links between maternal depression and mother's negative parenting and three child outcomes; psychopathology, social withdrawal, and empathy as related to child CT baseline and variability. Depressed mothers displayed more negative parenting and their children showed more Axis-I psychopathology and social withdrawal. SEM analysis revealed that maternal depression was associated with reduced CT variability, which predicted higher child psychopathology and social withdrawal. Whereas all children exhibited similar initial levels of CT, children of controls reduced CT levels over time while children of depressed mothers maintained high, non-flexible levels. Mother negativity was related to lower initial CT levels, which predicted decreased empathy. Findings suggest that chronic maternal depression may compromise children's social-emotional adjustment by diminishing HPA-system flexibility as well as limiting the mother's capacity to provide attuned and predictable caregiving.

Burning odor-elicited anxiety in OEF/OIF combat veterans: Inverse relationship to gray matter volume in olfactory cortex

Despite the anatomical overlap between the brain's fear/threat and olfactory systems, a very limited number of investigations have considered the role of odors and the central olfactory system in the pathophysiology of PTSD. The goal of the present study was to assess structural differences in primary and secondary olfactory cortex between combat veterans with and without PTSD (CV + PTSD, CV-PTSD, respectively). An additional goal was to determine the relationship between gray matter volume (GMV) in olfactory cortex and the distressing properties of burning-related odors. A region of interest voxel-based morphometric (VBM) approach was used to measure GMV in olfactory cortex in a well-characterized group of CV + PTSD (n = 20) and CV-PTSD (n = 25). Prior to the MRI exam, combat-related (i.e., burning rubber) and control odors were systematically sampled and rated according to their potential for eliciting PTSD symptoms. Results showed that CV + PTSD exhibited significantly reduced GMV in anterior piriform (primary olfactory) and orbitofrontal (secondary olfactory) cortices compared to CV-PTSD (both p < .01). For the entire group, GMV in bilateral anterior piriform cortex was inversely related to burning rubber odor-elicited memories of trauma (p < .05). GMV in orbitofrontal cortex was inversely related to both clinical and laboratory measures of PTSD symptoms (all p < .05). In addition to replicating an established inverse relationship between GMV in anxiety-associated brain structures and PTSD symptomatology, the present study extends those findings by being the first report of volumetric decreases in olfactory cortex that are inversely related to odor-elicited PTSD symptoms. Potential mechanisms underlying these findings are discussed.

Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study

Research in humans and animals has shown that negative childhood experiences (NCE) can have long-term effects on the structure and function of the brain. Alterations have been noted in grey and white matter, in the brain's resting state, on the glutamatergic system, and on neural and behavioural responses to aversive stimuli. These effects can be linked to psychiatric disorder such as depression and anxiety disorders that are influenced by excessive exposure to early life stressors. The aim of the current study was to investigate the effect of NCEs on these systems. Resting state functional MRI (rsfMRI), aversion task fMRI, glutamate magnetic resonance spectroscopy (MRS), and diffusion magnetic resonance imaging (dMRI) were combined with the Childhood Trauma Questionnaire (CTQ) in healthy subjects to examine the impact of NCEs on the brain. Low CTQ scores, a measure of NCEs, were related to higher resting state glutamate levels and higher resting state entropy in the medial prefrontal cortex (mPFC). CTQ scores, mPFC glutamate and entropy, correlated with neural BOLD responses to the anticipation of aversive stimuli in regions throughout the aversion-related network, with strong correlations between all measures in the motor cortex and left insula. Structural connectivity strength, measured using mean fractional anisotropy, between the mPFC and left insula correlated to aversion-related signal changes in the motor cortex. These findings highlight the impact of NCEs on multiple inter-related brain systems. In particular, they highlight the role of a prefrontal-insular-motor cortical network in the processing and responsivity to aversive stimuli and its potential adaptability by NCEs.

Childhood poverty and recruitment of adult emotion regulatory neurocircuitry

One in five American children grows up in poverty. Childhood poverty has far-reaching adverse impacts on cognitive, social and emotional development. Altered development of neurocircuits, subserving emotion regulation, is one possible pathway for childhood poverty's ill effects. Children exposed to poverty were followed into young adulthood and then studied using functional brain imaging with an implicit emotion regulation task focused. Implicit emotion regulation involved attention shifting and appraisal components. Early poverty reduced left dorsolateral prefrontal cortex recruitment in the context of emotional regulation. Furthermore, this emotion regulation associated brain activation mediated the effects of poverty on adult task performance. Moreover, childhood poverty also predicted enhanced insula and reduced hippocampal activation, following exposure to acute stress. These results demonstrate that childhood poverty can alter adult emotion regulation neurocircuitry, revealing specific brain mechanisms that may underlie long-term effects of social inequalities on health. The role of poverty-related emotion regulatory neurocircuitry appears to be particularly salient during stressful conditions.

