Abnormal left-sided orbitomedial prefrontal cortical-amygdala connectivity during happy and fear face processing: a potential neural mechanism of female MDD

Major depressive disorder associated alterations in the effective connectivity of the face processing network: a systematic review

Major depressive disorder (MDD) is marked by altered processing of emotional stimuli, including facial expressions. Recent neuroimaging research has attempted to investigate how these stimuli alter the directional interactions between brain regions in those with MDD; however, methodological heterogeneity has made identifying consistent effects difficult. To address this, we systematically examined studies investigating MDD-associated differences present in effective connectivity during the processing of emotional facial expressions. We searched five databases: PsycINFO, EMBASE, PubMed, Scopus, and Web of Science, using a preregistered protocol (registration number: CRD42021271586). Of the 510 unique studies screened, 17 met our inclusion criteria. These studies identified that compared with healthy controls, participants with MDD demonstrated (1) reduced connectivity from the dorsolateral prefrontal cortex to the amygdala during the processing of negatively valenced expressions, and (2) increased inhibitory connectivity from the ventromedial prefrontal cortex to amygdala during the processing of happy facial expressions. Most studies investigating the amygdala and anterior cingulate cortex noted differences in their connectivity; however, the precise nature of these differences was inconsistent between studies. As such, commonalities observed across neuroimaging modalities warrant careful investigation to determine the specificity of these effects to particular subregions and emotional expressions. Future research examining longitudinal connectivity changes associated with treatment response may provide important insights into mechanisms underpinning therapeutic interventions, thus enabling more targeted treatment strategies.

Facing emotions: real-time fMRI-based neurofeedback using dynamic emotional faces to modulate amygdala activity

Introduction

Maladaptive functioning of the amygdala has been associated with impaired emotion regulation in affective disorders. Recent advances in real-time fMRI neurofeedback have successfully demonstrated the modulation of amygdala activity in healthy and psychiatric populations. In contrast to an abstract feedback representation applied in standard neurofeedback designs, we proposed a novel neurofeedback paradigm using naturalistic stimuli like human emotional faces as the feedback display where change in the facial expression intensity (from neutral to happy or from fearful to neutral) was coupled with the participant's ongoing bilateral amygdala activity.

Methods

The feasibility of this experimental approach was tested on 64 healthy participants who completed a single training session with four neurofeedback runs. Participants were assigned to one of the four experimental groups (n = 16 per group), i.e., happy-up, happy-down, fear-up, fear-down. Depending on the group assignment, they were either instructed to "try to make the face happier" by upregulating (happy-up) or downregulating (happy-down) the amygdala or to "try to make the face less fearful" by upregulating (fear-up) or downregulating (fear-down) the amygdala feedback signal.

Results

Linear mixed effect analyses revealed significant amygdala activity changes in the fear condition, specifically in the fear-down group with significant amygdala downregulation in the last two neurofeedback runs as compared to the first run. The happy-up and happy-down groups did not show significant amygdala activity changes over four runs. We did not observe significant improvement in the questionnaire scores and subsequent behavior. Furthermore, task-dependent effective connectivity changes between the amygdala, fusiform face area (FFA), and the medial orbitofrontal cortex (mOFC) were examined using dynamic causal modeling. The effective connectivity between FFA and the amygdala was significantly increased in the happy-up group (facilitatory effect) and decreased in the fear-down group. Notably, the amygdala was downregulated through an inhibitory mechanism mediated by mOFC during the first training run.

Discussion

In this feasibility study, we intended to address key neurofeedback processes like naturalistic facial stimuli, participant engagement in the task, bidirectional regulation, task congruence, and their influence on learning success. It demonstrated that such a versatile emotional face feedback paradigm can be tailored to target biased emotion processing in affective disorders.

Inhibitory temporo-parietal effective connectivity is associated with explicit memory performance in older adults

Successful explicit memory encoding is associated with inferior temporal activations and medial parietal deactivations, which are attenuated in aging. Here we used dynamic causal modeling (DCM) of functional magnetic resonance imaging data to elucidate effective connectivity patterns between hippocampus, parahippocampal place area (PPA), and precuneus during encoding of novel visual scenes. In 117 young adults, DCM revealed pronounced activating input from the PPA to the hippocampus and inhibitory connectivity from the PPA to the precuneus during novelty processing, with both being enhanced during successful encoding. This pattern could be replicated in two cohorts (N = 141 and 148) of young and older adults. In both cohorts, older adults selectively exhibited attenuated inhibitory PPA-precuneus connectivity, which correlated negatively with memory performance. Our results provide insight into the network dynamics underlying explicit memory encoding and suggest that age-related differences in memory-related network activity are, at least partly, attributable to altered temporo-parietal neocortical connectivity.

Automatic Positive and Negative Emotion Regulation in Adolescents with Major Depressive Disorder

INTRODUCTION

Adolescents with major depressive disorder (MDD) exhibit hypoactivity to positive stimuli and hyperactivity to negative stimuli in terms of neural responses. Automatic emotion regulation (AER) activates triple networks (i.e., the central control network, default mode network, and salience network). Based on previous studies, we hypothesized that adolescents with MDD exhibit dissociable spatiotemporal deficits during positive and negative AER.

METHODS

We first collected EEG data from 32 adolescents with MDD and 35 healthy adolescents while they performed an implicit emotional Go/NoGo task. Then, we characterized the spatiotemporal dynamics of cortical activity during AER.

RESULTS

In Go trials, MDD adolescents exhibited reduced N2 amplitudes, enhanced theta power for positive pictures, and stronger bottom-up information flow from the left orbitofrontal cortex (OFC) to the right superior frontal gyrus compared to top-down information flow than the controls. In contrast, in NoGo trials, MDD adolescents exhibited elevated P3 amplitudes, enhanced theta power, and stronger top-down information flows from the right middle frontal gyrus to the right OFC and the left insula than the controls.

CONCLUSION

Overall, adolescents with MDD exhibited impaired automatic attention to positive emotions and impaired automatic response inhibition. These findings have potential implications for the clinical treatment of adolescents with MDD.

Effective connectivity during face processing in major depression - distinguishing markers of pathology, risk, and resilience

BACKGROUND

Aberrant brain connectivity during emotional processing, especially within the fronto-limbic pathway, is one of the hallmarks of major depressive disorder (MDD). However, the methodological heterogeneity of previous studies made it difficult to determine the functional and etiological implications of specific alterations in brain connectivity. We previously reported alterations in psychophysiological interaction measures during emotional face processing, distinguishing depressive pathology from at-risk/resilient and healthy states. Here, we extended these findings by effective connectivity analyses in the same sample to establish a refined neural model of emotion processing in depression.

METHODS

Thirty-seven patients with MDD, 45 first-degree relatives of patients with MDD and 97 healthy controls performed a face-matching task during functional magnetic resonance imaging. We used dynamic causal modeling to estimate task-dependent effective connectivity at the subject level. Parametric empirical Bayes was performed to quantify group differences in effective connectivity.

RESULTS

MDD patients showed decreased effective connectivity from the left amygdala and left lateral prefrontal cortex to the fusiform gyrus compared to relatives and controls, whereas patients and relatives showed decreased connectivity from the right orbitofrontal cortex to the left insula and from the left orbitofrontal cortex to the right fusiform gyrus compared to controls. Relatives showed increased connectivity from the anterior cingulate cortex to the left dorsolateral prefrontal cortex compared to patients and controls.

CONCLUSIONS

Our results suggest that the depressive state alters top-down control of higher visual regions during face processing. Alterations in connectivity within the cognitive control network present potential risk or resilience mechanisms.

Functional MRI in major depressive disorder: A review of findings, limitations, and future prospects

Objective diagnosis and prognosis in major depressive disorder (MDD) remains a challenge due to the absence of biomarkers based on physiological parameters or medical tests. Numerous studies have been conducted to identify functional magnetic resonance imaging‐based biomarkers of depression that either objectively differentiate patients with depression from healthy subjects, predict personalized treatment outcome, or characterize biological subtypes of depression. While there are some findings of consistent functional biomarkers, there is still lack of robust data acquisition and analysis methodology. According to current findings, primarily, the anterior cingulate cortex, prefrontal cortex, and default mode network play a crucial role in MDD. Yet, there are also less consistent results and the involvement of other regions or networks remains ambiguous. We further discuss image acquisition, processing, and analysis limitations that might underlie these inconsistencies. Finally, the current review aims to address and discuss possible remedies and future opportunities that could improve the search for consistent functional imaging biomarkers of depression. Novel acquisition techniques, such as multiband and multiecho imaging, and neural network‐based cleaning approaches can enhance the signal quality in limbic and frontal regions. More comprehensive analyses, such as directed or dynamic functional features or the identification of biological depression subtypes, can improve objective diagnosis or treatment outcome prediction and mitigate the heterogeneity of MDD. Overall, these improvements in functional MRI imaging techniques, processing, and analysis could advance the search for biomarkers and ultimately aid patients with MDD and their treatment course.

