Convergence of fMRI and ERP measures of emotional face processing in combat-exposed U. S. military veterans

Engagement and Disengagement: From the Basic Science of Emotion Regulation to an Anxiety Spectrum

Emotion regulation strategies vary in depth of processing. For instance, reappraisal requires greater engagement than distraction. This affects short-term and long-term response to stimuli. In this review, I describe how the "engagement-disengagement dimension" improves understanding of emotion regulation in normative contexts and in internalizing psychopathology. Part 1 reviews work from my laboratory and others, suggesting that relatively disengaged emotion regulation strategies (e.g., distraction), may have short-term benefits (e.g., faster implementation), but may come with long-term costs (e.g., increased processing of stimuli at subsequent encounter). Therefore, depending on the desired outcome, the adaptive selection of an emotion regulation strategy will be determined by extent of emotional engagement-disengagement. In Part 2, I describe how individuals with more comorbid internalizing psychopathology (e.g., multiple anxiety and depressive diagnoses) are characterized by disengagement from negative stimuli as measured by the late positive potential (LPP). In addition, I introduce a brain profile I have termed, HARM-A (heightened "alarm" and reduced motivated attention), which is characterized by a combination of heightened "alarm" (i.e., increased amygdala) and emotional disengagement (i.e., blunted LPPs) in response to negative stimuli. HARM-A prospectively predicts worse outcomes over 2 years in a mixed internalizing sample. As such, chronic disengagement from negative stimuli appears to contribute to more comorbid and more severe internalizing psychopathology. Overall, emotional disengagement can be beneficial in the short term but may be poorly suited to emotional coping in the longer term.

Late positive potential reveals sustained threat contingencies despite extinction in adolescents but not adults

BACKGROUND

Major theories link threat learning processes to anxiety symptoms, which typically emerge during adolescence. While this developmental stage is marked by substantial maturation of the neural circuity involved in threat learning, research directly examining adolescence-specific patterns of neural responding during threat learning is scarce. This study compared adolescents and adults in acquisition and extinction of conditioned threat responses assessed at the cognitive, psychophysiological, and neural levels, focusing on the late positive potential (LPP), an event-related potential (ERP) component indexing emotional valence.

METHOD

Sixty-five adults and 63 adolescents completed threat acquisition and extinction, 24 h apart, using the bell conditioning paradigm. Self-reported fear, skin conductance responses (SCR), and ERPs were measured.

RESULTS

Developmental differences emerged in neural and psychophysiological responses during threat acquisition, with adolescents displaying heightened LPP responses to threat and safety cues as well as heightened threat-specific SCR compared to adults. During extinction, SCR suggested comparable reduction in conditioned threat responses across groups, while LPP revealed incomplete extinction only among adolescents. Finally, age moderated the link between anxiety severity and LPP-assessed extinction, whereby greater anxiety severity was associated with reduced extinction among younger participants.

CONCLUSIONS

In line with developmental theories, adolescence is characterized by a specific age-related difficulty adapting to diminishing emotional significance of prior threats, contributing to heightened vulnerability to anxiety symptoms. Further, LPP appears to be sensitive to developmental differences in threat learning and may thus potentially serve as a useful biomarker in research on adolescents, threat learning, and anxiety.

A Neurobiological Profile Underlying Comorbidity Load and Prospective Increases in Dysphoria in a Focal Fear Sample

BACKGROUND

Knowledge of the neural mechanisms underlying increased disease burden in anxiety disorders that is unaccounted for by individual categorical diagnoses could lead to improved clinical care. Here, we tested the utility of a joint functional magnetic resonance imaging-electroencephalography neurobiological profile characterized by overvaluation of negative stimuli (amygdala) in combination with blunted elaborated processing of these same stimuli (the late positive potential [LPP], an event-related potential) in predicting increased psychopathology across a 2-year period in people with anxiety disorders.

METHODS

One hundred ten participants (64 female, 45 male, 1 other) including 78 participants with phobias who varied in the extent of their internalizing comorbidity and 32 participants who were free from psychopathology viewed negative and neutral pictures during separate functional magnetic resonance imaging blood oxygen level-dependent and electroencephalogram recordings. Dysphoria was assessed at baseline and 2 years later.

RESULTS

Participants with both heightened amygdala activation and blunted LPPs to negative pictures showed the greatest increases in dysphoria 2 years later. Cross-sectionally, participants with higher comorbidity load (≥2 additional diagnoses, n = 34) showed increased amygdala activation to negative pictures compared with participants with lower comorbidity load (≤1 additional diagnosis, n = 44) and compared with participants free from psychopathology. In addition, high comorbid participants showed reduced LPPs to negative pictures compared with low comorbid participants.

CONCLUSIONS

Heightened amygdala in response to negative stimuli in combination with blunted LPPs could indicate overvaluation of threatening stimuli in the absence of elaborated processing that might otherwise help regulate threat responding. This brain profile could underlie the worsening and maintenance of internalizing psychopathology over time.