A low cortisol response to acute stress is related to worse basal memory performance in older people

Age-related memory decline has been associated with a faulty regulation of the hypothalamus-pituitary-adrenal axis (HPA-axis). The aim of this study was to investigate whether the magnitude of the stress-induced cortisol increase is related to memory performance when memory is measured in non-stressful conditions. To do so, declarative and working memory performance were measured in 31 men and 35 women between 55 and 77 years of age. On a different day, the magnitude of their cortisol response to acute psychosocial stress was measured. The relationship between the cortisol response and memory performance was U shaped: a low cortisol response to stress was related to poorer declarative and working memory performance, whereas those who did not increase their cortisol levels and those who had the largest cortisol increase had better declarative and working memory capabilities. Sex did not moderate these relationships. These results suggest that a low cortisol response to stress could reflect a defective HPA-axis response to stressors that is accompanied by poorer memory performance. Conversely, a high cortisol response seems to reflect a correct functioning of the HPA-axis and may protect against memory deficits in the later stages of human life.

Cerebral functional imaging using near-infrared spectroscopy during repeated performances of motor rehabilitation tasks tested on healthy subjects

To investigate the relationship between the frontal and sensorimotor cortices and motor learning, hemodynamic responses were recorded from the frontal and sensorimotor cortices using functional near infrared spectroscopy (NIRS) while healthy subjects performed motor learning tasks used in rehabilitation medicine. Whole-head NIRS recordings indicated that response latencies in the anterior dorsomedial prefrontal cortex (aDMPFC) were shorter than in other frontal and parietal areas. Furthermore, the increment rate of the hemodynamic responses in the aDMPFC across the eight repeated trials significantly correlated with those in the other areas, as well as with the improvement rate of task performance across the 8 repeated trials. In the second experiment, to dissociate scalp- and brain-derived hemodynamic responses, hemodynamic responses were recorded from the head over the aDMPFC using a multi-distance probe arrangement. Six probes (a single source probe and 5 detectors) were linearly placed 6 mm apart from each of the neighboring probes. Using independent component analyses of hemodynamic signals from the 5 source-detector pairs, we dissociated scalp- and brain-derived components of the hemodynamic responses. Hemodynamic responses corrected for scalp-derived responses over the aDMPFC significantly increased across the 8 trials and correlated with task performance. In the third experiment, subjects were required to perform the same task with and without transcranial direct current stimulation (tDCS) of the aDMPFC before the task. The tDCS significantly improved task performance. These results indicate that the aDMPFC is crucial for improved performance in repetitive motor learning.

Can pharmacological and psychological treatment change brain structure and function in PTSD? A systematic review

While there is evidence of clinical improvement of posttraumatic stress disorder (PTSD) with treatment, its neural underpinnings are insufficiently clear. Moreover, it is unknown whether similar neurophysiological changes occur in PTSD specifically after child abuse, given its enduring nature and the developmental vulnerability of the brain during childhood. We systematically reviewed PTSD treatment effect studies on structural and functional brain changes from PubMed, EMBASE, PsycINFO, PILOTS and the Cochrane Library. We included studies on adults with (partial) PTSD in Randomized Controlled Trials (RCT) or pre-post designs (excluding case studies) on pharmacotherapy and psychotherapy. Risk of bias was evaluated independently by two raters. Brain coordinates and effect sizes were standardized for comparability. We included 15 studies (6 RCTs, 9 pre-post), four of which were on child abuse. Results showed that pharmacotherapy improved structural abnormalities (i.e., increased hippocampus volume) in both adult-trauma and child abuse related PTSD (3 pre-post studies). Functional changes were found to distinguish between groups. Adult-trauma PTSD patients showed decreased amygdala and increased dorsolateral prefrontal activations post-treatment (4 RCTs, 5 pre-post studies). In one RCT, child abuse patients showed no changes in the amygdala, but decreased dorsolateral prefrontal, dorsal anterior cingulate and insula activation post-treatment. In conclusion, pharmacotherapy may reduce structural abnormalities in PTSD, while psychotherapy may decrease amygdala activity and increase prefrontal, dorsal anterior cingulate and hippocampus activations, that may relate to extinction learning and re-appraisal. There is some evidence for a distinct activation pattern in child abuse patients, which clearly awaits further empirical testing.

