Climate change on the brain: Neural correlates of climate anxiety

Climate change is a global crisis impacting individuals' mental health. Climate anxiety is an emerging area of interest within popular culture and the scientific community. Yet, little is known about the mechanisms underlying climate anxiety. We provide evidence that climate anxiety is related to gray matter volume in the midcingulate cortex as well as its level of functional connectivity with the insula cortex. These neuroanatomical and neurofunctional features of climate anxiety are involved in identifying and anticipating potential threats within the environment and preparing an appropriate action response to such threats. These neural correlates align with those observed in anxiety disorders. Yet, climate anxiety itself as well as the neural correlates of climate anxiety were related to pro-environmental behavior. This may suggest that the midcingulate and insula are part of a network linked to an adaptive aspect of climate anxiety in motivating behavioral engagement.

The gray matter morphology associated with the electrophysiological response to errors in individuals with high trait anxiety

Enhanced error monitoring has been associated with higher levels of anxiety. This has been consistently demonstrated in its most reliable electrophysiological index, the error-related negativity (ERN), such that increased ERN is related with elevated anxiety symptomology. However, it is still unclear whether the structural properties of the brain are associated with individual differences in ERN amplitude. Moreover, the relationship between ERN and anxiety has recently been suggested to be moderated by sex, but the degree to which sex moderates the association between brain structure and ERN amplitude is unknown. The present study investigated the association between gray matter volume (GMV) and ERN amplitude in individuals with high trait anxiety (N = 98) as well as the role of sex in moderating this association. The ERN was elicited from a flanker task, whereas structural MRI images were obtained from whole brain structural T1-weighted MRI scans. The results of voxel-based morphometry analyses showed that the relationship between ERN difference scores and GMV was moderated by sex in the dorsal anterior cingulate cortex (dACC). This sex difference was derived from a negative correlation between ERN difference scores and dACC GMV in females and a positive correlation in males. Our findings are in accordance with the critical role of the dACC serving as a neural substrate of error monitoring. It also provides further evidence for sex-specific associations with brain structures related to error monitoring.

Reliability of attention bias and attention bias variability to climate change images in the dot-probe task

Climate change is one of the most pressing issues of the 21st century, which is perhaps why information about climate change has been found to capture observers' attention. One of the most common ways of assessing individual differences in attentional processing of climate change information is through the use of reaction time difference scores. However, reaction time-based difference scores have come under scrutiny for their low reliability. Given that a primary goal of the field is to link individual differences in attention processing to participant variables (e.g., environmental attitudes), we assessed the reliability of reaction time-based measures of attention processing of climate change information utilizing an existing dataset with three variations of the dot-probe task. Across all three samples, difference score-based measures of attentional bias were generally uncorrelated across task blocks (r = -0.25 to 0.31). We also assessed the reliability of newer attention bias variability measures that are thought to capture dynamic shifts in attention toward and away from salient information. Although these measures were initially found to be correlated across task blocks (r = 0.17-0.67), they also tended to be highly correlated with general reaction time variability (r = 0.49-0.83). When controlling for general reaction time variability, the correlations across task blocks for attention bias variability were much weaker and generally nonsignificant (r = -0.25 to 0.33). Furthermore, these measures were unrelated to pro-environmental disposition indicating poor predictive validity. In short, reaction time-based measures of attentional processing (including difference score and variability-based approaches) have unacceptably low levels of reliability and are therefore unsuitable for capturing individual differences in attentional bias to climate change information.

Eye-size effects in the dot-probe task: Greater sclera exposure predicts delayed disengagement from fearful faces

Fearful facial expressions are nonverbal and biologically salient signals of potential threat that automatically hold, capture, and direct observers' attention. They are characterized by enlarged eye whites and dilated pupils, and fearful eyes alone are sufficient to capture attention. The morphological properties of the eye region, such as sclera exposure, are thought to play an important role in nonverbal communication. Specifically, increased sclera exposure associated with fearful expressions has been shown to moderate how observers' shift their attention toward the direction of another's gaze. Yet, the extent to which variability in sclera exposure possibly impacts the capture and hold of attention by fearful faces is untested. To address this, a sample of 249 adults completed a dot-probe task of selective attention with fearful and neutral faces. The results suggested that (1) fearful faces were prioritized over neutral faces (i.e., they captured and held attention), (2) greater sclera exposure at target locations facilitated reaction times, and (3) attention was held by greater sclera exposure of fearful faces at task irrelevant locations resulting in delayed disengagement. Collectively, the results indicate that fearful facial expressions and sclera exposure modulate spatial attention through independent and interactive mechanisms. Sclera exposure appears to be an important facilitator of nonverbal communication and perhaps represents an understudied variable in social cognition more broadly.

