Biology subjects

Obleser, J.

Publications and source records attributed to Obleser, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Executive and language systems competitively shape predictive processing during reading

When we read, our brains constantly generate predictions about upcoming words, which is thought to make comprehension faster and more efficient. Yet it remains unclear whether this predictive mechanism relies on the same domain-general executive resources the brain uses for other demanding cognitive tasks, or operates largely independently within the language system. Here we tested this question using transcranial magnetic stimulation (TMS) in twenty-five healthy adults, who performed self-paced naturalistic reading, an n-back task, and a dual task of concurrent reading and n-back, allowing us to place competing demands on cognitive resources. In three sessions, we stimulated the left angular gyrus alone, the angular gyrus together with dorsolateral prefrontal cortex, a hub of executive control, or delivered sham stimulation, and used computational modeling of decision-making to isolate how each brain state altered the underlying cognitive processes. Combined stimulation of the angular gyrus and prefrontal cortex selectively weakened the reading-time costs of unexpected words, but only when reading competed with the working-memory task, revealing that linguistic prediction draws on executive resources specifically under cognitive load. Computational models showed that the relationship was bidirectional: Unpredictable words also disrupted concurrent working-memory decisions, slowing the accumulation of evidence and increasing response caution. Together, these findings show that predictive language processing is not a fixed, encapsulated function but is dynamically coupled to executive control when cognitive demands compete. Our results provide evidence that prediction during language comprehension is embedded within a broader, demand-sensitive cognitive architecture that flexibly coordinates linguistic and executive resources.

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bioRxiv2026

Low-dose ketamine tilts the cortical excitation--inhibition balance irrespective of systemic physiological response

Non-invasive proxies of cortical excitation--inhibition (E:I) balance, are increasingly used to understand human neural dynamics; especially so the aperiodic (1/f) electroencephalographic (EEG) exponent. Ketamine, an NMDA-receptor antagonist, is thought to shift this balance toward excitation. Propofol, a GABAA-receptor agonist, should behave oppositely. Here we show that these pharmacological manipulations at low doses tilt the noninvasive read-out of E:I balance as predicted, and we demonstrate this effect to be robust against potential mediation by the ketamine-related systemic cardiovascular response. In a single-blind, placebo-controlled crossover study, 25 healthy adults received low, subanesthetic doses of ketamine, propofol, or placebo by target-controlled infusion during resting-state EEG. We further analyzed electrocardiogram (ECG) and dissociating ratings. Ketamine flattened the aperiodic exponent (i.e., a shift toward excitation) and raised heart rate and blood pressure; propofol exerted its effects in the opposite direction, while both agents reduced alpha oscillatory power. Critically, the cardiovascular response did not mediate the cortical E:I shift. Controlling for heart rate left the ketamine effect not only intact but numerically stronger, suggesting that E:I balance findings might even be underestimated when ignoring the systemic physiological response.

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bioRxiv2026

Auditory Attention Implements Complementary but Independent Cortical Mechanisms of Enhancement and Suppression

In noisy environments, goal-directed behavior requires the brain to prioritize task-relevant sound and to suppress distraction. While mechanisms of proactive attention in the presence of foreknowledge about targets and distractors are well-characterized, the neural dynamics governing reactive auditory attention in the absence of foreknowledge remain less understood. To fill this gap, we recorded the electroencephalogram (EEG) from N = 34 participants performing an auditory search task. Participants identified an amplitude-modulated spoken target number amid distractor numbers of varying salience. Presenting stimuli from three spatial locations enabled isolation of lateralized electrophysiological responses to targets and distractors. We quantified selection of targets versus distractors by continuously tracking participants cursor movements on a virtual response pad. Behaviorally, the target-directedness of cursor movements (i.e., towardness) increased for target repetitions (positive priming) and decreased when the target was a distractor from the previous trial (negative priming), indicating respective enhancement and suppression. Neurally, lateral targets evoked an N2ac component reflecting reactive enhancement. Importantly, we here demonstrate for the first time in an auditory attention task that distracting sounds evoke an auditory distractor positivity (PD) component. Target enhancement and distractor suppression were largely independent: their neural and behavioral markers were not significantly correlated and they originated from distinct cortical sources. Furthermore, shorter N2ac-but not PD-latencies related to higher towardness. By dissociating neural signatures and behavioral relevance of enhancement and suppression, our findings refine biased-competition models of attention, demonstrating that reactive selection relies on separable mechanisms rather than a single competitive gain process. Significance statementEveryday listening requires the rapid selection of relevant sounds and ignoring distraction, even when there is no prior knowledge of what will be heard. Here, we reveal the neural mechanisms that enable such reactive auditory attention. Combining electroencephalography with continuous measures of behavior, we show that target enhancement and distractor suppression are supported by distinct neural processes, indexed by the N2ac and the auditory PD component. These processes are largely independent, with only enhancement predicting behavior. This dissociation challenges unitary accounts of attentional selection and instead supports models in which separable mechanisms of enhancement and suppression operate in parallel. Our findings provide a mechanistic framework for understanding how the human brain flexibly prioritizes information in complex listening environments.