Posttraumatic stress disorder: a theoretical model of the hyperarousal subtype

Posttraumatic stress disorder (PTSD) is a frequent and distressing mental disorder, about which much remains to be learned. It is a heterogeneous disorder; the hyperarousal subtype (about 70% of occurrences and simply termed PTSD in this paper) is the topic of this article, but the dissociative subtype (about 30% of occurrences and likely involving quite different brain mechanisms) is outside its scope. A theoretical model is presented that integrates neuroscience data on diverse brain regions known to be involved in PTSD, and extensive psychiatric findings on the disorder. Specifically, the amygdala is a multifunctional brain region that is crucial to PTSD, and processes peritraumatic hyperarousal on grounded cognition principles to produce hyperarousal symptoms. Amygdala activity also modulates hippocampal function, which is supported by a large body of evidence, and likewise amygdala activity modulates several brainstem regions, visual cortex, rostral anterior cingulate cortex (rACC), and medial orbitofrontal cortex (mOFC), to produce diverse startle, visual, memory, numbing, anger, and recklessness symptoms. Additional brain regions process other aspects of peritraumatic responses to produce further symptoms. These contentions are supported by neuroimaging, neuropsychological, neuroanatomical, physiological, cognitive, and behavioral evidence. Collectively, the model offers an account of how responses at the time of trauma are transformed into an extensive array of the 20 PTSD symptoms that are specified in the Diagnostic and Statistical Manual of Mental Disorders, Fifth edition. It elucidates the neural mechanisms of a specific form of psychopathology, and accords with the Research Domain Criteria framework.

Chronic stress exposure may affect the brain's response to high calorie food cues and predispose to obesogenic eating habits

Exaggerated reactivity to food cues involving calorically-dense foods may significantly contribute to food consumption beyond caloric need. Chronic stress, which can induce palatable "comfort" food consumption, may trigger or reinforce neural pathways leading to stronger reactions to highly rewarding foods. We implemented functional magnetic resonance imaging (fMRI) to assess whether chronic stress influences activation in reward, motivation and executive brain regions in response to pictures of high calorie and low calorie foods in thirty women. On separate lab visits, we also assessed food intake from a snack food buffet and circulating cortisol. In women reporting higher chronic stress (HCS), pictures of high calorie foods elicited exaggerated activity in regions of the brain involving reward, motivation, and habitual decision-making. In response to pictures of high calorie food, higher chronic stress was also associated with significant deactivation in frontal regions (BA10; BA46) linked to strategic planning and emotional control. In functional connectivity analysis, HCS strengthened connectivity between amygdala and the putamen, while LCS enhanced connectivity between amygdala and the anterior cingulate and anterior prefrontal cortex (BA10). A hypocortisolemic signature and more consumption of high calorie foods from the snack buffet were observed in the HCS group. These results suggest that persistent stress exposure may alter the brain's response to food in ways that predispose individuals to poor eating habits which, if sustained, may increase risk for obesity.

Magnetic resonance imaging in paediatric psychoneuroendocrinology: a new frontier for understanding the impact of hormones on emotion and cognition

Mounting magnetic resonance imaging (MRI) research is characterising the neurobiological trajectories of healthy human brain development. In parallel, studies increasingly acknowledge the relevance of perturbations of these trajectories for adolescent and adult psychopathology. Although an influence of steroid hormones on mood and anxiety disorders has been demonstrated in adults, very little is known about how steroid hormones alter human brain development and contribute to adolescent psychopathology. This review focuses on recent evidence obtained from structural and functional MRI in children and adolescents with genetic endocrine disorders and with characteristic fluctuations in androgen or oestrogen levels (familial male precocious puberty, congenital adrenal hyperplasia, Klinefelter syndrome and Turner syndrome). It aims to highlight how neurobiological findings from these paediatric endocrine disorders can provide insight into the contribution of sex steroids with respect to the development of neurocircuitry involved in affective processing (amygdala, hippocampus) and cognitive control (prefrontal cortex, inferior frontal gyrus, striatum). In addition, findings from these populations may also provide important information on aberrant psychological processes relevant for the clinical care and management of these populations. Finally, the findings are discussed within the context of current frameworks in animal models, such as the organisational-activational hypothesis or the aromatisation hypothesis. The review ends with a discussion of open questions for future enquiry with the goal of integrating translational models with current knowledge of endocrine disorders and developmental studies in healthy populations.

Reflections on the interaction of psychogenic stress systems in humans: the stress coherence/compensation model

Although stress simultaneously affects and causes changes in central nervous system systems together with the sympathetic nervous system and the hypothalamus-pituitary-adrenal axis, this interaction and its behavioral consequences are rarely assessed. The current paper first describes the different systems involved in the perception and processing of stressful stimuli on an anatomical and functional level, and the available measures to assess changes in these systems. It then explores, based on theoretical and empirical grounds, the interaction of the systems. This is followed by a review of previous stress models, and how these attempted to integrate the interaction of these systems. Then, it complements previous models by suggesting a complementary regulation of the stress systems, and discusses potential behavioral consequences. Finally, based on the three-system approach to assess stress it is argued that psychological measures, together with physiological and endocrine measures are indispensable. However, the lack of consensus on how to best assess the central and sympathetic nervous system components of stress make it more difficult to include measures of all systems routinely in future stress studies. Thus, the paper closes by giving some recommendations on how to include a minimum of feasible stress measures for all systems involved in stress processing and regulation.

