International Journal of Psychophysiology

BackgroundAutonomous sensory meridian response (ASMR) and music-induced frisson are sensory-affective phenomena characterized by tingling, chills, and pronounced emotional responses. Previous research has mainly focused on physiological changes during these experiences, whereas much less is known about whether baseline physiological state is associated with subsequent susceptibility. ObjectiveTo examine whether baseline autonomic flexibility, indexed primarily by heart rate variability (HRV), is associated with later ASMR/frisson responsiveness. Resting EEG measures were included as secondary exploratory markers. MethodsFifteen participants were recruited by convenience sampling; after artifact-based exclusion, 10 participants were included in the analyses. A 5-minute resting baseline EEG and ECG was recorded prior to stimulus presentation. Participants were then exposed to auditory and audiovisual ASMR stimuli, classical music excerpts, and a control stimulus, and reported whether they had experienced ASMR-typical sensations or frisson. Main analyses examined associations between baseline physiological parameters and a combined response-positive outcome. Exploratory analyses included participant-level correlations, comparisons between susceptible and non-susceptible participants, and stimulus-specific effect sizes. ResultsHRV-related measures showed the clearest and most consistent pattern of association with responsiveness. Higher baseline total HRV power was associated with a greater number of response-positive stimuli (r = 0.756, p = 0.011), with similar positive associations for high-frequency HRV (HF; r = 0.672, p = 0.033) and baseline heart rate slope (r = 0.751, p = 0.012). Stimulus-specific analyses likewise showed the most consistent positive baseline effects for total HRV power, with HF and heart rate slope pointing in the same direction. Frontal alpha asymmetry (FAA) was negatively associated with responsiveness ({rho} = -0.862, p = 0.001), but EEG findings overall were less consistent than the HRV-related pattern and are best interpreted as secondary exploratory observations. ConclusionsIn this exploratory pilot sample, baseline HRV, particularly total HRV power, showed the most coherent physiological association with susceptibility to ASMR and music-induced frisson. The findings are consistent with the possibility that these experiences depend not only on stimulus properties, but also on pre-existing physiological state. Given the small sample and exploratory design, the results should be interpreted as hypothesis-generating and require replication in larger confirmatory studies.

Emotion is key to human communication, inferring emotion in a speakers voice is a cross-cultural and cross-linguistic capability. Electroencephalography (EEG) studies of neural mechanisms supporting emotion perception have reported that early components of the event-related potential (ERP) are modulated by emotion. However, the nature of emotions effect, especially on the P200 component, is disputed. We hypothesised that early acoustic features of emotional utterances might account for ERP modulations previously attributed to emotion. We recorded multi-channel EEG from healthy participants (n = 30) tasked with recognising the emotion of utterances. We used fifty vocalisations in five emotions - anger, happiness, neutral, sadness and pleasure - drawn from the Montreal Affective Voices dataset. We statistically quantified instantaneous associations between ERP amplitudes, emotion categories, and acoustic features, specifically, intensity, pitch, first formant, and second formant. We found that shortly after utterance onset (120-250 ms, i.e., P200, early P300) ERP amplitude for sad vocalisations was less than for other emotional categories. Moreover, ERP amplitude at around 180 ms for happy vocalisation was less than for anger, sadness, and pleasure. Our analysis showed that acoustic intensity explains most of these early-latency effects. We also found that, at longer latency (220-500 ms; late P200, P300) ERP amplitude for neutral vocalisations was less than for other emotional categories. Furthermore, there were also ERP differences between anger and happiness, anger and pleasure, anger and sadness, happiness and pleasure, as well as happiness and sadness in shorter windows during this late period. Acoustic pitch and, to a lesser degree, acoustic intensity explain most of these later effects. We conclude that acoustic features can account for early ERP modulations evoked by emotional utterances. Because previous studies used a variety of stimuli, our result likely resolves previous disputes on emotions effect on P200.

