Human Lateral Frontal Pole Contributes to Control over Emotional Approach-Avoidance Actions

Medial anterior prefrontal cortex stimulation downregulates implicit reactions to threats and prevents the return of fear

Downregulating emotional overreactions toward threats is fundamental for developing treatments for anxiety and post-traumatic disorders. The prefrontal cortex (PFC) is critical for top-down modulatory processes, and despite previous studies adopting repetitive transcranial magnetic stimulation (rTMS) over this region provided encouraging results in enhancing extinction, no studies have hitherto explored the effects of stimulating the medial anterior PFC (aPFC, encompassing the Brodmann area 10) on threat memory and generalization. Here we showed that rTMS over the aPFC applied before threat memory retrieval immediately decreases implicit reactions to learned and novel stimuli in humans. These effects enduringly persisted 1 week later in the absence of rTMS. No effects were detected on explicit recognition. Critically, rTMS over the aPFC resulted in a more pronounced reduction of defensive responses compared to rTMS targeting the dorsolateral PFC. These findings reveal a previously unexplored prefrontal region, the modulation of which can efficiently and durably inhibit implicit reactions to learned threats. This represents a significant advancement toward the long-term deactivation of exaggerated responses to threats.

Information-based TMS to mid-lateral prefrontal cortex disrupts action goals during emotional processing

The ability to respond to emotional events in a context-sensitive and goal-oriented manner is essential for adaptive functioning. In models of behavioral and emotion regulation, the lateral prefrontal cortex (LPFC) is postulated to maintain goal-relevant representations that promote cognitive control, an idea rarely tested with causal inference. Here, we altered mid-LPFC function in healthy individuals using a putatively inhibitory brain stimulation protocol (continuous theta burst; cTBS), followed by fMRI scanning. Participants performed the Affective Go/No-Go task, which requires goal-oriented action during affective processing. We targeted mid-LPFC (vs. a Control site) based on the individualized location of action-goal representations observed during the task. cTBS to mid-LPFC reduced action-goal representations in mid-LPFC and impaired goal-oriented action, particularly during processing of negative emotional cues. During negative-cue processing, cTBS to mid-LPFC reduced functional coupling between mid-LPFC and nodes of the default mode network, including frontopolar cortex-a region thought to modulate LPFC control signals according to internal states. Collectively, these results indicate that mid-LPFC goal-relevant representations play a causal role in governing context-sensitive cognitive control during emotional processing.

Correlation of Disease Severity, Proinflammatory Cytokines, and Reduced Brain Gray Matter Volumes in Patients with Atopic Dermatitis

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease. However, few studies have investigated brain changes associated with chronic inflammation. We hypothesized that chronic inflammation might be related to brain structural alterations in patients with AD. Objectives: To investigate the association between disease severity (Eczema Area and Severity Index [EASI]), proinflammatory cytokines, and differences in brain gray matter (GM) volume in patients with AD. Methods: Nineteen patients with AD and 19 age- and sex-matched healthy subjects were enrolled. All participants underwent clinical assessment and brain magnetic resonance imaging. Voxel-based morphometry was performed to analyze GM volume differences. Results: Patients with AD exhibited significantly decreased GM volume in many brain regions, such as bilateral precentral gyrus, right frontal pole, and right middle temporal gyrus (P < 0.001), compared with healthy subjects. Notably, in patients with AD, the GM volume in right middle temporal gyrus was negatively associated with both EASI score and proinflammatory cytokines (sIL-2R [soluble interleukin 2 receptor] and TNF-α receptor-1), whereas the GM volume in left precentral gyrus was negatively associated with both EASI score and proinflammatory cytokines (sIL-2R and CRP). Conclusion: Patients with AD demonstrated significant brain GM volume reduction in many brain regions, which is related to disease severity and proinflammatory cytokines.

Voxelwise Multivariate Analysis of Brain-Psychosocial Associations in Adolescents Reveals 6 Latent Dimensions of Cognition and Psychopathology

BACKGROUND

Adolescence heralds the onset of considerable psychopathology, which may be conceptualized as an emergence of altered covariation between symptoms and brain measures. Multivariate methods can detect such modes of covariation or latent dimensions, but none specifically relating to psychopathology have yet been found using population-level structural brain data. Using voxelwise (instead of parcellated) brain data may strengthen latent dimensions' brain-psychosocial relationships, but this creates computational challenges.

METHODS

We obtained voxelwise gray matter density and psychosocial variables from the baseline (ages 9-10 years) Adolescent Brain Cognitive Development (ABCD) Study cohort (N = 11,288) and employed a state-of-the-art segmentation method, sparse partial least squares, and a rigorous machine learning framework to prevent overfitting.

