Biology subjects

Skipper, J. I.

Publications and source records attributed to Skipper, J. I..

At least 19 recordsLinked to original sources

bioRxiv2026

Brain-thought states during movie-watching reflect shared sensory anchors and film- and person- specific processes in association cortex

Naturalistic paradigms such as movie-watching have transformed functional neuroimaging by capturing cognitive dynamics during rich, real-world experiences. A fundamental challenge, however, is determining whether the neural signatures identified during these experiences reflect general principles of cognition or the specific contexts in which they are measured. To address this question, we combined fMRI data from participants watching eight diverse films with continuous reports of ongoing thought. We found that the generalizability of brain-thought relationships depends on the cognitive process being recruited. Neural signatures linked to sensory processing remained robust across films, whereas those involving memory-related association networks depended on how we modelled between-film variability, indicating that cognition becomes increasingly context-dependent along the cortical hierarchy from sensory to association cortex. Within default and limbic networks, we identified two contrasting memory-related states with opposite consequences for comprehension. One, reflecting the integration of prior knowledge with ongoing experience, predicted better narrative comprehension and was revealed only after accounting for between-film variability. The other, associated with stimulus-independent thought, predicted poorer comprehension and emerged only when between-film variability was not modelled. Together, these findings establish when brain-experience relationships measured during naturalistic paradigms can generalize across contexts and when they instead reflect interactions between cognition and the specific environments in which cognition unfolds. More broadly, the consistency of a given brain-experiential association may depend less on where it occurs in the brain and more on the viewer's contextual experience: perceiving the film, drawing on memory to understand it, or drifting away.

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bioRxiv2026

Language-associated brain representations covary with disruption of selfhood under psilocybin

Language helps organise experience into an idiosyncratic, temporally extended sense of self. We therefore used fMRI to investigate whether greater similarity between participants in the activity of language-associated brain regions accompanied psilocybin-induced loss of selfhood. Participants heard music and viewed moving clouds at baseline and after 19 mg psilocybin. At each brain location and time point, we tested whether similarity increased with each pair's summed rank on the Ego Dissolution Inventory (EDI; N=43). We grouped independent components of these associations by time course and decoded each group's map with Neurosynth. Elementary visual imagery (SI; N=49) and baseline activity served as comparators. Under psilocybin, one group formed a distributed, left-lateralised frontotemporal network matching the Neurosynth language map (r=.382, spatial-null p<.001, q=.003), nearly twice the largest comparator estimate (SI: r=.208, p=.004, q=.028; baseline: r<.12). In exploratory analyses, resting-state connectivity of this network decreased with posterior visual cortex and increased with thalamic and frontal regions. Participants with higher EDI scores showed larger changes (Spearman's rho=.455, Bonferroni-adjusted p=.048; SI: rho=.008), most strongly for items describing loss of ego or identity (rho=.43 to .51). We propose that language-associated systems incorporate each person's semantic and autobiographical context into experience, and that disrupting them contributes to loss of ego and identity.

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bioRxiv2026

Psychedelics restructure information in the human brain

How do psychedelic drugs alter human brain function? Answering this question relies on our ability to understand how information is stored, transferred, and transformed across the cortex. Here, we leverage a precise mathematical framework for multivariate information decomposition to construct the first comprehensive picture of these processes across five compounds: LSD, psilocybin, ketamine, DMT and 5-MeO-DMT (N=80). We provide a formal and empirical explanation of major prior results, revealing sets of competing underlying phenomena masked by extant approaches. We extend this analysis to novel higher-order phenomena, and we demonstrate how all of these observations can emerge from a minimal generative model in which neural populations operate with reduced self-coupling. In sum, our results suggest that the psychedelic brain is one in which cortical populations become alike, but not necessarily together. This has important implications for models of how psychedelics reorganize brain dynamics to alter subjective experience and alleviate mental health conditions.

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bioRxiv2026

What is it like to be a blob? A distributed, decentred and context-sensitive neurobiology of consciousness

Consciousness is often studied by asking whether particular brain regions or systems are privileged. We tested a distributed, decentred and context-sensitive alternative using 579 consciousness-focused neuroimaging studies. Semantic clustering of titles and abstracts identified seven domains whose corrected meta-analytic maps showed limited overlap and no invariant cross-domain core. These maps occupied 18.0% of grey matter while extending across 91.0% of brain regions. After controlling for reporting topography, distributed cognitive, sensorimotor and organismic-affective maps reconstructed the residual consciousness landscape better than spatial surrogates. Organismic-affective maps contributed most, but functional contributions varied contextually across domains. Theory-associated regional loci added no additional meaningful prediction. Information carried by the functional families was both redundant and synergistic. Coactivation-network and hypergraph analyses revealed a shared network repertoire but context-dependent higher-order coalitions. These results argue against an invariant core, supporting a distributed neurobiology of consciousness in which specialised systems are weighted and combined differently across contexts.

