Psychophysiology

Intelligence or general cognitive ability (GCA) is fundamental to human behavior and cognition. It impacts important life outcomes like educational success and even health and longevity have been related to differences in GCA. Understanding the biological basis of such individual variations presents a crucial goal of neuroscience. The mismatch negativity (MMN) is an event-related brain potential that can be measured when--within a series of frequent standard stimuli, rare deviants are presented--and is suggested to reflect conscious (active) or unconscious (passive) detection processes of the brain. Importantly, variations in MMN amplitude and latency have been linked to differences in GCA. Yet findings vary considerably. This preregistered meta-analysis provides a comprehensive and structured overview of the current state of research. Following the study selection process in accordance with the PRISMA guidelines, and the rating of study design quality with the Study Design and Implementation Assessment Device for Individual Difference Research (DIAD-ID), the association between GCA and MMN amplitude and latency was examined in 695 healthy adults across 13 included studies. The estimated across-sample associations between MMN and GCA were small, but significant (MMN amplitude-GCA: r = -0.08, MMN latency-GCA: r = -0.13; p < 0.05) and moderators were identified. Between-sample heterogeneity was moderate, with no evidence of publication bias. Our findings suggest that higher cognitive ability is associated with slightly stronger and faster MMN responses. However, the low estimated across-sample effect sizes and the small number of included studies also highlight the need for more research.

The olfactory and intranasal trigeminal systems interact closely, influencing chemosensory perception, yet the mechanisms underlying their interaction remain poorly understood and have been studied mainly in young adults. We aimed to characterize olfactory-trigeminal interactions in aging by comparing electrophysiological and behavioral responses under ipsilateral and contralateral olfactory-trigeminal co-stimulation, to determine the relative contributions of peripheral and central mechanisms. Using chemosensory event-related potentials and a localization task, 44 healthy older adults (66.3 {+/-} 4.6 years; 29 women) were tested under four conditions: pure trigeminal (carbon dioxide; CO2), pure olfactory (2-phenylethanol; PEA), ipsilateral co-stimulation (PEA+CO2 in the same nostril), and contralateral co-stimulation (PEA+CO2 in opposite nostrils). Ipsilateral, but not contralateral olfactory-trigeminal co-stimulation, improved trigeminal localization performance and induced larger late positive component amplitudes. Together, these findings suggest that olfactory-trigeminal interactions are driven primarily by peripheral rather than central mechanisms. This study also provides normative CSERP data for healthy older adults.

Creative performance fluctuates from moment to moment, suggesting that it depends partly on transient internal states present before creative thinking begins. Although such fluctuations have been identified in central neural activity, it remains unclear whether they are also reflected in autonomic physiology. We examined whether cardiac and electrodermal activity during a brief pre-trial resting period was associated with subsequent creative performance. Photoplethysmography, electrocardiography, and electrodermal activity were recorded while 28 participants completed the Alternative Uses Test and Fusion Innovation Test, assessing divergent and convergent creative thinking, respectively. Data from 27 participants was included in the analyses. Heart rate, heart rate variability, tonic skin conductance level, and phasic skin conductance activity were extracted from observation windows ranging from 11 to 30 s within a 30-s pre-trial rest period. Trial-level creativity was evaluated using GPT-based ratings of novelty, feasibility, and goal attainment. Linear mixed-effects models showed that higher pre-trial tonic skin conductance level was consistently associated with better subsequent creative performance across tasks, with overall model fit peaking at a 21-s observation window. Permutation-based feature-importance analysis provided convergent support for the contribution of tonic skin conductance, whereas the cardiac and phasic electrodermal indicators showed no reliable independent associations. However, the model explained only a small proportion of behavioral variance. These findings suggest that tonic sympathetic arousal reflects a momentary physiological state associated with creativity potential, while autonomic signals alone remain insufficient for accurate individual-level prediction.