Structured AbstractO_ST_ABSObjectiveC_ST_ABSTo facilitate the scalability of EEG research, this paper compares the data quality and evaluates the absolute agreement of EEG features between laboratory and clinic settings. MethodsResting state EEG recordings were obtained from 36 participants (11 infants, 10 children, and 15 adults) from the waiting room of a primary care clinic and a laboratory. Intraclass correlation coefficients (ICC(2,1)) quantified the absolute agreement between laboratory and clinic settings for periodic power bands, alpha peak characteristics, and aperiodic components. The mean absolute difference (MAD) between laboratory and clinic recorded EEGs were calculated to describe signal consistency across settings. ResultsMore components were rejected from clinic-recorded EEGs, though data quality otherwise did not differ between settings. The ICC (2,1) for all EEG measures were generally in the good-to-excellent range across ages and regions of interest. The MAD decreased with age and was largest in the alpha frequency range. ConclusionsHigh quality EEG data can be collected from outpatient clinic settings among infants, children, and adults. There is high reliability in the parameterized periodic and aperiodic EEG features between laboratory and clinic settings. SignificanceFuture research may collect EEG datasets from naturalistic settings with confidence in their reliability relative to laboratory recordings.

Phasic increase of frontal midline theta (Fm theta) has been described as a key indicator of cognitive processing, while relatively lower task-related Fm theta is associated with reduced cognitive strain, reflecting less intensive cognitive processing. In a previous investigation, reduced task-related Fm theta in relation to higher expertise, as well as higher setting anticipation performance in the domain of volleyball was identified. In the present study a single-session sham-controlled neurofeedback training (NFT) intervention was conducted to investigate the feasibility of Fm theta downregulation for the improvement of volleyball setting anticipation. A total of 24 volleyball novices was allocated to "Real" (n = 12) and "Sham" (n = 12) Fm theta downregulation NFT groups. NFT-related Fm theta, pre-/post-NFT setting anticipation task performance and task-related Fm theta, as well as resting EEG activity were analyzed. Incongruous with our expectations, the Real NFT group showed a tendency toward stronger Fm theta synchronization compared with the Sham group during NFT. Anticipation task performance did not change significantly from before to after NFT in both groups, yet a significant reduction of task-related Fm theta was observed in the Real NFT group following NFT. A post-NFT rebound of Fm theta could be responsible for this result. With our findings we provide further evidence for the existence of an apparent paradox of Fm theta downregulation, in which cognitive control mechanisms, associated with oscillatory Fm theta activity, appear to hinder explicit downregulation of Fm theta through classical neurofeedback learning mechanisms.

The study of contemplative practices has evolved into a mature field, yet current taxonomies tend to classify all mantra-based meditation approaches as a single category, overlooking potentially different neural states induced by different mantras or different instructions. To address this gap, we conducted a study of 50 novice subjects practicing two types of mantra-based meditation over a six week period to evaluate changes in Electroencephalography (EEG) during and after meditation. Participants were randomly assigned to meditating with the Hare Krishna (HK) and Sa-Ta-Na-Ma (SA) mantras. Using spectral parameterization, we assessed the effects of each type of meditation on individual alpha power (IAP), individual alpha frequency (IAF) and center of gravity (CoG). The results revealed marked differences in alpha dynamics between the two practices. On the one hand, the HK group exhibited widespread IAP decrease and an IAF/CoG increase during mantra meditation that was maintained during rest after the meditation, which became more pronounced after training in the HK meditation. On the other hand, the SA group showed a localized IAP reduction during meditation and significant reduction of IAF during meditation after training. We suggest that the higher cognitive demands of HK induce a more activating, attentionally focused state, whereas SA promotes a more relaxed state. Additional psychological data show that both meditation groups had reduction in stress. Thus, these findings challenge the monolithic classification of mantra meditation and highlight the importance of differentiating practices according to their mechanisms, particularly for their targeted application in mental health contexts.