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bioRxiv2026

An adolescent neuroimaging database combining movie-watching, eye-tracking and cognitive tasks

Adolescence is a critical period of neurodevelopment, yet most neuroimaging datasets focus on adult populations, leaving a gap in our understanding of how the brain processes information during this formative stage. Here we present a multimodal neuroimaging dataset acquired from 41 adolescent participants aged 11-18 years, combining 3T fMRI data with concurrent eye-tracking and physiological monitoring during naturalistic movie-watching. Data are shared in BIDS-compliant format and technical validation demonstrates good data quality across participants, with low head motion and strong inter-subject neural synchronisation during movie-watching. In addition to the scanning session, participants completed remote assessments covering a broad range of self-reported developmental and mental health traits, alongside cognitive tasks targeting reward-based and social learning. This dataset offers a rich resource for studying the adolescent brain, with particular utility for research on individual differences in mental health and cognition. All data and processing code is openly available to facilitate reproducible science.

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bioRxiv2025

A neuroimaging database combining movie-watching, eye-tracking, sensorimotor mapping, and cognitive tasks

We provide a multimodal naturalistic neuroimaging database (NNDb-3T+), designed to support the study of brain function under both naturalistic and controlled experimental conditions. The database includes high-quality 3T fMRI data from 40 participants acquired during full-length movie-watching and three sensory mapping tasks: somatotopy, retinotopy, and tonotopy. Each participant also completed synchronised eye-tracking during movie-watching and retinotopy, physiological recordings, and a battery of behavioural and cognitive assessments. Data were collected across two MRI sessions and a remote testing session, with all data organised in a BIDS-compliant format. Technical validation confirms high data quality, with minimal head motion, accurate eye-tracker calibration, and robust task-evoked activation patterns. The database provides a unique resource for investigating individual differences, functional topographies, multimodal integration, and naturalistic cognition. All raw and preprocessed data, quality metrics, and preprocessing scripts are publicly available to support reproducible research.

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bioRxiv2025

Inner speech and the neurobiology of psychosis

Aberrations of inner speech have been linked to psychotic symptoms such as thought insertion and auditory verbal hallucinations. These symptoms may reflect failures of prediction and source monitoring. Normally, efference copies of speech motor commands are sent to auditory cortices and suppressed, helping distinguish self-generated from external input. If suppression malfunctions, predicted auditory input may become perceptually salient. Further, if self-monitoring or error detection-related regions are also impaired (e.g., anterior cingulate cortex, ACC), inner speech may be misattributed as external. We tested this proposal using neuroimaging meta-analyses, examining how the brain systems in overt and inner speech production in neurotypical participants overlap with findings from psychosis-spectrum participants performing a range of tasks. They showed increased activity in motor-related regions associated with inner speech (e.g., ventral premotor cortices) and decreased grey matter in bilateral auditory cortices and ACC, in regions specific to overt speech. Coactivation-based network analyses revealed that these ventral premotor and auditory regions form distinct, inversely coupled audiomotor networks. Classification suggests the ventral premotor network supports higher-level language processing, while the audiomotor network supports lower-level speech and self-referential processing. Overall, results accord with the proposal that psychotic symptoms like auditory verbal hallucinations derive from phenotypic hyperactivation in inner speech-related regions that yield affectively salient efference copy signals that are insufficiently suppressed and monitored as self-produced. In line with a hierarchical predictive-processing account, disruption of a distributed recurrent system distorts self-awareness and conscious experience.

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bioRxiv2025

Situation Models in the Brain are Used to Resolve Word References

Resolving the meaning of a pronoun requires retrieving information about a unique individual (a referent) from many remembered experiences and inferences throughout sensory and cognitive modalities, from vision and audition to episodic memory and social cognition. Here, we hypothesize that the functional neuroanatomy of pronoun interpretation involves interaction across distributed neural networks, during which each referent activates its own unique sensorimotor neural fingerprint associated with these experiences. To test this hypothesis, we collected fMRI data from 20 people watching a full-length movie, and developed a 3D branched convolutional neural network to distinguish movie characters from the fMRI signal across distributed sensorimotor regions. The same model distinguished the characters referenced by pronouns, using these same sensorimotor regions, supplemented by the hippocampus, precuneus, and medial prefrontal cortices. This work has far-reaching implications for understanding the relations among the many domains and modalities of neural representation required for ecological language comprehension. In particular, the demonstration that situation models, implemented in distributed sensory-motor and association cortices, are involved in resolving reference, suggests a whole brain distribution for language processing.