Immersive virtual reality (VR) can preserve the logic of laboratory attention tasks while altering the perceptual-action context in which attentional control is expressed. In this study, we examined the neural underpinnings of location-response compatibility in a VR adaptation of the Attention Network Test-Revised (ANT-VR), using a restricted preprocessing multiverse to account for uncertainty arising from defensible EEG analysis choices. Forty-four young adults contributed complete ANT-VR behavioural data. Target-locked EEG analyses were conducted across 192 preprocessing branches, with branch-level participant contributions varying after quality check and trial-count filtering. The contrast compared location-response incompatible with compatible trials and was balanced within participants across cue-target interval, cue condition, flanker congruency, and, for spatial-cue trials, conditions in which spatial cues were valid or invalid for subsequent targets. Across the multiverse, the N2pc-window posterior-lateralisation contrast could be defined in all branches and showed high directional stability: the median incompatible-minus-compatible effect was 0.30 uV [IQR: 0.22 to 0.41], with positive effects in 192/192 branches, nominal evidence in 79/192 branches, and Holm-corrected evidence in 42/192 branches. Comparison across ERP measures indicated that this pattern was more consistent for N2pc-window posterior lateralisation than for P1, posterior N1, frontocentral N2, P3, or response-referenced C3/C4 measures. Comparison across C3/C4 reference frames further constrained the interpretation: target-location-referenced C3/C4 showed the strongest effect, whereas response-referenced C3/C4 was weaker. Behavioural analyses showed no reliable compatibility differences. These findings suggest that location-response compatibility in immersive ANT-VR modulates target-locked lateralised neural activity associated with spatial selection and target-location coding, rather than producing broad sensory, conflict-related, P3-related, or specifically response-referenced modulation.

Spontaneous thought changes over time, yet the moment-to-moment factors shaping these changes remain poorly understood. We examined whether heartbeat-related bodily processing, operating largely outside explicit awareness, is associated with the organization of ongoing thought. Forty adults performed an auditory attention task with intermittent thought probes in which auditory events were scheduled either 200 ms after each detected R peak (synch condition) or independently of ongoing cardiac timing (asynch condition), with occasional omissions in both conditions. Heartbeat-synchronous omissions in this paradigm have been shown to induce cardiac deceleration and modulate heartbeat-evoked potentials (HEPs). The score of the heartbeat counting task (HCT) served as a behavioral index related to cardiac interoceptive accuracy. The results showed that higher HCT score was associated with a stronger synch-asynch shift toward more self-related and less task/self-unrelated thought. HEPs showed a synch-related negative shift across several thought groups, although the magnitude of this condition effect did not reliably differ among thought groups. Overall thought-group distributions were similar across conditions, while transition analyses suggested a tendency in the synch condition toward more frequent transitions linking predominantly interoceptive stimulus-dependent thought with both on-task and self-related thought. Together, these findings suggest that heartbeat-related bodily processing may influence the organization of spontaneous thought, particularly in individuals with greater cardiac interoceptive accuracy. Bodily signals may therefore act as an automatic constraint on the ongoing stream of thought, biasing which thought contents and transitions become more likely over time.

The vestibular system has been implicated in several aspects of self-representation, including bodily self-location, yet its role in episodic source and reality monitoring remains unclear. Moreover, symptoms of depersonalisation and derealisation (DPDR) have been associated with both vestibular dysfunction and altered source and reality monitoring. We tested whether noisy galvanic vestibular stimulation (nGVS) modulates source and reality monitoring during a word-encoding paradigm and whether this increased symptoms of DPDR. Sixty young adults (N = 30 active nGVS, N = 30 sham) encoded words that varied by context (spoken vs. imagined), agentic source (self vs. other), and valence (positive vs. threat) before completing source/reality judgments. Active nGVS reduced overall accuracy relative to sham on both reality and source monitoring. Across conditions, self-referential items were remembered with greater sensitivity compared to other-referential items, and spoken items were recalled with greater sensitivity than imagined items. We additionally show an interaction effect whereby active nGVS reduced accuracy specifically for imagined and threat-valenced items. Trait DPDR did not moderate the effects of stimulation, although higher trait DPDR was associated with a more liberal reality-monitoring response criterion. Results indicate that transient vestibular perturbation via nGVS can impair source monitoring for internalised and threatening stimuli and impairs cognitive distinctions between internally and externally generated events in general, supporting a role for vestibular input in maintaining self-other and reality boundaries in episodic memory.