Sex Differences in Anxiety: An Investigation of the Moderating Role of Sex in Performance Monitoring and Attentional Bias to Threat in High Trait Anxious Individuals

Anxiety disorders are more predominant in women than men, however there is a lack of understanding as to what neurocognitive mechanisms drive this sex difference. Recent investigation has found a potential moderating role of sex in the relationship between anxiety and the error related negativity (ERN)—a component of error-monitoring that is prevalent in high anxiety individuals—such that females display a positive relationship between anxiety/worry and ERN amplitude. We strove to further explore the influence of sex on the relationship between trait anxiety and performance monitoring, specifically with ERN, as well as extend this work to include another hallmark of anxiety, attentional bias to threat. To meet this end, participants performed the flanker and dot-probe tasks, respectively. We did not find a significant difference in the relationship between attention bias scores and anxiety for female vs. males participants. Furthermore, ΔERN amplitudes were greater in males compared to females, and males had more positive CRN amplitudes than females. There were no significant associations between ERN or ΔERN with anxiety in both male and female participants. However, there was a significant relationship between CRN amplitudes and trait anxiety in male but not female participants. Given these results, the effect of sex on the relationship between components of performance monitoring—namely the CRN and ERN—and anxiety may be more nuanced than the current understanding. Our study was limited to detecting medium to large sized moderation effects. Our findings may be important for future meta-analysis on sex differences in anxiety.

Enhanced contralateral theta oscillations and N170 amplitudes in occipitotemporal scalp regions underlie attentional bias to fearful faces

Attending toward fearful faces and other threatening stimuli increase the chance of survival. The dot-probe task is a commonly used measure of spatial attention. Event-related potentials (ERPs) have been found to be a reliable measure of attentional bias. The dot-probe literature suggests that posterior contralateral N170 amplitudes are more enhanced by fearful faces compared to ipsilateral amplitudes. However, ERP methods remove non-phase locked frequencies, which provides additional information about neural activity. Specifically, theta oscillations (5-7 Hz) have been linked to attentional processing. The purpose of this study was to examine the relationship between posterior contralateral theta oscillations and N170 amplitudes in the dot-probe task. A modified dot-probe task was used with fear and neutral facial expressions and EEG data was recorded from 33 electrodes. The ERP and time-frequency data were extracted from the P7 and P8 electrodes (left and right occipitotemporal regions). This study found enhanced N170 amplitude and theta oscillations in the electrodes posterior contralateral to the fearful face. Contralateral N170 amplitudes and theta oscillations were related such that greater N170 amplitudes were associated with greater theta oscillations. The results indicated that increased contralateral N170 and theta oscillations are related to each other and underlie attentional bias to fearful faces.

A systematic review of event-related potentials as outcome measures of attention bias modification

Attention bias modification (ABM) was initially developed with the goal of reducing attentional bias to threat-and subsequently anxious symptoms-in individuals with heightened anxiety. Although controversial, ABM appears to be generally effective in achieving this goal. Yet, the primary outcome measure of ABM (i.e., the reaction time-based differences score) has poor reliability and temporal resolution, which limits the inferences that can be drawn. In contrast, event-related potentials (ERPs) have superior reliability as well as temporal resolution and may therefore be better outcome measures of ABM. In this review, I systematically assess the research using ERPs as outcome measures in ABM protocols. I focus on the extent to which the ERPs modified by ABM represent earlier or later stages of information processing. In addition, I explore the extent to which ABM produces near and/or far transfer of learning effects on ERP measures. The reviewed literature suggests that ERPs are promising outcome measures of ABM. ABM modulates the effects of affective stimuli on posterior visually evoked ERPs (i.e., P1) as well as ERPs at anterior electrodes (i.e., P2, N2, and ERN). Based on the state of the field, several directions for future research are identified.