Deficient prefrontal-amygdalar connectivity underlies inefficient face processing in adolescent major depressive disorder

Adolescence represents a critical developmental period where the prevalence of major depressive disorder (MDD) increases. Aberrant emotion processing is a core feature of adolescent MDD that has been associated with functional alterations within the prefrontal-amygdala circuitry. In this study, we tested cognitive and neural mechanisms of emotional face processing in adolescents with MDD utilizing a combination of computational modeling and neuroimaging. Thirty adolescents with MDD (age: M = 16.1 SD = 1.4, 20 females) and 33 healthy controls (age: M = 16.2 SD = 1.9, 20 females) performed a dynamic face- and shape-matching task. A linear ballistic accumulator model was fit to the behavioral data to study differences in evidence accumulation. We used dynamic causal modeling (DCM) to study effective connectivity in the prefrontal-amygdala network to reveal the neural underpinnings of cognitive impairments while performing the task. Face processing efficiency was reduced in the MDD group and most pronounced for ambiguous faces with neutral emotional expressions. Critically, this reduction was related to increased deactivation of the subgenual anterior cingulate (sgACC). Connectivity analysis showed that MDD exhibited altered functional coupling in a distributed network spanning the fusiform face area-lateral prefrontal cortex-sgACC and the sgACC-amygdala pathway. Our results suggest that MDD is related to impairments of processing nuanced facial expressions. Distributed dysfunctional coupling in the face processing network might result in inefficient evidence sampling and inappropriate emotional responses contributing to depressive symptomatology. Our study provides novel insights in the characterization of brain function in adolescents with MDD that strongly emphasize the critical role of aberrant prefrontal-amygdala interactions during emotional face processing.

The role of the dorsolateral and ventromedial prefrontal cortex in emotion regulation in females with major depressive disorder (MDD): A tDCS study

BACKGROUND

Individuals with major depressive disorder (MDD) have deficits in emotion regulation, which plays a putative role in psychopathology. The ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are assumed to be involved in respective processes. In the present study, we aimed to explore the effect of stimulation over the dlPFC and vmPFC on emotion regulation in female with MDD.

MATERIAL AND METHODS

Twenty women with MDD performed the Emotional Stroop, Emotional Go/No-Go, and Emotional 1-Back tasks during transcranial direct current stimulation (tDCS) in three separate sessions with the following electrode montages: anodal dlPFC (F3)/cathodal vmPFC (Fp2), anodal vmPFC (Fp2)/cathodal dlPFC (F3), and sham stimulation.

RESULTS

Independent of the valence of the respective stimuli, accuracy and speed of interference control, accuracy of pre-potent inhibition, and accuracy, but not speed, of working memory performance improved during anodal left dlPFC/cathodal right vmPFC stimulation. Independent of stimulation conditions, interference control was reduced for sad faces, as compared to happy and neutral faces, and working memory performance was faster for happy than for neutral and sad faces. For the impact of stimulation on specific emotional qualities, anodal left dlPFC/cathodal right vmPFC, compared to sham stimulation, led to improved interference control of sad and neutral faces in the emotional Stroop task, as shown by faster reaction times. Furthermore, in that task accuracy with respect to neutral and happy face conditions was higher during both real stimulation conditions, as compared to sham stimulation.

CONCLUSION

The dlPFC is involved in emotion regulation in MDD. Emotional valence is moreover relevant for the effect of stimulation over this area on interference control in MDD.

Prefrontal cortex and depression

The prefrontal cortex (PFC) has emerged as one of the regions most consistently impaired in major depressive disorder (MDD). Although functional and structural PFC abnormalities have been reported in both individuals with current MDD as well as those at increased vulnerability to MDD, this information has not translated into better treatment and prevention strategies. Here, we argue that dissecting depressive phenotypes into biologically more tractable dimensions - negative processing biases, anhedonia, despair-like behavior (learned helplessness) - affords unique opportunities for integrating clinical findings with mechanistic evidence emerging from preclinical models relevant to depression, and thereby promises to improve our understanding of MDD. To this end, we review and integrate clinical and preclinical literature pertinent to these core phenotypes, while emphasizing a systems-level approach, treatment effects, and whether specific PFC abnormalities are causes or consequences of MDD. In addition, we discuss several key issues linked to cross-species translation, including functional brain homology across species, the importance of dissecting neural pathways underlying specific functional domains that can be fruitfully probed across species, and the experimental approaches that best ensure translatability. Future directions and clinical implications of this burgeoning literature are discussed.

Dynamic Causal Modeling on the Identification of Interacting Networks in the Brain: A Systematic Review

Dynamic causal modeling (DCM) has long been used to characterize effective connectivity within networks of distributed neuronal responses. Previous reviews have highlighted the understanding of the conceptual basis behind DCM and its variants from different aspects. However, no detailed summary or classification research on the task-related effective connectivity of various brain regions has been made formally available so far, and there is also a lack of application analysis of DCM for hemodynamic and electrophysiological measurements. This review aims to analyze the effective connectivity of different brain regions using DCM for different measurement data. We found that, in general, most studies focused on the networks between different cortical regions, and the research on the networks between other deep subcortical nuclei or between them and the cerebral cortex are receiving increasing attention, but far from the same scale. Our analysis also reveals a clear bias towards some task types. Based on these results, we identify and discuss several promising research directions that may help the community to attain a clear understanding of the brain network interactions under different tasks.

Dynamic Causal Modeling Self-Connectivity Findings in the Functional Magnetic Resonance Imaging Neuropsychiatric Literature

Dynamic causal modeling (DCM) is a method for analyzing functional magnetic resonance imaging (fMRI) and other functional neuroimaging data that provides information about directionality of connectivity between brain regions. A review of the neuropsychiatric fMRI DCM literature suggests that there may be a historical trend to under-report self-connectivity (within brain regions) compared to between brain region connectivity findings. These findings are an integral part of the neurologic model represented by DCM and serve an important neurobiological function in regulating excitatory and inhibitory activity between regions. We reviewed the literature on the topic as well as the past 13 years of available neuropsychiatric DCM literature to find an increasing (but still, perhaps, and inadequate) trend in reporting these results. The focus of this review is fMRI as the majority of published DCM studies utilized fMRI and the interpretation of the self-connectivity findings may vary across imaging methodologies. About 25% of articles published between 2007 and 2019 made any mention of self-connectivity findings. We recommend increased attention toward the inclusion and interpretation of self-connectivity findings in DCM analyses in the neuropsychiatric literature, particularly in forthcoming effective connectivity studies of substance use disorders.

Multiscale neural modeling of resting-state fMRI reveals executive-limbic malfunction as a core mechanism in major depressive disorder

Major depressive disorder (MDD) represents a grand challenge to human health and society, but the underlying pathophysiological mechanisms remain elusive. Previous neuroimaging studies have suggested that MDD is associated with abnormal interactions and dynamics in two major neural systems including the default mode - salience (DMN-SAL) network and the executive - limbic (EXE-LIM) network, but it is not clear which network plays a central role and which network plays a subordinate role in MDD pathophysiology. To address this question, we refined a newly developed Multiscale Neural Model Inversion (MNMI) framework and applied it to test whether MDD is more affected by impaired circuit interactions in the DMN-SAL network or the EXE-LIM network. The model estimates the directed connection strengths between different neural populations both within and between brain regions based on resting-state fMRI data collected from normal healthy subjects and patients with MDD. Results show that MDD is primarily characterized by abnormal circuit interactions in the EXE-LIM network rather than the DMN-SAL network. Specifically, we observe reduced frontoparietal effective connectivity that potentially contributes to hypoactivity in the dorsolateral prefrontal cortex (dlPFC), and decreased intrinsic inhibition combined with increased excitation from the superior parietal cortex (SPC) that potentially lead to amygdala hyperactivity, together resulting in activation imbalance in the PFC-amygdala circuit that pervades in MDD. Moreover, the model reveals reduced PFC-to-hippocampus excitation but decreased SPC-to-thalamus inhibition in MDD population that potentially lead to hypoactivity in the hippocampus and hyperactivity in the thalamus, consistent with previous experimental data. Overall, our findings provide strong support for the long-standing limbic-cortical dysregulation model in major depression but also offer novel insights into the multiscale pathophysiology of this debilitating disease.

Multimodal brain imaging connectivity analyses of emotional and motivational deficits in depression among women

BACKGROUND

Major depressive disorder (MDD) is characterized by impaired cortical-subcortical functional connectivity. Apathy adds to functional impairment, but its cerebral basis in MDD remains unknown. Our objective was to describe impairments in functional connectivity during emotional processing in MDD (with varying levels of congruency and attention), and to determine their correlation with apathy.