Menstrual symptoms vary across the cycle, yet most research assumes a normative 28-day cycle with fixed phase durations, obscuring the physiological relevance of natural cycle variation. Using the mcPHASES dataset, we characterised cycle and phase length variation across 96 menstrual cycles from 37 participants, with ovulation timing estimated from daily urinary luteinizing hormone measurements using a Bayesian hierarchical model, and examined associations with daily symptoms in a subset of 64 cycles from 35 participants with complete symptom data. Twelve physical, mental, and behavioural symptom domains were modelled using Bayesian ordinal regression, with posterior uncertainty in phase-length predictors propagated via a measurement error framework. Total cycle length was not associated with daily symptom burden, except sleep disturbances. By contrast, phase length decomposition revealed systematic associations across multiple domains: longer menstrual phase length was broadly associated with greater symptom intensity spanning physical, gastrointestinal, affective, and sleep domains; longer luteal phase duration was associated with greater fatigue and more frequent headaches, but lower sore breast intensity and lower stress; and longer follicular phase duration and later ovulation were each associated with greater sore breast intensity and more frequent mood swings. These associations require knowledge of actual ovulation timing and cannot be recovered from cycle length alone, indicating that the common assumption of a fixed 14-day luteal phase introduces systematic misclassification of hormonal exposure. Daily symptom intensity was also predominantly person-specific, with cycle phase explaining little of the between-person variance across most symptoms. These findings indicate that calendar-based phase assignment is insufficient for research and clinical assessment of hormone-sensitive conditions, and that person-specific baselines, rather than population-level phase averages, are needed for clinically meaningful symptom monitoring.

Gut-brain communication has emerged as a rapidly expanding field of research, with recent electrophysiological studies revealing rhythmic gut-brain coupling between gastric activity and brain oscillations in humans. Gut motility is a key determinant of gastrointestinal function, but it remains unclear whether individual differences in gut motility reflected by weekly bowel movements (e.g., defecation frequency) are associated with differences in gut-brain coupling. Here, we address this question by examining women with self-reported daily bowel movements (N = 38) and women with less frequent bowel movements (N = 38). We recorded simultaneous electroencephalography (EEG) and electrogastrography (EGG) at fasting state, performed cognitive assessments, and analysed faecal short-chain fatty acids (SCFAs) as markers of colonic fermentation. In a subset of participants, EEG-EGG coupling was assessed twice over an interval of at least eight weeks to assess test-retest reliability. In this group, EEG-EGG coupling showed moderate test-retest reliability (Intraclass Correlation Coefficient (ICC) = 0.50). When comparing the two groups of women, the phase-amplitude coupling (PAC) analysis between EEG and EGG signals revealed a significantly stronger gut-brain coupling in women with daily bowel movements compared to women with less frequent bowel movements (p = 0.03). We additionally found that women with daily bowel movements made less errors in the cognitive tasks and had higher levels of faecal SCFAs. A path analysis suggested that bowel movements significantly affect gut-brain phase-amplitude coupling through faecal SCFAs. However, neither faecal SCFAs nor phase-amplitude coupling significantly predicted cognitive performance, suggesting the existence of alternative pathways for the association between bowel movements and cognitive performance. Together, our findings suggest that the strength of gut-brain coupling is associated with bowel movements and cognitive performance, making EEG-EGG coupling a promising marker of human gut-brain interactions.

