Abnormal prefrontal activity subserving attentional control of emotion in remitted depressed patients during a working memory task with emotional distracters

Transdiagnostic neural markers of emotion-cognition interaction in psychotic disorders

Deficits in working memory (WM) and emotion processing are prominent impairments in psychotic disorders, and have been linked to reduced quality of life and real-world functioning. Translation of knowledge regarding the neural circuitry implementing these deficits into improved diagnosis and targeted treatments has been slow, possibly because of categorical definitions of disorders. Using the dimensional Research Domain Criteria (RDoC) framework, we investigated the clinical and practical utility of transdiagnostic behavioral and neural measures of emotion-related WM disruption across psychotic disorders. Behavioral and functional MRI data were recorded while 53 participants with psychotic disorders and 29 participants with no history of psychosis performed a modified n-back task with fear and neutral distractors. Hierarchical regression analyses showed that psychotic symptoms entered after diagnosis accounted for unique variance in fear versus neutral accuracy and activation in the ventrolateral, dorsolateral, and dorsomedial prefrontal cortex, but diagnostic group entered after psychotic symptoms did not. These results remained even after controlling for negative symptoms, disorganized symptoms, and dysphoria. Finally, worse accuracy and greater prefrontal activity were associated with poorer social functioning and unemployment across diagnostic groups. Present results support the transdiagnostic nature of behavioral and neuroimaging measures of emotion-related WM disruption as they relate to psychotic symptoms, irrespective of diagnosis. They also provide support for the practical utility of these markers in explaining real-world functioning. Overall, these results elucidate key aspects of the RDoC construct of WM maintenance by clarifying its transdiagnostic importance and clinical utility in psychotic disorders. (PsycINFO Database Record

Functional reorganisation in chronic pain and neural correlates of pain sensitisation: A coordinate based meta-analysis of 266 cutaneous pain fMRI studies

Maladaptive mechanisms of pain processing in chronic pain conditions (CP) are poorly understood. We used coordinate based meta-analysis of 266 fMRI pain studies to study functional brain reorganisation in CP and experimental models of hyperalgesia. The pattern of nociceptive brain activation was similar in CP, hyperalgesia and normalgesia in controls. However, elevated likelihood of activation was detected in the left putamen, left frontal gyrus and right insula in CP comparing stimuli of the most painful vs. other site. Meta-analysis of contrast maps showed no difference between CP, controls, mood conditions. In contrast, experimental hyperalgesia induced stronger activation in the bilateral insula, left cingulate and right frontal gyrus. Activation likelihood maps support a shared neural pain signature of cutaneous nociception in CP and controls. We also present a double dissociation between neural correlates of transient and persistent pain sensitisation with general increased activation intensity but unchanged pattern in experimental hyperalgesia and, by contrast, focally increased activation likelihood, but unchanged intensity, in CP when stimulated at the most painful body part.

Cognitive Deficits as a Mediator of Poor Occupational Function in Remitted Major Depressive Disorder Patients

Cognitive deficits in major depressive disorder (MDD) patients have been described in numerous studies. However, few reports have aimed to describe cognitive deficits in the remitted state of MDD and the mediational effect of cognitive deficits on occupational outcome. The aim of the current review is to synthesize the literature on the mediating and moderating effects of specific domains of cognition on occupational impairment among people with remitted MDD. In addition, predictors of cognitive deficits found to be vocationally important will be examined. Upon examination of the extant literature, attention, executive function and verbal memory are areas of consistent impairment in remitted MDD patients. Cognitive domains shown to have considerable impact on vocational functioning include deficits in memory, attention, learning and executive function. Factors that adversely affect cognitive function related to occupational accommodation include higher age, late age at onset, residual depressive symptoms, history of melancholic/psychotic depression, and physical/psychiatric comorbidity, whereas higher levels of education showed a protective effect against cognitive deficit. Cognitive deficits are a principal mediator of occupational impairment in remitted MDD patients. Therapeutic interventions specifically targeting cognitive deficits in MDD are needed, even in the remitted state, to improve functional recovery, especially in patients who have a higher risk of cognitive deficit.

Experimental Medicine in Psychiatry New Approaches in Schizophrenia, Depression and Cognition

The use of experimental medicine studies to bridge the gap between Phase 1 and 2 drug trials and so to enhance translation of basic neuroscience studies using experimental animals to the clinic is proposed. Illustrative examples are provided for affective disorders and schizophrenia in relation also to cognitive dysfunction.

A functional MRI study of altered spontaneous brain activity pattern in patients with congenital comitant strabismus using amplitude of low-frequency fluctuation

OBJECTIVE

The aim of this study was to use amplitude of low-frequency fluctuation (ALFF) to investigate local features of spontaneous brain activity in patients with congenital comitant strabismus and clarify their relationship with emotional and psychosocial problems.

METHODS

A total of 20 patients with congenital comitant strabismus (ten males and ten females), and 20 healthy controls (ten males and ten females) closely matched in age, sex, and education underwent resting-state functional magnetic resonance imaging scans. The ALFF method was used to assess local features of spontaneous brain activity. Congenital comitant strabismus patients were distinguished from healthy controls by receiver operating characteristic curve. Correlation analysis was performed to explore the relationships between the observed mean ALFF signal values of the different areas and the Chinese version of the Hospital Anxiety and Depression Scale.

RESULTS

Compared with healthy controls, patients with congenital comitant strabismus had significantly lower ALFF in the bilateral medialfrontal gyrus and higher values in the bilateral cerebellum posterior lobe and left angular gyrus. In the congenital comitant strabismus group, the Hospital Anxiety and Depression Scale-depression score showed a negative correlation with the ALFF signal values of the bilateral medial frontal gyrus (r=-0.550, P=0.012) and a negative correlation was noted between the mean ALFF signal values of the left angular gyrus and strabismus duration (r=-0.515, P=0.020).

CONCLUSION

Congenital comitant strabismus mainly involves dysfunction in the bilateral medial frontal gyrus, bilateral cerebellum posterior lobe, and left angular gyrus, which may reflect the underlying pathologic mechanism of congenital strabismus.

