Biological Psychology

BACKGROUND: An individual's adaptation to threatening environments under uncertainty is reflected in stress responses. Predictability (the ability to anticipate events) and controllability (the ability to control outcomes) are central to how one adapts, yet their joint influence on aversive learning remains unclear. METHODS: Thirty healthy adults completed a probabilistic aversive learning task in which cue-outcome contingencies varied across levels of predictability and controllability, i.e. whether shock intensity depended on prediction accuracy. Prediction accuracy, reaction time, subjective stress ratings, and skin conductance responses were recorded throughout. Trial-wise learning dynamics were estimated using the Volatile Kalman Filter. RESULTS: Prediction accuracy reduced as environments became less predictable and negatively associated with higher learning rates across predictability levels, with the strongest relationship observed in highly predictable blocks. Skin conductance responses showed that moderately predictable environments elicited responses like those in highly predictable environments when accurate predictions reduced shock intensity, but resembled responses in unpredictable environments when shock intensity was uncontrollable. Model comparison revealed a double dissociation between subjective stress ratings and skin conductance responses. Subjective ratings were best explained by model-derived volatility when prediction accuracy determined shock intensity and by belief uncertainty when it was independent of prediction accuracy, whereas skin conductance responses showed the reverse pattern. Reaction times were best explained by belief uncertainty when predictions influenced shock intensity. Higher anxiety was associated with elevated learning rates in highly and moderately predictable blocks when predictions did not control shock intensity.

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.

Financial exploitation often arises in social contexts in which individuals must evaluate fairness, trust, and interpersonal information during financial decisions. We examined whether neural responses to fairness in social versus nonsocial contexts relate to financial exploitation vulnerability and whether these relationships vary with age, emotional intelligence, and affect. A total of 310 adults spanning ages 21-89 completed an fMRI Ultimatum Game in which they accepted or rejected offers from human and computer partners, along with measures of financial exploitation vulnerability, emotional intelligence, and affect. Participants were strongly sensitive to offer fairness, and individual differences in behavioral sensitivity to partner type were associated with social-relative anterior insula responses to unfairness. Greater baseline negative affect was associated with stronger anterior insula differentiation between social and nonsocial fairness. Financial exploitation vulnerability was associated with prefrontal responses to social-relative fairness in ways that depended on individual characteristics: age moderated its association with dorsomedial prefrontal cortex activation, whereas emotional intelligence moderated its association with dorsolateral prefrontal cortex activation. Whole-brain connectivity analyses further showed that age moderated associations between emotional intelligence and executive control network connectivity with posterior cingulate and right temporoparietal regions. These findings suggest that vulnerability to financial exploitation is reflected in how social context is integrated with affective and individual characteristics across adulthood.

Self-control is the capacity to resist self-defeating behavior in favor of long-term goals. Such behavioral control is fundamental to adaptive human behavior, yet its neural mechanism remains unclear. A key limitation of prior research is that tasks often conflate self-control with cost-benefit evaluation, making it difficult to isolate self-control encoding. We introduced a novel dynamometer-based task where participants chose between high-effort, larger-later (L) and low-effort, smaller-sooner (S) rewards. In some trials, referred to as temptation trials, participants could maintain their initial commitment (LL/SS) or switch (LS/SL). Twenty-six participants performed the task during a 32-channel EEG recording. Behavioral results showed a significant shift from L to S options in temptation trials, suggesting frequent yielding to temptation. EEG activity covaried with switching behavior. The late positive potential (LPP) differentiated stay (LL) from switch (LS) trials before initial choice, localizing to the posterior cingulate visual area and left somatosensory regions. Enhanced LPP in LS trials is thought to reflect heightened motivational conflict and attentional engagement with alternatives. Time-resolved multivariate decoding reliably discriminated LL from LS outcomes, peaking 304-348ms post-option presentation. This was driven by distributed frontal and centroparietal networks, demonstrating that a neural bias toward yielding is established well before the initial choice at the network level. The EEG activity preceding switching predicted the final choice, reflecting reward anticipation rather than self-control signals. Together, these findings suggest that proactive neural states during deliberation, established before the choice, shape self-control success and failure.

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.