RESULTS

We found 6 latent dimensions, 4 of which pertain specifically to mental health. The mental health dimensions were related to overeating, anorexia/internalizing, oppositional symptoms (all ps < .002) and attention-deficit/hyperactivity disorder symptoms (p = .03). Attention-deficit/hyperactivity disorder was related to increased and internalizing symptoms related to decreased gray matter density in dopaminergic and serotonergic midbrain areas, whereas oppositional symptoms were related to increased gray matter in a noradrenergic nucleus. Internalizing symptoms were related to increased and oppositional symptoms to reduced gray matter density in the insular, cingulate, and auditory cortices. Striatal regions featured strongly, with reduced caudate nucleus gray matter in attention-deficit/hyperactivity disorder and reduced putamen gray matter in oppositional/conduct problems. Voxelwise gray matter density generated stronger brain-psychosocial correlations than brain parcellations.

CONCLUSIONS

Voxelwise brain data strengthen latent dimensions of brain-psychosocial covariation, and sparse multivariate methods increase their psychopathological specificity. Internalizing and externalizing symptoms are associated with opposite gray matter changes in similar cortical and subcortical areas.

A potential brain functional biomarker distinguishing patients with Crohn's disease with different disease stages: a resting-state fMRI study

Background

The previous studies have demonstrated that patients with Crohn's disease in remission (CD-R) have abnormal alterations in brain function. However, whether brain function changes in patients with Crohn's disease in activity (CD-A) and the relationship with CD-R are still unclear. In this study, we aimed to investigate whether the different levels of disease activity may differentially affect the brain function and to find the brain functional biomarker distinguishing patients with different disease stages by measuring the amplitude of low frequency fluctuations (ALFF).

Methods

121 patients with CD and 91 healthy controls (HCs) were recruited. The clinical and psychological assessment of participants were collected. The criteria for the disease activity were the Crohn's disease activity index (CDAI) scores. CD-R refers to CD patients in remission which the CDAI score is less than 150. Conversely, CD-A refers to CD patients in activity which the CDAI score is ≥150. The ALFF was compared among three groups by performing one-way analysis of variance, followed by a post hoc two-sample t-test. Differences among the groups were selected as seeds for functional connectivity analyses. We also investigated the correlation among clinical, psychological scores and ALFF. Binary logistic regression analysis was used to examine the unique contribution of the ALFF characteristics of the disease stages.

Results

There were widespread differences of ALFF values among the 3 groups, which included left frontal pole (FP_L), right supramarginal gyrus (SG_R), left angular gyrus (AG_L), right cingulate gyrus (CG_R), right intracalcarine cortex (IC_R), right parahippocampal gyrus (PG_R), right lingual gyrus (LG_R), right precuneous cortex (PC_R), left occipital fusiform gyrus (OFG_L). Significant brain regions showing the functional connections (FC) increased in FP_L, SG_R, PC_R and OFG_L between CD-A and HCs. The erythrocyte sedimentation rate had a negative correlation with the ALFF values in PC_R in the patients with CD. The phobic anxiety values had a negative correlation with the ALFF values in OFG_L. The psychoticism values had a negative correlation with ALFF values in the IC_R. And the hostility values had a positive correlation with the ALFF values in CG_R. Significant brain regions showing the FC increased in FP_L, SG_R, CG_R, PG_R, LG_R and OFG_L between CD-R and HCs. In binary logistic regression models, the LG_R (beta = 5.138, p = 0.031), PC_R (beta = 1.876, p = 0.002) and OFG_L (beta = 3.937, p = 0.044) was disease stages predictors.

Conclusion

The results indicated the significance of the altered brain activity in the different disease stages of CD. Therefore, these findings present a potential identify neuroimaging-based brain functional biomarker in CD. Additionally, the study provides a better understanding of the pathophysiology of CD.

Treatment response with ketamine in chronic suicidality: An open label functional connectivity study

BACKGROUND

Ketamine has recently been proposed as a treatment option for suicidality. Whilst its mechanism of action has been explored at molecular levels, the effect on the brain at the organ level remains unclear. Here we investigate immediate post-treatment and prolonged large-scale resting-state neural network changes to elucidate the neuronal underpinnings associated with ketamine's therapeutic effects.

METHODS

Twenty-eight adults (aged 22-72 years) participated in the Oral Ketamine Trial On Suicidality, which is an open-label trial of weekly sub-anaesthetic doses of oral ketamine over 6 weeks. MRI was acquired at baseline, post-treatment, and follow-up. Functional connectivity changes at post-treatment and follow-up were examined using seed based and independent component analysis.