Amygdala and dorsomedial hyperactivity to emotional faces in youth with remitted Major Depression

We present neuroimaging markers of the remitted state of major depressive disorder (rMDD) during facial emotion perception in 84 individuals during fMRI. Participants comprised 47 individuals (aged 18-23) diagnosed with rMDD and 37 healthy controls (HCs). Participants classified emotional faces or animals (control condition) in the Facial Emotion Perception Test (FEPT) during fMRI. Behavioural performance on the FEPT did not differ significantly between groups. During fMRI, both groups demonstrated significant blood oxygen level-dependent (BOLD) activity in bilateral inferior frontal gyri for the faces minus animals (F-A) contrast. The rMDD group additionally showed BOLD activity during F-A in numerous regions, including the bilateral paracingulate gyri, middle temporal gyri and right amygdala. The rMDD group exhibited significantly greater activity than the HC group in regions including the bilateral middle temporal gyri and left superior frontal gyrus. Although the rMDD group did not manifest the behavioural performance deficits on facial emotion recognition tasks that have been observed in actively depressed individuals, the rMDD group nevertheless showed increased BOLD activity compared with never-depressed controls during F-A in multiple posterior brain regions, suggesting that persistent effects of illness or possible trait vulnerabilities may distinguish individuals with rMDD from never-depressed controls.

Neural reward processing in individuals remitted from major depression

BACKGROUND

Dysfunctional behavioural and neural processing of reward has been found in currently depressed individuals. However, little is known about altered reward processing in remitted depressed individuals.

METHOD

A total of 23 medication-free individuals with remitted major depressive disorder (rMDD) and 23 matched healthy controls (HCs) performed a reward task during functional magnetic resonance imaging. We also investigated reward dependence, novelty seeking and harm avoidance using the Tridimensional Personality Questionnaire and their association with neural responses of reward processing.

RESULTS

Compared to HCs, individuals with rMDD exhibited enhanced responses to reward-predicting cues in the hippocampus, amygdala and superior frontal gyrus. When reward was delivered, rMDD subjects did not significantly differ from HCs. In both groups neural activity during reward anticipation was negatively correlated with harm avoidance.

CONCLUSIONS

Our results show that rMDD is characterized by hyperactivation in fronto-limbic regions during reward anticipation. Alterations in neural activation during reward processing might reflect an increased effort in remitted depressed individuals to allocate neural activity for executive and evaluative processes during anticipatory reward processing.

Emotion regulation deficits in euthymic bipolar I versus bipolar II disorder: a functional and diffusion-tensor imaging study

OBJECTIVES

Emotion regulation deficits are a core feature of bipolar disorder. However, their potential neurobiological underpinnings and existence beyond bipolar I disorder remain unexplored. Our main goal was to investigate whether both individuals with bipolar I and bipolar II disorder show deficits in emotion regulation during an attention control task, and to explore the neurophysiological underpinnings of this potential deficit.

METHODS

Twenty healthy controls, 16 euthymic participants with bipolar I disorder, and 19 euthymic participants with bipolar II disorder completed psychometric and clinical assessments, a neuroimaging emotion regulation paradigm, and an anatomical diffusion-weighted scan. Groups were matched for age, gender, and verbal IQ.

RESULTS

During the presence of emotional distracters, subjects with bipolar I disorder showed slowed reaction times to targets, and increased blood oxygenation level-dependent (BOLD) responses in the amygdala, accumbens, and dorsolateral prefrontal cortex, but not increased inverse functional connectivity between these prefrontal and subcortical areas, and altered white matter microstructure organization in the right uncinate fasciculus. Subjects with bipolar II disorder showed no altered reaction times, increased BOLD responses in the same brain areas, increased inverse functional connectivity between the prefrontal cortex and amygdala, and no abnormalities in white matter organization.

CONCLUSIONS

Participants with bipolar I disorder showed abnormalities in functional and anatomical connectivity between prefrontal cortices and subcortical structures in emotion regulation circuitry. However, these deficits did not extend to subjects with bipolar II disorder, suggesting fundamental differences in the pathophysiology of bipolar disorder subtypes.

Phosphodiesterase-4D Knock-down in the Prefrontal Cortex Alleviates Chronic Unpredictable Stress-Induced Depressive-Like Behaviors and Memory Deficits in Mice

Phosphodiesterase 4 (PDE4) has four isoforms (PDE4A-D) with at least 25 splice variants. PDE4 subtype nonselective inhibitors produce potent antidepressant-like and cognition-enhancing effects via increased intracellular cyclic AMP (cAMP) signaling in the brain. Our previous data have demonstrated that long-form PDE4Ds appear to be involved in these pharmacological properties of PDE4 inhibitors in the normal animals. However, it is not clear whether long-form PDE4Ds are critical for the behaviors and related cellular signaling/neuronal plasticity/neuroendocrine alterations in the depressed animals. In the present study, animals exposed to the chronic unpredictable stress (CUS), a rodent model of depression, exhibited elevated corticosterone, depressive-like behavior, memory deficits, accompanied with decreased cAMP-PKA-CREB and cAMP-ERK1/2-CREB signaling and neuroplasticity. These alterations induced by CUS were reversed by RNA interference (RNAi)-mediated prefrontal cortex long-form PDE4Ds (especially PDE4D4 and PDE4D5) knock-down, similar to the effects of the PDE4 subtype nonselective inhibitor rolipram. Furthermore, these effects of RNAi were not enhanced by rolipram. These data indicate a predominant role of long-form PDE4Ds in the pharmacotherapies of PDE4 inhibitors for depression and concomitant memory deficits. Long-form PDE4Ds, especially PDE4D4 and PDE4D5, appear to be the promising targets for the development of antidepressants with high therapeutic indices.

Reduced default mode network suppression during a working memory task in remitted major depression

Insufficient default mode network (DMN) suppression was linked to increased rumination in symptomatic Major Depressive Disorder (MDD). Since rumination is known to predict relapse and a more severe course of MDD, we hypothesized that similar DMN alterations might also exist during full remission of MDD (rMDD), a condition known to be associated with increased relapse rates specifically in patients with adolescent onset. Within a cross-sectional functional magnetic resonance imaging study activation and functional connectivity (FC) were investigated in 120 adults comprising 78 drug-free rMDD patients with adolescent- (n = 42) and adult-onset (n = 36) as well as 42 healthy controls (HC), while performing the n-back task. Compared to HC, rMDD patients showed diminished DMN deactivation with strongest differences in the anterior-medial prefrontal cortex (amPFC), which was further linked to increased rumination response style. On a brain systems level, rMDD patients showed an increased FC between the amPFC and the dorsolateral prefrontal cortex, which constitutes a key region of the antagonistic working-memory network. Both whole-brain analyses revealed significant differences between adolescent-onset rMDD patients and HC, while adult-onset rMDD patients showed no significant effects. Results of this study demonstrate that reduced DMN suppression exists even after full recovery of depressive symptoms, which appears to be specifically pronounced in adolescent-onset MDD patients. Our results encourage the investigation of DMN suppression as a putative predictor of relapse in clinical trials, which might eventually lead to important implications for antidepressant maintenance treatment.

