Frontolimbic activity and cognitive bias in major depression

Computational Modeling of Self-Referential Processing Reveals Domain General Associations with Adolescent Anxiety Symptoms

What an adolescent thinks about themselves, commonly termed self-referential processing, has significant implications for youth long-term psychological well-being. Self-referential processing plays an important role in anticipatory and reactive processing in social contexts and contributes to symptoms of social anxiety. Previous work examining self-referential processing largely focuses on child and adolescent depression, relying on endorsement and reaction time for positive and negative self-describing adjectives in a self-referential encoding task (SRET). Here, we employ computational methods to interrogate the latent processes underlying choice reaction times to evaluate the fit of several drift-diffusion models of youth SRET performance. A sample of 106 adolescent, aged 12-17 (53% male; M_age = 14.49, SD = 1.70) completed the SRET and self-report measures of anxiety and depression. Our results support the utility of modeling the SRET, where the rate of evidence accumulation (i.e., drift rate) during negative self-referential processing was related to social anxiety above-and-beyond mean task performance. Our regression analyses indicated that youth efficiency in processing of self-referential views was domain general to anxiety, highlighting the importance of assessing both social and physiological anxiety symptoms when predicting SRET performance. The computational modeling results revealed that self-referential views are not uniquely related to depression-related constructs but also facets of anxiety.

Sex and age differences in cognitive bias and neural activation in response to cognitive bias testing

Cognitive symptoms of depression, including negative cognitive bias, are more severe in women than in men. Current treatments to reduce negative cognitive bias are not effective and sex differences in the neural activity underlying cognitive bias may play a role. Here we examined sex and age differences in cognitive bias and functional connectivity in a novel paradigm. Male and female rats underwent an 18-day cognitive bias procedure, in which they learned to discriminate between two contexts (shock paired context A, no-shock paired context B), during either adolescence (postnatal day (PD 40)), young adulthood (PD 100), or middle-age (PD 210). Cognitive bias was measured as freezing behaviour in response to an ambiguous context (context C), with freezing levels akin to the shock paired context coded as negative bias. All animals learned to discriminate between the two contexts, regardless of sex or age. However, adults (young adults, middle-aged) displayed a greater negative cognitive bias compared to adolescents, and middle-aged males had a greater negative cognitive bias than middle-aged females. Females had greater neural activation of the nucleus accumbens, amygdala, and hippocampal regions to the ambiguous context compared to males, and young rats (adolescent, young adults) had greater neural activation in these regions compared to middle-aged rats. Functional connectivity between regions involved in cognitive bias differed by age and sex, and only adult males had negative correlations between the frontal regions and hippocampal regions. These findings highlight the importance of examining age and sex when investigating the underpinnings of negative cognitive bias and lay the groundwork for determining what age- and sex-specific regions to target in future cognitive bias studies.

Self-referential Processing in Remitted Depression: An Event-Related Potential Study

Background

Identifying mechanisms of major depressive disorder that continue into remission is critical, as these mechanisms may contribute to subsequent depressive episodes. Biobehavioral markers related to depressogenic self-referential processing biases have been identified in adults with depression. Thus, we investigated whether these risk factors persisted during remission as well as contributed to the occurrence of stress and depressive symptoms over time.

Methods

At baseline, adults with remitted depression (n = 33) and healthy control subjects (n = 33) were administered diagnostic and stress interviews as well as self-report symptom measures. In addition, participants completed a self-referential encoding task while electroencephalography data were acquired. Stress interviews and self-report symptom measures were readministered at the 6-month follow-up assessment.

Results

Drift diffusion modeling showed that compared with healthy individuals, adults with remitted depression exhibited a slower drift rate to negative stimuli, indicating a slower tendency to reject negative stimuli as self-relevant. At the 6-month follow-up assessment, a slower drift rate to negative stimuli predicted greater interpersonal stress severity among individuals with remitted depression but not healthy individuals while controlling for both baseline depression symptoms and interpersonal stress severity. Highlighting the specificity of this effect, results were nonsignificant when predicting noninterpersonal stress. For self-relevant positive words endorsed, adults with remitted depression exhibited smaller left- than right-hemisphere late positive potential amplitudes; healthy control subjects did not show hemispheric differences.