BackgroundThe maturation of the autonomic nervous system (ANS) has been suggested to play a crucial role in the development of emotion regulation and later psychosocial functioning. However, longitudinal evidence linking early autonomic development to long-term outcomes remains limited. This longitudinal study investigated the interplay between birth-related factors, early autonomic activity, and psychosocial outcomes across development. MethodsThe sample comprised 101 participants followed from two weeks to 14 years of age, with heart rate (HR) and vagally ediated heart rate variability (vmHRV) assessed at 2 weeks, 6 weeks, 3 months, 14 months, and 14 years. Linear models were used to examine associations between birth-related factors and early HR and vmHRV, as well as whether HR and vmHRV trajectories during the first 14 months predicted psychosocial outcomes at 5 and 14 years. ResultsMultiple birth-related factors significantly predicted HR and vmHRV at two weeks after birth. Moreover, flatter age-related increases in vmHRV and weaker decreases in HR during infancy predicted higher maternally reported psychosocial difficulties at 14 years in males only, with no such effects at 5 years or in females. ConclusionsThese findings underscore the importance of early autonomic maturation in shaping later psychosocial functioning, with effects on adolescent outcomes observed in males only. Early ANS trajectories may represent meaningful predictors of neurodevelopmental outcomes, highlighting their potential relevance for early identification of later psychosocial risk in a sex-specific manner.

When in a stressful situation, making fast and accurate decisions is crucial. Previous work has shown that sensorimotor decisions can improve under threat. However, it is unclear if these improvements are achieved by improvements in perceptual or motor performance. Here, we present two hypotheses for how threat might influence motor preparation and use muscular stretch reflexes to test both. The task-unspecific hypothesis predicts that threat promotes motor preparation irrespective of the reach target, through tonic upregulation of the short latency stretch reflex. In contrast, the task-specific hypothesis predicts that threat increases sensory processing for a specific reach target, leading to direction-selective up- and down-regulation of the long latency stretch reflex. Participants were asked to reach to one of two targets that appeared shortly before a perturbation eliciting a stretch reflex, they performed this task either under threat of an electric shock or under safe circumstances. Skin conductance and heart rate results show that the threat manipulation significantly increased sympathetic activation, but not parasympathetic activation. Supporting the task-specific hypothesis, the EMG findings demonstrate a direction-selective modulation of the long-latency response of stretch reflexes, starting ~100 ms after perturbation onset. Our results suggest that stress affects action preparation through upregulation of cortical visuomotor circuits.

Recognizing others emotions is central to social interaction. Traditional biological psychology infers emotional responding via laboratory measures, whereas contemporary computer vision algorithms claim to identify emotions unobtrusively from facial video. However, the validity of such algorithms for classifying spontaneous emotional responses occurring without explicit communicative intent remains debated. We compared established psychophysiological measures (EEG, facial EMG, EDA activity) with the open-source facial behavior toolkit OpenFace for classifying participants spontaneous responses during free viewing of happiness-inducing, disgust-inducing, and neutral pictures. Participants provided valence and arousal ratings and later selected the basic emotion that best matched their reaction which served as the classification criterion. Using within-participants single-trial support vector machine (SVM) classification, EEG achieved the highest accuracy (40%), followed by facial EMG (37%); OpenFace reached 36%. All methods except EDA exceeded chance performance (33.3%) and were lower compared to human raters (48%). Predictions declined slightly for across-participants SVMs, being at chance for OpenFace and EDA. The results indicate that in principle both, psychophysiological measures and video-derived facial action units, can capture diagnostically relevant aspects of emotional responding during picture viewing, but that their performance is limited when expressions are spontaneous and not produced for communicative purposes. Inter-individual variability in expressivity and physiological responding likely contributes to these limitations and should be considered when deploying automatic emotion recognition in research or applied settings.

Laboratory stress tasks are widely used to assess individual differences in acute stress reactivity, yet it remains unclear how these responses correspond to stress experienced in everyday life. Here, we combined the Montreal imaging stress task (MIST) with ecological momentary assessment (EMA) over three months to assess acute and everyday stress in 67 healthy women. Greater within-person variability in everyday stress, but not average stress levels, were associated with stronger overall stress-related brain responses (b = 0.73, p = .039), with a whole-brain association particularly evident in the bilateral caudate (rROI = .32, pcluster.FWE < .001). Greater everyday stress variability was also associated with stronger stress-related functional connectivity between the ventromedial prefrontal cortex (vmPFC) and parietal and posterior medial regions (pcluster.FWE < .001). We conclude that acute neural stress responses relate more closely to fluctuations in perceived stress than to how stressed an individual feels on average. This suggests that laboratory stress tasks capture acute stress responsivity that is distinct from average stress exposure, highlighting the importance of considering what these tasks measure when interpreting individual differences in acute stress responses.