Functional neuro-anatomy of social cognition in posttraumatic stress disorder: A systematic review

OBJECTIVE

Post-traumatic stress disorder (PTSD) is a common mental disorder following one or more traumatic events in which patients exhibit behavioural and emotional disturbances. Recent studies report alterations in social cognition with cerebral functioning modifications. While it is now established that brain function can be modified and severely altered following successive childhood traumas, less studies have focused on brain alterations in adults with normal social cognition development.

METHODS

We conducted a selective literature review by querying PubMed and Embase databases for titles of articles research on PTSD adults published from January 2000 to December 2021 focusing on adulthood traumatic events.

RESULTS

Majority of studies reported frontolimbic rupture, with limbic structures like amygdala missing top-down control of frontal regulation. These cerebral dysfunctions could be observed even without overt behavioural defects on social cognition tests.

CONCLUSION

These results can be analysed in light of intrinsic cerebral networks and we propose an attentional model of social threat information processing opening up perspective of social attentional rehabilitation in adjunction to usual care.

The role of sex and emotion on emotion perception in artificial faces: An ERP study

Sex has a significant impact on the perception of emotional expressions. However, it remains unclear whether sex influences the perception of emotions in artificial faces, which are becoming popular in emotion research. We used an emotion recognition task with FaceGen faces portraying six basic emotions aiming to investigate the effect of sex and emotion on behavioural and electrophysiological parameters. 71 participants performed the task while EEG was recorded. The recognition of sadness was the poorest, however, females recognized sadness better than males. ERP results indicated that fear, disgust, and anger evoked higher amplitudes of late positive potential over the left parietal region compared to neutral expression. Females demonstrated higher values of global field power as compared to males. The interaction between sex and emotion on ERPs was not significant. The results of our study may be valuable for future therapies and research, as it emphasizes possibly distinct processing of emotions and potential sex differences in the recognition of emotional expressions in FaceGen faces.

Neural effects of sleep deprivation on inhibitory control and emotion processing

Sleep deprivation is commonplace and impairs memory, inhibition, cognitive flexibility and attention. However, little is known about the neurophysiological impact of sleep deprivation in the context of go/no-go (GNG) task performance and emotion processing. To address this knowledge gap, 12 females performed two computerized GNG tasks (shapes; emotional facial expressions) and an object hit and avoid (OHA) task after a night of typical sleep and 24hours without sleep. Electroencephalographic (EEG) recordings were taken during a 3-minute eyes-open resting period as well as during GNG task performance. Resting EEG power in the theta band was 33% higher for the sleep-deprived than control condition (p < 0.05), whereas alpha activity was unchanged. When sleep deprived, participants had ~6% slower response times (go trials) and made ~7% more total errors during GNG tasks (p < 0.05). Reaction time and overall accuracy were ~25% and ~9% worse for the emotional compared to shape GNG task (p < 0.05), respectively, which suggests interference of emotion processing on task performance. Smaller differences in amplitude between go and no-go trials for the N2 and both the N2 and P3 event-related potential components were found during sleep deprivation for the emotional and shape GNG tasks, respectively (p < 0.05). No changes to the N170 component were found. Lastly, participants hit more distractors during the OHA when sleep deprived (p < 0.05). Altogether, these results indicate sleep deprivation slows neural processing and impairs inhibitory task performance, possibly due to a more bottom-up, stimulus-driven approach to inhibiting motor responses.

Modulation of threat extinction by working memory load: An event-related potential study

Distraction is typically discouraged during exposure therapy for anxiety, because it is thought to interfere with extinction learning by diverting attention away from anxiety-provoking stimuli. Working memory load is one form of distraction that might interfere with extinction learning. Alternatively, working memory load might reduce threat responding and benefit extinction learning by engaging prefrontal brain regions that have a reciprocal relationship with brain circuits involved in threat detection and processing. Prior work examining the effect of working memory load on threat extinction has been limited and has found mixed results. Here, we used the late positive potential (LPP), an event-related potential that is larger for threatening compared to non-threatening stimuli to assess the effect of working memory load on threat extinction. After acquisition, 38 participants performed three blocks of an extinction task interspersed with low and high working memory load trials. Results showed that overall, the LPP was reduced under high compared to low working memory load, and that working memory load slowed extinction learning. Results provide empirical evidence in support of limiting distraction during exposure therapy in order to optimize extinction learning efficiency.

Comorbid anxiety and depression: Opposing effects on the electrocortical processing of negative imagery in a focal fear sample

BACKGROUND

Anxiety and depression are highly comorbid and share clinical characteristics, such as high levels of negative emotion. Attention toward negative stimuli in anxiety and depression has been studied primarily using negative pictures. Yet, negative mental imagery-that is, mental representations of imagined negative events or stimuli-might more closely mirror patient experience.

METHODS

The current study presents the first examination of neural response to negative imagery in 57 adults (39 female) who all shared a common "focal fear" diagnosis (i.e., specific phobia or performance-only social anxiety disorder), but varied in levels of comorbid anxiety and depression. After listening to standardized descriptions of negative and neutral scenes, participants imagined these scenes as vividly as possible. Associations between categorical and continuous measures of depression, generalized anxiety disorder (GAD), and social anxiety disorder with electrocortical and subjective responses to negative imagery were assessed.