Mindfulness-based interventions are increasingly delivered online, yet evidence for short programs often relies on self-report outcomes. We tested whether a brief online mindfulness meditation training produces detectable changes in autonomic regulation during a standardized stress-to-meditation sequence. Healthy adults with no meditation experience were randomized to a four-week online mindfulness meditation program (MG) or an active health-management program (CG). Before and after training, participants completed a laboratory session consisting of rest, a mental arithmetic stress task, guided focused-attention breathing meditation, and post-rest while ECG was recorded. Across the training period, both groups showed reduced negative affective symptoms, but only the mindfulness group showed an increase in the Observing facet. Critically, frequency-domain HRV indices during the laboratory protocol showed a group-specific post-training pattern: MG exhibited lower LF/HF and higher normalized HF power (nHF) compared with pre-training, and MG differed from CG in the post-training session. Within MG, training-related improvement in FFMQ Non-reactivity was positively associated with nHF during the post-stress meditation period. These findings indicate that a brief online mindfulness program can modulate HRV during a stress-to-meditation context and that post-stress autonomic modulation during meditation covaries with acceptance-related skill acquisition.

Stressors are commonly used in rats to induce models of anxiety or depression. The effectiveness of these stressors is often evaluated using specific behavioural tests. In a previous meta-analysis of chronic variable stress (CVS) procedures, we predicted that longer and more intensive stress procedures would result in larger effect sizes in behavioural tests. However, we found that the duration or intensity of CVS procedures did not correlate strongly with the magnitude of the effect sizes reported in behaviouraltests. In that study, we were concerned that the large and unexplained diversity in CVS procedure design, both in terms of duration and the types of stressors used, made it challenging to detect the factors that were influencing effect size. In an effort to address this, we explore here the use of a much simpler stress procedure - chronic restraint stress (CRS) - to study the relationship between the duration of CRS procedures and the effect sizes obtained in subsequent behavioural tests. We searched PubMed for articles using CRS procedures with rats, systematically documented the total duration of restraint, and carried out a meta-analysis of the effect sizes obtained in four behavioural tests: the forced swim test (FST), the sucrose preference test (SPT), the elevated plus maze (EPM) and the open field test (OFT). We found that chronic restraint stress increased immobility in the FST, decreased sucrose preference in the SPT, decreased time spent in the open arms of the EPM but had no effect on time spent in the centre of the OFT. However, the effect sizes in all behavioural tests, except the SPT, were not moderated by the duration of the CRS procedure, indicating that longer CRS procedures are associated with larger effect sizes in the SPT but not in the FST or EPM.

The identification of objective, dimensional indices of mental health is of central importance in the pursuit of transdiagnostic multi-dimensional frameworks of psychopathology. Altered visual processing occupies a specific domain of interest and motivated the present investigation aimed to quantify the visuocortical impact of affective naturalistic distractor cues on limited capacity attentional resources in obsessive-compulsive disorder (OCD). The current investigation examined the extent to which attentional resources are allocated toward task cues under affective and disorder-relevant distraction in participants with OCD (N = 33) and control participants (N = 31). Steady-state visual evoked potentials (ssVEPs) in response to task-relevant cues were examined using a foreground task where participants detected coherent motion in a flickering random dot kinematogram (RDK) overlaid on naturalistic distractor pictures ranging in emotional content (pleasant, neutral, unpleasant, and OCD-evoking pictures). Amplitude envelopes of ssVEPs in response to the motion stimulus served as an index of visuocortical engagement with task-relevant cues. Data were also fitted to the distraction under competition model (DUC), a computational framework of attention selection. Group differences emerged with stronger visuocortical competition effects (attenuated task engagement) for the OCD group, driven largely by the unpleasant pictures, followed by the OCD-evoking pictures. Furthermore, the DUC model fit well in both groups, demonstrated the dominance of the visuocortical competition observed in response to the unpleasant pictures, and revealed the presence of substantial competition in response to the OCD-evoking pictures in the OCD group.