METHODS

We used the Variable Attention Affective Task during functional MRI, followed by diffusion-weighted MRI, to assess 55 right-handed women (30 with MDD and 25 healthy controls) between September 2012 and February 2015. We estimated functional connectivity using generalized psychophysiologic interaction and anatomic connectivity with tract-based spatial statistics. We measured apathy using the Apathy Evaluation Scale.

RESULTS

We found decreased functional connectivity between the left amygdala and the left anterior cingulate cortex (ACC) during negative stimuli in participants with MDD (t54 = 4.2; p = 0.035, family-wise error [FWE]-corrected). During high-attention stimuli, participants with MDD showed reduced functional connectivity between the right dorsolateral prefrontal cortex (dlPFC) and the right ACC (t54 = 4.06, pFWE = 0.02), but greater functional connectivity between the right dlPFC and the right amygdala (t54 = 3.35, p = 0.048). Apathy was associated with increased functional connectivity between the right dlPFC and the right ACC during high-attention stimuli (t28 = 5.2, p = 0.01) and increased fractional anisotropy in the right posterior cerebellum, the anterior and posterior cingulum and the bilateral internal capsule (all pFWE < 0.05).

LIMITATIONS

Limitations included a moderate sample size, concomitant antidepressant therapy and no directed connectivity.

CONCLUSION

We found that MDD was associated with impairments in cortical-subcortical functional connectivity during negative stimuli that might alter the recruitment of networks engaged in attention. Apathy-related features suggested networks similar to those observed in degenerative disorders, but possible different mechanisms.

Effects of social subordination and oestradiol on resting-state amygdala functional connectivity in adult female rhesus monkeys

Preclinical studies demonstrate that chronic stress modulates the effects of oestradiol (E2) on behaviour through the modification of the amygdala and the medial prefrontal cortex (mPFC) neuronal structure. Clinical studies suggest that alterations in amygdala functional connectivity (FC) with the mPFC may be associated with stress-related phenotypes, including mood and anxiety disorders. Thus, identifying the effects of stress and E2 on amygdala-mPFC circuits is critical for understanding the neurobiology underpinning the vulnerability to stress-related disorders in women. In the present study, we used a well-validated rhesus monkey model of chronic psychosocial stress (subordinate social rank) to examine effects of E2 on subordinate (SUB) (i.e. high stress) and dominant (DOM) (i.e. low stress) female resting-state amygdala FC with the mPFC and with the whole-brain. In the non-E2 treatment control condition, SUB was associated with stronger left amygdala FC to subgenual cingulate (Brodmann area [BA] 25: BA25), a region implicated in several psychopathologies in people. In SUB females, E2 treatment strengthened right amygdala-BA25 FC, induced a net positive amygdala-visual cortex FC that was positively associated with frequency of submissive behaviours, and weakened positive amygdala-para/hippocampus FC. Our findings show that subordinate social rank alters amygdala FC and the impact of E2 on amygdala FC with BA25 and with regions involved in visual processing and memory encoding.

Association between dynamic resting-state functional connectivity and ketamine plasma levels in visual processing networks

Numerous studies demonstrate ketamine’s influence on resting-state functional connectivity (rsFC). Seed-based and static rsFC estimation methods may oversimplify FC. These limitations can be addressed with whole-brain, dynamic rsFC estimation methods. We assessed data from 27 healthy subjects who underwent two 3 T resting-state fMRI scans, once under subanesthetic, intravenous esketamine and once under placebo, in a randomized, cross-over manner. We aimed to isolate only highly robust effects of esketamine on dynamic rsFC by using eight complementary methodologies derived from two dynamic rsFC estimation methods, two functionally defined atlases and two statistical measures. All combinations revealed a negative influence of esketamine on dynamic rsFC within the left visual network and inter-hemispherically between visual networks (p < 0.05, corrected), hereby suggesting that esketamine’s influence on dynamic rsFC is highly stable in visual processing networks. Our findings may be reflective of ketamine’s role as a model for psychosis, a disorder associated with alterations to visual processing and impaired inter-hemispheric connectivity. Ketamine is a highly effective antidepressant and studies have shown changes to sensory processing in depression. Dynamic rsFC in sensory processing networks might be a promising target for future investigations of ketamine’s antidepressant properties. Mechanistically, sensitivity of visual networks for esketamine’s effects may result from their high expression of NMDA-receptors.

Valence-Dependent Coupling of Prefrontal-Amygdala Effective Connectivity during Facial Affect Processing

Despite the importance of the prefrontal-amygdala (AMY) network for emotion processing, valence-dependent coupling within this network remains elusive. In this study, we assessed the effect of emotional valence on brain activity and effective connectivity. We tested which functional pathways within the prefrontal-AMY network are specifically engaged during the processing of emotional valence. Thirty-three healthy adults were examined with functional magnetic resonance imaging while performing a dynamic faces and dynamic shapes matching task. The valence of the facial expressions varied systematically between positive, negative, and neutral across the task. Functional contrasts determined core areas of the emotion processing circuitry, comprising the medial prefrontal cortex (MPFC), the right lateral prefrontal cortex (LPFC), the AMY, and the right fusiform face area (FFA). Dynamic causal modelling demonstrated that the bidirectional coupling within the prefrontal-AMY circuitry is modulated by emotional valence. Additionally, Bayesian model averaging showed significant bottom-up connectivity from the AMY to the MPFC during negative and neutral, but not positive, valence. Thus, our study provides strong evidence for alterations of bottom-up coupling within the prefrontal-AMY network as a function of emotional valence. Thereby our results not only advance the understanding of the human prefrontal-AMY circuitry in varying valence context, but, moreover, provide a model to examine mechanisms of valence-sensitive emotional dysregulation in neuropsychiatric disorders.

Evaluating the organizational structure and specificity of network topology within the face processing system

There is increasing appreciation that network-level interactions among regions produce components of face processing previously ascribed to individual regions. Our goals were to use an exhaustive data-driven approach to derive and quantify the topology of directed functional connections within a priori defined nodes of the face processing network and evaluate whether the topology is category-specific. Young adults were scanned with fMRI as they viewed movies of faces, objects, and scenes. We employed GIMME to model effective connectivity among core and extended face processing regions, which allowed us to evaluate all possible directional connections, under each viewing condition (face, object, place). During face processing, we observed directional connections from the right posterior superior temporal sulcus to both the right occipital face area and right fusiform face area (FFA), which does not reflect the topology reported in prior studies. We observed connectivity between core and extended regions during face processing, but this limited to a feed-forward connection from the FFA to the amygdala. Finally, the topology of connections was unique to face processing. These findings suggest that the pattern of directed functional connections within the face processing network, particularly in the right core regions, may not be as hierarchical and feed-forward as described previously. Our findings support the notion that topologies of network connections are specialized, emergent, and dynamically responsive to task demands.

White matter - emotion processing activity relationships in youth offspring of bipolar parents

BACKGROUND

Early detection of Bipolar Disorder (BD) is critical for targeting interventions to delay or prevent illness onset. Yet, the absence of objective BD biomarkers makes accurately identifying at-risk youth difficult. In this study, we examined how relationships between white matter tract (WMT) structure and activity in emotion processing neural circuitry differentiate youth at risk for BD from youth at risk for other psychiatric disorders.

METHODS

Offspring (ages 8-17) of parents with BD (OBP, n = 32), offspring of comparison parents with non-BD psychopathology (OCP, n = 30), and offspring of healthy parents (OHP, n = 24) underwent diffusion tensor and functional magnetic resonance imaging while performing an emotional face processing task. Penalized and multiple regression analyses included GROUP(OBP,OCP)xWMT interactions as main independent variables, and emotion processing activity as dependent variables, to determine significant group differences in WMT-activity relationships.

RESULTS

8 GROUPxWMT interaction variables contributed to 16.5% of the variance in amygdala and prefrontal cortical activity to happy faces. Of these, significant group differences in slopes (inverse for OBP, positive for OCP) existed for the relationship between forceps minor radial diffusivity and rostral anterior cingulate activity (p = 0.014). Slopes remained significantly different in unmedicated youth without psychiatric disorders (p = 0.017) and were moderated by affective lability symptoms (F(1,29) = 5.566, p = 0.036).

LIMITATIONS

Relatively small sample sizes were included.

CONCLUSIONS

Forceps minor radial diffusivity-rostral anterior cingulate activity relationships may reflect underlying neuropathological processes that contribute to affectively labile youth at risk for BD and may help differentiate them from youth at risk for other psychiatric disorders.