The influence of levetiracetam in cognitive performance in healthy individuals: neuropsychological, behavioral and electrophysiological approach

OBJECTIVE

The present study sought to analyze the influence of Levetiracetam (LEV) in cognitive performance by identifying the changes produced by LEV in reaction time, in neuropsychological assessment of attention and memory and in absolute theta power in frontal activity.

METHODS

Twelve healthy subjects (5 men and 7 women; mean age, 30.08 years, standard deviation, 4.71) were recruited for this study. The neuropsychological tests: Trail Making Test (A and B), Digit Span (direct and indirect numerical orders/working memory); Stroop test (inhibitory control of attention); Tower of London (planning and decision-making) and a quantitative electroencephalography were applied in 2 different days after and before the participants ingested the capsule of placebo or 500 mg LEV.

RESULTS

A two-way-ANOVA was implemented to observe the interaction between conditions (placebo or LEV 500 mg) and moments (pre- and post-ingestion of LEV or placebo). The data were analyzed by the SPSS statistical package (p<0.05). For the neuropsychological parameter, the Trail Making Test (A) was the only test that showed significant difference for condition in the task execution time (p=0.026). Regarding the reaction time in the behavioral parameter, an interaction between both factors (p=0.034) was identified through a two-way-ANOVA (condition versus moment). Electrophysiological measures showed a significant interaction for electrodes: F7, F3, and FZ.

CONCLUSIONS

The findings showed that LEV promotes an important cognitive enhancement in the executive functions.

Functional neuroimaging correlates of autobiographical memory deficits in subjects at risk for depression

Overgeneral autobiographical memory (AM) manifests in individuals with major depressive disorder (MDD) tested during depressed (dMDD) or remitted phases (rMDD), and healthy individuals at high-risk (HR) for developing MDD. The current study aimed to elucidate differences in hemodynamic correlates of AM recall between rMDDs, HRs, and controls (HCs) to identify neural changes following previous depressive episodes without the confound of current depressed mood. HCs, HRs, and unmedicated rMDDs (n = 20/group) underwent fMRI while recalling AMs in response to emotionally valenced cue words. HRs and rMDDs recalled fewer specific and more categorical AMs relative to HCs. During specific AM recall, HRs had increased activity relative to rMDDs and HCs in left ventrolateral prefrontal cortex (VLPFC) and lateral orbitofrontal cortex. During positive specific AM recall, HRs and HCs had increased activity relative to rMDDs in bilateral dorsomedial prefrontal cortex (DMPFC) and left precuneus. During negative specific AM recall HRs and HCs had increased activity in left VLPFC and right DMPFC, while rMDDs had increased activity relative to HRs and HCs in right DLPFC and precuneus. Differential recruitment of medial prefrontal regions implicated in emotional control suggests experiencing a depressive episode may consequently reduce one’s ability to regulate emotional responses during AM recall.

Dysfunction of emotional brain systems in individuals at high risk of mood disorder with depression and predictive features prior to illness

BACKGROUND

Abnormalities of emotion-related brain circuitry, including cortico-thalamic-limbic regions underpin core symptoms of bipolar disorder (BD) and major depressive disorder (MDD). It is unclear whether these abnormalities relate to symptoms of the disorder, are present in unaffected relatives, or whether they can predict future illness.

METHOD

The Bipolar Family Study (BFS) is a prospective longitudinal study that has examined individuals at familial risk of mood disorder and healthy controls on three occasions, 2 years apart. The current study concerns imaging data from the second assessment; 51 controls and 81 high-risk (HR) individuals performing an emotional memory task. The latter group was divided into 61 HR individuals who were well, and 20 who met diagnostic criteria for MDD. At the time of the third assessment a further 11 HR individuals (from the Well group) had developed MDD. The current analyses focused on (i) differences between groups based on diagnostic status at the time of the scan, and (ii) predictors of future illness, comparing the 11 HR individuals who became unwell after the second scanning assessment to those who remained well.

RESULTS

All groups demonstrated typical emotional modulation of memory and associated brain activations. For analysis (i) the HR MDD group demonstrated increased thalamic activation v. HR Well. (ii) HR Well individuals who subsequently became ill showed increased activation of thalamus, insula and anterior cingulate compared to those who remained well.

CONCLUSIONS

These findings suggest evidence for specific changes related to the presence of illness and evidence that changes in brain function in cortico-thalamic-limbic regions precede clinical illness.

A two-factor model of relapse/recurrence vulnerability in unipolar depression

The substantial health burden associated with major depressive disorder (MDD) is a product of both its high prevalence and the significant risk of relapse, recurrence, and chronicity. Establishing recurrence vulnerability factors (VFs) could improve the long-term management of MDD by identifying the need for further intervention in seemingly recovered patients. We present a model of sensitization in depression vulnerability, with an emphasis on the integration of behavioral and neural systems accounts. Evidence suggests that VFs fall into 2 categories: dysphoric attention and dysphoric elaboration. Dysphoric attention is driven by fixation on negative life events, and is characterized behaviorally by reduced executive control, and neurally by elevated activity in the brain's salience network. Dysphoric elaboration is driven by rumination that promotes overgeneral self- and contextual appraisals, and is characterized behaviorally by dysfunctional attitudes, and neurally by elevated connectivity within normally distinct prefrontal brain networks. Although few prospective VF studies exist from which to catalogue a definitive neurobehavioral account, extant data support the value of the proposed 2-factor model. Measuring the continued presence of these 2 VFs during recovery may more accurately identify remitted patients who would benefit from targeted prophylactic intervention.

Neural correlates during working memory processing in major depressive disorder

BACKGROUND

Functional magnetic resonance imaging (fMRI) studies in major depressive disorder (MDD) have revealed cortical-limbic-subcortical dysfunctions during working memory (WM) processing, but the results are inconsistent and it is unclear to what extent these findings are influenced by demographic, clinical characteristics and task performance of patients. The present study conducted a quantitative coordinate-based meta-analysis of fMRI data to investigate the hypothesized dysfunction in the neural correlates during WM processing in MDD.

METHODS

A systematic research was conducted for fMRI studies during WM processing comparing MDD patients with healthy controls (HC). Meta-analysis was performed using effect size signed differential mapping (ES-SDM). Meta-regression analyses with age, sex and medication as factors were performed in MDD group.