Conclusions

Self-referential processing deficits persist into remission. In line with the stress generation framework, these biases predicted the occurrence of interpersonal stress, which may provide insight about a potential pathway for the re-emergence of depressive symptoms.

Neurophysiological Markers Related to Negative Self-referential Processing Differentiate Adolescent Suicide Ideators and Attempters

Background

Adolescent suicide is a major public health concern, and presently, there is a limited understanding of the neurophysiological correlates of suicidal behaviors. Cognitive models of suicide indicate that negative views of the self are related to suicidal thoughts and behaviors, and this study investigated whether behavioral and neural correlates of self-referential processing differentiate suicide ideators from recent attempters.

Methods

Adolescents with depression reporting current suicidal ideation and no lifetime suicide attempts (suicide ideators, n = 30) and past-year suicide attempts (recent attempters, n = 26) completed a self-referential encoding task while high-density electroencephalogram data were recorded. Behavioral analyses focused on negative processing bias (i.e., tendency to attribute negative information as being self-relevant) and drift rate (i.e., slope of reaction time and response type that corresponds to how quickly information is accumulated to make a decision about whether words are self-referent). Neurophysiological markers probing components reflecting early semantic monitoring (P2), engagement (early late positive potential), and effortful encoding (late late positive potential) also were tested.

Results

Adolescent suicide ideators and recent suicide attempters reported comparable symptom severity, suicide ideation, and mental disorders. Although there were no behavioral differences, compared with suicide ideators, suicide attempters exhibited greater P2 amplitudes for negative versus positive words, which may reflect enhanced attention and arousal in response to negative self-referential stimuli. There were no group differences for the early or late late positive potential.

Conclusions

Enhanced sensory arousal in response to negative stimuli-that is, attentional orienting to semantic, emotional, and self-relevant features-differentiates adolescent suicide attempters from ideators and thus may signal risk for suicidal behavior.

Review of Abnormal Self-Knowledge in Major Depressive Disorder

Background: Major depressive disorder (MDD) is an affective disorder that is harmful to both physical and mental health. Abnormal self-knowledge, which refers to abnormal judgments about oneself, is a core symptom of depression. However, little research has summarized how and why patients with MDD differ from healthy individuals in terms of self-knowledge. Objective: To gain a better understanding of MDD, we reviewed previous studies that focused on the behavioral and neurological changes of self-knowledge in this illness. Main Findings: On the behavioral level, depressed individuals exhibited negative self-knowledge in an explicit way, while more heterogeneous patterns were reported in implicit results. On the neurological level, depressed individuals, as compared with non-depressed controls, showed abnormal self-referential processing in both early perception and higher cognitive processing phases during the Self-Referential Encoding Task. Furthermore, fMRI studies have reported aberrant activity in the medial prefrontal cortex area for negative self-related items in depression. These results revealed several behavioral features and brain mechanisms underlying abnormal self-knowledge in depression. Future Studies: The neural mechanism of implicit self-knowledge in MDD remains unclear. Future research should examine the importance of others' attitudes on the self-concept of individuals with MDD, and whether abnormal self-views may be modified through cognitive or pharmacological approaches. In addition, differences in abnormal self-knowledge due to genetic variation between depressed and non-depressed populations remain unconfirmed. Importantly, it remains unknown whether abnormal self-knowledge could be used as a specific marker to distinguish healthy individuals from those with MDD. Conclusion: This review extends our understanding of the relationship between self-knowledge and depression by indicating several abnormalities among individuals with MDD and those who are at risk for this illness.