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bioRxiv2025

Reduced susceptibility to experimentally-induced complex visual hallucinations with age

Visual hallucinations occur across many clinical conditions, but can also be induced experimentally in healthy individuals, using high-frequency flicker (Ganzflicker) and sensory deprivation (Ganzfeld). It is unclear how hallucinatory proneness changes across the lifespan, with prior questionnaire-based studies showing mixed results. As factors such as multi-sensory acuity loss and relatively increased reliance on prior knowledge may increase as we age, and these are considered risk factors for hallucination proneness, we hypothesised that reported decreases in hallucinations might reflect stigma-related underreporting. We therefore sought to measure hallucination proneness in 44 healthy adults spanning the adult lifespan (younger age group; n=22; age 19-39 years, mean 27.2 {+/-} 5.5; older age group n=22; age 59-79 years, mean 68.0 {+/-} 5.8), quantifying the tendency to experience complex and simple hallucinations in an experimental environment designed to elicit hallucinations. We find that reports of complex hallucinations (those representing objects, scenes, etc) are lower in older adults than in younger adults, both in real time and retrospectively. None of our measured cognitive or sensory measures (visual acuity, contrast sensitivity, perceptual reorganisation, imagery vividness, memory inhibition, and suggestibility) mediate this relationship. We conclude that reduced complex hallucination proneness appears normative in ageing, and that experiencing hallucinations in older individuals may signal underlying pathology.

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bioRxiv2025

Speech markers of psychedelic-induced psychological change

5-MeO-DMT, a potent, short-acting psychedelic, induces profound shifts in cognition, affect, and self-awareness. Because language explicitly expresses these domains and voice implicitly conveys them, both may serve as potential biomarkers of behavioural change. This study introduces a novel framework for analysing baseline language and vocal features, pre- to post-psychedelic changes, assessing their potential to predict subjective experiences and psychological outcomes. Daily voice journals from 29 participants were collected via RetreatBot for two weeks before and after 5-MeO-DMT (1x12 mg). Transcripts were analysed using NLP (bag-of-words for vocabulary; transformer model for textual affect), and acoustic features (e.g., pitch, jitter, shimmer) were extracted to assess vocal dynamics. Following 5-MeO-DMT, speech markers revealed increased cognitive language, decreased social words, and altered voice quality (increased jitter/shimmer). Baseline speech patterns predicted psychological preparedness, ego dissolution anxiety, emotional breakthrough, and post-experience well-being. This first longitudinal analysis of speech markers following psychedelic use demonstrates a shift from external focus to introspection. Speech markers predicted and tracked psychological transformation, establishing vocal journaling as a valuable framework for monitoring psychedelic-induced changes and facilitating integration.

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bioRxiv2024

Complex slow waves radically reorganise human brain dynamics under 5-MeO-DMT

5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a psychedelic drug known for its uniquely profound effects on subjective experience, reliably eradicating the perception of time, space, and the self. However, little is known about how this drug alters large-scale brain activity. We collected naturalistic electroencephalography (EEG) data of 29 healthy individuals before and after inhaling a high dose (12mg) of vaporised synthetic 5-MeO-DMT. We replicate work from rodents showing amplified low-frequency oscillations, but extend these findings with novel tools for characterising the organisation and dynamics of complex low-frequency spatiotemporal fields of neural activity. We find that 5-MeO-DMT radically reorganises low-frequency flows of neural activity, causing them to become incoherent, heterogeneous, viscous, fleeting, nonrecurring, and to cease their typical travelling forwards and backwards across the cortex compared to resting state. Further, we find a consequence of this reorganisation in broadband activity, which exhibits slower, more stable, low-dimensional behaviour, with increased energy barriers to rapid global shifts. These findings provide the first detailed empirical account of how 5-MeO-DMT sculpts human brain dynamics, revealing a novel set of cortical slow wave behaviours, with significant implications for extant neuroscientific models of serotonergic psychedelics.