RESULTS

Functional MRI data of 160 MDD patients and 203 HC from 13 WM experiments across 11 studies were included in this meta-analysis. In the pooled meta-analysis of all included studies, significant increased activation during WM in the left lateral prefrontal cortex, left precentral gyrus, left insula, right superior temporal and right supramarginal areas, and significant decreased activity in the right precentral gyrus, right precuneus and right insula were observed in MDD compared with controls. In the subgroup analysis of the studies with matched task performance, MDD subgroup showed hyperactivation only in the left prefrontal cortex and hypoactivation in the regions similar to the pooled analysis. The meta-regression with age, sex and medication showed no significance in MDD group.

CONCLUSIONS

Regardless of differences in task performance between groups, patients with MDD showed consistent functional abnormalities in the cortical-limbic-subcortical circuitry during WM processing. Distinct patterns of neural engagement may reflect compensatory neural strategies to potential dysfunction in MDD.

The neuroscience of depression: implications for assessment and intervention

Major Depressive Disorder (MDD) is among the most prevalent of all psychiatric disorders and is the single most burdensome disease worldwide. In attempting to understand the profound deficits that characterize MDD across multiple domains of functioning, researchers have identified aberrations in brain structure and function in individuals diagnosed with this disorder. In this review we synthesize recent data from human neuroimaging studies in presenting an integrated neural network framework for understanding the impairments experienced by individuals with MDD. We discuss the implications of these findings for assessment of and intervention for MDD. We conclude by offering directions for future research that we believe will advance our understanding of neural factors that contribute to the etiology and course of depression, and to recovery from this debilitating disorder.

Alterations in amplitude of low frequency fluctuation in treatment-naïve major depressive disorder measured with resting-state fMRI

There are limited resting-state functional magnetic resonance imaging (fMRI) studies in major depressive disorder (MDD). Of these studies, functional connectivity analyses are mostly used. However, a new method based on the magnitude of low frequency fluctuation (LFF) during resting-state fMRI may provide important insight into MDD. In this study, we examined the amplitude of LFF (ALFF) within the whole brain during resting-state fMRI in 30 treatment-naïve MDD subjects and 30 healthy control (HC) subjects. When compared with HC, MDD subjects showed increased ALFF in the frontal cortex (including the bilateral ventral/dorsal anterior cingulate cortex, orbitofrontal cortex, premotor cortex, ventral prefrontal cortex, left dorsal lateral frontal cortex, left superior frontal cortex), basal ganglia (including the right putamen and left caudate nucleus), left insular cortex, right anterior entorhinal cortex and left inferior parietal cortex, together with decreased ALFF in the bilateral occipital cortex, cerebellum hemisphere, and right superior temporal cortex. These findings may relate to characteristics of MDD, such as excessive self-referential processing and deficits in cognitive control of emotional processing, which may contribute to the persistent and recurrent nature of the disorder.

Neuropsychological care and rehabilitation of cancer patients with chemobrain: strategies for evaluation and intervention development

Malignant tumors and their various treatments such as chemotherapy, radiotherapy and hormonal therapy can deleteriously affect a large number of cancer patients and survivors on multiple dimensions of psychosocial and neurocognitive functioning. Oncology researchers and clinicians are increasingly cognizant of the negative effects of cancer and its treatments on the brain and its mental processes and cognitive outcomes. Nevertheless, effective interventions to treat cancer and treatment-related neurocognitive dysfunction (CRND), also known as chemobrain, are still lacking. The paucity of data on effective treatments for CRND is due, at least partly, to difficulties understanding its etiology, and a lack of reliable methods for assessing its presence and severity. This paper provides an overview of the incidence, etiology, and magnitude of CRND, and discusses the plausible contributions of psychological, motor function, and linguistic and behavioral complications to CRND. Strategies for reliable neuropsychological screening and assessment, and development and testing of effective ways to mitigate CRND are also discussed.

Neutral face distractors differentiate performance between depressed and healthy adolescents during an emotional working memory task

The aim of the present study is to examine the effect of neutral and emotional facial expressions on voluntary attentional control using a working memory (WM) task in adolescents with major depressive disorder (MDD). We administered the Emotional Face n-back (EFNBACK) task, a visual WM task with neutral, happy and angry faces as distractors to 22 adolescents with MDD (mean age 15.7 years) and 21 healthy controls (HC) (mean age 14.7 years). There was a significant group by distractor type interaction (p = 0.045) for mean percent accuracy rates. Group comparisons showed that MDD youth were less accurate on neutral trials than HC (p = 0.027). The two groups did not differ on angry, happy and blank trials (p > 0.05). Reaction time did not differ across groups. In addition, when comparing the differences between accuracies on neutral trials and each of the happy and angry trials, respectively [(HAP-NEUT) and (ANG-NEUT)], there was a group effect on (HAP-NEUT) where the difference was larger in MDD than HC (p = 0.009) but not on ANG-NEUT (p > 0.05). Findings were independent of memory load. Findings indicate that attentional control to neutral faces is impaired and negatively affected performance on a WM task in adolescents with MDD. Such an impact of neutral faces on attentional control in MDD may be at the core of the social-cognitive impairment observed in this population.

Frontoparietal function in young people with dysthymic disorder (DSM-5: Persistent depressive disorder) during spatial working memory

BACKGROUND

Dysthymic disorder (DD) is a depressive disorder characterised by persistent low and/or irritable mood and has been identified as a major risk factor for developing major depressive disorder (MDD). MDD and DD have been associated with executive function difficulties of working memory and attention. Little is known about how executive function networks in the brain are affected in children and adolescents with MDD and even less in DD. This study used fMRI and two spatial working memory paradigms to investigate associated brain function in young people with DD and an age-, gender- and IQ- matched typically developing group.

METHODS

Nineteen male patients with DD (mean age 11.2±1.5 years) diagnosed according to DSM-IV criteria and 16 typically developing boys (mean age 10.5±1.1 years) performed a mental rotation and a delay-match to sample (DMTS) task while undergoing fMRI. All participants were medication-naïve at the time of testing.

RESULTS

Compared to typically developing young people, the DD group showed less activation in left frontal regions including left ventro- and dorsolateral prefrontal cortices (PFC) during mental rotation. Medial frontal regions including dorsomedial PFC, anterior cingulate cortex and frontal pole also showed relatively reduced activation. During the DMTS task patients showed significantly more activation in the right precuneus and posterior cingulate cortex.

LIMITATIONS

This was a cross-sectional study with a small sample limiting the generalizability of the results.

CONCLUSIONS

The results complement previous findings in adults with MDD that have shown differential activation of left PFC regions during working memory tasks. Additionally, altered function of cortical midline structures in young patients with DD was identified. This supports findings in children, adolescents and adults with MDD suggesting that the pathophysiology of depressive disorders extends to DD as a risk factor for MDD and exhibits continuity over the lifespan.