Change in Quantitative EEG Theta Cordance as a Potential Predictor of Repetitive Transcranial Magnetic Stimulation Clinical Outcome in Major Depressive Disorder

Repetitive transcranial magnetic stimulation (rTMS) has demonstrated efficacy in major depressive disorder (MDD), although clinical outcome is variable. Change in the resting-state quantitative electroencephalogram (qEEG), particularly in theta cordance early in the course of treatment, has been linked to antidepressant medication outcomes but has not been examined extensively in clinical rTMS. This study examined change in theta cordance over the first week of clinical rTMS and sought to identify a biomarker that would predict outcome at the end of 6 weeks of treatment. Clinically stable outpatients (n = 18) received nonblinded rTMS treatment administered to the dorsolateral prefrontal cortex (DLPFC). Treatment parameters (site, intensity, number of pulses) were adjusted on an ongoing basis guided by changes in symptom severity rating scale scores. qEEGs were recorded at pretreatment baseline and after 1 week of left DLPFC (L-DLPFC) rTMS using a 21-channel dry-electrode headset. Analyses examined the association between week 1 regional changes in theta band (4-8 Hz) cordance, and week 6 patient- and physician-rated outcomes. Theta cordance change in the central brain region predicted percent change in Inventory of Depressive Symptomology-Self-Report (IDS-SR) score, and improvement versus nonimprovement on the Clinical Global Impression-Improvement Inventory (CGI-I) ( R² = .38, P = .007; and Nagelkerke R² = .78, P = .0001, respectively). The cordance biomarker remained significant when controlling for age, gender, and baseline severity. Treatment-emergent change in EEG theta cordance in the first week of rTMS may predict acute (6-week) treatment outcome in MDD. This oscillatory synchrony biomarker merits further study in independent samples.

Brain-Based Biomarkers for the Treatment of Depression: Evolution of an Idea

An ambition of depression biomarker research is to augment psychometric and cognitive assessment of clinically relevant phenomena with neural measures. Although such applications have been slow to arrive, we observe a steady evolution of the idea and anticipate emerging technologies with some optimism. To highlight critical themes and innovations in depression biomarker research, we take as our point of reference a specific research narrative. We begin with an early model of frontal-limbic dysfunction, which represents a conceptual shift from localized pathology to understanding symptoms as an emergent property of distributed networks. Over the decades, this model accommodates perspectives from neurology, psychiatry, clinical, and cognitive neuroscience, and preserves past insight as more complex methods become available. We also track the expanding mission of brain biomarker research: from the development of diagnostic tools to treatment selection algorithms, measures of neurocognitive functioning and novel targets for neuromodulation. To conclude, we draw from this particular research narrative future directions for biomarker research. We emphasize integration of measurement modalities to describe dynamic change in domain-general networks, and we speculate that a brain-based framework for psychiatric problems may dissolve classical diagnostic and disciplinary boundaries. (JINS, 2017, 23, 870-880).

Brain Functional Effects of Psychopharmacological Treatment in Major Depression: a Focus on Neural Circuitry of Affective Processing

In the last two decades, neuroimaging research has reached a much deeper understanding of the neurobiological underpinnings of major depression (MD) and has converged on functional alterations in limbic and prefrontal neural networks, which are mainly linked to altered emotional processing observed in MD patients. To date, a considerable number of studies have sought to investigate how these neural networks change with pharmacological antidepressant treatment. In the current review, we therefore discuss results from a) pharmacological functional magnetic resonance imaging (fMRI) studies investigating the effects of selective serotonin or noradrenalin reuptake inhibitors on neural activation patterns in relation to emotional processing in healthy individuals, b) treatment studies in patients with unipolar depression assessing changes in neural activation patterns before and after antidepressant pharmacotherapy, and c) predictive neural biomarkers of clinical response in depression. Comparing results from pharmacological fMRI studies in healthy individuals and treatment studies in depressed patients nicely showed parallel findings, mainly for a reduction of limbic activation in response to negative stimuli. A thorough investigation of the empirical findings highlights the importance of the specific paradigm employed in every study which may account for some of the discrepant findings reported in treatment studies in depressed patients.

Principal components of electrocortical activity during self-evaluation indicate depressive symptom severity

Negative self-evaluation is an important psychological characteristic of depression. In order to study the underlying neural mechanisms, we examined event-related potentials (ERPs) during a self-evaluation task in a community sample (N = 150) of adults reporting a range of depressive symptoms. Principal components analysis (PCA) was used to separate processes that overlap in the average ERP, and neural source analysis was applied to localize the ERP components, with a particular focus on the frontal networks that are thought to be critical to affective self-regulation in depression. Consistent with previous research, individuals reporting greater depression showed enhanced negativity over medial frontal regions as well as attenuation of the late positive potential over parietal regions. Examining loadings of frontal sources on the ERP components showed that activity in the right inferior frontal region may be particularly important for depressed individuals: activity in this region declined as symptoms became more severe. Characterizing brain mechanisms of self-evaluation on the timescale of cognitive events may provide insight into the neural mechanisms of self-regulation that are important in cognitive therapy, and that could be made more amenable to change through increasing neuroplasticity with targeted non-invasive neuromodulation.

