Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the mature human nervous system, plays a central role in neurodevelopment, emotion regulation, and sensory processing. Many psychiatric drugs act on the GABAergic system, highlighting its importance for healthy brain function. Individual differences in brain and circulating GABA levels have traditionally been attributed to genetic variation. However, several gut bacteria produce neuroactive compounds, including GABA, raising the possibility that microbial variation influences peripheral and central GABA levels and related measures in humans. This relationship remains largely unexplored. In a cross-sectional study of 251 healthy adults, we investigated associations between gut microbiota composition, central and peripheral GABA, and associated features. Brain GABA was quantified using magnetic resonance spectroscopy, blood GABA using enzyme-linked immunosorbent assays, and gut microbiota profiles using absolute and relative abundance measures derived from Flow Cytometry Fluorescent In Situ Hybridisation and 16S rRNA gene sequencing. Motor cortex GABA+ levels were positively associated with greater numbers of Bacteroides/Prevotella bacteria. A similar association was observed for blood GABA, which was additionally associated with greater numbers of lactic acid bacteria, Eubacterium rectale/Clostridium coccoides, and Clostridium histolyticum groups, and with predicted microbial gene pathways involved in GABA, propionate, and butyrate biosynthesis. No association was observed between brain and blood GABA concentrations. These findings provide new evidence for relationships between gut bacterial groups and central and peripheral GABA pools, supporting future longitudinal studies of causal links between gut microbiota and host GABA levels, as well as the potential for future intervention studies to influence GABAergic processing.

Despite the importance of audition in spatial, semantic, and social function, there is no consensus regarding the detailed organisation of human auditory cortex. Using a novel computational model to analyse a high-powered naturalistic audiovisual movie-watching dataset, we simultaneously estimate spectral tuning properties and category selectivity to reveal the modes of organisation and computational motifs that characterise human auditory cortex. We find that regions more remote from the auditory core exhibit more compressive, non-linear response properties and finely-tuned, speech-selective receptive fields in low frequency portions of the tonotopic map. These patterns of organisation mirror aspects of the visual cortical hierarchy, wherein tuning properties progress from a stimulus category-agnostic ‘front end’ towards more advanced regions increasingly optimised for behaviorally relevant stimulus categories.

Reduced visual attention to social stimuli in autism is often attributed to diminished social reward sensitivity. However, most evidence comes from research using positive content (e.g. smiling faces), making it unclear whether reduced social attention generalises to negative social scenes. If group differences persist when social stimuli are negative, this would challenge purely reward-based explanations. We tested whether autistic adults show reduced preferential attention to negative social stimuli. Autistic (n=30) and non-autistic (n=51) adults completed a preferential looking task in which negative social and non-social images were presented side-by-side while eye movements were recorded. Social images depicted humans in negative contexts (e.g., conflict), and non-social images depicted negative scenes without people (e.g., natural disasters, pollution). Each pair was shown intact and phase-scrambled (rendering social content unidentifiable). Social preference was defined as the proportion of gaze time on the social image. Mixed-effects models tested effects of Group, Stimulus Type (intact vs scrambled), and their interaction. Time-series examined how social preference evolved over time. Non-autistic adults allocated greater viewing time to intact negative social images than autistic adults, but groups did not differ for scrambled images, indicating effects depended on social content rather than low-level visual features. Time-series analysis showed group differences emerged late in viewing: both groups showed early bias towards social content that declined, but only non-autistic participants showed later increases in social preference. Autistic adults allocate less attention to negative social content, extending evidence for reduced preference beyond positive scenes and challenging explanations based solely on social reward sensitivity.