Childhood abuse is related to working memory impairment for positive emotion in female university students

Childhood abuse is an important risk factor for depression, anxiety disorders, and substance use later in life. One possible mechanism underlying this association could be deficits in cognitive processing of emotional information. This study tested the impact of distracting emotional information on working memory performance in 21 young women with a history of sexual and physical abuse during childhood/adolescence (mean age = 20.0), and compared their performance to 17 individuals reporting nonabuse-related childhood stress (mean age = 19.6) and a control group of 17 women without a history of childhood stress (mean age = 20.0). During the most difficult distractor condition, working memory accuracy for positive versus neutral incidental emotional stimuli was reduced in women reporting a history of abuse relative to both control groups (with and without nonabuse-related childhood stress). The current results reveal aberrant responses to positive stimuli and are consistent with the notion of persistent influence of childhood abuse on processes critical for emotional well-being and emotion control.

Frontal-subcortical volumetric deficits in single episode, medication-naïve depressed patients and the effects of 8 weeks fluoxetine treatment: a VBM-DARTEL study

BACKGROUND

Convergent studies suggest that morphological abnormalities of frontal-subcortical circuits which involved with emotional and cognitive processing may contribute to the pathophysiology of major depressive disorder (MDD). Antidepressant treatment which has been reported to reverse the functional abnormalities of frontal-subcortical circuits in MDD may have treating effects to related brain morphological abnormalities. In this study, we used voxel-based morphometry method to investigate whole brain structural abnormalities in single episode, medication-naïve MDD patients. Furthermore, we investigated the effects of an 8 weeks pharmacotherapy with fluoxetine.

METHODS

28 single episode, medication-naïve MDD participants and 28 healthy controls (HC) acquired the baseline high-resolution structural magnetic resonance imaging (sMRI) scan. 24 MDD participants acquired a follow-up sMRI scan after 8 weeks antidepressant treatment. Gray matter volumetric (GMV) difference between groups was examined.

RESULTS

Medication-naïve MDD had significantly decreased GMV in the right dorsolateral prefrontal cortex and left middle frontal gyrus as well as increased GMV in the left thalamus and right insula compared to HC (P<0.05, corrected). Moreover, treated MDD had significantly increased GMV in the left middle frontal gyrus and right orbitofrontal cortex compared to HC (P<0.05, corrected). No difference on GMV was detected between medication-naïve MDD group and treated MDD group.

CONCLUSIONS

This study of single episode, medication-naïve MDD subjects demonstrated structural abnormalities of frontal-subcortical circuitsin the early stage of MDD and the effects of 8 weeks successful antidepressant treatment, suggesting these abnormalities may play an important role in the neuropathophysiology of MDD at its onset.

Enduring influence of early temperament on neural mechanisms mediating attention-emotion conflict in adults

BACKGROUND

Behavioral inhibition, a temperament identified in early childhood, is often associated with dysregulated attention and affective processing, particularly in response to threat. Longitudinal studies find that the manifestation of perturbed attention and affective processing often dissipates with age. Yet, childhood behavioral inhibition continues to predict perturbed brain function into adulthood. This suggests that adults with childhood behavioral inhibition may engage compensatory processes to effectively regulate emotion-related attention. However, it is unknown whether perturbations in brain function reflect compensation for attention bias to emotional stimuli generally, or to threatening contexts more specifically. The present study tests these possibilities.

METHODS

Adults with and without a history of stable childhood behavioral inhibition completed an attention-control task in the context of threatening and nonthreatening stimuli while undergoing functional magnetic resonance imaging. Participants were asked to identify the gender of fearful (threatening) and happy (nonthreatening) faces, while ignoring both the face emotion and overlaid congruent (low attention control, LAC) or incongruent (high attention control, HAC) gender words.

RESULTS

When fearful faces were present, adults with stable childhood behavioral inhibition exhibited more activity in striatum, cingulate, and dorsolateral prefrontal cortex for HAC trials compared with LAC trials, relative to those without behavioral inhibition. When happy faces were present, the opposite activation pattern emerged. No group differences in behavior were observed.

CONCLUSIONS

Among adults, stable childhood behavioral inhibition predicts neural, but not behavioral, responding when attention control is engaged in discrete emotional contexts. This suggests a mechanism by which adults may compensate for the behavioral manifestation of threat-based attention biases.

Remitted major depression is characterized by reduced prefrontal cortex reactivity to reward loss

BACKGROUND

Major depression (MDD) is characterized by anhedonia. Although a growing body of literature has linked anhedonia in MDD to reduced frontostriatal activity during reward gains, relatively few studies have examined neural responsivity to loss, and no studies to date have examined neural responses to loss in euthymic individuals with a history of MDD.

METHODS

An fMRI monetary incentive delay task was administered to 19 participants with remitted MDD (rMDD) and 19 never depressed controls. Analyses examined group activation differences in brain reward circuitry during monetary loss anticipation and outcomes. Secondary analyses examined the association between self-reported rumination and brain activation in the rMDD group.

RESULTS

Compared to controls, the rMDD group showed less superior frontal gyrus activation during loss anticipation and less inferior and superior frontal gyri activation during loss outcomes (cluster corrected p's<.05). Ruminative Responses Scale scores were negatively correlated with superior frontal gyrus activation (r=-.68, p=.001) during loss outcomes in the rMDD group.

LIMITATIONS

Replication with a larger sample is needed.

CONCLUSIONS

Euthymic individuals with a history of MDD showed prefrontal cortex hypoactivation during loss anticipation and outcomes, and the degree of superior frontal gyrus hypoactivation was associated with rumination. Abnormal prefrontal cortex responses to loss may reflect a trait-like vulnerability to MDD, although future research is needed to evaluate the utility of this functional neural endophenotype as a prospective risk marker.

Neural mechanisms of cognitive reappraisal in remitted major depressive disorder

BACKGROUND

Down-regulation of negative emotions by cognitive strategies relies on prefrontal cortical modulation of limbic brain regions, and impaired frontolimbic functioning during cognitive reappraisal has been observed in affective disorders. However, no study to date has examined cognitive reappraisal in unmedicated euthymic individuals with a history of major depressive disorder relative to symptom-matched controls. Given that a history of depression is a critical risk factor for future depressive episodes, investigating the neural mechanisms of emotion regulation in remitted major depressive disorder (rMDD) may yield novel insights into depression risk.

METHOD

We assessed 37 individuals (18 rMDD, 19 controls) with functional magnetic resonance imaging (fMRI) during a task requiring cognitive reappraisal of sad images.