Association of Neuroimaging Measures of Emotion Processing and Regulation Neural Circuitries With Symptoms of Bipolar Disorder in Offspring at Risk for Bipolar Disorder

IMPORTANCE

Bipolar disorder (BD) is difficult to distinguish from other psychiatric disorders. Neuroimaging studies can identify objective markers of BD risk.

OBJECTIVE

To identify neuroimaging measures in emotion processing and regulation neural circuitries and their associations with symptoms specific to youth at risk for BD.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional (August 1, 2011, to July 31, 2017) and longitudinal (February 1, 2013, to November 30, 2017) neuroimaging study performed at the University of Pittsburgh Medical Center compared a sample of 31 offspring of parents with BD (OBP) with 28 offspring of comparison parents with non-BD psychopathologies (OCP) and 21 offspring of healthy parents (OHP); OBP, OCP, and OHP were recruited from the Bipolar Offspring Study and the Longitudinal Assessment of Manic Symptoms Study.

MAIN OUTCOMES AND MEASURES

Group differences in activity and functional connectivity during emotional face processing and n-back task performance in amygdala, dorsolateral and ventrolateral prefrontal cortices (PFC), caudal anterior cingulate cortices (cACC), and rostral anterior cingulate cortices (rACC) neuroimaging measures showing between-group differences and symptom severity (anxiety, affective lability, depression, mania). We hypothesized that elevated amygdala activity and/or lower PFC activity and abnormal amygdala to PFC functional connectivity would distinguish OBP from OCP and OHP, and magnitudes of these abnormalities would positively correlate with elevated symptom severity. We explored associations between changes in neuroimaging and symptom measures over follow-up (mean [SD], 2.9 [1.4] years) in a subset of participants (n = 30).

RESULTS

Eighty participants were included (mean [SD] age, 14.2 (2.1) years; 35 female). Twelve neuroimaging measures explained 51% of the variance in the results of neuroimaging measures overall. Of the 12, 9 showed significant main associations of the group; however, after post hoc analyses and Bonferroni corrections, only 7 showed statistically significant associations between groups (corrected P < .05 for all). Of the 7, 2 showed significant relationships with symptoms. Offspring of parents with BD had greater right rACC activity when regulating attention to happy faces vs OCP (mean [SD] difference, 0.744 [0.249]; 95% CI, 0.134-1.354; P = .01), which positively correlated with affective lability severity (ρ = 0.304; uncorrected P = .006). Offspring of parents with BD had greater amygdala to left cACC functional connectivity when regulating attention to fearful faces vs OCP (mean [SD] difference, 0.493 [0.169]; 95% CI, 0.079-0.908; P = .01). Increases in this measure positively correlated with increases in affective lability over follow-up (r = 0.541; P = .003).

CONCLUSIONS AND RELEVANCE

Greater anterior cingulate cortex activity and functional connectivity during emotion regulation tasks may be specific markers of BD risk. These findings highlight potential neural targets to aid earlier identification of and guide new treatment developments for BD.

Cortical and subcortical changes in patients with premenstrual syndrome

BACKGROUND

Premenstrual syndrome (PMS) is characterized by a series of emotional, physical and behavioral symptoms. Although PMS is related to dysfunctions of the central nervous system, the neuropathological mechanism of PMS still has not been clearly established. The aim of this study is to evaluate potential differences in both cortical thickness and subcortical volumes in PMS patients compared to healthy controls (HCs).

METHODS

Twenty PMS patients and twenty HCs underwent a structural magnetic resonance imaging scan and clinical assessment. Cortical thickness and subcortical volumes were computed using the FreeSurfer image analysis suite. Relationships between cortical thickness/subcortical volumes and the daily rating of severity of problems (DRSP) score were then measured in patients.

RESULTS

Compared to HCs, PMS patients exhibited reduced cortical thickness in the medial prefrontal cortex (MPFC), orbitofrontal cortex (OFC) and insula, and increased subcortical volumes of the amygdala, thalamus and pallidum. Furthermore, negative correlations were detected between the DRSP and cortical thickness in the anterior cingulate cortex and precuneus.

LIMITATIONS

The study is limited by a small sample size and narrow age range of participants.

CONCLUSIONS

Our findings indicate that the abnormal morphological changes are mainly implicated in emotional regulation and visceral perception in PMS patients. We hope that our study may contribute to a better understanding of PMS.

Age-Related Developmental and Individual Differences in the Influence of Social and Non-social Distractors on Cognitive Performance

This study sought to examine age-related differences in the influences of social (neutral, emotional faces) and non-social/non-emotional (shapes) distractor stimuli in children, adolescents, and adults. To assess the degree to which distractor, or task-irrelevant, stimuli of varying social and emotional salience interfere with cognitive performance, children (N = 12; 8-12y), adolescents (N = 17; 13-17y), and adults (N = 17; 18-52y) completed the Emotional Identification and Dynamic Faces (EIDF) task. This task included three types of dynamically-changing distractors: (1) neutral-social (neutral face changing into another face); (2) emotional-social (face changing from 0% emotional to 100% emotional); and (3) non-social/non-emotional (shapes changing from small to large) to index the influence of task-irrelevant social and emotional information on cognition. Results yielded no age-related differences in accuracy but showed an age-related linear reduction in correct reaction times across distractor conditions. An age-related effect in interference was observed, such that children and adults showed slower response times on correct trials with socially-salient distractors; whereas adolescents exhibited faster responses on trials with distractors that included faces rather than shapes. A secondary study goal was to explore individual differences in cognitive interference. Results suggested that regardless of age, low trait anxiety and high effortful control were associated with interference to angry faces. Implications for developmental differences in affective processing, notably the importance of considering the contexts in which purportedly irrelevant social and emotional information might impair, vs. improve cognitive control, are discussed.

Inhibition of Information Flow to the Default Mode Network During Self-Reference Versus Reference to Others

The default mode network (DMN), a network centered around the cortical midline, shows deactivation during most cognitive tasks and pronounced resting-state connectivity, but is actively engaged in self-reference and social cognition. It is, however, yet unclear how information reaches the DMN during social cognitive processing. Here, we addressed this question using dynamic causal modeling (DCM) of functional magnetic resonance imaging (fMRI) data acquired during self-reference (SR) and reference to others (OR). Both conditions engaged the left inferior frontal gyrus (LIFG), most likely reflecting semantic processing. Within the DMN, self-reference preferentially elicited rostral anterior cingulate and ventromedial prefrontal cortex (rACC/vmPFC) activity, whereas OR engaged posterior cingulate and precuneus (PCC/PreCun). DCM revealed that the regulation of information flow to the DMN was primarily inhibitory. Most prominently, SR elicited inhibited information flow from the LIFG to the PCC/PreCun, while OR was associated with suppression of the connectivity from the LIFG to the rACC/vmPFC. These results suggest that task-related DMN activation is enabled by inhibitory down-regulation of task-irrelevant information flow when switching from rest to stimulus-specific processing.

Influence of Familial Risk for Depression on Cortico-Limbic Connectivity During Implicit Emotional Processing

Imbalances in cortico-limbic activity and functional connectivity (FC) supposedly underlie biased emotional processing and present putative intermediate phenotypes (IPs) for major depressive disorder (MDD). To prove the validity of these IPs, we assessed them in familial risk. In 70 healthy first-degree relatives of MDD patients and 70 controls, brain activity and seed-based amygdala FC were assessed during an implicit emotional processing task for fMRI containing angry and fearful faces. Using the generalized psychophysiological interaction approach, amygdala FC was assessed (a) across conditions to provide comparable data to previous studies and (b) compared between conditions to elucidate its implications for emotional processing. Associations of amygdala FC with self-reported negative affect were explored post hoc. Groups did not differ in brain activation. In relatives, amygdala FC across conditions was decreased with superior and medial frontal gyrus (SFG, MFG) and increased with subgenual and perigenual anterior cingulate cortex (sgACC, pgACC). NA was inversely correlated with amygdala FC with MFG, pgACC and their interaction in relatives. Relatives showed aberrant condition-dependent modulations of amygdala FC with visual cortex, thalamus and orbitofrontal cortex. Our results do not support imbalanced cortico-limbic activity as IP for MDD. Diminished amygdala-dorsomedial prefrontal FC in relatives might indicate insufficient regulatory capacity, which appears to be compensated by ventromedial prefrontal regions. Differential task-dependent modulations of amygdala FC are discussed as a stronger involvement of automatic instead of voluntary emotional processing pathways. Reliability and etiological implications of these results should be investigated in future studies including longitudinal designs and patient-risk-control comparisons.