Despite the importance of sustaining attention focus throughout a task, sustained attention research demonstrates a rapid decline of task-focus with time-on-task. Separate research body highlights perceptual load as critical determinant of focused attention, showing that increased perceptual load draws more neural energy into task-relevant processing (Bruckmaier et al., 2020) and improves attention focus (Lavie, 2005). However, the effect of perceptual load on the neurophysiological mechanisms underlying time-on-task impact on sustained attention remains unknown. This was the aim of the present study. Participants performed a gradual continuous-performance task, detecting infrequent mountain scenes, among streams of city scenes, under either high or low perceptual load (with or without overlaid salt-and-pepper noise, respectively). EEG was recorded and parameterised into periodic and aperiodic components; the aperiodic 1/f slope linked with excitation-inhibition (E/I) balance: steeper slopes reflecting reduced E/I ratio (Gao et al., 2017). Time-on-task resulted in a wide-spread increase in alpha power, and a steeper 1/f slope in a left temporal-parietal cluster, accompanied by reduced detection sensitivity and increased response variability, as well as increased mind wandering, with reduced thoughts detail. Perceptual load improved task focus, as indexed by reduced mind wandering, but exacerbated the effect of time-on-task on detection sensitivity, and the 1/f slope, which was steeper with time-on-task in a right parieto-occipital cluster with increased load. Overall, the findings suggest that sustained attention decline with time-on-task can be attributed to depletion of neural energy needed for excitatory signalling, which is further drained with increased processing demands in tasks of high perceptual load.

BackgroundHigh-frequency heart-rate variability (HF-HRV) is a downstream marker of cortico-autonomic regulation linked to executive function. A recent proposal suggests it indexes regulatory processes because it is both a product of and contributor to neural organization within the prefrontal cortex. The oscillatory phase of HF-HRV has been reported to modulate fronto-central EEG amplitude at rest, and this coupling is attenuated in individuals with schizophrenia relative to healthy controls. We evaluated this brain-body correspondence in relation to anxiety symptomatology, which is likewise associated with autonomic dysregulation. MethodsConcurrent EEG and electrocardiography (ECG) were recorded in 22 nonclinical adults at rest and during a mental arithmetic task. Participants rated anxiety severity using the Generalized Anxiety Disorder 7-item scale (GAD-7). We evaluated between-person associations between anxiety severity and HF-HRV-EEG coupling, as well as within-person differences in coupling between rest and mental arithmetic. ResultsAnxiety symptomatology was associated with decreased resting-state phase-amplitude coupling between HF-HRV phase and fronto-central theta amplitude, independent of EEG and HRV covariates. Relative to rest, HF-HRV-theta coupling increased during a cognitive task, independent of condition-related changes in EEG, HR, or respiration. Anxiety severity moderated the task-evoked changes in heart-brain coupling such that more anxious individuals exhibited larger condition-related differences. Simple-slope analyses indicated anxietys effect on coupling at rest was absent when engaged in a task. ConclusionsHF-HRV-theta phase-amplitude coupling captured anxiety-related and state-dependent variance not evident in conventional cardiac or neural indices. This coupling may index a state-sensitive component of cortico-autonomic regulation, although its putative functional role requires direct testing.