Numerous studies have shown that adults with depression have distinct oculomotor alterations during saccade tasks, but whether similar alterations occur in adolescents is largely unknown. The purpose of this study was to test if eye-tracking during a structured saccade task could distinguish a group of adolescents with depression from healthy controls. We hypothesized that, due to overlapping circuitry between depression pathology and the oculomotor system, adolescents with depression would show alterations in fixation, saccade, and pupil behaviour. 51 adolescents with depression and 66 age-matched healthy controls completed the Interleaved Pro- and Anti-Saccade Task (IPAST) and several self-reported questionnaires for psychiatric symptoms. Oculomotor outcomes included fixation acquisition, fixation breaks, correct rate, saccadic reaction time, rate of correct express-latency pro-saccades, rate of express- and regular-latency anti-saccade errors, baseline pupil size, as well as pupil constriction and dilation sizes following task instruction. In comparison to healthy controls, adolescents with depression displayed impairments acquiring fixation (p<.001), made more fixation breaks in pro- (p=.023) and anti-saccade trials (p=.005), more anti-saccade errors (p=.013), more express-latency saccades overall (ps=.016), had a smaller pupil constriction in pro-saccade trials (p=.047) and had a smaller pupil dilation in pro- (p=.011) and anti-saccade trials (p=.041). No differences were found for saccadic reaction time, rate of correct pro-saccades, rate of regular-latency anti-saccade errors, pupil constriction size during anti-saccade trials, or baseline pupil size. Patients had psychiatric comorbidities and were using psychotropic medication. While this reflected clinical reality, these factors may have influenced oculomotor behaviour. Adolescents with depression had altered fixation, saccade, and pupil behaviour during IPAST. Given that many cases of adolescent depression remain undetected, accessible and objective screening approaches are highly needed. This oculomotor phenotype may be used in the development of such a screening tool to detect those at risk.

RelevanceFor performance in a dynamically changing environment, not only the speed of a sensorimotor reaction is important, but also the speed of its recovery (relaxation) after a previous response. GoalTo investigate whether the neural pathways from various receptors or their groups are functionally independent in the process of recovery after excitation transmission. MethodsIn over 20 subjects, the latent period of a simple sensorimotor reaction (SSMR) to visual, auditory, and tactile stimuli was recorded with varying interstimulus intervals. The relaxation parameters of the variable component of the reaction time were extracted by approximating the data with a multiexponential model. The key paradigm involved alternating stimulation of different sensors: spectrally different (red/blue light), totally different (sounds of different frequencies), or spatially separated (different areas of the retina/skin). ResultsIt was shown that alternating stimulation, compared to isolated stimulation of a single type/location, leads to a significant reduction in the time constants of SSMR relaxation. The effect was revealed for all studied modalities. ConclusionThe obtained data indicate the functional independence of neural channels processing information from different receptors or their groups during the recovery phase after excitation transmission, up to the level of the motor center. This suggests a higher degree of specificity in the organization of sensorimotor responding than might be assumed based on data about the diffuse nature of cortical activation recorded by EEG and fMRI methods.

Excessive self-blaming emotions are commonly observed in anxiety disorders, with qualitatively similar symptomatology reported in subclinical populations. Interpretation of moral information requires assessing the social conceptual information, a process overseen by the superior anterior temporal lobe (sATL). Feelings of self-blame evoke interactions of sATL and socio-affective regions, and previous research shows that subclinical anxiety modulates the organisation of the self-blame circuitry. This study aimed to extend these findings by exploring links of trait-anxiety with (i) self-blaming emotions and associated behaviours in an experimental task, and (ii) self-blame-dependent neural activity and connectivity, as observed during reliving of autobiographical guilt memories. We also explored the role of resting-state fMRI in linking these phenomena. Increased anxiety was linked to stronger self-blaming emotions, and more pronounced self-attacking and hiding. When experiencing negative emotions about themselves (i.e. shame and self-anger), anxious individuals were also less likely to disengage from self-focused thoughts. These behavioural findings were paralleled by enhanced self-blame-related connectivity between the left sATL and bilateral posterior subgenual cingulate cortex. Distinct patterns of activity and connectivity within the ATL-related circuitry were furthermore linked to individual differences in intensity of the self-blaming emotions and approach-avoidance motivation towards the guilt memories. As such, the results of the current study link stronger self-blaming emotions in anxious individuals with specific maladaptive patterns of behaviour. Furthermore, the work provides robust evidence for the important role of ATL-related circuitry in self-blame processing, supporting its broader involvement in social conceptual processing and its alterations in subclinical anxiety.