Our sensory systems work together to generate a cohesive experience of the world around us. Watching others being touched activates brain areas representing our own sense of touch: the visual system recruits touch-related computations to simulate bodily consequences of visual inputs 1 . One long-standing question is how the brain implements this interface between visual and somatosensory representations 2 . Here, to address this question, we developed a model to simultaneously map somatosensory body part tuning and visual field tuning throughout the brain. Applying our model to ongoing co-activations during rest resulted in detailed maps of body-part tuning in the brain’s endogenous somatotopic network. During video watching, somatotopic tuning explains responses throughout the entire dorsolateral visual system, revealing an array of somatotopic body maps that tile the cortical surface. The body-position tuning of these maps aligns with visual tuning, predicting both preferences for visual field locations and visual-category preferences for body parts. These results reveal a mode of brain organization in which aligned visual–somatosensory topographic maps connect visual and bodily reference frames. This cross-modal interface is ideally situated to translate raw sensory impressions into more abstract formats that are useful for action, social cognition and semantic processing 3 .

The ability to attend to social stimuli is fundamental for processing social cues and shaping social behavior, yet cultural variability in this capacity remains relatively unexplored. Social attention is typically tested using preferential-looking paradigms in labs, which have demonstrated that autistic individuals attend less to social stimuli. Such studies are limited, by the fact that they have almost all been conducted in Western Europe and the USA. To address this gap, our objective was to test the cultural generalizability of these results by investigating whether autistic symptoms are negatively associated with social attention in a traditionally understudied sample: Indian adults. Additionally, we tested the specificity of this relation by investigating whether a similar association exists with the traits of attention-deficit/hyperactivity disorder (ADHD). Our study involved 121 young adults from Kerala, India. Autistic and ADHD traits were evaluated using the Autism Spectrum Quotient (AQ) and Adult ADHD Self-Report Scale (ASRS), respectively. The participants’ gaze behavior was recorded during a preferential-looking task, where pairs of social and non-social images were presented simultaneously. Individuals with higher autistic traits exhibited a reduced preference for social stimuli. No such association of social attention was noted with ADHD traits. Follow-up analysis of AQ subscales indicated that the association between gaze duration and autistic traits was driven by the social, and not the attention to detail factor of autistic traits. Our results provide new evidence for the cultural generalizability of the social attention task and offer the potential for culture-agnostic phenotypic assessments for adults with autism.

Many children with Developmental Language Disorder (DLD) find learning new words difficult, which negatively affects their educational and psycho-social outcomes. Word learning involves encoding, consolidation and reconsolidation of words, but the most challenging phase and factors which moderate word learning remain unclear. We conducted a systematic review and meta-analysis to determine which phase is most challenging and which factors predict oral word learning success in children with DLD. The search including PsycINFO, PubMed, Web of Science, and LLBA identified forty-six studies published before April 2024 comparing children with DLD and typically developing (TD) age-matched peers in word learning tasks. Seventy-eight effect sizes were calculated for encoding (n DLD = 1462, n TD = 2161), eight for consolidation (n DLD = 107, n TD = 112), and 19 for reconsolidation (n DLD = 296, n TD = 278). The random effect model identified an effect for encoding (k = 78, d = 0.82, [0.66, 0.98], p < .001) but not consolidation (k = 8, d =-0.2, [-0.68, 0.29], p = .43) or reconsolidation (k = 19, d = 0.23, [-0.14, 0.59], p = .22) of new words. The moderator analysis via random effects models identified verbal short-term memory and lexical knowledge as significant moderators of encoding, while word length was the most important task characteristic. Despite limited data for consolidation and reconsolidation, our findings provide new insights into oral word learning difficulties in children with DLD. These insights help clinicians and teachers identify support strategies while also highlighting gaps in existing research, driving future studies forward.