RESULTS

The seed-based connectivity analysis revealed significantly reduced connectivity at post-treatment from the right hippocampus to both right and left superior frontal gyrus, from the left anterior parahippocampus to right superior frontal gyrus, left superior frontal gyrus, right middle frontal gyrus, and left frontal operculum cortex. Compared with baseline, the ICA showed reduced anterior default mode network connectivities to bilateral posterior cingulate cortex, middle and anterior cingulate cortex, lingual gyrus, and cuneus and increased connectivity of the frontoparietal network to the right superior parietal lobule at post-treatment.

LIMITATIONS

Open label pilot study.

CONCLUSIONS

We have shown sub-anaesthetic doses of ketamine alters connectivity in networks which have been shown to be aberrantly hyper-connected in numerous psychiatric conditions. These neurocircuitry changes are supported by significant reductions in suicide ideation. Our results provide support for the use of ketamine as a treatment for suicidality.

Age-related intrinsic functional connectivity underlying emotion utilization

Previous studies investigated the age-related positivity effect in terms of emotion perception and management, whereas little is known about whether the positivity effect is shown in emotion utilization (EU). If yes, the EU-related intrinsic functional connectivity and its age-associated alterations remain to be elucidated. In this study, we collected resting-state functional magnetic resonance imaging data from 62 healthy older adults and 72 undergraduates as well as their self-ratings of EU. By using the connectome-based predictive modeling (CPM) method, we constructed a predictive model of the positive relationship between EU self-ratings and resting-state functional connectivity. Lesion simulation analyses revealed that the medial-frontal network, default mode network, frontoparietal network, and subcortical regions played key roles in the EU-related CPM. Older subjects showed significantly higher EU self-ratings than undergraduates, which was associated with strengthened connectivity between the left dorsolateral prefrontal cortex and bilateral frontal poles, and between the left frontal pole and thalamus. A mediation analysis indicated that the age-related EU network mediated the age effect on EU self-ratings. Our findings extend previous research on the age-related "positivity effect" to the EU domain, suggesting that the positivity effect on the self-evaluation of EU is probably associated with emotion knowledge which accumulates with age.

Predicting individual differences in behavioral activation and behavioral inhibition from functional networks in the resting EEG

The behavioral activation system (BAS) and behavioral inhibition system (BIS) are thought to underly affective dispositions and self-regulatory processes. The BAS is sensitive to reward and involved in approach behaviors, and the BIS is sensitive to punishment and involved in avoidance behaviors. Trait BAS and BIS relate to distinct behavioral profiles and neural activity, but little is known about how trait BAS and BIS relate to functional networks in EEG. We applied a data-driven method called connectome predictive modeling (CPM) to identify networks relating to trait BAS and BIS and tested whether the strength of those networks predicted trait BAS and BIS in novel subjects using a leave-one-out cross-validation procedure. Adult participants (N = 107) completed a resting state task with eyes closed and eyes open, and trait BAS and BIS were measured via Carver and White's (1994) BIS and BAS scales. We hypothesized distinct positive (more synchronization) and negative (less synchronization) networks would relate to trait BAS and BIS. For eyes closed, we identified two negative networks, one in theta and one in alpha predicted BIS. We identified three positive networks, one in theta and one in beta predicted Fun Seeking and one in theta predicted Drive. For eyes open, negative theta and alpha networks predicted BIS, a positive theta network predicted Fun Seeking, and a negative gamma network predicted mean BAS. Visualization of the networks are presented. Discussion centers on the observed networks and how to advance application of CPM to EEG, including with clinical implications.

Social avoidance behavior modulates motivational responses to social reward-threat conflict signals: A preliminary fMRI study

Social avoidance behavior (SAB) produces impairment in multiple domains and contributes to the development and maintenance of several psychiatric disorders. Social behaviors such as SAB are influenced by approach-avoidance (AA) motivational responses to affective facial expressions. Notably, affective facial expressions communicate varying degrees of social reward signals (happiness), social threat signals (anger), or social reward-threat conflict signals (co-occurring happiness and anger). SAB is associated with dysregulated modulation of automatic approach-avoidance (AA) motivational responses exclusively to social reward-threat conflict signals. However, no neuroimaging research has characterized SAB-related modulation of automatic and subjective AA motivational responses to social reward-threat conflict signals. We recruited 30 adults reporting clinical, moderate, or minimal SAB based on questionnaire cutoff scores. SAB groups were matched on age range and gender. During fMRI scanning, participants completed implicit and subjective approach-avoidance tasks (AATs), which involved more incidental or more explicit evaluation of facial expressions that parametrically varied in social reward signals (e.g., 50%_Happy), social threat signals (e.g., 50%_Angry), or social reward-threat conflict signals (e.g., 50%_Happy + 50%_Angry). In the implicit AAT, SAB was associated with slower automatic avoidance actions and weaker amygdala-pgACC connectivity exclusively as a function of social reward-threat conflict signals. In the subjective AAT, SAB was associated with smaller increases in approach ratings, smaller decreases in avoidance ratings, and weaker dlPFC-pgACC connectivity exclusively in response to social reward-threat conflict signals. Thus, SAB is associated with dysregulated modulation of automatic and subjective AA motivational sensitivity to social reward-threat conflict signals, which may be facilitated by overlapping neural systems.