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bioRxiv2024

Mapping patterns of thought onto brain activity during movie-watching

Movie-watching is a central aspect of our lives and an important paradigm for understanding the brain mechanisms behind cognition as it occurs in daily life. Contemporary views of ongoing thought argue that the ability to make sense of events in the here and now depend on the neural processing of incoming sensory information by auditory and visual cortex, which are kept in check by systems in association cortex. However, we currently lack an understanding of how patterns of ongoing thoughts map onto the different brain systems when we watch a film, partly because methods of sampling experience disrupt the dynamics of brain activity and the experience of movie-watching. Our study established a novel method for mapping thought patterns onto the brain activity that occurs at different moments of a film, which does not disrupt the time course of brain activity or the movie-watching experience. We found moments when experience sampling highlighted engagement with multi-sensory features of the film or highlighted thoughts with episodic features, regions of sensory cortex were more active and subsequent memory for events in the movie was better--on the other hand, periods of intrusive distraction emerged when activity in regions of association cortex within the frontoparietal system was reduced. These results highlight the critical role sensory systems play in the multi- modal experience of movie-watching and provide evidence for the role of association cortex in reducing distraction when we watch films. Significance statementStates like movie-watching provide a window into the brain mechanisms behind cognition in daily life. However, we know relatively little about the mapping between brain activity during movies and associated thought patterns because of difficulties in measuring cognition without disrupting how brain activity naturally unfolds. We establish a novel method to link different experiential states to brain activity during movie-watching with minimal interruptions to viewers or disruptions to brain dynamics. We found states of sensory engagement occur in moments of films when activity in visual and auditory cortex are high. In contrast, states of distraction are reduced when activity in frontoparietal regions is high. Our study, therefore, establishes both sensory and association cortex as core features of the movie-watching experience.

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bioRxiv2023

Where the present gets remembered: Sensory regions communicate with the brain over the longest timescales.

In natural contexts, the brain simultaneously processes sensory information over diverse timescales. Here we reveal how this is reflected in the organisation of asynchronous connectivity in the brain. In 86 individuals watching feature-length movies during functional neuroimaging, we calculated the delay at peak connectivity between brain regions. We found the longest delays in received whole-brain functional connectivity within sensory regions (:S 18 seconds). Two complementary dimensionality reduction approaches were used to probe the spatial organisation of connection delays and weights. First, clustering of received delays separated sensory, and transmodal/associative outputting regions, suggesting that putatively localised functions are associated with asynchronous local-to-whole-brain connectivity patterns. Next, we organised delayed connectivity maps by likeness, unveiling five orthogonal gradients of variation, each demonstrating associations between early-sensory and transmodal/associative regions. Together, these findings challenge contemporary conceptualisations of the brains temporal hierarchy by emphasising the role of sensory regions as sites of integration across timescales.

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bioRxiv2023

The entire brain, more or less is at work: 'Language regions' are artefacts of averaging

Models of the neurobiology of language suggest that a small number of anatomically fixed brain regions are responsible for language functioning. This derives from centuries of aphasia studies and decades of neuroimaging. The latter rely on thresholded measures of central tendency applied to activity patterns from heterogeneous stimuli. We hypothesised that these methods obscure the whole brain distribution of regions supporting language. Specifically, language regions are connectivity hubs, coordinating varying peripheral activity that averages out following thresholding. We tested this with neuroimaging meta-analyses and movie-fMRI. Results show that words localise to language regions when averaged but are distributed throughout the brain when examining specific linguistic representations. These language regions are partially connectivity hubs that are spatiotemporally dynamic, making connections with [~]40% of the brain periphery outside those regions, and only appearing in the aggregate over time. Hub-periphery connections encode linguistic representations, not the language regions alone. Results replicate with audiobook-fMRI. Finally, intracranial neuronal recordings support findings, showing language regions are hub-like, with linguistic representations decodable throughout the brain. Together, these four studies suggest that language regions are artefacts of averaging heterogeneous language representations. Instead, they are connectivity hubs coordinating whole-brain distributed network representations, suggesting why their damage results in aphasia.