The ability to attend to social stimuli is fundamental for processing social cues and shaping social behavior, yet cultural variability in this capacity remains relatively unexplored. Social attention is typically tested using preferential-looking paradigms in labs, which have demonstrated that autistic individuals attend less to social stimuli. Such studies are limited, by the fact that they have almost all been conducted in Western Europe and the USA. To address this gap, our objective was to test the cultural generalizability of these results by investigating whether autistic symptoms are negatively associated with social attention in a traditionally understudied sample: Indian adults. Additionally, we tested the specificity of this relation by investigating whether a similar association exists with the traits of attention-deficit/hyperactivity disorder (ADHD). Our study involved 121 young adults from Kerala, India. Autistic and ADHD traits were evaluated using the Autism Spectrum Quotient (AQ) and Adult ADHD Self-Report Scale (ASRS), respectively. The participants' gaze behavior was recorded during a preferential-looking task, where pairs of social and non-social images were presented simultaneously. Individuals with higher autistic traits exhibited a reduced preference for social stimuli. No such association of social attention was noted with ADHD traits. Follow-up analysis of AQ subscales indicated that the association between gaze duration and autistic traits was driven by the social, and not the attention to detail factor of autistic traits. Our results provide new evidence for the cultural generalizability of the social attention task and offer the potential for culture-agnostic phenotypic assessments for adults with autism.

Our sensory systems work together to generate a cohesive experience of the world around us. Watching others being touched activates brain areas representing our own sense of touch: the visual system recruits touch-related computations to simulate bodily consequences of visual inputs. One long-standing question is how the brain implements this interface between visual and somatosensory representations. To address this question, we developed a method to simultaneously map somatosensory body part tuning and visual field tuning throughout the brain. Applying this method on ongoing co-activations during rest resulted in detailed maps of the body-part tuning in the brain's endogenous somatotopic network. During movie watching, somatotopic tuning explains responses throughout the entire dorsolateral visual system, revealing an array of somatotopic body maps that tile the cortical surface. The tuning of these maps aligned with those of visual maps, and predicted both preferences for visual field locations and the visual-category preferences for body parts. These results reveal a mode of brain organization in which aligned visual-somatosensory topographic maps connect visual and bodily reference frames. This cross-modal interface is ideally situated to translate raw sensory impressions into more abstract formats useful for action, social cognition, and semantic processing. ### Competing Interest Statement The authors have declared no competing interest.

A robust learning system balances adaptability to new experiences with stability of its foundational architecture. To investigate how the human brain implements this we used a new approach to study plasticity and stability across hierarchical processing stages in visual cortex. We compare the rod system of individuals born with rod-only photoreceptor inputs (achromatopsia) to the typically developed rod system, allowing us to dissociate impacts of life-long versus transient responses to altered input. Cortical input stages (V1) exhibited high stability, with structural hallmarks of deprivation and no retinotopic reorganisation. However, plasticity manifested as reorganised read-out of these inputs by higher-order cortex, in a pattern that could compensate for the lower resolution of a rod-only system and its lack of high-density foveal input. We propose that these hierarchical dynamics robustly optimize processing of available input and could reflect a broader principle of brain organisation with important implications for emerging sight-recue therapies.

Although exposure-based therapy has been found to be effective at alleviating symptoms of social anxiety disorder, it often does not lead to full remission, and relapse after treatment is common. Exposure therapy is based on theoretical principles of extinction of conditioned fear responses. However, there are inconsistencies in findings across experiments that have investigated the effect of social anxiety on threat conditioning and extinction processes. This systematic review and meta-analysis aimed to examine whether elevated levels of social anxiety are associated with abnormalities in threat conditioning and extinction processes. A second aim was to examine the sensitivity of various study designs and characteristics to detect social anxiety-related differences in threat conditioning and extinction. A systematic search was conducted, which identified twenty-three experiments for inclusion in the review. The findings did not demonstrate compelling evidence that high levels of social anxiety are associated with atypical threat conditioning or extinction. Further, when systematically examining the data, there was no convincing support that the use of a particular psychophysiological measure, subjective rating, or experimental parameter yields more consistent associations between social anxiety and conditioning processes during threat acquisition or extinction. Meta-analyses demonstrated that during threat extinction, the use of anxiety ratings as a dependent variable, socially relevant unconditioned stimuli, and a higher reinforcement schedule produced more detectable effects of social anxiety on compromised extinction processes compared to any other dependent variable (subjective or physiological) or experimental parameter. Overall, the results of this study suggest that social anxiety is not reliably related to deficits in conditioning and extinction processes in the context of laboratory-based Pavlovian conditioning paradigms.