Default mode network deactivation during emotion processing predicts early antidepressant response

Several previous functional magnetic resonance imaging (fMRI) studies have demonstrated the predictive value of brain activity during emotion processing for antidepressant response, with a focus on clinical outcome after 6-8 weeks. However, longitudinal studies emphasize the paramount importance of early symptom improvement for the course of disease in major depressive disorder (MDD). We therefore aimed to assess whether neural activity during the emotion discrimination task (EDT) predicts early antidepressant effects, and how these predictive measures relate to more sustained response. Twenty-three MDD patients were investigated once with ultrahigh-field 7T fMRI and the EDT. Following fMRI, patients received Escitalopram in a flexible dose schema and were assessed with the Hamilton Depression Rating Scale (HAMD) before, and after 2 and 4 weeks of treatment. Deactivation of the precuneus and posterior cingulate cortex (PCC) during the EDT predicted change in HAMD scores after 2 weeks of treatment. Baseline EDT activity was not predictive of HAMD change after 4 weeks of treatment. The precuneus and PCC are integral components of the default mode network (DMN). We show that patients who exhibit stronger DMN suppression during emotion processing are more likely to show antidepressant response after 2 weeks. This is, to our knowledge, the first study to show that DMN activity predicts early antidepressant effects. However, DMN deactivation did not predict response at 4 weeks, suggesting that our finding is representative of early, likely treatment-related, yet unspecific symptom improvement. Regardless, early effects may be harnessed for optimization of treatment regimens and patient care.

Functional magnetic resonance imaging correlates of emotion recognition and voluntary attentional regulation in depression: A generalized psycho-physiological interaction study

BACKGROUND

Major depression is characterized by an impaired ability to evaluate and modify emotional responses as well as attention deficits, however the neural origins of these features are unresolved. The aim of the study was to investigate activation and functional connectivity changes during recognition and voluntary attentional regulation of emotion in 34 patients with major depressive disorder (MDD) compared to 35 controls.

METHODS

We employed an fMRI task in which participants assessed the valence or the shape of emotional stimuli. Then we analysed BOLD responses and functional connectivity using psycho-physiological interaction during the two conditions.

RESULTS

Patients showed more incorrect responses across both trial types. Recognition trials recruited areas belonging to the ventral system, which is involved in the generation and automatic processing of emotion. Shift of attention away from the emotional content activated areas belonging to the dorsal emotion regulation system. Patients showed hyper-connectivity between and within the default mode and task positive networks. While shifting attention away from emotion, patients had a reduced response of the anterior insula and increased connectivity across areas involved in emotion generation and regulation. Connectivity between the amygdala and visual areas was also altered in patients compared to controls during evaluation of negative and positive pictures, which might be related to biased valence processing. Finally, during regulation of negative trials and recognition of positive trials patients showed decreased coupling in areas involved in attention allocation and emotional regulation.

LIMITATIONS

Most of the patients were medicated, although potential effects of treatment were investigated.

CONCLUSIONS

Overall, our findings are compatible with abnormal functional coupling in MDD of regions involved in perception, recognition and attention allocation, especially during regulation of negative images and valence evaluation of positive images.

Paradoxical Prefrontal-Amygdala Recruitment to Angry and Happy Expressions in Pediatric Posttraumatic Stress Disorder

The neural substrates of pediatric posttraumatic stress disorder (PTSD) remain incompletely understood, but likely involve abnormal function and development of emotion processing circuitry. Valence-specific and age-related abnormalities during emotion processing have not been elucidated. We examined implicit emotional face processing in pediatric PTSD, predicting abnormalities specific to threat-related emotion. Youth (ages 8-18 years) with PTSD (n=25) and healthy youth (n=28) completed a dynamic emotional face task during fMRI, viewing faces changing from neutral to angry or happy, or changing shape control. Group and cross-sectional age-related differences in activation and functional connectivity were examined in amygdala/hippocampus, medial prefrontal cortex (mPFC), and whole-brain analyses. The post hoc analyses examined the relationship of neural abnormalities with symptom measures of PTSD, anxiety, and depression. Compared with decreased activation with age in healthy youth, PTSD youth showed increased amygdala activation to emotional faces with age. In a group by emotion interaction, PTSD youth showed dorsal (d)ACC hyperactivation to happy faces relative to healthy youth, with no difference for angry faces. Connectivity analyses revealed paradoxical coupling in prefrontal-amygdala circuits, including dACC-dorsomedial (dm)PFC, amygdala-dmPFC, and amygdala-ventrolateral (vl)PFC. In each case, PTSD youth showed reduced connectivity to angry faces, but increased connectivity to happy faces, the reverse of healthy youth. Valence-abnormal recruitment was associated with greater symptom severity, implicating a role in trauma-related psychopathology in youth. Notably, impaired recruitment during angry faces and heightened recruitment to happy faces may reflect increased salience and ambiguity of positive emotional expressions in pediatric PTSD. Finally, age-related findings suggest a developmental sensitization of the amygdala across emotional expressions in youth with PTSD. These findings provide novel insights into the underlying pathophysiology of pediatric PTSD, extending beyond abnormal neural responses to canonical threat.

Within- and Between-Session Changes in Neural Activity During Emotion Processing in Unipolar and Bipolar Depression

BACKGROUND

Bipolar disorder (BD) and unipolar depression (UD) can be difficult to distinguish clinically, particularly during episodes of depression. In this study we test for differences between BD, UD, and healthy control (HC) adults regarding within- and between-session changes in BOLD response during implicit emotional processing.

METHODS

During fMRI, HC adults (N=19) and depressed adults with UD (N=19) and BD (N=16) performed an implicit emotion-processing task. Each participant was scanned twice, separated by 6-months, resulting in 108 scans. BOLD response and linear change in BOLD response were examined within and between sessions.

RESULTS

We observed within-session linear decreases in BOLD signal (irrespective of group, condition, or session) in the left amygdala, a right-sided temporo-parietal region, and a right-sided fronto-insular region. Furthermore, we observed group differences in within-session BOLD signal change (p<0.05, FWE corrected) in a left-sided striatal-insular-thalamic region. Individuals with BD demonstrated a linear decrease in BOLD signal compared to HC (p<0.008, FWE corrected) across this region and compared to UD in the posterior insula portion of the region (p<0.008, FWE corrected). Finally, we observed main effects of emotional valence in bilateral visuo-spatial processing regions as well as in the left and right amygdala.

CONCLUSIONS

Individuals with BD demonstrated linear attenuation of BOLD response to emotional stimuli within left-sided striatal-insular-thalamic regions. Individuals with BD may either have experienced abnormal habituation in this region or disengaged quickly from processing the emotional stimuli, despite comparable task performance. This pattern may represent an underlying pathophysiological process associated with BD that differs from UD.

Social functioning in major depressive disorder

Depression is associated with social risk factors, social impairments and poor social functioning. This paper gives an overview of these social aspects using the NIMH Research and Domain Criteria 'Systems for Social Processes' as a framework. In particular, it describes the bio-psycho-social interplay regarding impaired affiliation and attachment (social anhedonia, hyper-sensitivity to social rejection, competition avoidance, increased altruistic punishment), impaired social communication (impaired emotion recognition, diminished cooperativeness), impaired social perception (reduced empathy, theory-of-mind deficits) and their impact on social networks and the use of social media. It describes these dysfunctional social processes at the behavioural, neuroanatomical, neurochemical and genetic levels, and with respect to animal models of social stress. We discuss the diagnostic specificity of these social deficit constructs for depression and in relation to depression severity. Since social factors are importantly involved in the pathogenesis and the consequences of depression, such research will likely contribute to better diagnostic assessments and concepts, treatments and preventative strategies both at the diagnostic and transdiagnostic level.

Cortical-Subcortical Interactions in Depression: From Animal Models to Human Psychopathology

Depression is a debilitating disorder causing significant societal and personal suffering. Improvements in identification of major depressive disorder (MDD) and its treatment are essential to reduce its toll. Recent developments in rodent models of MDD and neuroimaging of humans suffering from the disorder provide avenues through which gains can be made towards reducing its burden. In this review, new findings, integrating across rodent models and human imaging are highlighted that have yielded new insights towards a basic understanding of the disorder. In particular, this review focuses on cortical-subcortical interactions underlying the pathophysiology of MDD. In particular, evidence is accruing that dysfunction in prefrontal-subcortical circuits including the amygdala, ventral striatum (VS), hippocampus and dorsal raphe nucleus (DRN) are associated with MDD status.