Dorsal anterior cingulate cortex intrinsic functional connectivity linked to electrocortical measures of error monitoring

The error-related negativity (ERN) is a response-locked event-related potential, occurring approximately 50 ms following an erroneous response at frontocentral electrode sites. Source localization and functional magnetic resonance imaging (fMRI) research indicate that the ERN is likely generated by activity in the dorsal anterior cingulate cortex (dACC). The dACC is thought to be a part of a broader network of brain regions that collectively comprise an error monitoring network. However, little is known about how intrinsic connectivity within the dACC-based error monitoring network contributes to variability in ERN amplitude. The purpose of this study was to assess the relationship between dACC functional connectivity and ERN amplitude. In a sample of highly trait anxious individuals, the ERN was elicited in a flanker task and functional connectivity was assessed in a 10-min resting-state fMRI scan. Results suggest that the strength of dACC seeded functional connectivity with the supplementary motor area is correlated with the ΔERN (i.e., incorrect-correct responses) amplitude such that greater ΔERN amplitude was accompanied by greater functional coupling between these regions. In sum, ERN amplitude appears to be related to the strength of functional connectivity between error monitoring and motor control regions of the brain.

Elevated levels of serum, but not salivary, brain-derived neurotrophic factor following mild traumatic brain injury in collegiate athletes post return-to-play

Brain-derived neurotrophic factor (BDNF) helps restore neuronal function following mild traumatic brain injury. BDNF levels can be obtained in blood serum and more recently in saliva. However, the relationship between serum and salivary BDNF is poorly understood—especially in relation to alterations in BDNF levels following mild traumatic brain injury. In this study, serum and salivary BDNF were collected from a sample of 42 collegiate student athletes. Half of the participants were recently cleared by a physician and/or an athletic trainer to return-to-play after experiencing a sports-related concussion. The other half had not experienced a concussion within the past year and were matched by age, sex, sport, and time of sample. Results suggest that incidences of depression, anxiety, and stress were all elevated in the concussion group, relative to the control participants. When controlling for stress-related negative affect, serum BDNF was elevated in the concussion group. However, there was no difference in salivary BDNF. Serum and salivary BDNF were uncorrelated across the entire sample. Yet, these measures of BDNF were correlated in the concussion group, but not the control group. In sum, serum BDNF is elevated in concussion post return-to-play; however, further research is needed to explore the utility of salivary BDNF following concussion.

Affective Images of Climate Change

Climate change is not only a scientific phenomenon, but also a cultural one. Individuals' opinions on climate change are often based on emotion rather than on scientific evidence. Therefore, research into the emotional characteristics of the imagery that the non-expert public find relevant to climate change is important in order to build a database of effective climate change imagery, which can then be used by scientists, policymakers, and practitioners in mobilizing climate adaptation and resilience efforts. To this end, we collected ratings of relevance to climate change as well as emotional arousal and valence on 320 images to assess the relationship between relevance to climate change and the emotional qualities of the image. In addition, participants' environmental beliefs were measured, to investigate the relationship between beliefs and image ratings. The results suggest that images rated highly relevant to climate change are higher in negative emotional valence and emotional arousal. Overall, images were rated as being more relevant to climate change by participants with higher pro-environmental disposition. Critically, we have compiled the mean relevance, valence, and arousal ratings of each of these 320 images into a database that is posted online and freely available (https://affectiveclimateimages.weebly.com; https://www.nmu.edu/affectiveclimateimages) for use in future research on climate change visuals.

Variability in anterior insula grey matter volume correlates with awareness for peri-threshold backward-masked fearful faces

The threshold for conscious perception of stimuli within the environment varies from individual to individual. Functional neuroimaging studies have suggested that insular cortex activity is positively correlated with perceptual awareness. However, few studies have tested the relationship between awareness and structural variability in the insula. The purpose of this study was to examine structural differences in brain morphology related to perceptual awareness of fearful faces. This study hypothesized that there would be a positive correlation between insular grey matter volume and scores on the forced-choice awareness check task. The forced-choice awareness check task was designed to assess awareness for the presence and location of backward masked fearful and neutral faces, masked with neutral faces. The participants responded by indicating the side on which the masked fearful face appeared, or whether there were two neutral faces. The task included a total of 60 trials. T1-weighted magnetic resonance images were collected to measure grey matter volumes. Individuals that were more aware of backward masked fearful faces had greater grey matter volume in the insula, middle cingulate, anterior temporal pole, ventral striatum, and hippocampus.

No Money, No Problem: Enhanced Reward Positivity in the Absence of Monetary Reward

The reward-related positivity (RewP) is an event-related potential (ERP) with a positive amplitude occurring approximately 250–350 ms post-feedback at frontocentral electroencephalogram (EEG) electrode sites. The RewP is typically elicited in monetary gambling tasks and has a relatively larger amplitude for positive vs. negative outcomes. However, the extent to which RewP amplitude is modulated by non-monetary feedback is less clear. To address this issue, EEG was used to record reward-related electrocortical activity during a simple non-monetary gambling task. We hypothesized that the RewP would be enhanced for non-monetary wins relative to losses, which was supported by the results. In our supplementary material, we provide additional analyses suggesting that this effect was not observed for the P3. In sum, RewP amplitudes were larger for positive (nonmonetary) feedback relative to negative feedback at frontocentral electrode sites—suggesting that monetary reward is not necessary to elicit the RewP.