Neonatal NMDA receptor blockade alters anxiety- and depression-related behaviors in a sex-dependent manner in mice

There is increasing evidence that N-methyl-D-aspartate (NMDA) receptor blockade in the neonatal period has a long-lasting influence on brain and behavior development and has been linked to an increased risk for neuropsychiatric disorders in later life. We sought to determine whether postnatal NMDA receptor blockade can affect normal development of body weight, corticosterone levels, anxiety- and depression-related behaviors in male and female mice in adulthood. For this purpose, male and female NMRI mice were treated with either saline or phencyclidine (PCP; 5 and 10 mg/kg, s.c.) on postnatal days (PND) 7, 9, and 11, and then subjected to different behavioral tests, including open field, elevated plus-maze, elevated zero-maze, light-dark box, tail suspension test and forced swimming test in adulthood. The results indicated that neonatal PCP treatment reduced body weight during neonatal and adulthood periods, and did not alter baseline corticosterone levels in both male and female mice. Moreover, this study obtained some experimental evidence showing the PCP at dose of 10 mg/kg increases stress-induced corticosterone levels, anxiety- and depression-related behaviors in males, while decreasing levels of anxiety without any significant effect on depression in female mice in adulthood. These data support the argument that neonatal NMDA receptor blockade can lead to behavioral abnormalities and psychiatric diseases in adulthood. Collectively, our findings suggest that neonatal exposure to PCP may have profound effects on the development of anxiety- and depression-related behaviors in a sex- and dose-dependent manner in mice.

Increased neuronal apoptosis in medial prefrontal cortex is accompanied with changes of Bcl-2 and Bax in a rat model of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by traumatic experience, which affects a patient's quality of life and social stability. The objective of this study was to determine the apoptosis-related genes B-cell lymphoma 2 (Bcl-2) and BCL2-associated X (Bax) expressions and medial prefrontal cortex (mPFC) neuronal apoptosis after PTSD in rat model and therefore to provide experimental evidence to reveal PTSD pathogenesis. The single-prolonged stress (SPS) method was used to set up the rat PTSD models. Chemiluminescence was used to determine serum corticosterone levels. Neuronal apoptosis was detected using transmission electron microscopy, Hoechst staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Immunohistochemistry, immunofluorescence, RT-PCR, and Western blot were used to detect the expressions of Bcl-2 and Bax protein in mPFC. Our results showed an increased mPFC neuronal apoptosis after SPS stimulation. The number of apoptotic cells peaked on day 7. The expressions of Bcl-2 and Bax peaked on days 4 and 7. The Bcl-2/Bax ratio elevated on days 1 and 4 but decreased markedly on day 7. These results indicated that SPS stimulation increased the number of apoptotic neurons, up-regulated the expressions of Bcl-2 and Bax, and altered the Bcl-2/Bax ratio in the mPFC of PTSD rats.

Thermotherapy to the facial region in and around the eyelids altered prefrontal hemodynamic responses and autonomic nervous activity during mental arithmetic

To investigate neural mechanisms of local thermotherapy to reduce mental stress, participants were required to perform mental arithmetic after treatment by a heat- and steam-generating sheet on the facial eyelid region while hemodynamic activity and ECGs were monitored. The results indicated that thermotherapy decreased hemodynamic activity in the anterior dorsomedial prefrontal cortex (aDMPFC) involved in sympathetic activity. Consistently, thermotherapy increased parasympathetic activity while it decreased sympathetic activity. Furthermore, thermotherapy increased hemodynamic activity in the dorsolateral prefrontal cortex (DLPFC) during mental arithmetic. These hemodynamic responses in the DLPFC during mental arithmetic were negatively correlated with that in the aDMPFC during thermotherapy. The results suggest that thermotherapy in the facial eyelid region is useful to ameliorate mental fatigue through its effects on the prefrontal cortex.

Endogenous cortisol is associated with functional connectivity between the amygdala and medial prefrontal cortex

Whether glucocorticoids mediate medial prefrontal cortex (mPFC) regulation of the amygdala in humans remains unclear. In the current study we investigated whether cortisol levels under relatively stress-free circumstances are related to amygdala resting-state functional connectivity with the mPFC. Resting-state fMRI data were acquired from 20 healthy male participants. Salivary cortisol was sampled at multiple times throughout the experiment. The cortisol area under the curve increase (AUCi) was calculated as a measure of cortisol dynamics. Next, seed based correlations were employed on the resting-state fMRI data to reveal regions of amygdala functional connectivity related to variations in cortisol AUCi. The resulting statistical maps were corrected for multiple comparisons using cluster based thresholding (Z>2.3, p<.05). Two regions in the mPFC showed decreasing negative functional connectivity with the amygdala when a lesser decrease in cortisol AUCi was observed: the perigenual anterior cingulate cortex and medial frontal pole (BA10). Although we initially showed a relation with cortisol AUCi, it seemed that the baseline cortisol levels were actually driving this effect: higher baseline cortisol levels related to stronger negative functional connectivity with the mPFC. Endogenous cortisol levels may modulate amygdala functional connectivity with specific regions in the mPFC, even under relatively stress-free circumstances. Our results corroborate previous findings from both animal and human studies, suggesting cortisol-mediated regulation of the amygdala by the mPFC. We propose that through this feedback mechanism the stress response might be adjusted, pointing to the putative role of cortisol in modulating stress- and, more generally, emotional responses.