RESULTS

Both groups demonstrated decreased self-reported negative affect after cognitive reappraisal and no group differences in the effects of cognitive reappraisal on mood were evident. Functional MRI results indicated greater paracingulate gyrus (rostral anterior cingulate cortex, Brodmann area 32) activation and decreased right midfrontal gyrus (Brodmann area 6) activation during the reappraisal of sad images.

LIMITATIONS

Trial-by-trial ratings of pre-regulation affect were not collected, limiting the interpretation of post-regulation negative affect scores.

CONCLUSIONS

Results suggest that activation of rostral anterior cingulate cortex, a region linked to the prediction of antidepressant treatment response, and of the right midfrontal gyrus, a region involved in cognitive control in the context of cognitive reappraisal, may represent endophenotypic markers of future depression risk. Future prospective studies will be needed to validate the predictive utility of these neural markers.

HPA-axis hormone modulation of stress response circuitry activity in women with remitted major depression

Decades of clinical and basic research indicate significant links between altered hypothalamic-pituitary-adrenal (HPA)-axis hormone dynamics and major depressive disorder (MDD). Recent neuroimaging studies of MDD highlight abnormalities in stress response circuitry regions which play a role in the regulation of the HPA-axes. However, there is a dearth of research examining these systems in parallel, especially as related to potential trait characteristics. The current study addresses this gap by investigating neural responses to a mild visual stress challenge with real-time assessment of adrenal hormones in women with MDD in remission and controls. Fifteen women with recurrent MDD in remission (rMDD) and 15 healthy control women were scanned on a 3T Siemens MR scanner while viewing neutral and negative (stress-evoking) stimuli. Blood samples were obtained before, during, and after scanning for the measurement of HPA-axis hormone levels. Compared to controls, rMDD women demonstrated higher anxiety ratings, increased cortisol levels, and hyperactivation in the amygdala and hippocampus, p<0.05, family-wise error (FWE)-corrected in response to the stress challenge. Among rMDD women, amygdala activation was negatively related to cortisol changes and positively associated with the duration of remission. Findings presented here provide evidence for differential effects of altered HPA-axis hormone dynamics on hyperactivity in stress response circuitry regions elicited by a well-validated stress paradigm in women with recurrent MDD in remission.

RNA interference-mediated phosphodiesterase 4D splice variants knock-down in the prefrontal cortex produces antidepressant-like and cognition-enhancing effects

BACKGROUND AND PURPOSE

Phosphodiesterase 4 (PDE4) inhibitors produce potent antidepressant-like and cognition-enhancing effects. However, their clinical utility is limited by the major side effect of emesis, which appears to be PDE4 isoform-specific. Although PDE4D subtype plays the pivotal role in these therapeutic profiles, it is also the primary subtype responsible for emesis. Therefore, the aim of present research was to investigate whether long-form PDE4D variants mediate antidepressant-like and cognition-enhancing effects, but are irrespective with emesis.

EXPERIMENTAL APPROACH

In mice microinfused with lentiviral vectors that contained shRNA-mir hairpin structure targeting long-form PDE4Ds into bilateral prefrontal cortices, the tail-suspension and forced-swim tests were used to measure antidepressant-like effects; novel object recognition and Morris water-maze tasks were used to determine cognition-enhancing effects. The emetic potential was assessed by alpha2 adrenergic receptor-mediated anaesthesia, a surrogate measure of emesis. Intracellular cAMP signalling was analysed by time-resolved FRET immunoassay and Western-blot. Dendritic complexity was assessed by Golgi staining.

KEY RESULTS

Microinfusions of lentiviral PDE4D-shRNA down-regulated PDE4D4 and PDE4D5, and imitated the antidepressant-like and cognition-enhancing effects of the prototypical PDE4 inhibitor rolipram. The behavioural effects were related to dendritic complexity and mediated by the increased cAMP signalling. In addition, these effects were not enhanced in the presence of rolipram. Finally, while rolipram shortened the duration of combined anaesthesia, RNA interference-mediated PDE4D knock-down in the prefrontal cortex did not.

CONCLUSION AND IMPLICATIONS

These data suggest that long-form PDE4Ds, at least PDE4D4 and PDE4D5, may be the promising targets for the development of PDE4 variant-selective inhibitors as the new pharmacotherapies for depressive disorders and neurodegenerative diseases involving memory deficits.

The role of serotonin in cognitive function: evidence from recent studies and implications for understanding depression

BACKGROUND

Symptoms of cognitive impairment such as poor concentration, memory loss and difficulty with decision making are prevalent in patients with depression, but currently are not specific targets for treatment. However, patients can continue to demonstrate cognitive impairments even when apparently clinically recovered. Drugs that potentiate serotonin (5-HT) function, such as selective serotonin reuptake inhibitors (SSRIs), are the mainstay of treatment for depression. Nevertheless, our understanding of the effects of SSRIs and other conventional antidepressant therapy on cognitive function in healthy humans and depressed patients remains limited.

OBJECTIVE

The purpose of this article is to provide a concise overview for clinicians on the impact of pharmacological manipulation of 5-HT on cognitive function in healthy humans with additional reference to animal models where human data are lacking, particularly regarding specific 5-HT receptor subtype modulation.

FINDINGS

The most consistent observation following manipulation of serotonin levels in humans is that low extracellular 5-HT levels are associated with impaired memory consolidation. Preclinical data show that agonism and antagonism at specific 5-HT receptors can exert effects in animal models of cognition.

CONCLUSIONS

Larger, consistently designed studies are needed to understand the roles of 5-HT in cognition in healthy and depressed individuals. Efforts to target specific 5-HT receptors to improve cognitive outcomes are warranted.

Fronto-limbic function in unaffected offspring at familial risk for bipolar disorder during an emotional working memory paradigm

Evidence from neuroimaging studies indicate that individuals with bipolar disorder (BD) exhibit altered functioning of fronto-limbic systems implicated in voluntary emotion regulation. Few studies, however, have examined the extent to which unaffected youth at familial risk for BD exhibit such alterations. Using an fMRI emotional working memory paradigm, we investigated the functioning of fronto-limbic systems in fifteen healthy bipolar offspring (8-17 years old) with at least one parent diagnosed with BD (HBO), and 16 age-matched healthy control (HC) participants. Neural activity and functional connectivity analyses focused on a priori neural regions supporting emotion processing (amygdala and ventral striatum) and voluntary emotion regulation (ventrolateral prefrontal cortex (VLPFC), dorsolateral prefrontal cortex (DLPFC), and anterior cingulate cortex (ACC)). Relative to HC, HBO exhibited greater right VLPFC (BA47) activation in response to positive emotional distracters and reduced VLPFC modulation of the amygdala to both the positive and negative emotional distracters; there were no group differences in connectivity for the neutral distracters. These findings suggest that alterations in the functioning of fronto-limbic systems implicated in voluntary emotion regulation are present in unaffected bipolar offspring. Future longitudinal studies are needed to determine the extent to which such alterations represent neurodevelopmental markers of risk for future onset of BD.