The mental health and wellbeing or `mind health', which we define as the ability to navigate challenges and function productively, of adolescents has declined substantially over the last two decades corresponding with fundamental changes in their daily environments. These include the widespread adoption of smartphones and social media as well as reduced sleep and time spent in nature. Device free, nature-rich summer camps represent a shift in environment that has been shown to have behavioral and mental health benefits. However, neural mechanisms underlying these changes remain unknown. Here we examined EEG spectral and complexity measures in adolescents ( N=30) before and after a three-week device-free, nature-rich residential summer camp. Following the intervention, participants exhibited steeper aperiodic slopes, increased DFA scaling exponents, reduced entropy and Lempel-Ziv complexity, and decreased alpha and beta power, a convergent pattern consistent with a shift toward more structured or less random neural dynamics characterized by relatively greater inhibitory influence. These neural changes co-varied with reduced restlessness and hyperactivity, improved focus, sleep quality, and overall mind health in a subsample (N=23) with both EEG recordings and self-reported mind health data. Precision analyses further confirmed the specificity of this relationship. Subjects who showed EEG changes beyond a defined threshold showed improvements in mind health metrics with high precision up to 100\%. Our findings demonstrate that the benefits of device-free, nature immersion with peers extend beyond self-reported mind health to measurable shifts in underlying brain dynamics, suggesting that exposure to device-free natural environments supports adolescent neural and psychological health. Trial registration : ClinicalTrials.gov NCT07761143.

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 gastrics intrinsic slow-wave rhythm couples to ongoing cortical activity in humans, but the functional significance of this gastric-brain coupling remains poorly understood. Using simultaneous electroencephalography and electrogastrography, we examined how gastric-brain coupling changes during a mental task and subsequent recovery and whether these dynamics relate to autonomic responses in healthy adults (HA) and individuals with Irritable Bowel Syndrome (IBS), a disorder of gut-brain interactions. In HA, gastric-brain coupling decreased during mental task and gradually returned to baseline during recovery, primarily for cortical alpha rhythms. Greater reductions in gastric-brain coupling were associated with stronger sympathetic arousal, indicating that gastric-brain coupling is associated with physiological responses to cognitive demand. In IBS, gastric-brain coupling dynamics were preserved. However, unlike HA, sympathetic arousal was not associated with gastric-brain coupling reductions, suggesting an alteration in the functional relationship between gastric-brain coupling and autonomic regulation despite preserved coupling dynamics. Further, in HA, greater reductions in gastric-brain coupling were associated with higher anxiety and neuroticism and lower interoceptive awareness. In contrast, these relationships were reversed in IBS, with greater gastric-brain coupling dynamics observed in individuals with higher anxiety and neuroticism and lower interoceptive awareness. Together, gastric-brain coupling emerges as a dynamic physiological process associated with autonomic responses to cognitive demand. In IBS, these dynamics are preserved but their physiological and psychological associations are altered, indicating a dissociation between gastric-brain coupling and its functional correlates. Significance StatementThe functional role of gastric-brain coupling remains largely unknown. We show that coupling between the gastrics intrinsic slow-wave rhythm and cortical activity is dynamically reduced during mental engagement and recovers afterward, primarily through alpha rhythms. In healthy adults, these changes follow sympathetic arousal, linking gastric-brain coupling to autonomic responses to cognitive demands. In irritable bowel syndrome, coupling dynamics remain intact but lose their relationship with autonomic responses and show altered associations with anxiety, neuroticism, and interoceptive awareness. These findings suggest that gastric-brain coupling contributes to the physiological organization of brain-body states and that irritable bowel syndrome may involve altered functional interpretation of visceral signals despite preserved gastric-brain coupling dynamics.