Emotional face expression recognition in problematic Internet use and excessive smartphone use: task-based fMRI study

Growing literature indicates that problematic Internet use (PIU) and excessive smartphone use (ESU) are associated with breakdown of functional brain networks. The effects of PIU&ESU on emotional face expression (EFE) recognition are not well understood, however behavioural investigations and fMRI studies of different addiction forms indicated the impairment of this function. The Facial Emotion Recognition Paradigm was used to probe cortico-limbic responses during EFE recognition. Combined fMRI and psychophysiological analysis were implemented to measure EFE-related functional brain changes in PIU&ESU. Self-reported questionnaires were used to assess PIU&ESU. Positive associations were found between the extent of PIU&ESU and functional connections related to emotional cognitive control and social brain networks. Our findings highlight the involvement of social functioning, especially EFE recognition in PIU&ESU. Therefore, we emphasize that besides the brain's executive and reward systems, the social brain network might be the next candidate to be involved in the pathogenesis of PIU&ESU.

Structural brain alterations associated with suicidal thoughts and behaviors in young people: results from 21 international studies from the ENIGMA Suicidal Thoughts and Behaviours consortium

Identifying brain alterations associated with suicidal thoughts and behaviors (STBs) in young people is critical to understanding their development and improving early intervention and prevention. The ENIGMA Suicidal Thoughts and Behaviours (ENIGMA-STB) consortium analyzed neuroimaging data harmonized across sites to examine brain morphology associated with STBs in youth. We performed analyses in three separate stages, in samples ranging from most to least homogeneous in terms of suicide assessment instrument and mental disorder. First, in a sample of 577 young people with mood disorders, in which STBs were assessed with the Columbia Suicide Severity Rating Scale (C-SSRS). Second, in a sample of young people with mood disorders, in which STB were assessed using different instruments, MRI metrics were compared among healthy controls without STBs (HC; N = 519), clinical controls with a mood disorder but without STBs (CC; N = 246) and young people with current suicidal ideation (N = 223). In separate analyses, MRI metrics were compared among HCs (N = 253), CCs (N = 217), and suicide attempters (N = 64). Third, in a larger transdiagnostic sample with various assessment instruments (HC = 606; CC = 419; Ideation = 289; HC = 253; CC = 432; Attempt=91). In the homogeneous C-SSRS sample, surface area of the frontal pole was lower in young people with mood disorders and a history of actual suicide attempts (N = 163) than those without a lifetime suicide attempt (N = 323; FDR-p = 0.035, Cohen's d = 0.34). No associations with suicidal ideation were found. When examining more heterogeneous samples, we did not observe significant associations. Lower frontal pole surface area may represent a vulnerability for a (non-interrupted and non-aborted) suicide attempt; however, more research is needed to understand the nature of its relationship to suicide risk.

Get to grips with motivation: Slipping and gripping movements are biased by approach-avoidance context

People are better at approaching appetitive cues signaling reward and avoiding aversive cues signaling punishment than vice versa. This action bias has previously been shown in approach-avoidance tasks involving arm movements in response to appetitive or aversive cues. It is not known whether appetitive or aversive stimuli also bias more distal dexterous actions, such as gripping and slipping, in a similar manner. To test this hypothesis, we designed a novel task involving grip force control (gripping and slipping) to probe gripping-related approach and avoidance behavior. 32 male volunteers, aged 18–40 years, were instructed to either grip (“approach”) or slip (”avoid”) a grip-force device with their right thumb and index finger at the sight of positive or negative images. In one version of this pincer grip task, participants were responding to graspable objects and in another version of the task they were responding to happy or angry faces. Bayesian repeated measures Analysis of variance revealed extreme evidence for an interaction between response type and cue valence (Bayes factor = 296). Participants were faster to respond in affect-congruent conditions (“approach appetitive,” “avoid aversive”) than in affect-incongruent conditions (“approach aversive,” “avoid appetitive”). This bias toward faster response times for affect-congruent conditions was present regardless of whether it was a graspable object or a face signaling valence. Since our results mirror the approach and avoidance effects previously observed for arm movements, we conclude that a tendency favoring affectively congruent cue-response mappings is an inherent feature of motor control and thus also includes precision grip.