RESULTS

Individuals who were more depressed showed reduced electrocortical processing of negative imagery, whereas those with GAD showed increased electrocortical processing of negative imagery-but only when controlling for depression. Furthermore, participants with higher levels of depression rated negative imagery as less negative and those with greater social anxiety symptoms rated negative imagery more negatively.

CONCLUSIONS

Depression and GAD are characterized by opposing electrocortical response to negative imagery; moreover, depression may suppress GAD-related increases in the electrocortical processing of negative imagery. Results highlight distinctions between different dimensions of distress-based psychopathology, and reveal the unique and complex contribution of comorbid depression to affective response in anxiety.

Perceived social support moderates neural reactivity to emotionally valenced stimuli during pregnancy

Reactivity to emotional information, measurable at the level of neural activity using event-related potentials, is linked to symptoms of affective disorders. Behavioral evidence suggests that contextual factors, such as social support, can alter emotional reactivity such that affective responding is normalized when social support is high. This possibility remains largely untested at the neural level, specifically through approaches that can offer insight into the mechanistic processes contributing to individual differences in emotional reactivity. Yet, such knowledge could be useful for prevention and intervention efforts, particularly with groups at risk for increased emotional reactivity, such as pregnant mothers for whom emotional distress predicts both maternal and child outcomes. Expectant mothers took part in a longitudinal study that tested whether the late positive potential (LPP), a neural index of reactivity to emotional information, was moderated by maternal perceptions of social support. In the third trimester of pregnancy, lower perceived social support was associated with an absence of a traditional LPP effect, which differentiates valenced from neutral stimuli. Findings suggest that perceptions of social support may normalize emotional processing at the neural level and highlight the potential importance of social support modulation of emotional reactivity during times of known biological change.

Impaired Frontoparietal Connectivity in Traumatic Individuals with Disorders of Consciousness: A Dynamic Brain Network Analysis

Recent advances in neuroimaging have demonstrated that patients with disorders of consciousness (DOC) may retain residual consciousness through activation of a complex functional brain network. However, an understanding of the hierarchy of residual consciousness and dynamic network connectivity in DOC patients is lacking. This study aimed to investigate residual consciousness and the dynamics of neural processing in DOC patients. We included 42 patients with DOC, categorized by aetiology. Event-related potentials combined with time-varying electroencephalography networks were used to probe affective consciousness in DOC and examine the related network mechanisms. The results showed an obvious frontal P3a component among patients in minimally conscious state (MCS), while a prominent N1 was observed in unresponsive wakefulness syndrome (UWS). No late positive potential (LPP) was detected in these patients. Next, we divided the results by aetiology. Patients with nontraumatic injury presented an obvious frontal P3a response compared to those with traumatic injury. With respect to the dynamic network mechanism, patients with UWS, both with and without trauma, exhibited impaired frontoparietal network connectivity during the middle to late emotion processing period (P3a and LPP). Surprisingly, unconscious post-traumatic patients had an evident deficit in top-down connectivity. This, it appears that early automatic sensory identification is preserved in UWS and that exogenous attention was preserved even in MCS. However, high-level cognitive abilities were severely attenuated in unconscious patients. We also speculate that reduced frontoparietal connectivity may be useful as a biomarker to distinguish patients in an MCS from those with UWS given the same aetiology.

Nonlinear relations between post-traumatic stress symptoms and electrocortical reactivity during emotional face processing in combat-exposed veterans

Combat-related post-traumatic stress symptoms (PTSS) are prevalent among recently deployed veterans, making identification of biomarkers of PTSS in this population a public health priority. Given the link between threat processing neurobiology and PTSS, the threat-related late positive potential (LPP), an ERP reflective of attentional processing sensitive to emotion and its regulation, may have utility as a cost-effective biomarker. Existing PTSS/threat-related LPP findings are mixed, possibly due to variability in PTSS across samples, but this has never been explicitly tested. To address this gap, LPP amplitudes to angry, fearful, and happy emotional face stimuli were recorded among 81 combat-exposed veterans at a VA hospital. A quadratic relationship between self-reported PTSS and LPP amplitude modulation by angry faces emerged such that greater PTSS was related to a decreased LPP response to angry faces among veterans with subthreshold PTSD and an enhanced LPP response to angry faces among veterans with probable PTSD. These results suggest that prior mixed findings may be due to variability in PTSS severity. In addition, exploratory moderation analysis revealed that PTSS was positively associated with late LPP modulation for veterans reporting low cognitive reappraisal use and negatively associated with late LPP modulation for veterans reporting high cognitive reappraisal use. All results were specific to the 1,000-3,000 ms LPP time window. Thus, the functional nature of LPP modulation by direct threat cues may depend upon PTSS severity and/or related variables (e.g., cognitive reappraisal utilization).