BackgroundSelf-compassion has shown to be an effective emotion regulation strategy, but its neural mechanisms remain understudied in adolescents with depression who suffer from social exclusion. This study employed event-related potentials to investigate the psychophysiological mechanisms underlying impaired self-compassion in adolescents with depression during social exclusion. MethodsThirty-seven adolescents with major depressive disorder (age = 16.46 {+/-} 2.02) and thirty-two demographically matched healthy controls (age = 16.54 {+/-} 2.29) completed a social exclusion scenario imagination task. This task presented participants with social exclusion scenarios, asking them to imagine themselves as the excluded individual and subsequently rate their negative emotions. The regulation session required participants to use self-compassionate statements to regulate their emotional responses while imagining and rate how much self-compassion they have engaged in; the non-regulation required them not to use those statements and rate their negative emotions immediately following imagination. EEG signals were recorded during the task, and the late positive potential (LPP) was analyzed to examine the neural responses associated with self-compassion regulation following social exclusion. ResultsCompared with the non-regulation condition, both groups showed less negative emotion during the self-compassion regulation condition. Adolescents with depression exhibited significantly lower self-compassion ratings than healthy controls, and showed a significantly smaller decrease in negative emotions. Higher self-compassion ratings were correlated with greater emotion regulation effect, particularly in adolescents with depression. Furthermore, LPP amplitudes were significantly higher in adolescents with depression than in healthy controls during both regulation and non-regulation conditions. ConclusionsAdolescents with depression were characterized by impairment in using self-compassion to downregulate negative emotions when confronted with social exclusion. LPP amplitudes were consistently elevated in adolescents with depression, underscoring their potential as a critical focus for psychophysiologically-informed therapies.

Subject-independent affect regression from physiological signals remains challenging because emotional responses vary substantially across individuals, widely used datasets provide only coarse trial-level annotations, and heterogeneous physiological modalities may not contribute reliably when treated as if they were interchangeable predictors. We have developed AffectRoute, a protocol-conditioned subject-independent affect regression that is conditioned on the protocol and assigns separate predictive functions to information from the population, electroencephalography (EEG), and peripheral physiological signals (PPS). First, a source-population prior establishes a trial-level affective anchor using only the data from source participants. TrajBridge then combines an EEG representation that is supervised by REFED for participant-specific adjustments with temporal structure obtained from the continuous REFED annotations in order to create a weakly supervised segment-resolved pseudo-trajectory and to establish a frozen trial-level baseline. PhysioRoute next reduces the remaining error by breaking down the residual correction into a source-derived direction, which is estimated from the out-of-fold residuals within the source group, and a channel-specific magnitude derived from the PPS. When evaluated on DEAP and DREAMER using a leave-one-subject-out approach at the participant level, AffectRoute showed consistent step-by-step improvements in both the mean absolute error and the concordance correlation coefficient. A method that relied solely on the source data was clearly worse than PhysioRoute, showing that the final improvement cannot be accounted for by transferable source residual regularity alone. Conventional alternatives to fusing the PPS were also found to be consistently less effective, although analyses at the channel level and with a leave-one-channel-out design showed that the peripheral contributions are axis-dependent yet distributed across channels. These results indicate that structured residual inference is an effective alternative to unrestricted multimodal fusion for subject-independent affect regression.

Conflict monitoring and error processing are fundamental mechanisms underlying cognitive control and decision-making, and have been consistently associated with increased activity in the anterior midcingulate cortex (aMCC). Despite the extensive literature supporting this association, there remains a substantial gap in establishing a causal relationship between the aMCC and cognitive control processes. In the present study, we used low-intensity transcranial ultrasound stimulation (TUS), an emerging technique that enables non-invasive, deep, and focal neuromodulation, to investigate the causal role of the aMCC in behavioral and electrophysiological markers of cognitive control. Nineteen participants received 5Hz rTUS targeting the aMCC and the posterior cingulate cortex (PCC) on separate days, followed by performance of a Flanker task during EEG recording. Our findings demonstrate that TUS of aMCC modulated the relationship between conflict monitoring and the N2 component, but did not affect the coupling between error processing and the ERN, relative to the TUS of PCC, suggesting a dissociable contribution from both regions to cognitive control. These results were further supported by exploratory drift diffusion model (DDM) analyses, which revealed that, for most participants, TUS of aMCC enhanced suppression of flanker distractors. Importantly, after TUS of aMCC, but also PCC, we observed higher accuracy during early compared with later task blocks, corroborating previous findings suggesting that TUS effects are temporally dynamic and characterized by a limited post-stimulation window. HIGHLIGHTSO_LIaMCC-TUS selectively enhances response conflict sensitivity and modulates its coupling with the N2 compared with PCC-TUS. C_LIO_LIExploratory DDM analyses suggest that aMCC-TUS improves suppression of conflict-inducing distractors. C_LIO_LIaMCC-TUS and PCC-TUS both increase behavioral accuracy during the early stages of task performance. C_LIO_LITUS effects show a transient temporal profile, peaking 17-27 minutes after stimulation and declining after [~]37 minutes. C_LI