AimsDue to the multifaceted nature of "impulsivity", its measurement remains fragmented. Here, we developed the Risky Social Choices task to provide evidence for its validity and reliability, while testing the hypothesis that impaired access to implicit knowledge of negative long-term consequences is of distinct importance for "impulsive" decision-making in a general population sample. MethodsForty participants chose whether to engage in risk-taking behaviors, which combined web-based AI-generated videos with narrated hypothetical scenarios and measured worries related to negative long-term consequences, approach-related motivation for short-term rewards, response time to and accuracy of recognizing degraded auditory prime words denoting negative long-term consequences. ResultsA pre-registered multi-step regression model was constructed with worry, motivation, response time and accuracy as predictors and percentage of risky choices as the outcome. Among all predictors, only prime word recognition accuracy was significantly negatively associated with risky choices, confirming our hypothesis of the role of reduced implicit access to negative long-term consequences in risk-taking decisions. In contrast, approach-related motivation for rewards was the only predictor significantly positively related to percentage of risky choices. DiscussionAs predicted, the negative association between risky choices and implicit access to negative long-term consequences supports its role as a distinct aspect of "impulsivity". The novel task successfully captured this aspect, paving the way for a more precise neurocognitive characterization of clinical conditions where "impulsivity" plays a key role. The findings unveil the importance of implicit social sequential knowledge for impulsivity in neurotypical populations, so far only investigated in patients with brain lesions.

BackgroundChronobiology research has historically focused on circadian rhythms; however, longer infradian rhythms are prevalent in human physiology and may have important implications for health and wellbeing. Previous studies have identified widespread infradian rhythms across human physiology, often in the context of hormonal regulation and disease. Despite growing evidence of their ubiquity, the mechanisms, significance, and clinical relevance of these rhythms remain poorly understood, largely due to lack of longitudinal datasets and robust detection methods. The emergence of new wearable technologies enables rich, continuous data capture within individuals, allowing physiological rhythms to be studied at scale. MethodsThis study analyzed a cohort of healthy, young adults (N=623), with up to four years of wearable and questionnaire data collected through the University of Notre Dames (USA) NetHealth project. Participants who recorded at least three months of continuous (>80% adherence) heart rate data were included and significant infradian rhythms were identified using wavelet analysis. Unsupervised non-negative matrix factorization was performed to cluster similar wavelet power spectrum distributions. Individuals heart rate rhythms were compared to known environmental cycles (day-of-week, lunar, seasonal) and considering demographics and social networks. A second, smaller cohort (N=70) with heart rate and menstrual timing were included to analyze the interplay of hormonal regulation on monthly cycles. Multinomial logistic regression, and statistical tests (i.e., one-way ANOVA) were applied to quantify the effects of environmental, behavioral and demographic factors on heart rate rhythms. FindingsSignificant infradian rhythms of heart rate were detected in 69.7% (365/523) of the cohort and 35.9% (188/523) had two or more rhythms. Annual, biannual and 10-week rhythms were the most common. Within the 4-45-day band, individuals clustered into four multiday chronotypes based on dominant periodicities in their wavelet power spectra: weekly ([~]7 days), shorter-monthly ([~]25 days), longer-monthly ([~]35 days), and multi-month (>35 days). Heart rate rhythms were influenced by environmental cycles (day-of-week and seasonality) but were not tightly correlated to external cues. Additionally, heart rate rhythms were synchronized to the menstrual cycle in most menstruating females, although monthly rhythms were also observed in males and menopausal women. InterpretationThe prevalence of infradian, or multiday heart rate rhythms in healthy young people motivates further scientific investigation to understand the mechanisms of these rhythms and their potential association with autonomic function, and risk of disease or disease-specific symptoms. Characterizing physiological rhythms can drive new insights into how multiscale fluctuations modulate disease symptoms across neurological, psychiatric, and broader health conditions.