Climate change images produce an attentional bias associated with pro-environmental disposition

Humans have developed mechanisms to prioritize certain sensory input(s). Emotionally salient stimuli automatically capture observers' attention at the cost of less salient information. This prioritized processing is called attentional bias. Images of climate change have been found to elicit emotional responses. Yet, to date, there is no research assessing the extent to which climate change-relevant images produce an attentional bias. In a sample of college students (N = 39), we found that (1) climate change-related images capture attention and that (2) this attentional bias is related to individual differences in environmental disposition. Thus, images of climate change are salient-attention grabbing-signals related to pro-environmental orientation.

Temporal dynamics in attention bias: effects of sex differences, task timing parameters, and stimulus valence

New methods of calculating indices from the dot-probe task measure temporal dynamics in attention bias or fluctuations in attention bias towards and away from emotional stimuli over time. However, it is unclear how task-specific parameters such as stimulus valence and stimulus onset asynchrony (SOA) as well as participant sex affect temporal dynamics in attention bias. To address this, male and female participants (N = 106) completed either a fearful or happy face dot-probe task with four levels of SOA (84 ms, 168 ms, 336 ms, and 672 ms). Results suggest that temporal dynamics in attention bias are (1) greatest at the longest SOA, (2) greater in females, and (3) insensitive to stimulus valence. These findings indicate that participant sex and task timing, but not stimulus valence, are related to temporal dynamics in attention bias and should be considered in future studies utilizing this approach.

Extended testing with the dot-probe task increases test-retest reliability and validity

The dot-probe task is used to measure attentional biases toward threat. However, the test-retest reliability and validity of the task have been called into question. No studies to date have included an extended number of testing sessions or tailored the task to individual participants by incorporating self-relevant stimuli-doing so may improve reliability. Here, participants provided 10 words that caused them anxiety and 10 neutral words which were incorporated into a dot-probe task for 6 sessions. The test-retest reliability of their bias indices was stronger in bottom-target trials relative to top-target trials and stronger among later relative to earlier sessions. State and trait anxiety were moderately correlated with bias indices in later sessions, but not earlier sessions. Overall reaction time in each session was moderately correlated with state and trait anxiety. These results suggest that including extended testing may facilitate dot-probe task test-retest reliability and validity.

Lost emotion: Disrupted brain-based tracking of dynamic affective episodes in anxiety and depression

In our day-to-day lives we are confronted with dynamic sensory inputs that elicit a continuously evolving emotional response. Insight into the brain basis of the dynamic nature of emotional reactivity may be critical for understanding chronic symptoms of anxiety and depression. Here, individuals with generalized anxiety disorder, major depressive disorder, and healthy controls watched a video with dynamic affective content while fMRI activity was recorded. Across all participants there was a large-scale tracking of affective content in emotion processing regions and the default mode network. Anxious and depressed individuals displayed less brain-based coupling within these regions and the extent of this uncoupling correlated with variability in emotional numbing. Thus, abnormal neural tracking of affective information during dynamic emotional episodes appears to represent a disconnection between affective cues in the environment and an individual's response to these cues-providing a putative neural basis for context insensitive affective reactivity and emotional numbing.

Acute psychological stress induces short-term variable immune response

In spite of advances in understanding the cross-talk between the peripheral immune system and the brain, the molecular mechanisms underlying the rapid adaptation of the immune system to an acute psychological stressor remain largely unknown. Conventional approaches to classify molecular factors mediating these responses have targeted relatively few biological measurements or explored cross-sectional study designs, and therefore have restricted characterization of stress-immune interactions. This exploratory study analyzed transcriptional profiles and flow cytometric data of peripheral blood leukocytes with physiological (endocrine, autonomic) measurements collected throughout the sequence of events leading up to, during, and after short-term exposure to physical danger in humans. Immediate immunomodulation to acute psychological stress was defined as a short-term selective up-regulation of natural killer (NK) cell-associated cytotoxic and IL-12 mediated signaling genes that correlated with increased cortisol, catecholamines and NK cells into the periphery. In parallel, we observed down-regulation of innate immune toll-like receptor genes and genes of the MyD88-dependent signaling pathway. Correcting gene expression for an influx of NK cells revealed a molecular signature specific to the adrenal cortex. Subsequently, focusing analyses on discrete groups of coordinately expressed genes (modules) throughout the time-series revealed immune stress responses in modules associated to immune/defense response, response to wounding, cytokine production, TCR signaling and NK cell cytotoxicity which differed between males and females. These results offer a spring-board for future research towards improved treatment of stress-related disease including the impact of stress on cardiovascular and autoimmune disorders, and identifies an immune mechanism by which vulnerabilities to these diseases may be gender-specific.