The neuropsychology of self-reflection in psychiatric illness

The development of robust neuropsychological measures of social and affective function-which link critical dimensions of mental health to their underlying neural circuitry-could be a key step in achieving a more pathophysiologically-based approach to psychiatric medicine. In this article, we summarize research indicating that self-reflection (the inward attention to personal thoughts, memories, feelings, and actions) may be a useful model for developing such a paradigm, as there is evidence that self-reflection is (1) measurable with self-report scales and performance-based tests, (2) linked to the activity of a specific neural circuit, and (3) dimensionally related to mental health and various forms of psychopathology.

Do prefrontal midline electrodes provide unique neurophysiologic information in Major Depressive Disorder?

Brain oscillatory activity from the midline prefrontal region has been shown to reflect brain dysfunction in subjects with Major Depressive Disorder (MDD). It is not known, however, whether electrodes from this area provide unique information about brain function in MDD. We examined a set of midline sites and two other prefrontal locations for detecting cerebral activity differences between subjects with MDD and healthy controls. Resting awake quantitative EEG (qEEG) data were recorded from 168 subjects: 47 never-depressed adults and 121 with a current major depressive episode. Individual midline electrodes (Fpz, Fz, Cz, Pz, and Oz) and prefrontal electrodes outside the hairline (Fp1, Fp2) were examined with absolute and relative power and cordance in the theta band. We found that MDD subjects exhibited higher values of cordance (p = 0.0066) at Fpz than controls; no significant differences were found at other locations, and power measures showed trend-level differences. Depressed adults showed higher midline cordance than did never-depressed subjects at the most-anterior midline channel. Salient abnormalities in MDD may be detectable by focusing on the prefrontal midline region, and EEG metrics from focused electrode arrays may offer clinical practicality for clinical monitoring.

One ring to rule them all?--Temporospatial specificity of deep brain stimulation for treatment-resistant depression

Deep brain stimulation (DBS) for intractable cases of depression has emerged as a valuable therapeutic option during the last decade. While several locations have been intensely investigated in recent years, the literature is lacking an all-encompassing perspective thereupon asking if and how these stimulation sites relate to each other and what this may imply for the underlying mechanisms of action of this treatment modality. We aim at proposing a model of DBS mechanism of action with particular focus on several puzzling aspects regarding an apparent temporo-spatial specificity of antidepressant action, i.e. the discrepancy between protracted response after initiation of stimulation and rapid relapse upon discontinuation, as well as differential effects on psychopathology. We suggest that the pre-treatment depressive state is determined by the interaction of individual traits with dysfunctional adaptive processes as responses to stress, resulting in a disease-associated, overtly dysfunctional, equilibrium. The antidepressant action of DBS is thought to modify and re-set this equilibrium in a temporospatially distinct manner by influencing the activity states of two different brain circuitries. The idea of sequential and temporospatially distinct mechanisms of action bears implications for the assessment of psychopathology and behavior in clinical and preclinical studies as well as investigations into brain circuit activity states.

A developmental study of the feedback-related negativity from 10-17 years: age and sex effects for reward versus non-reward

We employed event-related potentials to examine the feedback-related negativity (FRN), during a non-learning reward versus non-reward task. We compared 10-12-year-old, 13-14-year-old, and 15-17-year-old youth (n = 91). Age effects included a larger FRN for younger age groups, regardless of feedback type, and a decrease in peak latency for feedback, across age groups as a linear trend. Males showed larger responses irrespective of feedback type and longer latency for rewarded feedback. Source modeling revealed reward/non-reward differences in the anterior cingulate cortex (ACC) and orbitofrontal cortex, most strongly in the subgenual ACC. Males showed more subgenual ACC activity for feedback overall.