The neural basis of difficulties disengaging from negative irrelevant material in major depression

Recurrent uncontrollable negative thoughts are a hallmark of depressive episodes. Deficits in cognitive control have been proposed to underlie this debilitating aspect of depression. Here, we used functional neuroimaging during an emotional working memory (WM) task to elucidate the neural correlates of these difficulties in cognitive control. In a WM manipulation involving depressed participants, the dorsal anterior cingulate and parietal and bilateral insular cortices were activated significantly more when negative words were removed from WM than when they were maintained in WM; in contrast, nondepressed participants exhibited stronger neural activations in these regions for positive than for negative material. These findings implicate anomalous activation of components of the task-positive network, known to be modulated by cognitive effort, in depression-associated difficulties in expelling negative material from WM. Future studies should examine the association between these aberrations and the maintenance of depressive symptoms.

Cognitive and neural aspects of information processing in major depressive disorder: an integrative perspective

Researchers using experimental paradigms to examine cognitive processes have demonstrated that Major Depressive Disorder (MDD) is associated not with a general deficit in cognitive functioning, but instead with more specific anomalies in the processing of negatively valenced material. Indeed, cognitive theories of depression posit that negative biases in the processing of information play a critical role in influencing the onset, maintenance, and recurrence of depressive episodes. In this paper we review findings from behavioral studies documenting that MDD is associated with specific difficulties in attentional disengagement from negatively valenced material, with tendencies to interpret information in a negative manner, with deficits in cognitive control in the processing of negative material, and with enhanced memory for negative material. To gain a better understanding of the neurobiological basis of these abnormalities, we also examine findings from functional neuroimaging studies of depression and show that dysfunction in neural systems that subserve emotion processing, inhibition, and attention may underlie and contribute to the deficits in cognition that have been documented in depressed individuals. Finally, we briefly review evidence from studies of children who are at high familial risk for depression that indicates that abnormalities in cognition and neural function are observable before the onset of MDD and, consequently, may represent a risk factor for the development of this disorder. By integrating research from cognitive and neural investigations of depression, we can gain a more comprehensive understanding not only of how cognitive and biological factors interact to affect the onset, maintenance, and course of MDD, but also of how such research can aid in the development of targeted strategies for the prevention and treatment of this debilitating disorder.

Reward circuitry dysfunction in psychiatric and neurodevelopmental disorders and genetic syndromes: animal models and clinical findings

This review summarizes evidence of dysregulated reward circuitry function in a range of neurodevelopmental and psychiatric disorders and genetic syndromes. First, the contribution of identifying a core mechanistic process across disparate disorders to disease classification is discussed, followed by a review of the neurobiology of reward circuitry. We next consider preclinical animal models and clinical evidence of reward-pathway dysfunction in a range of disorders, including psychiatric disorders (i.e., substance-use disorders, affective disorders, eating disorders, and obsessive compulsive disorders), neurodevelopmental disorders (i.e., schizophrenia, attention-deficit/hyperactivity disorder, autism spectrum disorders, Tourette's syndrome, conduct disorder/oppositional defiant disorder), and genetic syndromes (i.e., Fragile X syndrome, Prader-Willi syndrome, Williams syndrome, Angelman syndrome, and Rett syndrome). We also provide brief overviews of effective psychopharmacologic agents that have an effect on the dopamine system in these disorders. This review concludes with methodological considerations for future research designed to more clearly probe reward-circuitry dysfunction, with the ultimate goal of improved intervention strategies.

Prefrontal cortical response to emotional faces in individuals with major depressive disorder in remission

Abnormalities in the response of the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) to negative emotional stimuli have been reported in acutely depressed patients. However, there is a paucity of studies conducted in unmedicated individuals with major depressive disorder in remission (rMDD) to assess whether these are trait abnormalities. To address this issue, 19 medication-free rMDD individuals and 20 healthy comparison (HC) participants were scanned using functional magnetic resonance imaging while performing an implicit emotion processing task in which they labeled the gender of faces depicting negative (fearful), positive (happy) and neutral facial expressions. The rMDD and HC groups were compared using a region-of-interest approach for two contrasts: fear vs. neutral and happy vs. neutral. Relative to HC, rMDD showed reduced activation in left OFC and DLPFC to fearful (vs. neutral) faces. Right DLPFC activation to fearful (vs. neutral) faces in the rMDD group showed a significant positive correlation with duration of euthymia. The findings support deficits in left OFC and DLPFC responses to negative emotional stimuli during euthymic periods of MDD, which may reflect trait markers of the illness or a 'scar' due to previous depression. Recovery may also be associated with compensatory increases in right DLPFC functioning.

An fMRI study of attentional control in the context of emotional distracters in euthymic adults with bipolar disorder

Inability to modulate attention away from emotional stimuli may be a key component of dysregulated emotion in bipolar disorder (BD). Previous studies of BD indicate abnormalities in neural circuitry underlying attentional control, yet few studies examined attentional control in the context of emotional distracters. We compared activity and connectivity in neural circuitry supporting attentional control and emotion processing among 22 individuals with BD type 1, currently remitted and euthymic, and 19 healthy controls. Participants performed an emotional n-back paradigm, comprising high and low attentional demand conditions, each with either emotional (happy, fearful), neutral or no face flanker distracters. During the high attentional control demand conditions without emotional distracters, BD individuals showed reduced activity relative to controls in dorsolateral prefrontal cortex, dorsal anterior cingulate cortex (dACC), and inferior parietal cortex. During the high attentional control demand conditions with fearful-face distracters, BD individuals showed greater activity than controls in these regions and amygdala and striatum. Relative to controls, BD individuals also showed abnormal patterns of effective connectivity between dACC and amygdala during high attentional control demand with emotional face distracters. Inter-episode bipolar disorder is characterized by abnormal recruitment of attentional control neural circuitry, especially in the context of emotionally distracting information.

Does emotional memory enhancement assist the memory-impaired?

We review recent work on emotional memory enhancement in older adults and patients with mild cognitive impairment (MCI) or Alzheimer dementia (AD) and evaluate the viability of incorporating emotional components into cognitive rehabilitation for these groups. First, we identify converging evidence regarding the effects of emotional valence on working memory in healthy aging. Second, we introduce work that suggests a more complex role for emotional memory enhancement in aging and identify a model capable of unifying disparate research findings. Third, we survey the neuroimaging literature for evidence of a special role for the amygdala in MCI and early AD in emotional memory enhancement. Finally, we assess the theoretical feasibility of incorporating emotional content into cognitive rehabilitation given all available evidence.