Gender moderates the association between dorsal medial prefrontal cortex volume and depressive symptoms in a subclinical sample

Major depressive disorder is associated with lower medial prefrontal cortex volumes. The role that gender might play in moderating this relationship and what particular medial prefrontal cortex subregion(s) might be implicated is unclear. Magnetic resonance imaging was used to assess dorsal, ventral, and anterior cingulate regions of the medial prefrontal cortex in a normative sample of male and female adults. The Depression, Anxiety, and Stress Scale (DASS) was used to measure these three variables. Voxel-based morphometry was used to test for correlations between medial prefrontal gray matter volume and depressive traits. The dorsal medial frontal cortex was correlated with greater levels of depression, but not anxiety and stress. Gender moderates this effect: in males greater levels of depression were associated with lower dorsal medial prefrontal volumes, but in females no relationship was observed. The results indicate that even within a non-clinical sample, male participants with higher levels of depressive traits tend to have lower levels of gray matter volume in the dorsal medial prefrontal cortex. Our finding is consistent with low dorsal medial prefrontal volume contributing to the development of depression in males. Future longitudinal work is needed to substantiate this possibility.

Stick-slip instabilities in sheared granular flow: The role of friction and acoustic vibrations

We propose a theory of shear flow in dense granular materials. A key ingredient of the theory is an effective temperature that determines how the material responds to external driving forces such as shear stresses and vibrations. We show that, within our model, friction between grains produces stick-slip behavior at intermediate shear rates, even if the material is rate strengthening at larger rates. In addition, externally generated acoustic vibrations alter the stick-slip amplitude, or suppress stick-slip altogether, depending on the pressure and shear rate. We construct a phase diagram that indicates the parameter regimes for which stick-slip occurs in the presence and absence of acoustic vibrations of a fixed amplitude and frequency. These results connect the microscopic physics to macroscopic dynamics and thus produce useful information about a variety of granular phenomena, including rupture and slip along earthquake faults, the remote triggering of instabilities, and the control of friction in material processing.

Reward dysfunction in major depression: multimodal neuroimaging evidence for refining the melancholic phenotype

Reward dysfunction is thought to play a core role in the pathophysiology of major depressive disorder (MDD). Event-related potential (ERP) and functional magnetic resonance imaging (fMRI) studies have identified reward processing deficits in MDD, but these methods have yet to be applied together in a single MDD sample. We utilized multimodal neuroimaging evidence to examine reward dysfunction in MDD. Further, we explored how neurobiological reward dysfunction would map onto subtypes of MDD. The feedback negativity (FN), an ERP index of reward evaluation, was recorded in 34 unmedicated depressed individuals and 42 never-depressed controls during a laboratory gambling task. Ventral striatal (VS) activation to reward was recorded in a separate fMRI session, using an identical task, among a subgroup of 24 depressed individuals and a comparison group of 18 non-depressed controls. FN amplitude was blunted in MDD. This effect was driven by a MDD subgroup characterized by impaired mood reactivity to positive events, a core feature of melancholic MDD. A similar pattern was observed for VS activation, which was also blunted among the MDD subgroup with impaired mood reactivity. Neither FN amplitude nor VS activation was related to the full, DSM-defined melancholic or atypical MDD subtypes. Across the MDD sample, FN amplitude and VS activation were correlated, indicating convergence across methods. These results indicate that not all MDD is characterized by reward dysfunction, and that there is meaningful heterogeneity in reward processing within MDD. The current study offers neurobiological evidence that impaired mood reactivity is a key phenotypic distinction for subtyping MDD, and further suggests that the existing melancholic phenotype may require further refinement.