Quality control is a critical step in the processing and analysis of functional magnetic resonance imaging data. Its purpose is to remove problematic data that could otherwise lead to downstream errors in the analysis and reporting of results. The manual inspection of data can be a laborious and error-prone process that is susceptible to human error. The development of automated tools aims to mitigate these issues. One such tool is pyfMRIqc, which we previously developed as a user-friendly method for assessing data quality. Yet, these methods still generate output that requires subjective interpretations about whether the quality of a given dataset meets an acceptable standard for further analysis. Here we present a quality control protocol using pyfMRIqc and assess the inter-rater reliability of four independent raters using this protocol for data from the fMRI Open QC project (https://osf.io/qaesm/). Data were classified by raters as either “include,” “uncertain,” or “exclude.” There was moderate to substantial agreement between raters for “include” and “exclude,” but little to no agreement for “uncertain.” In most cases only a single rater used the “uncertain” classification for a given participant’s data, with the remaining raters showing agreement for “include”/“exclude” decisions in all but one case. We suggest several approaches to increase rater agreement and reduce disagreement for “uncertain” cases, aiding classification consistency.

Individuals with autism spectrum disorders typically exhibit reduced visual attention towards social stimuli relative to neurotypical individuals. Importantly, however, attention is not a static process, and it remains unclear how such effects may manifest over time. Exploring these momentary changes in gaze behaviour can more clearly illustrate how individuals respond to social stimuli and provide insight into the mechanisms underlying reduced social attention in autism spectrum disorder. Using a simple passive eye-tracking task with competing presentations of social and nonsocial stimuli, we examine the different ways in which attention to social stimuli evolves over time in neurotypical adults and adults with and autism spectrum disorders. Our temporal modelling of gaze behaviour revealed divergent temporal profiles of social attention in neurotypical and observers with autism. Neurotypical data showed an initial increase in social attention, a 'decay' and subsequent 'recovery' after prolonged viewing. By contrast, in individuals with autism spectrum disorder, social attention decayed over time in a linear fashion without recovery after prolonged viewing. We speculate that the 'gaze cascade' effect that maintains selection of social stimuli in neurotypical observers is disrupted in individuals with high autistic traits. Considering these temporal components of gaze behaviour may enhance behavioural phenotypes and theories of social attention in autism spectrum disorder. Lay abstract One behaviour often observed in individuals with autism is that they tend to look less towards social stimuli relative to neurotypical individuals. For instance, many eye-tracking studies have shown that individuals with autism will look less towards people and more towards objects in scenes. However, we currently know very little about how these behaviours change over time. Tracking these moment-to-moment changes in looking behaviour in individuals with autism can more clearly illustrate how they respond to social stimuli. In this study, adults with and without autism were presented with displays of social and non-social stimuli, while looking behaviours were measured by eye-tracking. We found large differences in how the two groups looked towards social stimuli over time. Neurotypical individuals initially showed a high probability of looking towards social stimuli, then a decline in probability, and a subsequent increase in probability after prolonged viewing. By contrast, individuals with autism showed an initial increase in probability, followed by a continuous decline in probability that did not recover. This pattern of results may indicate that individuals with autism exhibit reduced responsivity to the reward value of social stimuli. Moreover, our data suggest that exploring the temporal nature of gaze behaviours can lead to more precise explanatory theories of attention in autism.

Social motivation accounts of autism spectrum disorder (ASD) posit that individuals with ASD find social stimuli less rewarding than neurotypical (NT) individuals. Behaviorally, this is proposed to manifest in reduced social orienting (individuals with ASD direct less attention towards social stimuli) and reduced social seeking (individuals with ASD invest less effort to receive social stimuli). In two meta-analyses, involving data from over 6000 participants, we review the available behavioral studies that assess social orienting and social seeking behaviors in ASD. We found robust evidence for reduced social orienting in ASD, across a range of paradigms, demographic variables and stimulus contexts. The most robust predictor of this effect was interactive content - effects were larger when the stimulus involved an interaction between people. By contrast, the evidence for reduced social seeking indicated weaker evidence for group differences, observed only under specific experimental conditions. The insights gained from this meta-analysis can inform design of relevant task measures for social reward responsivity and promote directions for further study on the ASD phenotype.