Mental fatigue is induced by prolonged engagement in cognitively demanding tasks and impairs endurance performance. The neuropsychophysiological mechanisms underlying this decreased performance remain unclear, with suggestion that mental fatigue may disrupt motor command and consequently muscle activation. We aimed to test this hypothesis in a repeated cross-over design study in which 18 participants completed two experimental sessions involving a time-to-exhaustion cycling test at 80% of peak power output. Each cycling task was preceded by 1h of a prolonged Stroop task (Stroop session) or a neutral control task (Control session). Perception of effort and surface electromyography from ten lower-limb muscles of the right leg were recorded at regular intervals during cycling. Mental fatigue was higher in the Stroop compared to the Control session (p = .002). Endurance cycling time was 111 {+/-} 160 s shorter in the Stroop than in the Control session (p = .009). No significant differences in electromyography parameters were observed between Stroop and Control sessions, for any muscle (p > .05). Perception of effort was higher in the Stroop session from the onset of the cycling task (p = .006), and the rate of increase in perception of effort was significantly higher in the Stroop than Control session (p = .031). Our findings do not support the hypothesis that mental fatigue alters motor control or increases central motor command, as no changes in muscle activation were detected. Conversely, our results reinforce the notion that prolonged cognitive engagement impairs endurance performance primarily through an increased perception of effort. Future research should consider combining surface electromyography with more sensitive neurophysiological techniques to investigate potential subtle changes in motor drive during dynamic, whole-body tasks under mental fatigue. Impact statementOur study confirms that mental fatigue induced by prolonged cognitive exertion impairs cycling endurance performance. By combining measurements of perceptual responses and multi-muscle surface EMG during the endurance task, we observed that the decreased endurance performance is related to an increased perceived effort in the presence of mental fatigue, not related to alterations in motor command.

By relying on the observation of others experiences, humans learn about threat while avoiding harmful experiences. Yet, previous neuroscience research has focused on observational threats that are predictable. While the neurobiological distinction between temporally predictable (cued) and unpredictable (contextual) threats has been well-characterized in firsthand learning. In this study, we developed a novel observational paradigm in which participants learned from predictable (P) and unpredictable (U) observational threats, as well as a no-threat (N) condition and encountered the same conditions during an expression phase based on the NPU paradigm to investigate how the brain encodes predictable and unpredictable threat cues observed in others. Participants in Experiment 1 (n=20, male and female) and Experiment 2 (n=23, male and female) successfully learned threat contingencies, showing heightened threat expectations for predictable cues and unpredictable contexts. This converged with neural (fMRI, Experiment 2) responses in the anterior insula during the expression phase. Reflecting the dynamic process of learning, the amygdala responded to predictable threat cues with a linear decrease across trials. Interestingly, we found that responses to others pain was enhanced within the amygdala, insula and hippocampus, when participant could learn to predict threats, as compared to unpredictable conditions. Our findings suggest that humans learn to resolve temporal uncertainty, relying solely on observation, which thereby lays a foundation to the concept of fear and anxiety in social groups.