Shear flow of angular grains: acoustic effects and nonmonotonic rate dependence of volume

Naturally occurring granular materials often consist of angular particles whose shape and frictional characteristics may have important implications on macroscopic flow rheology. In this paper, we provide a theoretical account for the peculiar phenomenon of autoacoustic compaction-nonmonotonic variation of shear band volume with shear rate in angular particles-recently observed in experiments. Our approach is based on the notion that the volume of a granular material is determined by an effective-disorder temperature known as the compactivity. Noise sources in a driven granular material couple its various degrees of freedom and the environment, causing the flow of entropy between them. The grain-scale dynamics is described by the shear-transformation-zone theory of granular flow, which accounts for irreversible plastic deformation in terms of localized flow defects whose density is governed by the state of configurational disorder. To model the effects of grain shape and frictional characteristics, we propose an Ising-like internal variable to account for nearest-neighbor grain interlocking and geometric frustration and interpret the effect of friction as an acoustic noise strength. We show quantitative agreement between experimental measurements and theoretical predictions and propose additional experiments that provide stringent tests on the new theoretical elements.

Anticipation of high arousal aversive and positive movie clips engages common and distinct neural substrates

The neural correlates of anxious anticipation have been primarily studied with aversive and neutral stimuli. In this study, we examined the effect of valence on anticipation by using high arousal aversive and positive stimuli and a condition of uncertainty (i.e. either positive or aversive). The task consisted of predetermined cues warning participants of upcoming aversive, positive, 'uncertain' (either aversive or positive) and neutral movie clips. Anticipation of all affective clips engaged common regions including the anterior insula, dorsal anterior cingulate cortex, thalamus, caudate, inferior parietal and prefrontal cortex that are associated with emotional experience, sustained attention and appraisal. In contrast, the nucleus accumbens and medial prefrontal cortex, regions implicated in reward processing, were selectively engaged during anticipation of positive clips (depicting sexually explicit content) and the mid-insula, which has been linked to processing aversive stimuli, was selectively engaged during anticipation of aversive clips (depicting graphic medical procedures); these three areas were also activated during anticipation of 'uncertain' clips reflecting a broad preparatory response for both aversive and positive stimuli. These results suggest that a common circuitry is recruited in anticipation of affective clips regardless of valence, with additional areas preferentially engaged depending on whether expected stimuli are negative or positive.

Functional and structural amygdala - anterior cingulate connectivity correlates with attentional bias to masked fearful faces

An attentional bias to threat has been causally related to anxiety. Recent research has linked nonconscious attentional bias to threat with variability in the integrity of the amygdala - anterior cingulate pathway, which sheds light on the neuroanatomical basis for a behavioral precursor to anxiety. However, the extent to which structural variability in amygdala - anterior cingulate integrity relates to the functional connectivity within this pathway and how such functional connectivity may relate to attention bias behavior, remain critical missing pieces of the puzzle. In 15 individuals we measured the structural integrity of the amygdala - prefrontal pathway with diffusion tensor-weighted MRI (magnetic resonance imaging), amygdala-seeded intrinsic functional connectivity to the anterior cingulate, and attentional bias toward backward masked fearful faces with a dot-probe task. We found that greater biases in attention to threat predicted greater levels of uncinate fasciculus integrity, greater positive amygdala - anterior cingulate functional connectivity, and greater amygdala coupling with a broader social perception network including the superior temporal sulcus, tempoparietal junction (TPJ), and somatosensory cortex. Additionally, greater levels of uncinate fasciculus integrity correlated with greater levels of amygdala - anterior cingulate intrinsic functional connectivity. Thus, high bias individuals displayed a heightened degree of amygdala - anterior cingulate connectivity during basal conditions, which we believe predisposes these individuals to focus their attention on signals of threat within their environment.

Ventromedial prefrontal cortex reactivity is altered in generalized anxiety disorder during fear generalization

BACKGROUND

Fear generalization is thought to contribute to the development and maintenance of anxiety symptoms and accordingly has been the focus of recent research. Previously, we reported that in healthy individuals (N = 25) neural reactivity in the insula, anterior cingulate cortex (ACC), supplementary motor area (SMA), and caudate follow a generalization gradient with a peak response to a conditioned stimulus (CS) that declines with greater perceptual dissimilarity of generalization stimuli (GS) to the CS. In contrast, reactivity in the ventromedial prefrontal cortex (vmPFC), a region linked to fear inhibition, showed an opposite response pattern. The aim of the current study was to examine whether neural responses to fear generalization differ in generalized anxiety disorder (GAD). A second aim was to examine connectivity of primary regions engaged by the generalization task in the GAD group versus healthy group, using psychophysiological interaction analysis.

METHODS

Thirty-two women diagnosed with GAD were scanned using the same generalization task as our healthy group.