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bioRxiv2023

Individual differences in wellbeing are supported by separable sets of co-active self- and visual-attention-related brain networks

How does the brain support wellbeing? Because it is a multidimensional construct, it is likely the product of multiple co-active brain networks that vary across individuals. This is perhaps why prior neuroimaging studies have found inconsistent anatomical associations with wellbeing. Furthermore, these used laboratory-style or resting-state methods not amenable to finding manifold networks. To address these issues, we had participants watch a full-length romantic comedy-drama film during functional magnetic resonance imaging. We hypothesised that individual differences in wellbeing measured before scanning would be correlated with individual differences in brain networks associated with embodied and narrative self-related processing. Indeed, searchlight spatial inter-participant representational similarity and subsequent analyses revealed seven sets of co-activated networks associated with individual differences in wellbeing. Two were embodied self related, including brain regions associated with autonomic and affective processing. Three sets were narrative self related, involving speech, language, and autobiographical memory-related regions. Finally, two sets of visual-attention-related networks emerged. These results suggest that the neurobiology of wellbeing in the real world is supported by diverse but functionally definable and separable sets of networks. This has implications for psychotherapy where individualised interventions might target, e.g., neuroplasticity in language-related narrative over embodied self or visual-attentional related processes.

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bioRxiv2022

When Abstract Becomes Concrete: Naturalistic Encoding of Concepts in the Brain

Language is acquired and processed in complex and dynamic naturalistic contexts, involving simultaneous processing of connected speech, faces, bodies, objects, etc.. How words and their associated concepts are encoded in the brain during real-world processing is still unknown. Here, the representational structure of concrete and abstract concepts was investigated during movie watching to address the extent to which brain responses dynamically change depending on visual context. First, across contexts, concrete and abstract concepts are shown to encode different experience-based information in separable sets of brain regions. However, these differences are reduced when multimodal context is considered. Specifically, the response profile of abstract words becomes more concrete-like when these are processed in visual scenes highly related to their meaning. Conversely, when the visual context is unrelated to a given concrete word, the activation pattern resembles more that of abstract conceptual processing. These results suggest that while concepts generally encode habitual experiences, the underlying neurobiological organisation is not fixed but depends dynamically on available contextual information.

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bioRxiv2020

Reorganization of the neurobiology of language after sentence overlearning

There is a widespread assumption that there are a static set of language regions in the brain. Yet, people still regularly produce familiar formulaic expressions when those regions are severely damaged. This suggests that the neurobiology of language varies with the extent of word sequence learning and might not be fixed. We test the hypothesis that perceiving sentences is mostly supported by sensorimotor regions involved in speech production and not language regions after overlearning. Twelve participants underwent two sessions of behavioural testing and functional magnetic resonance imaging (fMRI), separated by 15 days. During this period, they repeated two sentences 30 times each, twice a day. In both fMRI sessions, participants passively listened to those two sentences and novel sentences. Lastly, they spoke novel sentences. Behavioural results confirm that participants overlearned sentences. Correspondingly, there was an increase or recruitment of sensorimotor regions involved in sentence production and a reduction in activity or inactivity for overlearned sentences in regions involved in listening to novel sentences. The global network organization of the brain changed by [~]45%, mostly through lost connectivity. Thus, there was a profound reorganization of the neurobiology of speech perception after overlearning towards sensorimotor regions not considered in most contemporary models and away from the language regions posited by those models. These same sensorimotor regions are generally preserved in aphasia and Alzheimers disease, perhaps explaining residual abilities with formulaic language. These and other results warrant reconsidering static neurobiological models of language.

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bioRxiv2020

Speech perception under the tent: A domain-general predictive role for the cerebellum

The role of the cerebellum in speech perception remains a mystery. Given its uniform architecture, we tested the hypothesis that it implements a domain-general mechanism whose role in speech is determined by connectivity. We collated all neuroimaging studies reporting cerebellar activity in the Neurosynth database (n = 8,206). From this set, we found all studies involving passive speech and sound perception (n = 72, 64% speech, 12.5% sounds, 12.5% music, and 11% tones) and speech production and articulation (n = 175). Standard and coactivation neuroimaging meta-analyses were used to compare cerebellar and associated cortical activations between passive perception and production. We found distinct regions of perception-and production-related activity in the cerebellum and regions of perception-production overlap. Each of these regions had distinct patterns of cortico-cerebellar connectivity. To test for domain generality versus specificity, we identified all psychological and task-related terms in the Neurosynth database that predicted activity in cerebellar regions associated with passive perception and production. Regions in the cerebellum activated by speech perception were associated with domain-general terms related to prediction. One hallmark of predictive processing is metabolic savings (i.e., decreases in neural activity when events are predicted). To test the hypothesis that the cerebellum plays a predictive role in speech perception, we examined cortical activation between studies reporting cerebellar activation and those without cerebellar activation during speech perception. When the cerebellum was active during speech perception there was far less cortical activation than when it was inactive. The results suggest that the cerebellum implements a domain-general mechanism related to prediction during speech perception.

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