Digital behaviour change interventions have emerged as a promising approach for improving health, well-being, and performance, yet relatively few studies have evaluated their effects using objective biological and neurophysiological measures. The present study examined the effectiveness of Autonomic, a neuroscience-informed digital coaching platform designed to improve student well-being through personalized behavioural interventions targeting sleep, stress, mood, energy, and focus. Thirty university students engaged with the platform for ten weeks and completed behavioural assessments, biomarker collection, and electroencephalographic (EEG) testing at baseline, five weeks, and ten weeks. Behavioural outcomes included self-reported ratings of focus, energy, sleep, mood, and stress. Biological measures included salivary cortisol and tear fluid dopamine concentrations. EEG assessments included resting-state recordings, frontal theta activity during a working memory task, and N200/P300 event-related potentials during a visual oddball task. Significant improvements were observed in self-reported focus, energy, and sleep quality across the intervention. Electrophysiological measures demonstrated reduced frontal theta power during working memory and shorter P300 latencies during attentional processing, consistent with more efficient cognitive processing following the intervention. Although cortisol, dopamine, and resting-state EEG measures did not reach statistical significance, all exhibited changes in the predicted direction. Collectively, these findings provide converging behavioural, biological, and neurophysiological evidence supporting the effectiveness of Autonomic. More broadly, the study demonstrates the value of combining objective biomarkers and EEG with traditional behavioural assessments when evaluating digital behaviour change interventions and highlights the potential of neuroscience-informed coaching platforms to improve health, well-being, and cognitive functioning in university students.

Interoception and homeostatic/allostatic control are not only fundamental for survival but play a key role for maintaining somatic and mental health. Furthermore, metacognitive evaluations of these processes, such as perceived failure of allostatic regulation, have been proposed to underlie the experience of chronic symptoms, such as chronic fatigue. A central question in this regard is what mechanisms the brain uses to evaluate control over bodily states. A prominent computational proposal posits that this is achieved by monitoring of interoceptive prediction errors (PEs). However, to date, this proposal has not been tested experimentally. Here, we tested this hypothesis by applying computational process models of perceived control to data from a novel behavioural paradigm, the Respiratory Metacognition of Control Task (RMCT). The RMCT manipulates control over breathing by changing inspiratory resistive loads as a function of control achieved in a gamified prediction task. We developed and compared trial-by-trial generative models of perceived explicit control in the RMCT, using data from 50 volunteers in a pre-registered analysis. Bayesian model selection suggested that perceived control over breathing is best explained as a function of both trial-wise interoceptive outcomes (breathing with or without an inspiratory resistive load) and trial-wise PEs about respiratory resistance. These results support a longstanding computational proposal of how the brain detects failures of bodily regulation and provide a mechanistic model for understanding inter-individual differences in perceived control over bodily states.

Increasing evidence implicates late chronotype and higher distinctness as two diurnal dimensions associated with a risk for affective dysregulation. Nonetheless, the underlying behavioural and neural mechanisms remain poorly understood. Previous works in depressive and anxious populations have demonstrated an important role of maladaptive self-blaming processes, with pivotal contributions from superior anterior temporal lobes (sATL), involved in social conceptual knowledge, and subgenual anterior cingulate cortex (sgACC), related to self-worth and social affiliative processing. In the current study, we first tested how diurnal rhythm characteristics were associated with self-blaming emotions and related coping mechanisms through hypothetical social scenarios where participants or their close friends acted towards one another against social norms. Secondly, to probe alterations in the neural correlates of self-blaming, the participants underwent functional neuroimaging during reliving of autobiographical guilt memories. On the behavioural level, late chronotypes demonstrated decreased self-distancing and contextually-maladaptive blaming patterns, i.e. increased blaming of the action recipients rather than the agents. This was paralleled by decreased self-blame-related activity in the sATL and sgACC. Distinctness was associated with altered task-dependent sATL connectivity with hippocampus, brainstem and cerebellum. Importantly, some of the neuroimaging findings reflected interactions between the diurnal rhythm characteristics and time-of-day. As such, the current work provides plausible correlates of adverse emotional outcomes in late chronotypes. Furthermore, it suggests that affective processing reflects an interplay between stable trait-like characteristics and dynamic state-like processes varying across the day, contributing to fine-grained understanding of how emotional cognition is embedded in the brain.

Motor effort has been shown to bias perceptual decisions toward less effortful choices, but it remains unknown whether this bias already takes effect during the early stages of decision formation through preparatory attentional allocation or sensory processing, or during later-stage evidence accumulation preceding response execution. This study investigated when motor effort becomes integrated into decision formation by focusing on the temporal evolution of neural processing during perceptual decision-making. While 64-channel EEG was recorded, twenty-four healthy adults performed an orientation discrimination task in which two Gabor patches appeared simultaneously in the left and right visual hemifield and decisions were reported using two pressure-sensitive response buttons requiring different levels of force. We found that motor effort modulated EEG activity at both the preparatory and later decision stages: pre-stimulus alpha power was reduced over the occipito-parietal cortex contralateral to the low-effort option, and mean centro-parietal positivity (CPP) amplitude preceding response execution was greater over centro-parietal cortex for low-effort choices, while leaving early sensory representations intact as indicated by no differences in P1 or N1 amplitude following stimulus onset. Trial-by-trial CPP amplitude preceding response execution increased with the likelihood of selecting the low-effort option, whereas the pre-stimulus alpha modulation was not associated with behavioral decision bias. These findings suggest that motor effort biases perceptual decisions primarily during later-stage evidence accumulation, thereby providing insight into the neural basis of embodied perceptual decision making.