RESULTS

Individuals with GAD exhibited a less discriminant vmPFC response pattern suggestive of deficient recruitment of vmPFC during fear inhibition. Across participants, there was enhanced anterior insula (aINS) coupling with the posterior insula, ACC, SMA, and amygdala during presentation of the CS, consistent with a modulatory role for the aINS in the execution of fear responses.

CONCLUSIONS

These findings suggest that deficits in fear regulation, rather than in the excitatory response itself, are more critical to the pathophysiology of GAD in the context of fear generalization.

Acute stress eliminates female advantage in detection of ambiguous negative affect

The human stress response evolved to maximize an individual's probability of survival when threatened. The present study addressed whether physical danger modulates perception of an unrelated ambiguous threat and, if so, to what extent this response is sex- specific. The authors utilized a first-time tandem skydive as a stressor, which had been previously validated as producing a highly-controlled, genuinely stressful environment. In a counter-balanced within-subjects design, participants wore a virtual reality helmet to complete an emotion-identification task during the plane's ascent (stress condition) and in the laboratory (control condition). Participants were presented static male faces morphed between 20-80% aggression, which gradually emerged from degraded images. Using a binary forced-choice design, participants identified each ambiguous face as aggressive or neutral. Results showed that participants characterized emotion more rapidly under stress versus control conditions. Unexpectedly, the results also show that while women were more sensitive to affect ambiguity than men under control conditions, they exhibited a marked decrease in sensitivity equivalent to men while under stress.

Acute Stress Eliminates Female Advantage in Detection of Ambiguous Negative Affect

The human stress response evolved to maximize an individual's probability of survival when threatened. The present study addressed whether physical danger modulates perception of an unrelated ambiguous threat and, if so, to what extent this response is sex-specific. The authors utilized a first-time tandem skydive as a stressor, which had been previously validated as producing a highly-controlled, genuinely stressful environment. In a counter-balanced within-subjects design, participants wore a virtual reality helmet to complete an emotion-identification task during the plane's ascent (stress condition) and in the laboratory (control condition). Participants were presented static male faces morphed between 20–80% aggression, which gradually emerged from degraded images. Using a binary forced-choice design, participants identified each ambiguous face as aggressive or neutral. Results showed that participants characterized emotion more rapidly under stress versus control conditions. Unexpectedly, the results also show that while women were more sensitive to affect ambiguity than men under control conditions, they exhibited a marked decrease in sensitivity equivalent to men while under stress.

Nonconscious attention bias to threat is correlated with anterior cingulate cortex gray matter volume: a voxel-based morphometry result and replication

An important aspect of the fear response is the allocation of spatial attention toward threatening stimuli. This response is so powerful that modulations in spatial attention can occur automatically without conscious awareness. Functional neuroimaging research suggests that the amygdala and anterior cingulate cortex (ACC) form a network involved in the rapid orienting of attention to threat. A hyper-responsive attention bias to threat is a common component of anxiety disorders. Yet, little is known of how individual differences in underlying brain morphometry relate to variability in attention bias to threat. Here, we performed two experiments using dot-probe tasks that measured individuals' attention bias to backward masked fearful faces. We collected whole-brain structural magnetic resonance images and used voxel-based morphometry to measure brain morphometry. We tested the hypothesis that reduced gray matter within the amygdala and ACC would be associated with reduced attention bias to threat. In Experiment 1, we found that backward masked fearful faces captured spatial attention and that elevated attention bias to masked threat was associated with greater ACC gray matter volumes. In Experiment 2, this association was replicated in a separate sample. Thus, we provide initial and replicating evidence that ACC gray matter volume is correlated with biased attention to threat. Importantly, we demonstrate that variability in affective attention bias within the healthy population is associated with ACC morphometry. This result opens the door for future research into the underlying brain morphometry associated with attention bias in clinically anxious populations.

The NIRS Analysis Package: noise reduction and statistical inference

Near infrared spectroscopy (NIRS) is a non-invasive optical imaging technique that can be used to measure cortical hemodynamic responses to specific stimuli or tasks. While analyses of NIRS data are normally adapted from established fMRI techniques, there are nevertheless substantial differences between the two modalities. Here, we investigate the impact of NIRS-specific noise; e.g., systemic (physiological), motion-related artifacts, and serial autocorrelations, upon the validity of statistical inference within the framework of the general linear model. We present a comprehensive framework for noise reduction and statistical inference, which is custom-tailored to the noise characteristics of NIRS. These methods have been implemented in a public domain Matlab toolbox, the NIRS Analysis Package (NAP). Finally, we validate NAP using both simulated and actual data, showing marked improvement in the detection power and reliability of NIRS.