Alcohol Use and Prefrontal Cortex Volume Trajectories in Young Adults with Mood Disorders and Associated Clinical Outcomes

(1) Background: Alcohol use in the course of mood disorders is associated with worse clinical outcomes. The mechanisms by which alcohol use alters the course of illness are unclear but may relate to prefrontal cortical (PFC) sensitivity to alcohol. We investigated associations between alcohol use and PFC structural trajectories in young adults with a mood disorder compared to typically developing peers. (2) Methods: 41 young adults (24 with a mood disorder, agemean = 21 ± 2 years) completed clinical evaluations, assessment of alcohol use, and two structural MRI scans approximately one year apart. Freesurfer was used to segment PFC regions of interest (ROIs) (anterior cingulate, orbitofrontal cortex, and frontal pole). Effects of group, alcohol use, time, and interactions among these variables on PFC ROIs at baseline and follow-up were modeled. Associations were examined between alcohol use and longitudinal changes in PFC ROIs with prospective mood. (3) Results: Greater alcohol use was prospectively associated with decreased frontal pole volume in participants with a mood disorder, but not typically developing comparison participants (time-by-group-by-alcohol interaction; p = 0.007); however, this interaction became a statistical trend in a sensitivity analysis excluding one outlier in terms of alcohol use. Greater alcohol use and a decrease in frontal pole volume related to longer duration of major depression during follow-up (p’s < 0.05). (4) Conclusion: Preliminary findings support more research on alcohol use, PFC trajectories, and depression recurrence in young adults with a mood disorder including individuals with heavier drinking patterns.

Prefrontal cortex interactions with the amygdala in primates

This review addresses functional interactions between the primate prefrontal cortex (PFC) and the amygdala, with emphasis on their contributions to behavior and cognition. The interplay between these two telencephalic structures contributes to adaptive behavior and to the evolutionary success of all primate species. In our species, dysfunction in this circuitry creates vulnerabilities to psychopathologies. Here, we describe amygdala-PFC contributions to behaviors that have direct relevance to Darwinian fitness: learned approach and avoidance, foraging, predator defense, and social signaling, which have in common the need for flexibility and sensitivity to specific and rapidly changing contexts. Examples include the prediction of positive outcomes, such as food availability, food desirability, and various social rewards, or of negative outcomes, such as threats of harm from predators or conspecifics. To promote fitness optimally, these stimulus-outcome associations need to be rapidly updated when an associative contingency changes or when the value of a predicted outcome changes. We review evidence from nonhuman primates implicating the PFC, the amygdala, and their functional interactions in these processes, with links to experimental work and clinical findings in humans where possible.

Amygdala in Action: Functional Connectivity during Approach and Avoidance Behaviors

Motivation is an important feature of emotion. By driving approach to positive events and promoting avoidance of negative stimuli, motivation drives adaptive actions and goal pursuit. The amygdala has been associated with a variety of affective processes, particularly the appraisal of stimulus valence that is assumed to play a crucial role in the generation of approach and avoidance behaviors. Here, we measured amygdala functional connectivity patterns while participants played a video game manipulating goal conduciveness through the presence of good, neutral, or bad monsters. As expected, good versus bad monsters elicited opposing motivated behaviors, whereby good monsters induced more approach and bad monsters triggered more avoidance. These opposing directional behaviors were paralleled by increased connectivity between the amygdala and medial brain areas, such as the OFC and posterior cingulate, for good relative to bad, and between amygdala and caudate for bad relative to good monsters. Moreover, in both conditions, individual connectivity strength between the amygdala and medial prefrontal regions was positively correlated with brain scores from a latent component representing efficient goal pursuit, which was identified by a partial least square analysis determining the multivariate association between amygdala connectivity and behavioral motivation indices during gameplay. At the brain level, this latent component highlighted a widespread pattern of amygdala connectivity, including a dorsal frontoparietal network and motor areas. These results suggest that amygdala-medial prefrontal interactions captured the overall subjective relevance of ongoing events, which could consecutively drive the engagement of attentional, executive, and motor circuits necessary for implementing successful goal-pursuit, irrespective of approach or avoidance directions.