Adulthood trauma and HPA-axis functioning in healthy subjects and PTSD patients: a meta-analysis

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA)-axis dysregulation has inconsistently been associated with posttraumatic stress disorder (PTSD). Yet, trauma exposure rather than PTSD may be responsible for HPA-axis dysregulation. In two meta-analyses, we assessed the association of adulthood trauma exposure and HPA-axis functioning in healthy subjects with and without PTSD.

METHOD

A literature search in Pubmed and PsychInfo, using keywords and MeSH terms such as cortisol, emotional trauma, and PTSD, was performed. Only studies that included mentally healthy trauma-exposed (TE) individuals as well as non-exposed (NE) healthy individuals and/or PTSD patients (PTSD) were selected. This resulted in 1511 studies of which ultimately, 37 studies (21 TE versus NE and 34 TE versus PTSD, N=2468) were included. Methodological quality of all studies was assessed according to specific quality criteria. Pooled effect sizes (Hedges's g) on cortisol levels were compared. For all analyses, random effect models were used.

RESULTS

Cortisol levels were neither significantly different between TE versus NE subjects (-0.029; 95%CI: -0.145; 0.088) nor between TE subjects versus PTSD patients (0.175; 95%CI: -0.012; -0.362). Subgroup analyses showed an increased cortisol suppression after the low dose dexamethasone suppression test (DST) in TE versus NE subjects (-0.509; 95%CI: -0.871; -0.148). This meta-analysis was limited by the fact that lifetime psychiatric illness and childhood trauma were not an exclusion criterion in all 37 studies.

CONCLUSION

Neither adulthood trauma exposure nor PTSD were associated with differences in HPA-axis functioning, although adulthood trauma may augment cortisol suppression after the DST. More evidence on other dynamic tests of HPA-axis functioning in PTSD and adulthood trauma exposure is needed.

Processing of emotional distraction is both automatic and modulated by attention: evidence from an event-related fMRI investigation

Traditionally, emotional stimuli have been thought to be automatically processed via a bottom-up automatic "capture of attention" mechanism. Recently, this view has been challenged by evidence that emotion processing depends on the availability of attentional resources. Although these two views are not mutually exclusive, direct evidence reconciling them is lacking. One limitation of previous investigations supporting the traditional or competing views is that they have not systematically investigated the impact of emotional charge of task-irrelevant distraction in conjunction with manipulations of attentional demands. Using event-related fMRI, we investigated the nature of emotion-cognition interactions in a perceptual discrimination task with emotional distraction by manipulating both the emotional charge of the distracting information and the demands of the main task. Our findings show that emotion processing is both automatic and modulated by attention, but emotion and attention were only found to interact when finer assessments of emotional charge (comparison of most vs. least emotional conditions) were considered along with an effective manipulation of processing load (high vs. low). The study also identified brain regions reflecting the detrimental impact of emotional distraction on performance as well as regions involved in coping with such distraction. Activity in the dorsomedial pFC and ventrolateral pFC was linked to a detrimental impact of emotional distraction, whereas the dorsal ACC and lateral occipital cortex were involved in helping with emotional distraction. These findings demonstrate that task-irrelevant emotion processing is subjective to both the emotional content of distraction and the level of attentional demand.

Implications of hypothalamic-pituitary-adrenal axis functioning in posttraumatic stress disorder

BACKGROUND

Cortisol secretions serve as the barometer of the hypothalamic-pituitary-adrenal (HPA) axis, which regulates and controls responses to stress. Studies of cortisol secretions in patients with posttraumatic stress disorder (PTSD) reveal inconsistent results.

PURPOSE

Current research on HPA axis functioning in PTSD is examined to elucidate the neuroendocrine contributions in the disorder, identify current treatment's impact on the HPA axis, and consider implications for nursing care and areas for future research.

FINDINGS

There is evidence for HPA dysregulation in PTSD, which contributes to widespread impairment in functions such as memory and stress reactivity and to physical morbidity via processes such as allostatic load. There is limited, but building, evidence that dehydroepiandrosterone (DHEA), which is released simultaneously with cortisol, may provide anti-glucocorticoid and neuroprotective effects.

CONCLUSION

Current treatments such as selective serotonin reuptake inhibitors and psychotherapy may have a beneficial impact on the HPA axis in PTSD populations. Somatic approaches to treating PTSD have not yet been studied in relation to their impact on HPA axis parameters in PTSD patients. Treatment studies of DHEA or glucocorticoids have not yet used HPA axis endpoints. PTSD treatment studies that include measures of HPA axis target mechanisms and consider HPA axis regulation as an additional treatment outcome are warranted.