Background: As a key mechanism of disorder, clinical anxiety changes how a defensive motivation system functions in active threat coping contexts. Building on initial evidence that a lab-based escape/avoid preparation task is sensitive to disruptions in underlying defensive activation, current research moved toward implementation as a clinical assessment by testing if task responding predicts symptoms in anxiety treatment seekers. Methods: In our escape/avoid task, unpleasant images are shown after 5.5-second cues that indicate if the upcoming image can be prevented (avoid context), terminated after onset (escape context), or not controlled (no-control comparator). To assess defensive activation during response preparation/threat anticipation, a startle reflex indicator of such activation is probed during each cue. Guided by prior data, 125 individuals were classified into groups based on whether startle was enhanced 1) in a no-control, relative to avoid, context, and 2) in an escape, relative to avoid, context. To test clinical correlates, anxiety (State-Trait Anxiety Inventory), depression (Beck Depression Inventory), and worry (Penn State Worry Questionnaire) were then compared across response groups. Results: Anxiety and worry were higher in participants with enhanced no-control and escape startle than in participants with enhanced no-control but not escape startle. Further, depression was higher in participants with under-enhancement of no-control startle than other groups. Finally, when comparing startle-based profiles to canonical questionnaire cut-off score-based groups, ~54-63% convergence emerged. Conclusions: Defensive profiling in escape/avoid contexts shows promise as a prognostic indicator, but a need to continue improving is also indicated. Possibilities to improve predictiveness and reliability are discussed.

Misophonia is increasingly conceptualized as more than a disorder of sound tolerance, with trigger over-reactivity shaped by the social meaning of sounds, inferred intentions, and representations of others actions. We tested a social-cognitive dysregulation model of misophonia in (N = 341) adults using behavioural measures of Theory of Mind and emotion recognition, alongside measures of reflective functioning, empathy, alexithymia, and mimicry. Dimensional associations with misophonia severity and its five different dimensions were examined while accounting for age, sex, sound sensitivity, and anxiety/depressive symptoms. Increased misophonia severity was associated with less accurate and slower mental-state inference and emotion recognition. ToM accuracy effects were evident for more complex, cognitive, and affective mentalizing, but not for simpler mentalizing or physical control judgments, while emotion-recognition accuracy differences emerged for positive but not negative stimuli. Greater severity was also characterized by reduced certainty and greater uncertainty about mental states, greater difficulty identifying one s own feelings, and elevated alexithymia, whereas global self-reported empathy was largely preserved. Misophonia severity further predicted a greater propensity to mimic trigger-producing actions or sounds; 41% of participants exceeding the S-Five clinical cutoff (> 87) endorsed mimicry, which was particularly associated with a subjective restoration of control. Findings remained robust following influential-case sensitivity analyses. These results reveal a selective disturbance in self-other representation spanning mentalizing, emotion decoding, emotional self-representation, and embodied regulatory processes. They position misophonia within a broader social-cognitive framework in which auditory-affective reactivity may intersect with altered inferential and sensorimotor processing, while stopping short of causal inference.