Impaired social perception from eyes and face visual cues: evidence from prefrontal cortex damage

Despite the key role that decoding of social-perceptual cues from faces plays in interpersonal communication, it is only recently that the potential of prefrontal cortex damage to disrupt this ability has been recognized. In fact, few studies to date had assessed whether the ability to identify the state of mind of others from the whole or part of the face is disrupted after prefrontal cortex damage and whether these two abilities are associated and share overlapped neural systems. In the present study, 30 patients with focal prefrontal lesions and 30 matched control subjects were assessed on their ability to recognize six basic emotions from facial expressions of the whole face and to identify states of mind of others from photographs of only the eyes using the "Reading the Mind in the Eyes Task". Results showed that frontal patients were significantly impaired compared with control subjects on both tasks. Moreover, regression analyses showed that these two abilities are associated and reciprocally predictive of one another. Finally, using voxel-based lesion analysis; we identified a partially common bilaterally distributed prefrontal network in the decoding of both emotional cues from both the whole face and eyes centered within the dorsomedial and ventral regions with extension to the lateral frontal pole.

Translating state-of-the-art brain magnetic resonance imaging (MRI) techniques into clinical practice: multimodal MRI differentiates dementia subtypes in a traditional clinical setting

BACKGROUND

This study sought to validate the clinical utility of multimodal magnetic resonance imaging (MRI) techniques in the assessment of neurodegenerative disorders. We intended to demonstrate that advanced neuroimaging techniques commonly used in research can effectively be employed in clinical practice to accurately differentiate heathy aging and dementia subtypes.

METHODS

Twenty patients with dementia of the Alzheimer's type (DAT) and 18 patients with Parkinson's disease dementia (PDD) were identified using gold-standard techniques. Twenty-three healthy, age and sex matched control participants were also recruited. All participants underwent multimodal MRI including T1 structural, diffusion tensor imaging (DTI), arterial spin labeling (ASL), and magnetic resonance spectroscopy (MRS). MRI modalities were evaluated by trained neuroimaging readers and were separately assessed using cross-validated, iterative discriminant function analyses with subsequent feature reduction techniques. In this way, each modality was evaluated for its ability to differentiate patients with dementia from healthy controls as well as to differentiate dementia subtypes.

RESULTS

Following individual and group feature reduction, each of the multimodal MRI metrics except MRS successfully differentiated healthy aging from dementia and also demonstrated distinct dementia subtypes. Using the following ten metrics, excellent separation (95.5% accuracy, 92.3% sensitivity; 100.0% specificity) was achieved between healthy aging and neurodegenerative conditions: volume of the left frontal pole, left occipital pole, right posterior superior temporal gyrus, left posterior cingulate gyrus, right planum temporale; perfusion of the left hippocampus and left occipital lobe; fractional anisotropy (FA) of the forceps major and bilateral anterior thalamic radiation. Using volume of the left frontal pole, right posterior superior temporal gyrus, left posterior cingulate gyrus, perfusion of the left hippocampus and left occipital lobe; FA of the forceps major and bilateral anterior thalamic radiation, neurodegenerative subtypes were accurately differentiated as well (87.8% accuracy, 95.2% sensitivity; 85.0% specificity).

CONCLUSIONS

Regional volumetrics, DTI metrics, and ASL successfully differentiated dementia patients from controls with sufficient sensitivity to differentiate dementia subtypes. Similarly, feature reduction results suggest that advanced analyses can meaningfully identify brain regions with the most positive predictive value and discriminant validity. Together, these advanced neuroimaging techniques can contribute significantly to diagnosis and treatment planning for individual patients.

Anterior prefrontal brain activity during emotion control predicts resilience to post-traumatic stress symptoms

Regulating social emotional actions is essential for coping with life stressors and is associated with control by the anterior prefrontal cortex (aPFC) over the amygdala. However, it remains unclear to what extent prefrontal emotion regulation capacities contribute to resilience against developing post-traumatic stress disorder (PTSD) symptoms. Here, 185 police recruits who experienced their core trauma in the line of duty participated in a prospective longitudinal study. Pre- and post-trauma, they performed a well-established functional magnetic resonance imaging (fMRI) approach-avoidance task, mapping impulsive and controlled emotional actions. Higher baseline aPFC, dorsal and medial frontal pole activity was related to lower PTSD symptoms after trauma exposure. aPFC activity predicted symptom development over and above self-reported and behavioural measures. Trauma exposure, but not trauma symptoms, predicted amygdala activation at follow-up. These findings suggest that prefrontal emotion regulation activity predicts increased resilience against developing post-traumatic stress symptoms and may provide fruitful starting points for prediction and intervention studies.