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

BACKGROUND

Both fear and pain processing are altered in post-traumatic stress disorder (PTSD), as evidenced by functional neuroimaging studies showing increased amygdala responses to threats, and increased insula, putamen and caudate activity in response to heat pain. Using psychophysiology and functional magnetic resonance imaging, we studied conditioned and unconditioned autonomic and neuronal responses in subjects with PTSD versus trauma-exposed non-PTSD control (TENC) subjects. A design using an electric shock selected by subjects to be 'highly annoying but not painful' as an unconditioned stimulus (US) with partially reinforced cues allowed us to partly disentangle the expectancy- and prediction-error components from sensory components of the unconditioned response.

RESULTS

Whereas responses to the conditioned stimulus (CS) were similar in PTSD and TENC, the former displayed higher putamen, insula, caudate and amygdala responses to the US. Reactivity to the US in the anterior insula correlated with PTSD symptom severity. Functional connectivity analyses using the putamen as a seed region indicated that TENC subjects had increased amygdala-putamen connectivity during US delivery; this connection was disengaged in PTSD.

CONCLUSIONS

Our results indicate that although neural processing of fear learning in people with PTSD seems to be comparable with controls, neural responses to unconditioned aversive stimuli in PTSD seem to be increased.

Brain stimulation in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a complex, heterogeneous disorder that develops following trauma and often includes perceptual, cognitive, affective, physiological, and psychological features. PTSD is characterized by hyperarousal, intrusive thoughts, exaggerated startle response, flashbacks, nightmares, sleep disturbances, emotional numbness, and persistent avoidance of trauma-associated stimuli. The efficacy of available treatments for PTSD may result in part from relief of associated depressive and anxiety-related symptoms in addition to treatment of core symptoms that derive from reexperiencing, numbing, and hyperarousal. Diverse, heterogeneous mechanisms of action and the ability to act broadly or very locally may enable brain stimulation devices to address PTSD core symptoms in more targeted ways. To achieve this goal, specific theoretical bases derived from novel, well-designed research protocols will be necessary. Brain stimulation devices include both long-used and new electrical and magnetic devices. Electroconvulsive therapy (ECT) and Cranial electrotherapy stimulation (CES) have both been in use for decades; transcranial magnetic stimulation (TMS), magnetic seizure therapy (MST), deep brain stimulation (DBS), transcranial Direct Current Stimulation (tDCS), and vagus nerve stimulation (VNS) have been developed recently, over approximately the past twenty years. The efficacy of brain stimulation has been demonstrated as a treatment for psychiatric and neurological disorders such as anxiety (CES), depression (ECT, CES, rTMS, VNS, DBS), obsessive-compulsive disorder (OCD) (DBS), essential tremor, dystonia (DBS), epilepsy (DBS, VNS), Parkinson Disease (DBS), pain (CES), and insomnia (CES). To date, limited data on brain stimulation for PTSD offer only modest guidance. ECT has shown some efficacy in reducing comorbid depression in PTSD patients but has not been demonstrated to improve most core PTSD symptoms. CES and VNS have shown some efficacy in reducing anxiety, findings that may suggest possible utility in relieving PTSD-associated anxiety. Treatment of animal models of PTSD with DBS suggests potential human benefit. Additional research and novel treatment options for PTSD are urgently needed. The potential usefulness of brain stimulation in treating PTSD deserves further exploration.

Stress-induced activation of the HPA axis predicts connectivity between subgenual cingulate and salience network during rest in adolescents

BACKGROUND

Responses to stress vary greatly in young adolescents, and little is known about neural correlates of the stress response in youth. The purpose of this study was to examine whether variability in cortisol responsivity following a social stress test in young adolescents is associated with altered neural functional connectivity (FC) of the salience network (SN) measured during resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Forty-nine typically developing young adolescents participated in a social stress test during which they contributed salivary cortisol samples. Following this, they underwent rs-fMRI scanning. We examined the association of FC of the SN [composed of anterior cingulate cortex and bilateral anterior insula regions] with cortisol responsivity.

RESULTS

Greater cortisol responsivity was significantly positively correlated with higher FC between subgenual anterior cingulate cortex (Cg25) and the SN, controlling for participant age. There were no regions of the brain that showed an inverse relation.

CONCLUSIONS

Brain systems that have been implicated in autonomic arousal and that influence subjective feeling states show altered FC associated with stress responsivity in early life.

Stress modulation of cognitive and affective processes

This review summarizes the major discussion points of a symposium on stress modulation of cognitive and affective processes, which was held during the 2010 workshop on the neurobiology of stress (Boulder, CO, USA). The four discussants addressed a number of specific cognitive and affective factors that are modulated by exposure to acute or repeated stress. Dr David Morilak discussed the effects of various repeated stress situations on cognitive flexibility, as assessed with a rodent model of attentional set-shifting task, and how performance on slightly different aspects of this test is modulated by different prefrontal regions through monoaminergic neurotransmission. Dr Serge Campeau summarized the findings of several studies exploring a number of factors and brain regions that regulate habituation of various autonomic and neuroendocrine responses to repeated audiogenic stress exposures. Dr Kerry Ressler discussed a body of work exploring the modulation and extinction of fear memories in rodents and humans, especially focusing on the role of key neurotransmitter systems including excitatory amino acids and brain-derived neurotrophic factor. Dr Israel Liberzon presented recent results on human decision-making processes in response to exogenous glucocorticoid hormone administration. Overall, these discussions are casting a wider framework on the cognitive/affective processes that are distinctly regulated by the experience of stress and some of the brain regions and neurotransmitter systems associated with these effects.