Background: Emotion dysregulation is common across psychiatric disorders, but the biological mechanisms underlying emotional vulnerability remain poorly understood. Cardiac vagal regulation and interoception, the perception of bodily signals, may jointly contribute to emotion regulation. We examined whether their interaction is associated with emotion dysregulation and psychopathology in adolescents receiving psychiatric inpatient treatment. Methods: We studied 279 adolescent psychiatric inpatients. Cardiac vagal regulation was assessed using heart rate variability and interoceptive accuracy using a measure of bodily signal perception. Structural equation modeling tested associations between cardiac vagal regulation, interoceptive accuracy, emotion dysregulation, depressive symptoms, and personality dysfunction, including sex specific pathways and interactions. Results: Here we show that associations between autonomic regulation, interoception, and psychopathology differ by sex. In male adolescents, lower cardiac vagal regulation is associated with greater emotion dysregulation, which is associated with higher depressive symptoms and greater personality dysfunction. These associations depend on interoceptive accuracy and are most evident at low to intermediate levels of bodily signal perception. Comparable pathways are absent in female adolescents. Conclusions: These findings indicate that interactions between cardiac regulation and bodily signal perception contribute to emotional vulnerability in a sex-dependent manner. Altered body-brain communication may contribute to divergent developmental pathways of psychopathology. Integrating sex specific autonomic and interoceptive processes may improve models of emotion regulation and psychiatric risk during adolescence.

Unobtrusive stress detection using wearable sensors could enable scalable, continuous mental-health monitoring. However, stress is an inherently subjective state that can only be inferred indirectly from physiological signals, making generalizable detection in naturalistic settings challenging. Although prior work has focused on improving model performance, it remains unclear whether wearable physiology supports a shared cross-individual mapping to subjective stress or whether this relationship is fundamentally person-specific. We evaluated feature-based and deep-learning models across multiple physiological modalities using ecological momentary assessment (EMA) as the reference standard, comparing within- and between-individual modeling approaches. Within-individual models achieved modest but consistent improvements in stress detection, whereas between-individual models consistently failed to generalize, yielding negative R2 values despite multimodal fusion and high-capacity architectures. Error analyses revealed regression to the mean, reduced sensitivity to high-stress states, and residual associations with general physiological activation, highlighting the limited stress specificity of wearable physiology. These findings suggest that wearable stress detection is fundamentally a personalized inference problem and that future systems should prioritize individual adaptation and contextual modeling over universal stress predictors.

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.

Humans coordinate their actions while their bodies and brains synchronize in social interactions, yet how behavioral, physiological, and neural dynamics interact during interpersonal coordination remains largely unknown. We investigated how respiration and individual differences influence behavioral and inter-brain synchrony in a musical synchronization task, which requires precise temporal alignment. Eighty-eight individuals first produced a familiar melody at their most comfortable rate to measure their spontaneous production rate (SPR). They then synchronized the melody with a randomly assigned unfamiliar partner under natural (unpaced), instructed in-phase, and instructed anti-phase breathing conditions, while hyperscanning 64-channel electroencephalography (EEG), respiration, auditory-motor timing, and perceived social connectedness were recorded. Relative to natural respiration, both in-phase and anti-phase breathing increased inter-brain phase-locking and perceived social closeness but reduced behavioral synchrony; the instructed respiratory phase relationship was mirrored in their inter-brain relative phase. Differences in phase of respiratory cycles (inhalation and exhalation) also influenced coordination: Inhalation was associated with stronger inter-brain synchronization but less precise and stable behavioral coordination than was exhalation. Moreover, Individual differences influenced coordination: Partners with the faster SPR consistently preceded the slower partners and exhibited an alpha-band inter-brain phase advance in synchronization, whereas dyads with similar SPR showed greater behavioral synchrony and smaller inter-brain phase difference. Our findings identify respiration as a previously overlooked factor that organizes behavioral and neural synchronization, while individual intrinsic rhythms constrain how interacting partners align in time. Together, these findings reveal a dynamic interplay between the rhythms of the body and brain during human social interactions.

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.

Touch moderates how we interact with objects, others, and ourselves, where self-touch is particularly important in self-care, although fewer studies have investigated its perception, especially with age. Here, women aged 20-28 and 65-75 years rated how self-applied creams felt on the cheek and forearm, using sensory and emotional descriptors in the Touch Perception Task. Factor analyses uncovered higher tactile dimensions, including Texture, Moisture, Positive Affect, and Negative Affect. Sensory dimensions were more intense in the young group, whereas Positive Affect was stronger in the older group. We then used network and clustering analyses to map how the descriptors interacted. Young participants showed significantly higher connectivity between descriptors, whereas older participants displayed fewer connections, but many became mixed sensory-emotional pairings. Clustering analyses revealed further changes in the tactile groupings with age. We conclude that aging reshapes touch into an emotionally-rich experience, which impacts how interact with ourselves and others.