Impaired Bottom-Up Effective Connectivity Between Amygdala and Subgenual Anterior Cingulate Cortex in Unmedicated Adolescents with Major Depression: Results from a Dynamic Causal Modeling Analysis

Major depressive disorder (MDD) is a significant contributor to lifetime disability and frequently emerges in adolescence, yet little is known about the neural mechanisms of MDD in adolescents. Dynamic causal modeling (DCM) analysis is an innovative tool that can shed light on neural network abnormalities. A DCM analysis was conducted to test several frontolimbic effective connectivity models in 27 adolescents with MDD and 21 healthy adolescents. The best neural model for each person was identified using Bayesian model selection. The findings revealed that the two adolescent groups fit similar optimal neural models. The best across-groups model was then used to infer upon both within-group and between-group tests of intrinsic and modulation parameters of the network connections. First, for model validation, within-group tests revealed robust evidence for bottom-up connectivity, but less evidence for strong top-down connectivity in both groups. Second, we tested for differences between groups on the validated parameters of the best model. This revealed that adolescents with MDD had significantly weaker bottom-up connectivity in one pathway, from amygdala to sgACC (p=0.008), than healthy controls. This study provides the first examination of effective connectivity using DCM within neural circuitry implicated in emotion processing in adolescents with MDD. These findings aid in advancing understanding the neurobiology of early-onset MDD during adolescence and have implications for future research investigating how effective connectivity changes across contexts, with development, over the course of the disease, and after intervention.

Neuroticism scores increase with late-life cognitive decline

OBJECTIVE

Neuroticism has been reported as both a risk factor for cognitive decline and a characteristic that increases in parallel with the development of mild cognitive impairment (MCI) and dementia. However, the evidence for these associations is inconclusive, and whether effects are stronger for particular cognitive domains is unknown. We investigated these issues and determined if associations differ among different components of neuroticism.

METHODS

A neuroticism scale (NEO-FFI) and neuropsychological test battery were administered to 603 older adults without dementia, with 493 of these reassessed two years later. Diagnoses of MCI and dementia (at follow-up) were made, and global cognition and performance in six cognitive domains quantified. The neuroticism components were negative affect, self-reproach, and proneness to psychological distress.

RESULTS

For the whole sample, neuroticism scores remained stable between baseline (15.3 ± 7.0) and follow-up (15.5 ± 7.0), as did all neuroticism component scores. However, there were declines in global cognition (p < 0.05) and particular cognitive domains (p < 0.001). Higher neuroticism was associated with poorer cognition cross-sectionally (p < 0.01), but did not predict cognitive decline. For 43 participants who developed incident MCI or dementia, there were increases in neuroticism (15.3 ± 6.4 to 17.1 ± 8.3, p < 0.05) and negative affect (p < 0.05). Declines in all cognitive measures except executive function were associated with increases in neuroticism and component scores (p < 0.05).

CONCLUSIONS

Late-life cognitive decline is associated with an increase in neuroticism scores. However, associations vary between different cognitive domains and components of neuroticism. An increase in neuroticism or negative affect scores may be a sign of MCI or dementia.

History of Depression and Frontostriatal Connectivity During Reward Processing in Late Adolescent Boys

Given that depression in men is associated with risk for seriously adverse consequences, evaluating how putative neural mechanisms of depression-such as reward-related frontostriatal connectivity-may be altered in late adolescent boys with a history of depression is an important research aim. Adolescents and adults with depression have been demonstrated to show blunted striatal response and heightened medial prefrontal cortex (mPFC) activation to winning reward. Function in reward circuits appears to be best understood as coordination of regions within frontostriatal circuitry, and alterations to this circuitry could occur in those with a history of depression. The current study evaluated functional connectivity between the nucleus accumbens and mPFC in a sample of 166 ethnically diverse boys with and without a history of depression. Participants completed an fMRI monetary reward paradigm at age 20. Lifetime history of depression and other psychiatric illnesses was measured prospectively and longitudinally, using structured clinical interviews at 7 time points from ages 8 to 20. Boys with a history of depression showed heightened positive connectivity between the nucleus accumbens and the mPFC relative to boys with no psychiatric history when winning rewards relative to losing rewards. This altered frontostriatal connectivity pattern was also associated with greater number of depressive episodes in the boys' lifetime. History of depression in late adolescent boys may be associated with altered coordination between the nucleus accumbens and mPFC when winning reward. This coordination could reflect oversignaling of the mPFC to dampen typical ventral striatum response or enhance weak ventral striatum response.

Functional brain-imaging correlates of negative affectivity and the onset of first-episode depression

BACKGROUND

The amygdala and subgenual anterior cingulate cortex (sACC) are key brain regions for the generation of negative affect. In this longitudinal fMRI study of adolescents we investigated how amygdala-sACC connectivity was correlated with negative affectivity (NA) both cross-sectionally and longitudinally, and examined its relationship to the onset of first-episode depression.

METHOD

Fifty-six adolescents who were part of a larger longitudinal study of adolescent development were included. They had no history of mental illness at the time of their baseline scan (mean age 16.5 years) and had a follow-up scan 2 years later (mean age 18.8 years). We used resting-state functional-connectivity MRI to investigate whether cross-sectional and change measures of amygdala-sACC connectivity were (i) correlated with NA and its change over time, and (ii) related to the onset of first-episode depression.

RESULTS

The magnitude of amygdala connectivity with sACC showed significant positive correlation with NA at both time-points. Further analysis confirmed that change in amygdala-sACC connectivity between assessments was correlated with change in NA. Eight participants developed a first episode of depression between the baseline and follow-up assessments: they showed increased amygdala-sACC connectivity at follow-up.

CONCLUSIONS

Amygdala-sACC connectivity is associated with NA in adolescence, with change in connectivity between these regions showing positive correlation with change in NA. Our observation that the onset of depression was associated with an increase in connectivity between the regions provides support for the neurobiological 'scar' hypothesis of depression.

Model specification and the reliability of fMRI results: implications for longitudinal neuroimaging studies in psychiatry

Functional Magnetic Resonance Imagine (fMRI) is an important assessment tool in longitudinal studies of mental illness and its treatment. Understanding the psychometric properties of fMRI-based metrics, and the factors that influence them, will be critical for properly interpreting the results of these efforts. The current study examined whether the choice among alternative model specifications affects estimates of test-retest reliability in key emotion processing regions across a 6-month interval. Subjects (N = 46) performed an emotional-faces paradigm during fMRI in which neutral faces dynamically morphed into one of four emotional faces. Median voxelwise intraclass correlation coefficients (mvICCs) were calculated to examine stability over time in regions showing task-related activity as well as in bilateral amygdala. Four modeling choices were evaluated: a default model that used the canonical hemodynamic response function (HRF), a flexible HRF model that included additional basis functions, a modified CompCor (mCompCor) model that added corrections for physiological noise in the global signal, and a final model that combined the flexible HRF and mCompCor models. Model residuals were examined to determine the degree to which each pipeline met modeling assumptions. Results indicated that the choice of modeling approaches impacts both the degree to which model assumptions are met and estimates of test-retest reliability. ICC estimates in the visual cortex increased from poor (mvICC = 0.31) in the default pipeline to fair (mvICC = 0.45) in the full alternative pipeline – an increase of 45%. In nearly all tests, the models with the fewest assumption violations generated the highest ICC estimates. Implications for longitudinal treatment studies that utilize fMRI are discussed.

Social anhedonia and medial prefrontal response to mutual liking in late adolescents

Anhedonia, a cardinal symptom of depression defined as difficulty experiencing pleasure, is also a possible endophenotype and prognostic factor for the development of depression. The onset of depression typically occurs during adolescence, a period in which social status and affiliation are especially salient. The medial prefrontal cortex (mPFC), a region implicated in reward, self-relevant processing, and social cognition, exhibits altered function in adults with anhedonia, but its association with adolescent anhedonia has yet to be investigated. We examined neural response to social reward in 27 late adolescents, 18-21years old, who varied in social anhedonia. Participants reported their social anhedonia, completed ratings of photos of unfamiliar peers, and underwent a functional magnetic resonance imaging task involving feedback about being liked. Adolescents with higher social anhedonia exhibited greater mPFC activation in response to mutual liking (i.e., being liked by someone they also liked) relative to received liking (i.e., being liked by someone whom they did not like). This association held after controlling for severity of current depressive symptoms, although depressive severity was also associated with greater mPFC response. Adolescents with higher levels of social anhedonia also had stronger positive connectivity between the nucleus accumbens and the mPFC during mutual versus received liking. These results, the first on the pathophysiology of adolescent anhedonia, support altered neural reward-circuit response to social reward in young people with social anhedonia.

Functional connectivity of negative emotional processing in adolescent depression

BACKGROUND

The subgenual anterior cingulate cortex (sgACC) and its connected circuitry have been heavily implicated in emotional functioning in adolescent-onset major depressive disorder (MDD). While several recent studies have examined sgACC functional connectivity (FC) in depressed youth at rest, no studies to date have investigated sgACC FC in adolescent depression during negative emotional processing.

METHODS

Nineteen medication-naïve adolescents with MDD and 19 matched healthy controls (HCL) performed an implicit fear facial affect recognition task during functional magnetic resonance imaging (fMRI). We defined seeds in bilateral sgACC and assessed FC using the psychophysiological interaction method. We also applied cognitive behavioral modeling to estimate group differences in perceptual sensitivity in this task. Finally, we correlated connectivity strength with clinical data and perceptual sensitivity.