Disordered corticolimbic interactions during affective processing in children and adolescents at risk for schizophrenia revealed by functional magnetic resonance imaging and dynamic causal modeling

CONTEXT

Disordered functional architecture of brain networks may contribute to the well-documented increased risk for psychiatric disorders in offspring of patients with schizophrenia.

OBJECTIVE

To investigate aberrant interactions between regions associated with affective processing in children and adolescent offspring of patients with schizophrenia (HR-SCZ group) and healthy control subjects using dynamic causal modeling of functional magnetic resonance imaging data.

DESIGN

Subjects participated in a continuous affective processing task during which positive, negative, and neutral valenced faces were presented. Interactions between regions in the brain's face- and emotion-processing network were modeled using dynamic causal modeling. Multiple competing models were evaluated by a combinatorial approach and distinguished at the second level using Bayesian model selection before parameter inference.

SETTING

Participants were recruited from the community.

PARTICIPANTS

Twenty-four controls with no family history of psychosis (to the second degree) and 19 children and adolescent offspring of a parent with schizophrenia (age range, 8 to 20 years).

RESULTS

Bayesian model selection revealed a winning model, the architecture of which revealed bidirectional frontolimbic connections that were modulated by valence. Analyses of parameter estimates revealed that HR-SCZ group members were characterized by (1) decreased driving inputs to the visual cortex; (2) decreased intrinsic coupling, most robustly between frontolimbic regions; and (3) increased modulatory inhibition by negative valence of frontolimbic connections (all P < .01, Bonferroni corrected).

CONCLUSIONS

These results are the first demonstration of network analyses techniques for functional magnetic resonance imaging data in children and adolescents at risk for schizophrenia. Dysfunctional interactions within the emotional processing network provide evidence of latent vulnerabilities that may confer risk for disordered adolescent development and eventually the emergence of the manifest disorder.

Recovery from depression

Full recovery from depression, as contrasted with symptom improvement, is a relatively new concept and therapeutic goal. It is an important goal, because the failure to achieve this goal leaves many patients with less productive and fulfilling lives, it leaves some children with lasting deficits, and it deprives families and societies of loved ones’ and employees’ care and investment. As a new therapeutic concept, recovery from depression is not as easy to define as it might seem; many or most patients were not euthymic before an episode of depression or have had some level of depression throughout their lives. There is no measurable definition of euthymia. In addition to definitional difficulties, we need to study and address other barriers to the achievement of recovery from depression. All the barriers to the diagnosis and treatment of depression are barriers against recovery: negative social and professional attitudes, comorbidity, lack of access to demonstrably efficacious professional and social services, and inability to match patients with the antidepressants most likely to help them. Efforts to address many of these knowledge and attitude gaps are already underway. Long-term studies are needed, both observational and experimental. Most published studies encompass only weeks or at best months of follow-up, but recovery must be sustained to be meaningful. As noted previously, there has been little or no attention to the developmental impact of depression. The restoration of premorbid function is not sufficient when depression has hindered a patient’s ability to form satisfying relationships and choose and perform satisfying work. We need to learn how to remediate patients whose history of depression has stifled their talents and aspirations. Studying these issues will not be easy, but millions of individuals with depression, and their physicians, will profit by it; it will be well worth the effort.

Remitted major depression is characterized by reward network hyperactivation during reward anticipation and hypoactivation during reward outcomes

BACKGROUND

Although functional brain imaging has established that individuals with unipolar major depressive disorder (MDD) are characterized by frontostriatal dysfunction during reward processing, no research to date has examined the chronometry of neural responses to rewards in euthymic individuals with a history of MDD.

METHOD

A monetary incentive delay task was used during fMRI scanning to assess neural responses in frontostriatal reward regions during reward anticipation and outcomes in 19 participants with remitted major depressive disorder (rMDD) and in 19 matched control participants.

RESULTS

During the anticipation phase of the task, the rMDD group was characterized by relatively greater activation in bilateral anterior cingulate gyrus, in right midfrontal gyrus, and in the right cerebellum. During the outcome phase of the task, the rMDD group was characterized by relatively decreased activation in bilateral orbital frontal cortex, right frontal pole, left insular cortex, and left thalamus. Exploratory analyses indicated that activation within a right frontal pole cluster that differentiated groups during reward anticipation predicted the number of lifetime depressive episodes within the rMDD group.

LIMITATIONS

Replication with larger samples is needed.

CONCLUSIONS

Results suggest a double dissociation between reward network reactivity and temporal phase of the reward response in rMDD, such that rMDD is generally characterized by reward network hyperactivation during reward anticipation and reward network hypoactivation during reward outcomes. More broadly, these data suggest that aberrant frontostriatal response to rewards may potentially represent a trait marker for MDD, though future research is needed to evaluate the prospective utility of this functional neural endophenotype as a marker of MDD risk.

The adaptive threat bias in anxiety: amygdala-dorsomedial prefrontal cortex coupling and aversive amplification

Functionally, anxiety serves to increase vigilance towards aversive stimuli and improve the ability to detect and avoid danger. We have recently shown, for instance, that anxiety increases the ability to a) detect and b) instigate defensive responses towards aversive and not appetitive face stimuli in healthy individuals. This is arguably the key adaptive function of anxiety, yet the neural circuitry underlying this valence-specific effect is unknown. In the present translational study, we sought evidence for the proposition that dorsomedial regions of the prefrontal (DMPFC) and cingulate cortex constitute the human homologue of the rodent prelimbic and are thus associated with increased amygdala responding during this adaptive threat bias in anxiety. To this end, we applied a novel functional connectivity analysis to healthy subjects (N=20) identifying the emotion of fearful and happy faces in an fMRI scanner under anxious (threat of unpredictable foot shock) and non-anxious (safe) conditions. We showed that anxiety significantly increased positive DMPFC-amygdala connectivity during the processing of fearful faces. This effect was a) valence-specific (it was not seen for happy faces), b) paralleled by faster behavioral response to fearful faces, and c) correlated positively with trait anxiety. As such we provide the first experimental support for an anxiety-mediated, valence-specific, DMPFC-amygdala aversive amplification mechanism in healthy humans. This may be homologous to the rodent prelimbic-amygdala circuit and may, given the relationship with trait anxiety, underlie vulnerability to anxiety disorders. This study thus pinpoints a key neural mechanism in adaptive anxiety and highlights its potential link to maladaptive anxiety.