Behavioral studies indicate that autistic traits predict reduced gaze toward social stimuli. Moreover, experiments that require participants to make an explicit choice between stimuli indicate reduced preferences for social stimuli in individuals with high autistic traits. These observations, in combination, fit with the idea that gaze is actively involved in the formation of choices-gaze toward a stimulus increases the likelihood of its subsequent selection. Although these aspects of gaze and choice behavior have been well characterized separately, it remains unclear how autistic traits affect the relationship between gaze and socially relevant choices. In a choice-based eye-tracking paradigm, we observed that autistic traits predict less frequent and delayed selection of social stimuli. Critically, eye tracking revealed novel phenomena underlying these choice behaviors: first, the relationship between gaze and choice behavior was weaker in individuals with high autistic traits-an increase in gaze to a stimulus was associated with a smaller increase in choice probability. Second, time-series analyses revealed that gaze became predictive of choice behaviors at longer latencies in observers with high autistic traits. This dissociation between gaze and choice in individuals with high autistic traits may reflect wider atypicalities in value coding. Such atypicalities may predict the development of atypical social behaviors associated with the autism phenotype. LAY SUMMARY: When presented with multiple stimuli to choose from, we tend to look more toward the stimuli we later choose. Here, we found that this relationship between looking and choosing was reduced in individuals with high autistic traits. These data indicate that autistic traits may be associated with atypical processing of value, which may contribute to the reduced preferences for social stimuli exhibited by individuals with autism.

A deeply challenging and popular question concerns what information is preserved during processing of invisible stimuli. Can an invisible stimulus reach processing stages commonly attributed to high-level semantic or cognitive processing? Continuous flash suppression (CFS) is a perceptual suppression technique that provides a means to test this question because it allows for keeping stimuli invisible for considerably more time than traditional suppression methods. Over the past 15 years, a substantive literature has accumulated and parts of this literature suggest that high-level processing of unseen stimuli as integrated, semantic entities can indeed occur. This notion of integrated high-level processing was recently challenged by highlighting that interocular suppression, the putative mechanism underlying CFS, likely relies on representations of fractionated stimuli early in visual cortex [ 1 Moors P. et al. Continuous flash suppression: stimulus fractionation rather than integration. Trends Cogn. Sci. 2017; 21: 719-721 Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar , 2 Zadbood A. et al. Stimulus fractionation by interocular suppression. Front. Hum. Neurosci. 2011; 5: 135 Crossref PubMed Google Scholar ]. That is, interocular competition acts on the low-level features that are the consequence of stimulus fractionation in early visual processing.

The visual probe (VP) paradigm provides evidence that emotional stimuli attract attention. Such effects have been reported even when stimuli are presented outside of awareness. These findings have shaped the idea that humans possess a processing pathway that detects evolutionarily significant signals independently of awareness. Here, we addressed 2 unresolved questions: First, if emotional stimuli attract attention, is this driven by their affective content, or by low-level image properties (e.g., luminance contrast)? Second, does attentional capture occur under conditions of genuine unawareness? We found that observers preferentially allocated attention to emotional faces under aware viewing conditions. However, this effect was best explained by low-level stimulus properties, rather than emotional content. When stimuli were presented outside of awareness (via continuous flash suppression or masking), we found no evidence that attention was directed toward emotional face stimuli. Finally, observer's awareness of the stimuli (assessed by d') predicted attentional cuing. Our data challenge existing literature: First, we cast doubt on the notion of preferential attention to emotional stimuli in the absence of awareness. Second, we question whether effects revealed by the VP paradigm genuinely reflect emotion-sensitive processes, instead suggesting they can be more parsimoniously explained by low-level variability between stimuli. (PsycINFO Database Record (c) 2019 APA, all rights reserved).