Emotional memory in early steroid abnormalities: an FMRI study of adolescents with congenital adrenal hyperplasia

Hormonal imbalances during development may have long-lasting effects. Using functional magnetic resonance imaging (fMRI), we compared 14 youths with Congenital Adrenal Hyperplasia (CAH), a genetic disorder of hormonal dysfunction, with 22 healthy controls on memory encoding of emotional faces. Patients remembered fewer faces than controls, particularly fearful faces. FMRI data to successfully encoded fearful faces revealed that males with CAH showed significant activations in amygdala, hippocampus, and anterior cingulate relative to unaffected males, while females with CAH demonstrated deactivations relative to unaffected females in these regions. Findings indicate that steroid abnormalities during development can have important effects on neural correlates of emotional memory.

Differential effects of alexithymia subscales on autonomic reactivity and anxiety during social stress

OBJECTIVES

Alexithymia is characterized by a difficulty in identifying and describing one's emotions. Recent research has associated differential effects of the alexithymia facets to hypothalamic-pituitary-adrenal (HPA) axis markers during stress. This study aimed to analyze how the facets of alexithymia interact with autonomic reactivity as well as self- and observer-rated anxiety during a social stress task.

METHODS

With the use of a public-speaking paradigm, skin conductance levels (SCLs) and heart rate (HR) during the defined periods of baseline, preparation, stress, and recovery were assessed in 60 volunteers (42 females, mean age 22.8) categorized as having either high (HDA) or low (LDA) degrees of alexithymia.

RESULTS

We found smaller SCLs during preparation and speech in the HDA group. Regression analyses indicated that only the alexithymia facet "difficulty in describing feelings" (DDF) was associated with smaller electrodermal responses. In the HDA group, self- and observer-rated anxiety was higher in the HDA than in the LDA group, which was attributable to higher scores in the subscales "difficulty in identifying feelings" (DIF) and "externally oriented thinking" (EOT).

CONCLUSIONS

Our data support and specify the decoupling hypothesis of alexithymia by showing that the facets of alexithymia are differentially related to autonomic reactivity as well as self- and observer-rated anxiety during social stress.

Brain axonal and myelin evaluation in heart failure

Although gray matter injury appears in heart failure (HF) patients, the presence, extent, and nature of axonal injury impacting on cardiovascular regulation and other functions is unclear. We performed diffusion tensor imaging (3.0-Tesla magnetic resonance imaging scanner) in 16 HF and 26 control subjects, and assessed whole-brain water diffusion parallel (axial diffusivity; axonal status) and perpendicular (radial diffusivity; myelin changes) to fibers. Regions with increased axial diffusivity only, indicating impaired axonal integrity, emerged in cardiovascular, hedonic, and pain regulatory areas, including basal forebrain, hypothalamic and limbic projections through the medial forebrain bundle and raphe magnus projections to the medulla and cerebellum. Other fiber paths between sites implicated in cognition, including limbic, basal-ganglia, thalamic, internal capsule, and corpus callosum were also altered. Sites with increased radial diffusivity only, indicating myelin breakdown, appeared in the corpus callosum, cingulate, and temporal, parietal, occipital, and frontal regions. Both higher axial and radial diffusivity, indicating loss of tissue integrity, appeared in parietal and occipital lobes, limbic regions, insula, internal capsule, cerebellum, and dorsolateral medulla. Axons and myelin are altered in HF, likely resulting from ischemic/hypoxic processes acting chronically and sub-acutely, respectively. The alterations would contribute to the multiple autonomic and neuropsychological symptoms found in HF.

The GABAergic deficit hypothesis of major depressive disorder

Increasing evidence points to an association between major depressive disorders (MDDs) and diverse types of GABAergic deficits. In this review, we summarize clinical and preclinical evidence supporting a central and causal role of GABAergic deficits in the etiology of depressive disorders. Studies of depressed patients indicate that MDDs are accompanied by reduced brain concentration of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) and by alterations in the subunit composition of the principal receptors (GABA(A) receptors) mediating GABAergic inhibition. In addition, there is abundant evidence that suggests that GABA has a prominent role in the brain control of stress, the most important vulnerability factor in mood disorders. Furthermore, preclinical evidence suggests that currently used antidepressant drugs (ADs) designed to alter monoaminergic transmission and nonpharmacological therapies may ultimately act to counteract GABAergic deficits. In particular, GABAergic transmission has an important role in the control of hippocampal neurogenesis and neural maturation, which are now established as cellular substrates of most if not all antidepressant therapies. Finally, comparatively modest deficits in GABAergic transmission in GABA(A) receptor-deficient mice are sufficient to cause behavioral, cognitive, neuroanatomical and neuroendocrine phenotypes, as well as AD response characteristics expected of an animal model of MDD. The GABAergic hypothesis of MDD suggests that alterations in GABAergic transmission represent fundamentally important aspects of the etiological sequelae of MDDs that are reversed by monoaminergic AD action.