Emotional valence modulates brain functional abnormalities in depression: evidence from a meta-analysis of fMRI studies

Models describing the neural correlates of biased emotion processing in depression have focused on increased activation of anterior cingulate and amygdala and decreased activation of striatum and dorsolateral prefrontal cortex. However, neuroimaging studies investigating emotion processing in depression have reported inconsistent results. This meta-analysis integrates these findings and examines whether emotional valence modulates such abnormalities. A systematic literature search identified 26 whole-brain and 18 region-of-interest studies. Peak coordinates and effect sizes were combined in an innovative parametric meta-analysis. Opposing effects were observed in the amygdala, striatum, parahippocampal, cerebellar, fusiform and anterior cingulate cortex, with depressed subjects displaying hyperactivation for negative stimuli and hypoactivation for positive stimuli. Anterior cingulate activity was also modulated by facial versus non-facial stimuli, in addition to emotional valence. Depressed subjects also showed reduced activity in left dorsolateral prefrontal cortex for negative stimuli and increased activity in orbitofrontal cortex for positive stimuli. Emotional valence is a moderator of neural abnormalities in depression, and therefore a critical feature to consider in models of emotional dysfunction in depression.

Neural responses to negative feedback are related to negative emotionality in healthy adults

Prior neuroimaging and electrophysiological evidence suggests that potentiated responses in the anterior cingulate cortex (ACC), particularly the rostral ACC, may contribute to abnormal responses to negative feedback in individuals with elevated negative affect and depressive symptoms. The feedback-related negativity (FRN) represents an electrophysiological index of ACC-related activation in response to performance feedback. The purpose of the present study was to examine the FRN and underlying ACC activation using low resolution electromagnetic tomography source estimation techniques in relation to negative emotionality (a composite index including negative affect and subclinical depressive symptoms). To this end, 29 healthy adults performed a monetary incentive delay task while 128-channel event-related potentials were recorded. We found that enhanced FRNs and increased rostral ACC activation in response to negative--but not positive--feedback was related to greater negative emotionality. These results indicate that individual differences in negative emotionality--a putative risk factor for emotional disorders--modulate ACC-related processes critically implicated in assessing the motivational impact and/or salience of environmental feedback.

Social exclusion in middle childhood: rejection events, slow-wave neural activity, and ostracism distress

This study examined neural activity with event-related potentials (ERPs) in middle childhood during a computer-simulated ball-toss game, Cyberball. After experiencing fair play initially, children were ultimately excluded by the other players. We focused specifically on “not my turn” events within fair play and rejection events within social exclusion. Dense-array ERPs revealed that rejection events are perceived rapidly. Condition differences (“not my turn” vs. rejection) were evident in a posterior ERP peaking at 420 ms consistent, with a larger P3 effect for rejection events indicating that in middle childhood rejection events are differentiated in <500 ms. Condition differences were evident for slow-wave activity (500-900 ms) in the medial frontal cortical region and the posterior occipital-parietal region, with rejection events more negative frontally and more positive posteriorly. Distress from the rejection experience was associated with a more negative frontal slow wave and a larger late positive slow wave, but only for rejection events. Source modeling with Geosouce software suggested that slow-wave neural activity in cortical regions previously identified in functional imaging studies of ostracism, including subgenual cortex, ventral anterior cingulate cortex, and insula, was greater for rejection events vs. “not my turn” events.

Abnormal sensitivity to negative feedback in late-life depression

AIMS

The purpose of the present study was to probe sensitivity to potentially misleading negative feedback on cognitive tasks as a possible mechanism of cognitive impairment in elderly patients with mild depression.

METHODS

A total of 22 mildly depressed elderly subjects were compared to 22 healthy controls, using a computerized Tower-of-London task.

RESULTS

Failure and magnitude of failure were significantly worse after negative but not positive feedback. Depression predicted failure after negative feedback but not the magnitude of failure. Neither failure nor magnitude of failure increased as a consequence of repeated negative feedback.

CONCLUSIONS

Altered sensitivity to negative feedback occurs in mild late-life unipolar depression and may represent a subtle context-specific phenomenon.