Can grammatical gender in a bilingual's first language shape gender-stereotype processing in a second language? Spanish (L1)-English (L2) bilinguals (n = 28) and English monolinguals (n = 28) completed an event-related potential (ERP) priming task in which English pronouns (SHE/HE) followed gender-stereotyped English nouns, half of which had gender-marked Spanish translation equivalents (e.g., NURSE 'enfermera/o', SURGEON 'cirujana/o'), and half unmarked translation equivalents (e.g., SINGER 'cantante', JANITOR 'conserje'). Both groups showed asymmetric stereotype priming: male pronouns elicited a larger N400 for incongruent than congruent primes, whereas female pronouns elicited a larger P300 for incongruent than congruent primes. Crucially, only bilinguals showed modulation by Spanish grammatical gender marking: the N400 effect for male pronouns was larger for primes with gender-marked than unmarked Spanish translations. These findings provide neural evidence that grammatical gender in a bilingual's first language can influence gender-stereotype processing in a second language, linking cross-linguistic activation to social cognition.

Background: Bipolar disorder is associated with persistent social, cognitive, and functional impairment during euthymia, yet the neural mechanisms underlying these deficits remain unclear. Alterations to self-referential processing are a candidate mechanism, but existing electrophysiological studies rely on emotionally valenced paradigms that potentially confound self-processing with emotional biases. Methods: We analysed electroencephalography from 28 patients with bipolar disorder (type I or II) and 28 age- and sex-matched healthy controls during an emotionally neutral colour judgment task with self-related (preference) and non-self-related (similarity) conditions. Late positive potentials, temporal generalisation decoding, and frequency band decoding (theta, alpha, beta) were used to characterise the temporal dynamics and oscillatory correlates of self versus non-self processing. Results: Controls showed higher overall event-related potential amplitudes and greater self versus non-self differentiation than patients (condition by group interaction, 337 to 946 ms). Broadband temporal generalisation decoding revealed extensive cross-temporal generalisation of the self versus non-self representation in controls, spanning most of the trial, but no significant generalisation in patients. Frequency analyses showed that alpha and beta carried self versus non-self information in both groups, with broader extent in controls, and that anterior theta carried this information in patients but not controls. Exploratory correlations linked decoding measures to rumination and anxiety but not to manic symptoms. Conclusions: The neural representation distinguishing self-referential from externally guided processing was both smaller in amplitude and less temporally sustained in bipolar disorder. Reduced persistence is not detectable by conventional amplitude analyses, and may bear on the self-related and social cognitive difficulties reported in this population.

Although a substantial body of evidence has demonstrated that emotional interference affects cognitive performance, relatively little is known about its temporal evolution and the respective brain regions underlying its regulation. The present study investigated the temporal dynamics of emotional interference and the contribution of prefrontal regions involved in its regulation. Forty-eight participants completed a 2-back task and a Set-switching task under neutral and negative emotional conditions while receiving sham, dorsolateral prefrontal cortex (dlPFC), or ventromedial prefrontal cortex (vmPFC) stimulation. Stimulation was administered either online during task performance or after a 5 min pre-task period. Consistent with previous findings, negative emotions impaired executive performance, particularly during high-demand updating conditions. Critically, time-resolved analyses revealed that emotional interference evolved dynamically throughout task performance and was differentially modulated by prefrontal stimulation. The most consistent stimulation effects emerged after approximately 10 minutes of cumulative stimulation exposure and varied as a function of the stimulation site, executive-control demands, and stimulation timing. Notably, online stimulation produced more consistent modulation than pre-task stimulation. Together, these findings indicate that both emotional interference and its neuromodulation are dynamic processes. More broadly, they suggest that the contribution of prefrontal control systems to emotion-cognition interactions may be better understood through their temporal evolution rather than through static measures of performance alone.