Exercise is a positive health behaviour associated with improved mood. However, the mechanisms underlying the benefits of exercise on affective health are unclear, particularly with respect to type of exercise and sex. Chronic exercise decreases neuroinflammation, which is linked to improvements in mood and anxiety. However, exercise is also a physiological stressor that can transiently upregulate systemic inflammation, and its effects on neuroinflammation are not well understood. This study examined how acute and chronic exercise affect circulating and brain cytokine levels and anxiety-related behaviour in young healthy male and female mice. In Experiment 1, mice were placed on a treadmill for a two-hour bout of moderate exercise. Two hours after exercise, animals were either tested in the open field or euthanized for measurement of cytokines (IL-1{beta}, TNF, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, IFN-{gamma}, KC/GRO). In Experiment 2, mice underwent an 8-week moderate treadmill exercise paradigm followed by open field testing and tissue collection. Acute exercise decreased time spent in the centre of the open field in males only, suggesting increased anxiety-like behaviour in males. Acute exercise increased IL-6 and decreased TNF in serum, and increased amygdala principal component 1 (loading IL-12p70, IL-10, IFN-{gamma}, and TNF) in both sexes. Chronic exercise increased open field centre entries, increased IL-6 in the prefrontal cortex, decreased TNF in the dorsal hippocampus, and had minimal effects on circulating cytokines in both sexes. These results demonstrate that the effects of exercise on anxiety-related behaviour and cytokine levels depend on recurrence, tissue, and brain region. New & NoteworthyOur work highlights the contrast between anxiogenic and anxiolytic effects of acute versus chronic exercise, respectively, in healthy mice. Acute and chronic exercise differentially affected circulating and brain cytokines, providing insight into physiological adaptations to exercise. Both sexes demonstrated similar cytokine responses to exercise. These similarities are novel with respect to exercise research and noteworthy given sex differences in anxiety with respect to acute exercise.

Creativity is one of the unique cognitive constructs in human beings and its neurobiological correlates are one of the current hot topics in neuroscience. The "Different Hearing" program (DHP) is an educational activity aimed at stimulating musical creativity by means of group composing in the classroom, alternative to the mainstream model of music education in Czechia. In our previous study, the data from task-related functional MRI with passive listening was analyzed. The results suggested that DHP training modified the response to diverse sound samples, differentially changing the engagement of functional networks known to be related to creative thinking, namely, increasing default mode network activation and decreasing activation of executive and salience networks. In the present study, we hypothesized that the DHP short-term (2 days) intense workshop would also induce changes in the resting-state networks that were significantly modified during task. To investigate it, seed-based, ROI-to-ROI resting-state functional connectivity and degree centrality analysis were performed on the acquired resting-state fMRI data. The results showed no significant group-by-time interaction.

Neuropsychiatric (depression, schizophrenia, etc.) and neurological disorders (Alzheimers disease, AD, Parkinsons disease) are characterized by disruptions in cognition including social interaction and recognition. Developing tools for the assessment of social behaviour in mouse models and its relevance is essential to further advance our understanding of social impairments in these diseases. In the Agora maze for rodents, stranger mice confined into cubicles around the perimeter of the open square mirror the agora (marketplace) in ancient cities. Up to 5 social interaction partners are presented and can be freely selected for interaction (exposure). In the discrimination phase one novel mouse (SNew) is presented while 4 familiar partners remain. Interaction time is recorded via video observation. In Exp 1, we validated the test with different strains of wild-type male mice (C57BL/6J, Balb/c, NMRI) that were able to readily identify SNew and spent significantly more time in zones adjacent to their cubicle; only NMRI mice did not prefer SNew. Exp. 2 explored 5xFAD Alzheimer mice and showed normal exploration and discrimination when aged 6 and 8 months old. Repeat of the experiment in a second cohort confirmed robustness of this phenotype, but also reproducibility of the behavioural paradigm. The Agora task allows semi-automated evaluation of preference for social novelty in a more complex paradigm by expanding the number of social interaction partners from 2 (three-chamber test) to 5 (or more), while still avoiding physical approaches and aggressive episodes. Thus, Agora provides a more physiological behavioural paradigm which is highly robust and reproducible. HighlightsO_LIMore comprehensive behavioural test bed for social recognition C_LIO_LIMale wild-type mice can identify a stranger mouse amongst 5 social interaction partners C_LIO_LINo deficit in amyloid-based Alzheimer model 5xFAD aged 6-8 months. C_LIO_LIRepeat of experiments returned highly robust and reproducible results. C_LI