Effects of acupuncture on the brain hemodynamics

Acupuncture therapy has been applied to various psychiatric diseases and chronic pain since acupuncture stimulation might affect brain activity. From this point of view, we investigated the effects of acupuncture on autonomic nervous system and brain hemodynamics in human subjects using ECGs, EEGs and near-infrared spectroscopy (NIRS). Our previous studies reported that changes in parasympathetic nervous activity were correlated with number of de-qi sensations during acupuncture manipulation. Furthermore, these autonomic changes were correlated with EEG spectral changes. These results are consistent with the suggestion that autonomic changes induced by needle manipulation inducing specific de-qi sensations might be mediated through the central nervous system, especially through the forebrain as shown in EEG changes, and are beneficial to relieve chronic pain by inhibiting sympathetic nervous activity. The NIRS results indicated that acupuncture stimulation with de-qi sensation significantly decreased activity in the supplementary motor complex (SMC) and dorsomedial prefrontal cortex (DMPFC). Based on these results, we review that hyperactivity in the SMC is associated with dystonia and chronic pain, and that in the DMPFC is associated with various psychiatric diseases with socio-emotional disturbances such as schizophrenia, attention deficit hyperactive disorder, etc. These findings along with the previous studies suggest that acupuncture with de-qi sensation might be effective to treat the various diseases in which hyperactivity in the SMA and DMPFC is suspected of playing a role.

Empathy-related Responding: Associations with Prosocial Behavior, Aggression, and Intergroup Relations

Empathy-related responding, including empathy, sympathy, and personal distress, has been implicated in conceptual models and theories about prosocial behavior and altruism, aggression and antisocial behavior, and intergroup relationships. Conceptual arguments and empirical findings related to each of these topics are reviewed. In general, there is evidence that empathy and/or sympathy are important correlates of, and likely contributors to, other-oriented prosocial behavior, the inhibition of aggression and antisocial behavior, and the quality of intergroup relationships. Applied implications of these findings, including preventative studies, are discussed, as are possible future directions.

Cortisol involvement in mechanisms of behavioral inhibition

We studied whether baseline cortisol is associated with post-error slowing, a measure that depends upon brain areas involved in behavioral inhibition. Moreover, we studied whether this association holds after controlling for positive associations with behavioral inhibition scores and error-related negativity (ERN) amplitudes that cortisol and post-error slowing may share. Healthy female volunteers performed a flanker task. Cortisol was independently positively associated with post-error slowing and the ERN, supporting hypotheses that cortisol is involved in behavioral inhibition. Additionally, cortisol mediated an association between ERN and more post-error slowing, which suppressed a direct association between ERN and less post-error slowing. The results are relevant, not only for researchers of behavioral inhibition, but also for researchers of the basic mechanisms of the ERN and post-error slowing, and may bring those literatures together.

Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study

Sui SG, Wu MX, King ME, Zhang Y, Ling L, Xu JM, Weng XC, Duan L, Shan BC, Li LJ. Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study.

OBJECTIVE

This study examined changes in brain grey matter in victims of rape (VoR) with and without post-traumatic stress disorder (PTSD). Previous research has focused on PTSD caused by various traumatic events, such as war and disaster, among others. Although considerable research has focused on rape-related PTSD, limited studies have been carried out in the context of Mainland China.

METHODS

The study included 11 VoR with PTSD, 8 VoR without PTSD and 12 healthy comparison (HC) subjects. We used voxel-based morphometry to explore changes in brain grey-matter density (GMD) by applying statistical parametric mapping to high-resolution magnetic resonance images.

RESULTS

Compared with HC, VoR with PTSD showed significant GMD reductions in the bilateral medial frontal cortex, left middle frontal cortex, middle temporal gyrus and fusiform cortex and significant GMD increases in the right posterior cingulate cortex, postcentral cortex, bilateral precentral cortex and inferior parietal lobule. Compared to VoR without PTSD, VoR with PTSD showed significant GMD reductions in the right uncus, left middle temporal gyrus, and the fusiform cortex, and increases in the left precentral cortex, inferior parietal lobule and right post-central cortex.

CONCLUSION

The findings of abnormal GMD in VoR with PTSD support the hypothesis that PTSD is associated with widespread anatomical changes in the brain. The medial frontal cortex, precentral cortex, posterior cingulate cortex, post-central cortex and inferior parietal lobule may play important roles in the neuropathology of PTSD.