Defensive freezing and its relation to approach-avoidance decision-making under threat

Successful responding to acutely threatening situations requires adequate approach-avoidance decisions. However, it is unclear how threat-induced states-like freezing-related bradycardia-impact the weighing of the potential outcomes of such value-based decisions. Insight into the underlying computations is essential, not only to improve our models of decision-making but also to improve interventions for maladaptive decisions, for instance in anxiety patients and first-responders who frequently have to make decisions under acute threat. Forty-two participants made passive and active approach-avoidance decisions under threat-of-shock when confronted with mixed outcome-prospects (i.e., varying money and shock amounts). Choice behavior was best predicted by a model including individual action-tendencies and bradycardia, beyond the subjective value of the outcome. Moreover, threat-related bradycardia (high-vs-low threat) interacted with subjective value, depending on the action-context (passive-vs-active). Specifically, in action-contexts incongruent with participants' intrinsic action-tendencies, stronger bradycardia related to diminished effects of subjective value on choice across participants. These findings illustrate the relevance of testing approach-avoidance decisions in relatively ecologically valid conditions of acute and primarily reinforced threat. These mechanistic insights into approach-avoidance conflict-resolution may inspire biofeedback-related techniques to optimize decision-making under threat. Critically, the findings demonstrate the relevance of incorporating internal psychophysiological states and external action-contexts into models of approach-avoidance decision-making.

The role of psychopathic traits, social anxiety and cortisol in social approach avoidance tendencies

Social anxiety and psychopathy have conceptually been linked to nearly opposite emotional, behavioral and endocrinological endophenotypes, representing social fearfulness and fearlessness, respectively. Although such a dimensional view has theoretical and practical implications, no study has directly compared social anxiety and psychopathy in terms of emotional experiences, relevant hormones (i.e. cortisol, testosterone) and behavioral tendencies (i.e. social approach-avoidance). Therefore, the present study examined 1) whether self-reported social anxiety and psychopathic traits are indeed anticorrelated, and 2) whether social anxiety, psychopathic traits, cortisol, testosterone and their interplay are differentially linked to social approach-avoidance tendencies. In a well-powered study, a sample of 196 healthy female participants, we assessed self-reported emotional and behavioral tendencies of social fear (i.e. social anxiety and social avoidance) and psychopathic traits (i.e. Factor I [interpersonal-affective deficit] and Factor II [impulsive behavior]). Furthermore, hormone levels were assessed, and approach-avoidance tendencies towards emotional (angry, happy) facial expressions were measured by means of a joystick reaction time task. Results confirmed that self-reported emotional tendencies of social anxiety and psychopathy Factor I (interpersonal-affective deficit) correlated negatively, but self-reported behavioral tendencies (social avoidance and psychopathy Factor II [impulsive behavior]) correlated positively. Furthermore, Structural Equation Modelling demonstrated that participants with higher social anxiety and higher cortisol levels showed an avoidance tendency towards happy faces, while participants with higher psychopathic traits showed an approach tendency towards angry faces. In sum, the notion that social anxiety and psychopathic traits are opposing ends of one dimension was supported only in terms of self-reported emotional experiences, but a comparable relationship with regard to behavioral and endocrinological aspects is debatable. The current findings stress the necessity to study emotional, endocrinological and behavioral factors in unison in order to better understand the shared and distinctive mechanisms of social anxiety and psychopathic traits.

Neural underpinnings of valence-action interactions triggered by cues and targets in a rewarded approach/avoidance task

Incentive-valence signals have a large impact on our actions in everyday life. While it is intuitive (and most often beneficial) to approach positive and avoid negative stimuli, these prepotent response tendencies can also be maladaptive, as exemplified by clinical conditions such as overeating or pathological gambling. We have recently shown that targets associated with monetary incentives can trigger such valence-action biases (target condition), and that these are absent when valence and action information are provided by advance cues (cue condition). Here, we explored the neural correlates underlying the absence of the behavioral bias in this condition using fMRI. Specifically, we tested in how far valence and action information are integrated at all in the cue condition (where no behavioral biases are observed), assessing activity at the moment of the cue (mainly preparation) and the target (mainly implementation). The cue-locked data was dominated by main effects of valence with increased activity for incentive versus no-incentive cues in a network including anterior insula, premotor cortex, (mostly ventral) striatum (voxel-wise analysis), and across five predefined regions of interest (ROI analysis). Only one region, the anterior cingulate cortex, featured a valence-action interaction, with increased activity for win-approach compared to no-incentive-approach cues. The target-locked data revealed a different interaction pattern with increased activity in loss-approach as compared to win-approach targets in the cerebellum (voxel-wise) and across all ROIs. For comparison, the uncued target condition (target-locked data only) featured valence and action main effects (incentive > no-incentive targets; approach > avoid targets), but no interactions. The results resonate with the common observations that performance benefits after incentive-valence cues are promoted by increased preparatory control. Moreover, the data provide support for the idea that valence and action information are integrated according to an evolutionary benefit (cue-locked), requiring additional neural resources to implement non-intuitive valence-action mappings (target-locked).