RESULTS

Depressed adolescents showed increased sgACC-amygdala FC and decreased sgACC-fusiform gyrus, sgACC-precuneus, sgACC-insula, and sgACC-middle frontal gyrus FC compared to HCL (p<0.05, corrected). Among the MDD, sgACC-precuneus FC negatively correlated with depression severity (p<0.05, corrected). Lastly, MDD adolescents exhibited poorer perceptual sensitivity in the task than HCL, and individual differences in perceptual sensitivity significantly correlated with sgACC FC and depression scores (p<0.05, corrected).

LIMITATIONS

Subjects were clinically homogenous, possibly limiting generalizability of the findings.

CONCLUSIONS

Adolescent depression is associated with biased processing of negative stimuli that may be driven by sgACC dysregulation and may possibly lead to an imbalance among intrinsic functional brain networks. This work also establishes the use of combining neuroimaging and cognitive behavioral modeling methods to investigate cognitive and neural differences between psychiatric and healthy populations.

Diagnostic and therapeutic utility of neuroimaging in depression: an overview

A growing number of studies have used neuroimaging to further our understanding of how brain structure and function are altered in major depression. More recently, these techniques have begun to show promise for the diagnosis and treatment of depression, both as aids to conventional methods and as methods in their own right. In this review, we describe recent neuroimaging findings in the field that might aid diagnosis and improve treatment accuracy. Overall, major depression is associated with numerous structural and functional differences in neural systems involved in emotion processing and mood regulation. Furthermore, several studies have shown that the structure and function of these systems is changed by pharmacological and psychological treatments of the condition and that these changes in candidate brain regions might predict clinical response. More recently, "machine learning" methods have used neuroimaging data to categorize individual patients according to their diagnostic status and predict treatment response. Despite being mostly limited to group-level comparisons at present, with the introduction of new methods and more naturalistic studies, neuroimaging has the potential to become part of the clinical armamentarium and may improve diagnostic accuracy and inform treatment choice at the patient level.

Amygdala and whole-brain activity to emotional faces distinguishes major depressive disorder and bipolar disorder

OBJECTIVES

It can be clinically difficult to distinguish depressed individuals with bipolar disorder (BD) and major depressive disorder (MDD). To examine potential biomarkers of difference between the two disorders, the current study examined differences in the functioning of emotion-processing neural regions during a dynamic emotional faces task.

METHODS

During functional magnetic resonance imaging, healthy control adults (HC) (n = 29) and depressed adults with MDD (n = 30) and BD (n = 22) performed an implicit emotional-faces task in which they identified a color label superimposed on neutral faces that dynamically morphed into one of four emotional faces (angry, fearful, sad, happy). We compared neural activation between the groups in an amygdala region-of-interest and at the whole-brain level.

RESULTS

Adults with MDD showed significantly greater activity than adults with BD in the left amygdala to the anger condition (p = 0.01). Results of whole-brain analyses (at p < 0.005, k ≥ 20) revealed that adults with BD showed greater activity to sad faces in temporoparietal regions, primarily in the left hemisphere, whereas individuals with MDD demonstrated greater activity than those with BD to displays of anger, fear, and happiness. Many of the observed BD-MDD differences represented abnormalities in functioning compared to HC.

CONCLUSIONS

We observed a dissociation between depressed adults with BD and MDD in the processing of emerging emotional faces. Those with BD showed greater activity during mood-congruent (i.e., sad) faces, whereas those with MDD showed greater activity for mood-incongruent (i.e., fear, anger, and happy) faces. Such findings may reflect markers of differences between BD and MDD depression in underlying pathophysiological processes.

Cortico-amygdala-striatal circuits are organized as hierarchical subsystems through the primate amygdala

The prefrontal and insula cortex, amygdala, and striatum are key regions for emotional processing, yet the amygdala's role as an interface between the cortex and striatum is not well understood. In the nonhuman primate (Macaque fascicularis), we analyzed a collection of bidirectional tracer injections in the amygdala to understand how cortical inputs and striatal outputs are organized to form integrated cortico-amygdala-striatal circuits. Overall, diverse prefrontal and insular cortical regions projected to the basal and accessory basal nuclei of the amygdala. In turn, these amygdala regions projected to widespread striatal domains extending well beyond the classic ventral striatum. Analysis of the cases in aggregate revealed a topographic colocalization of cortical inputs and striatal outputs in the amygdala that was additionally distinguished by cortical cytoarchitecture. Specifically, the degree of cortical laminar differentiation of the cortical inputs predicted amygdalostriatal targets, and distinguished three main cortico-amygdala-striatal circuits. These three circuits were categorized as "primitive," "intermediate," and "developed," respectively, to emphasize the relative phylogenetic and ontogenetic features of the cortical inputs. Within the amygdala, these circuits appeared arranged in a pyramidal-like fashion, with the primitive circuit found in all examined subregions, and subsequent circuits hierarchically layered in discrete amygdala subregions. This arrangement suggests a stepwise integration of the functions of these circuits across amygdala subregions, providing a potential mechanism through which internal emotional states are managed with external social and sensory information toward emotionally informed complex behaviors.

Reduced serotonin transporter availability decreases prefrontal control of the amygdala

After a threatening event, the risk of developing social psychopathologies is increased in short-allele (s) carriers of the serotonin transporter gene. The amygdala becomes overresponsive to emotional stimuli, an effect that could be driven by local hypersensitivity or by reduced prefrontal regulation. This study distinguishes between these two hypotheses by using dynamic causal modeling of fMRI data acquired in a preselected cohort of human s-carriers and homozygous long-allele carriers. Increased amygdala activity in s-carriers originates from reduced prefrontal inhibitory regulation when social emotional behavior needs to be controlled, suggesting a mechanism for increased vulnerability to psychopathologies.

Neural correlates of dysfunctional emotion regulation in major depressive disorder. A systematic review of neuroimaging studies

Abnormal emotion processing is a core feature of major depressive disorder (MDD). Since the emergence of functional neuroimaging techniques, many studies have been conducted in MDD subjects to elucidate the underlying abnormalities in the neural systems involved in emotion regulation. In this systematic review, we discuss this research in the context of the neural model of emotion regulation previously described by Phillips et al. (2008). This model differentiates between automatic and voluntary emotion regulation subprocesses. Automatic regulation subprocesses were shown to involve predominantly medial prefrontal cortical structures, in addition to the hippocampus and parahippocampus, while voluntary regulation processes additionally recruited lateral prefrontal cortical regions. In conclusion, although the available data is limited, findings suggest that MDD subjects demonstrate abnormally reduced activity in lateral prefrontal cortices during explicit voluntary control of emotional experience. During early, automatic stages of emotion regulation, on the other hand, MDD subjects appear to achieve successful emotion regulation by recruiting additional lateral prefrontal neural regions, that may be mediated by medial prefrontal, especially rostral/dorsal anterior cingulate gyrus (ACG) functioning. Dysfunctional automatic regulation may impair successful voluntary emotion regulation, and may present a target for novel therapeutic approaches in MDD.

Relation between structural and functional connectivity in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is characterized by abnormalities in both brain structure and function within a frontolimbic network. However, little is known about the relation between structural and functional abnormalities in MDD. Here, we used a multimodal neuroimaging approach to investigate the relation between structural connectivity and functional connectivity within the frontolimbic network.

METHODS

Eighteen MDD and 24 healthy control subjects were included, of which the integrity of the uncinate fasciculus was assessed that connects the subgenual anterior cingulate cortex (ACC) to the medial temporal lobe (MTL) with diffusion tensor imaging. Furthermore, we assessed the functional connectivity between these brain regions with functional magnetic resonance imaging.

RESULTS

The results showed that white matter integrity of the uncinate fasciculus was reduced and that functional connectivity between the subgenual ACC and MTL was enhanced in MDD. Importantly, we identified a negative correlation between uncinate fasciculus integrity and subgenual ACC functional connectivity with the bilateral hippocampus in MDD but not in healthy control subjects. Moreover, this negative structure-function relation in MDD was positively associated with depression severity.

CONCLUSIONS

These findings suggest that structural abnormalities in MDD are associated with increased functional connectivity between subgenual ACC and MTL and that these changes are concomitant with severity of depressive symptoms. This association indicates that structural abnormalities in MDD contribute to increased functional connectivity within the frontolimbic network.