The orienting of spatial attention to backward masked fearful faces is associated with variation in the serotonin transporter gene

Threat signals facilitate spatial attention, even when awareness of these signals has been restricted through the use of backward masking. However, unrestricted/unmasked threat cues tend to delay the disengagement of attention, whereas restricted/masked threat facilitates orienting, suggesting different underlying mechanisms. Within the general population, the serotonin transporter gene polymorphism (5HTTLPR) is associated with one's allocation of attention to unmasked threat signals. However, it is unclear to what extent the 5HTTLPR gene may be involved in nonconscious biases to masked threat, and whether or not such biases are driven by facilitated orienting or delayed disengagement. Participants were genotyped and performed a dot-probe task with backward masked fearful and neutral faces. Results indicate that short-allele carriers of the 5HTTLPR gene nonconsciously orient spatial attention to masked fearful faces. On the other hand, homozygous long-allele individuals tended to direct attention away from masked fearful faces. All participants' performance was at chance in a posttask assessment of awareness for the masked faces. The results add to current literature on the 5HTTLPR and attention biases, and suggest that threat signals facilitate the orienting of attention in short-allele carriers of the 5HTTLPR gene even under restricted processing conditions.

Emotional faces capture spatial attention in 5-year-old children

Emotional facial expressions are important social cues that convey salient affective information. Infants, younger children, and adults all appear to orient spatial attention to emotional faces with a particularly strong bias to fearful faces. Yet in young children it is unclear whether or not both happy and fearful faces extract attention. Given that the processing of emotional faces is believed by some to serve an evolutionarily adaptive purpose, attentional biases to both fearful and happy expressions would be expected in younger children. However, the extent to which this ability is present in young children and whether or not this ability is genetically mediated is untested. Therefore, the aims of the current study were to assess the spatial-attentional properties of emotional faces in young children, with a preliminary test of whether this effect was influenced by genetics. Five-year-old twin pairs performed a dot-probe task. The results suggest that children preferentially direct spatial attention to emotional faces, particularly right visual field faces. The results provide support for the notion that the direction of spatial attention to emotional faces serves an evolutionarily adaptive function and may be mediated by genetic mechanisms.

Emotional Faces Capture Spatial Attention in 5-Year-Old Children

Emotional facial expressions are important social cues that convey salient affective information. Infants, younger children, and adults all appear to orient spatial attention to emotional faces with a particularly strong bias to fearful faces. Yet in young children it is unclear whether or not both happy and fearful faces extract attention. Given that the processing of emotional faces is believed by some to serve an evolutionarily adaptive purpose, attentional biases to both fearful and happy expressions would be expected in younger children. However, the extent to which this ability is present in young children and whether or not this ability is genetically mediated is untested. Therefore, the aims of the current study were to assess the spatial-attentional properties of emotional faces in young children, with a preliminary test of whether this effect was influenced by genetics. Five-year-old twin pairs performed a dot-probe task. The results suggest that children preferentially direct spatial attention to emotional faces, particularly right visual field faces. The results provide support for the notion that the direction of spatial attention to emotional faces serves an evolutionarily adaptive function and may be mediated by genetic mechanisms.

Backward masked fearful faces enhance contralateral occipital cortical activity for visual targets within the spotlight of attention

Spatial attention has been argued to be adaptive by enhancing the processing of visual stimuli within the 'spotlight of attention'. We previously reported that crude threat cues (backward masked fearful faces) facilitate spatial attention through a network of brain regions consisting of the amygdala, anterior cingulate and contralateral visual cortex. However, results from previous functional magnetic resonance imaging (fMRI) dot-probe studies have been inconclusive regarding a fearful face-elicited contralateral modulation of visual targets. Here, we tested the hypothesis that the capture of spatial attention by crude threat cues would facilitate processing of subsequently presented visual stimuli within the masked fearful face-elicited 'spotlight of attention' in the contralateral visual cortex. Participants performed a backward masked fearful face dot-probe task while brain activity was measured with fMRI. Masked fearful face left visual field trials enhanced activity for spatially congruent targets in the right superior occipital gyrus, fusiform gyrus and lateral occipital complex, while masked fearful face right visual field trials enhanced activity in the left middle occipital gyrus. These data indicate that crude threat elicited spatial attention enhances the processing of subsequent visual stimuli in contralateral occipital cortex, which may occur by lowering neural activation thresholds in this retinotopic location.