Patients with Ventromedial Prefrontal Lesions Show an Implicit Approach Bias to Angry Faces

Damage to the ventromedial PFC (VMPFC) can cause maladaptive social behavior, but the cognitive processes underlying these behavioral changes are still uncertain. Here, we tested whether patients with acquired VMPFC lesions show altered approach-avoidance tendencies to emotional facial expressions. Thirteen patients with focal VMPFC lesions and 31 age- and gender-matched healthy controls performed an implicit approach-avoidance task in which they either pushed or pulled a joystick depending on stimulus color. Whereas controls avoided angry faces, VMPFC patients displayed an incongruent response pattern characterized by both increased approach and reduced avoidance of angry facial expressions. The approach bias was stronger in patients with higher self-reported impulsivity and disinhibition and in those with larger lesions. We further used linear ballistic accumulator modeling to investigate latent parameters underlying approach-avoidance decisions. Controls displayed negative drift rates when approaching angry faces, whereas VMPFC lesions abolished this pattern. In addition, VMPFC patients had weaker response drifts than controls during avoidance. Finally, patients showed reduced drift rate variability and shorter nondecision times, indicating impulsive and rigid decision-making. Our findings thus suggest that VMPFC damage alters the pace of evidence accumulation in response to social signals, eliminating a default, protective avoidant bias and facilitating a dysfunctional approach behavior.

Irritability Is Associated With Decreased Cortical Surface Area and Anxiety With Decreased Gyrification During Brain Development

Background: Brain development is of utmost importance for the emergence of psychiatric disorders, as the most severe of them arise before 25 years old. However, little is known regarding how early transdiagnostic symptoms, in a dimensional framework, are associated with cortical development. Anxiety and irritability are central vulnerability traits for subsequent mood and anxiety disorders. In this study, we investigate how these dimensions are related to structural changes in the brain to understand how they may increase the transition risk to full-blown disorders. Methods: We used the opportunity of an open access developmental cohort, the Healthy Brain Network, to investigate associations between cortical surface markers and irritability and anxiety scores as measured by parents and self-reports. Results: We found that in 658 young people (with a mean age of 11.6) the parental report of irritability is associated with decreased surface area in the bilateral rostral prefrontal cortex and the precuneus. Furthermore, parental reports of anxiety were associated with decreased local gyrification index in the anterior cingulate cortex and dorsomedial prefrontal cortex. Conclusions: These results are consistent with current models of emotion regulation network maturation, showing decreased surface area or gyrification index in regions associated with impaired affective control in mood and anxiety disorders. Our results highlight how dimensional traits may increase vulnerability for these disorders.

Improving emotional-action control by targeting long-range phase-amplitude neuronal coupling

Control over emotional action tendencies is essential for everyday interactions. This cognitive function fails occasionally during socially challenging situations, and systematically in social psychopathologies. We delivered dual-site phase-coupled brain stimulation to facilitate theta-gamma phase-amplitude coupling between frontal regions known to implement that form of control, while neuropsychologically healthy human male participants were challenged to control their automatic action tendencies in a social-emotional approach/avoidance-task. Participants had increased control over their emotional action tendencies, depending on the relative phase and dose of the intervention. Concurrently measured fMRI effects of task and stimulation indicated that the intervention improved control by increasing the efficacy of anterior prefrontal inhibition over the sensorimotor cortex. This enhancement of emotional action control provides causal evidence for phase-amplitude coupling mechanisms guiding action selection during emotional-action control. Generally, the finding illustrates the potential of physiologically-grounded interventions aimed at reducing neural noise in cerebral circuits where communication relies on phase-amplitude coupling.

Molecular and neurocircuitry mechanisms of social avoidance

Humans and animals live in social relationships shaped by actions of approach and avoidance. Both are crucial for normal physical and mental development, survival, and well-being. Active withdrawal from social interaction is often induced by the perception of threat or unpleasant social experience and relies on adaptive mechanisms within neuronal networks associated with social behavior. In case of confrontation with overly strong or persistent stressors and/or dispositions of the affected individual, maladaptive processes in the neuronal circuitries and its associated transmitters and modulators lead to pathological social avoidance. This review focuses on active, fear-driven social avoidance, affected circuits within the mesocorticolimbic system and associated regions and a selection of molecular modulators that promise translational potential. A comprehensive review of human research in this field is followed by a reflection on animal studies that offer a broader and often more detailed range of analytical methodologies. Finally, we take a critical look at challenges that could be addressed in future translational research on fear-driven social avoidance.