Childhood and adult trauma both correlate with dorsal anterior cingulate activation to threat in combat veterans

BACKGROUND

Prior studies of adult post-traumatic stress disorder (PTSD) suggest abnormal functioning of prefrontal and limbic regions. Cumulative childhood and adult trauma exposures are major risk factors for developing adult PTSD, yet their contribution to neural dysfunction in PTSD remains poorly understood. This study aimed to examine the neural correlates of childhood and adult trauma exposure and post-traumatic stress symptoms (PTSS) within a single model. Method Medication-free male combat veterans (n = 28, average age 26.6 years) with a wide range of PTSS were recruited from the community between 2010 and 2011. Subjects completed an emotional face-morphing task while undergoing functional magnetic resonance imaging (fMRI). Clinical ratings included the Clinician-Administered PTSD Scale (CAPS), Childhood Trauma Questionnaire (CTQ) and Combat Exposure Scale (CES). A priori regions were examined through multivariate voxelwise regression in SPM8, using depressive symptoms and IQ as covariates.

RESULTS

In the angry condition, CAPS scores correlated positively with activation in the medial prefrontal cortex [mPFC; Brodmann area (BA) 10, z = 3.51], hippocampus (z = 3.47), insula (z = 3.62) and, in earlier blocks, the amygdala. CES and CTQ correlated positively with activation in adjacent areas of the dorsal anterior cingulate cortex (dACC; BA 32, z = 3.70 and BA 24, z = 3.88 respectively). In the happy condition, CAPS, CTQ and CES were not correlated significantly with activation patterns.

CONCLUSIONS

dACC activation observed in prior studies of PTSD may be attributable to the cumulative effects of childhood and adult trauma exposure. By contrast, insula, hippocampus and amygdala activation may be specific to PTSS. The specificity of these results to threat stimuli, but not to positive stimuli, is consistent with abnormalities in threat processing associated with PTSS.

A face a mother could love: depression-related maternal neural responses to infant emotion faces

Depressed mothers show negatively biased responses to their infants' emotional bids, perhaps due to faulty processing of infant cues. This study is the first to examine depression-related differences in mothers' neural response to their own infant's emotion faces, considering both effects of perinatal depression history and current depressive symptoms. Primiparous mothers (n = 22), half of whom had a history of major depressive episodes (with one episode occurring during pregnancy and/or postpartum), were exposed to images of their own and unfamiliar infants' joy and distress faces during functional neuroimaging. Group differences (depression vs. no-depression) and continuous effects of current depressive symptoms were tested in relation to neural response to own infant emotion faces. Compared to mothers with no psychiatric diagnoses, those with depression showed blunted responses to their own infant's distress faces in the dorsal anterior cingulate cortex. Mothers with higher levels of current symptomatology showed reduced responses to their own infant's joy faces in the orbitofrontal cortex and insula. Current symptomatology also predicted lower responses to own infant joy-distress in left-sided prefrontal and insula/striatal regions. These deficits in self-regulatory and motivational response circuits may help explain parenting difficulties in depressed mothers.

The Role of Genetic Sex in Affect Regulation and Expression of GABA-Related Genes Across Species

Although circulating hormones and inhibitory gamma-aminobutyric acid (GABA)-related factors are known to affect mood, considerable knowledge gaps persist for biological mechanisms underlying the female bias in mood disorders. Here, we combine human and mouse studies to investigate sexual dimorphism in the GABA system in the context of major depressive disorder (MDD) and then use a genetic model to dissect the role of sex-related factors in GABA-related gene expression and anxiety-/depressive-like behaviors in mice. First, using meta-analysis of gene array data in human postmortem brain (N = 51 MDD subjects, 50 controls), we show that the previously reported down-regulation in MDD of somatostatin (SST), a marker of a GABA neuron subtype, is significantly greater in women with MDD. Second, using gene co-expression network analysis in control human subjects (N = 214; two frontal cortex regions) and expression quantitative trait loci mapping (N = 170 subjects), we show that expression of SST and the GABA-synthesizing enzymes glutamate decarboxylase 67 (GAD67) and GAD65 are tightly co-regulated and influenced by X-chromosome genetic polymorphisms. Third, using a rodent genetic model [Four Core Genotypes (FCG) mice], in which genetic and gonadal sex are artificially dissociated (N ≥ 12/group), we show that genetic sex (i.e., X/Y-chromosome) influences both gene expression (lower Sst, Gad67, Gad65 in XY mice) and anxiety-like behaviors (higher in XY mice). This suggests that in an intact male animal, the observed behavior represents the outcomes of male genetic sex increasing and male-like testosterone decreasing anxiety-like behaviors. Gonadal sex was the only factor influencing depressive-like behavior (gonadal males < gonadal females). Collectively, these combined human and mouse studies provide mechanistic insight into sexual dimorphism in mood disorders, and specifically demonstrate an unexpected role of male-like factors (XY genetic sex) on GABA-related genes and anxiety-like behaviors.

Individual differences in amygdala-medial prefrontal anatomy link negative affect, impaired social functioning, and polygenic depression risk

Individual differences in affective and social processes may arise from variability in amygdala-medial prefrontal (mPFC) circuitry and related genetic heterogeneity. To explore this possibility in humans, we examined the structural correlates of trait negative affect in a sample of 1050 healthy young adults with no history of psychiatric illness. Analyses revealed that heightened negative affect was associated with increased amygdala volume and reduced thickness in a left mPFC region encompassing the subgenual and rostral anterior cingulate cortex. The most extreme individuals displayed an inverse correlation between amygdala volume and mPFC thickness, suggesting that imbalance between these structures is linked to negative affect in the general population. Subgroups of participants were further evaluated on social (n = 206) and emotional (n = 533) functions. Individuals with decreased mPFC thickness exhibited the poorest social cognition and were least able to correctly identify facial emotion. Given prior links between disrupted amygdala-mPFC circuitry and the presence of major depressive disorder (MDD), we explored whether the individual differences in anatomy observed here in healthy young adults were associated with polygenic risk for MDD (n = 438) using risk scores derived from a large genome-wide association analysis (n = 18,759). Analyses revealed associations between increasing polygenic burden for MDD and reduced cortical thickness in the left mPFC. These collective findings suggest that, within the healthy population, there is significant variability in amygdala-mPFC circuitry that is associated with poor functioning across affective and social domains. Individual differences in this circuitry may arise, in part, from common genetic variability that contributes to risk for MDD.

Neural mechanisms of subclinical depressive symptoms in women: a pilot functional brain imaging study

BACKGROUND

Studies of individuals who do not meet criteria for major depressive disorder (MDD) but with subclinical levels of depressive symptoms may aid in the identification of neurofunctional abnormalities that possibly precede and predict the development of MDD. The purpose of this study was to evaluate relations between subclinical levels of depressive symptoms and neural activation patterns during tasks previously shown to differentiate individuals with and without MDD.

METHODS

Functional magnetic resonance imaging (fMRI) was used to assess neural activations during active emotion regulation, a resting state scan, and reward processing. Participants were twelve females with a range of depressive symptoms who did not meet criteria for MDD.

RESULTS

Increased depressive symptom severity predicted (1) decreased left midfrontal gyrus activation during reappraisal of sad stimuli; (2) increased right midfrontal gyrus activation during distraction from sad stimuli; (3) increased functional connectivity between a precuneus seed region and left orbitofrontal cortex during a resting state scan; and (4) increased paracingulate activation during non-win outcomes during a reward-processing task.

CONCLUSIONS

These pilot data shed light on relations between subclinical levels of depressive symptoms in the absence of a formal MDD diagnosis and neural activation patterns. Future studies will be needed to test the utility of these activation patterns for predicting MDD onset in at-risk samples.

Impaired prefrontal-amygdala effective connectivity is responsible for the dysfunction of emotion process in major depressive disorder: a dynamic causal modeling study on MEG

Depression is proved to be associated with the dysfunction of prefrontal-limbic neural circuit, especially during emotion processing procedure. Related explorations have been undertaken from the aspects of abnormal activation and functional connectivity. However, the mechanism of the dysfunction of coordinated interactions remains unknown and is still a matter of debate. The present study gave direct evidence of this issue from the aspect of effective connectivity via dynamic causal modeling (DCM). 20 major depressive disorder (MDD) patients and 20 healthy controls were recruited to attend facial emotional stimulus during MEG recording. Bayesian model selection (BMS) was applied to choose the best model. Results under the optimal model showed that top-down endogenous effective connectivity from the dorsolateral prefrontal cortex (DLPFC) to the amygdala was greatly impaired in patients relative to health controls; while bottom-up endogenous effective connectivity from the amygdala to the anterior cingulate cortex (ACC) as well as modulatory effective connectivity from ACC to DLPFC was significantly increased. We inferred the incapable DLPFC failed to exert influence on amygdala, and finally lead to enhanced amygdala-ACC and ACC-DLPFC bottom-up effects. Such impaired prefrontal-amygdala connectivity was supposed to be responsible for the dysfunction in MDD when dealing with emotional stimuli.