Historically, neural variability observed during task was interpreted as "noise," assumed to obscure meaningful signal and thus something to be minimized both analytically by researchers and functionally by the brain. Changes to this signal-to-noise ratio have been proposed as a possible neural mechanism behind the increased reaction-time variability (RTV) in attention deficit hyperactivity disorder (ADHD). However, not all variability is the same - in some cases, variability can have some underlying "statistical structure" that can be beneficial to information processing. The challenge lies in distinguishing meaningful variability from random noise. The edge-of-synchrony critical point, which describes a system poised between synchronous and asynchronous regimes, could be a good theoretical framework to study these different types of neural variability. In this study, we investigate whether changes in criticality and oscillatory dynamics preceded slower behavioral responses during a bimodal continuous performance task in ADHD. We find evidence that, prior to slower responses, neural dynamics shift toward criticality in both ADHD and control groups, suggesting that increase variability in ADHD and during attention lapses are related to structured variability and not necessarily random noise. Notably, these findings run counter predictions based on the proposed model and previous literature on neural noise in this population, challenging predictions of edge-of-synchrony criticality as a unifying account of neural variability and behavioral performance. Furthermore, this effect did not emerge at the between-subject level, underscoring the limitations of relying on between-subject correlations to infer neural mechanisms. Impact StatementOur findings add new perspective to the hypothesis that links neural variability to reaction time variability in adults with and without ADHD. We found that neural dynamics shift towards criticality prior to slow reaction times in adults with and without ADHD, but in ADHD, dynamics lie closer to criticality regardless of response type, suggesting a different "attractor" state.

BackgroundVitamins are important modulators of intestinal health and may affect the gut-brain axis through microbial metabolites such as short-chain fatty acids (SCFAs). However, the neurocognitive effects of colon-delivered vitamins in older adults remain unexplored - a critical gap given the gut-brain axiss emerging role in cognitive aging. ObjectiveWe investigated the effect of a colon-delivered multivitamin (CDMV) supplement on intestinal health and neurocognitive outcomes in older adults at risk of cognitive decline. MethodsWithin the double-blind randomized placebo-controlled trial COMBI (ClinicalTrials.govID: NCT05675007), we included 75 older adults (60-75 years) at risk of cognitive decline based on lifestyle-related factors. Participants consumed a colon-delivered capsule with vitamins B2, B3, B6, B9, C and D3, or a placebo, daily for six weeks. Pre- and post-intervention, we employed neuroimaging, feces- and blood collection. Primary outcomes were fecal SCFA concentrations, working memory (WM)-related fMRI responses, and WM performance measured with the n-back task. ResultsAfter adjusting for baseline values, we found no significant between-group differences in total fecal SCFA levels (p=0.30) and WM performance (p=0.50). Post-intervention WM-related fMRI responses in the hippocampus (p=0.01; p{superscript 2}=0.09) and dorsolateral prefrontal cortex (dlPFC) (p=0.06; p{superscript 2}=0.04), driven by the right dlPFC (p=0.02), were higher in the CDMV group compared to placebo. Independent of intervention group, post-pre increases in fecal SCFA levels were significantly correlated to increases in dlPFC fMRI responses ({rho}=0.31; p=0.02) and WM performance ({rho}=0.43; p=0.001). ConclusionsOur findings suggest that CDMV supplementation increases WM-related responses of the dlPFC and hippocampus in older adults, but this effect was not accompanied by changes in fecal SCFA levels or WM performance. The positive correlation of within-subject changes in fecal SCFAs with changes in WM dlPFC responses and performance across intervention groups provides human evidence for gut-brain communication in cognitive aging beyond cross-sectional associations.