Effect of negatively valenced words on deviant P3 during the three-stimulus oddball paradigm

The impact of fear and psychopathological symptoms on neural responses to naturalistic stimuli in adolescents

The presentation of real-world images can swiftly engage processing mechanisms within specific brain regions and neural pathways. In this study, we explore the effects of fear and psychopathological symptoms on neural processing of realistic stimuli during a free viewing naturalistic task in a sample of adolescents (11-16y). Thirty-one participants performed an experimental task consisting of the visualization of animal pictures according to three conditions - Snakes, Spiders, and Dogs - during EEG recordings. Dimensions of fear and psychopathological symptoms were previously assessed through The Fear Survey Schedule for Children- Revised and the Brief Symptom Inventory. Earlier and later visual processing was analyzed through ERP components' peak amplitudes. The results show a robust effect of psychopathology-related dimensions in the visual processing of naturalistic images, suggesting an increase of neural activity at later stages of visual processing (at the N200 time window) in symptomatic adolescents, corroborating the role of psychopathological symptoms in modulating neural responses to naturalistic images, and also guiding clinicians by providing additional data on how symptomatic adolescents perceive and process reality.

A key role of the hippocampal P3 in the attentional blink

The attentional blink (AB) refers to an impaired identification of target stimuli (T2), which are presented shortly after a prior target (T1) within a rapid serial visual presentation (RSVP) stream. It has been suggested that the AB is related to a failed transfer of T2 into working memory and that hippocampus (HC) and entorhinal cortex (EC) are regions crucial for this transfer. Since the event-related P3 component has been linked to inhibitory processes, we hypothesized that the hippocampal P3 elicited by T1 may impact on T2 processing within HC and EC. To test this hypothesis, we reanalyzed microwire data from 21 patients, who performed an RSVP task, during intracranial recordings for epilepsy surgery assessment (Reber et al., 2017). We identified T1-related hippocampal P3 components in the local field potentials (LFPs) and determined the temporal onset of T2 processing in HC/EC based on single-unit response onset activity. In accordance with our hypothesis, T1-related single-trial P3 amplitudes at the onset of T2 processing were clearly larger for unseen compared to seen T2-stimuli. Moreover, increased T1-related single-trial P3 peak latencies were found for T2[unseen] versus T2[seen] trials in case of lags 1 to 3, which was in line with our predictions. In conclusion, our findings support inhibition models of the AB and indicate that the hippocampal P3 elicited by T1 plays a central role in the AB.

Hypervigilance or shutdown? Electrophysiological processing of trauma-unrelated aversive stimuli after traumatic life events

Post-Traumatic Stress Disorder (PTSD) research indicates that hyper-reactivity to trauma-related stimuli reflects reduced prefrontal cortex (PFC) modulation of amygdala reactivity. However, other studies indicate a dissociative "shutdown" reaction to overwhelming aversive stimuli, possibly reflecting PFC over-modulation. To explore this, we used an Event-Related Potential (ERP) oddball paradigm to study P3 responses in the presence of the following: 1. Trauma-unrelated morbid distractors (e.g., "injured bear") related to the Rorschach inkblot test, and 2. Negative distractors (e.g., "significant failure"), among participants with high post-traumatic stress symptoms (PTS; n = 20), low PTS (n = 17), and controls (n = 15). Distractors were presented at 20% frequency amongst the more frequent (60%) neutral standard stimuli (e.g., "desk lamp") and the equally frequent (20%) neutral trauma-unrelated target stimulus ("golden fish"). P3 amplitudes were high in the presence of morbid distractors and low in the presence of negative distractors only amongst the control group. Possible mechanisms underlying the lack of P3 amplitude modulation after trauma are discussed.

Neuronal underpinnings of the attentional bias toward threat in the anxiety spectrum: Meta-analytical data on P3 and LPP event-related potentials

BACKGROUND

This systematic review analyzes brain responses at later stages of neuronal processing (P3 at 300-500 ms, and LPP at 300-700 ms). Both P3 and LPP are implicated in attentional threat bias in disorders grouped into fear and distress dimensions of the anxiety spectrum described by the Hierarchical Taxonomy Model of Psychopathology (HiTOP), but there are no consistent findings so far.

METHOD

Meta-analyses with between- (32 studies, n = 1631) and within-groups design (31 studies, n = 1699) were performed for assessing P3 and LPP modulation in negative, positive, and neutral stimuli, while also considering differences between controls and anxious individuals. Relevant moderators (e.g., age, sex, task) were controlled for and negative stimuli were further decomposed in terms of category (Relevant, Fear/Threat, or Unpleasant).

RESULTS

Increased P3 and LPP amplitudes were found for negative and positive stimuli, when compared to neutral stimuli (within-subjects analysis), confirming that both components are elicited by emotionally arousing information. Within-effects for negative and positive stimuli were higher for the anxious groups. Nonetheless, between-groups analyses showed that attentional threat bias occurs only in anxious groups when negative, personally relevant-threat information is presented. The HiTOP fear dimension moderated the findings.

LIMITATIONS

Potential missed studies; ERPs time windows' heterogeneity; adult sample only; the uneven number of computed effects; categorical analyses.

CONCLUSION

Attentional bias toward disorder-congruent threatening cues can be a transdiagnostic mechanism of HiTOP fear disorders, clustered within the anxiety spectrum.