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bioRxiv2026

Linguistic information compensates for age-related decline in attentional filtering

As we age, understanding speech in social situations imposes an increasingly difficult challenge to the auditory system. However, the attentional mechanisms underlying age-related speech comprehension difficulties in multitalker situations remain unclear. We collected EEG signals while 63 normal hearing participants from 19 to 71 years performed a speech comprehension task involving a multitalker paradigm at individually adjusted target-to-distractor ratios. Combining trial-resolved multivariate temporal response function modeling with detailed behavioral comprehension responses, we provide a window into lower-level impairments and higher-level compensatory mechanisms across the adult life span. Neuro-behavioral correlations on a trial-by-trial level provide direct evidence for increased distractor representation underlying reduced behavioral performance in late adulthood. This points towards increased distractibility as a potential mechanism underlying age-related speech comprehension deficits. Additionally, at the behavioral and neural levels, we show that older adults relied more on higher-level linguistic information. Finally, we show that an increased reliance on word-level linguistic information may compensate for increased distractor tracking and adaptively support comprehension performance across the adult life span. Specifically, we directly show that increased reliance on higher-level processing can offset age-related impairments in attentional filtering.

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bioRxiv2025

Speech, gait, and brain dynamics during natural conversation in motion

Communication connects us to others and immerses us in our environment. Mobile EEG and hearing aid-embedded motion sensors allow investigation of communi-cation and movement in real-world contexts. Here we reliably record and model neural responses to natural conversational speech while participants are walking, demonstrating the feasibility of combining EEG with whole-body movement moni-toring. Participants (N = 61) performed focused listening and natural conversation while walking indoors and outdoors. Motion sensors, EEG, and audio recordings captured behavioural, neural, and motor dynamics. Walking speed varied with en-vironment and task: faster outdoors and slower during speaking. Temporal align-ment between gait and speech revealed coordinated rhythmic interactions, stronger during speaking than listening. Auditory temporal response functions were preserved across listening tasks. Gait TRFs displayed lateralized and temporal dy-namics consistent across tasks. These results provide insight into the coordinated interplay of speech, brain activity, and movement. This highlights the potential of multimodal approaches in ecologically valid settings.

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bioRxiv2025

Head movements integrate with brain signals to guide attention

The brain is part of a moving body. Most insights about the relationship between neural activity and cognition come from studies involving movement-constrained participants. Here, we test the roles of neural alpha oscillations (~10 Hz) and head movements for auditory spatial attention in human participants (N=33). Neural attention filtering showed up as decreased alpha power in the electroencephalogram (EEG) contralateral to targets and vice versa for distractors. Gyroscopic tracking of head movements revealed consistent head turns towards lateral targets. Lateral distractors induced more variable movement patterns. Systematic miniature movements remained even when listeners were instructed not to move. Head rotations improved task accuracy by reducing target uncertainty. Trial-by-trial modulation of neural filtering and head rotation correlated positively, with neural alpha modulation being followed by lateral eye movements and head rotations. Spatial attention emerges from neural coding of relevant and irrelevant stimuli, co-occurring with lateral head rotations supporting sensory sampling.

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bioRxiv2025

Lifespan Variation in Perceptual Style Along an Autism-Schizotypy Continuum Explains Individual Responses to External Uncertainty

How the brain weighs prior knowledge against incoming evidence varies systematically across individuals - and this variation may lie at the heart of an Autism-Schizotypy Continuum (ASC) in the healthy population. In a large lifespan sample (N = 340; age 18-82), we used the Schizotypal Personality Questionnaire and a refined Autism Spectrum Quotient model to position individuals along this continuum, then asked how their placement predicts sensitivity to lexical surprisal during self-paced reading. First, perceptual style is not fixed: older adults showed reliably less schizotypal profiles, making the ASC a developmentally dynamic dimension. Second, ASC position interacted with age to modulate surprisal sensitivity across 160,000+ word-level reading times: autism-like profiles yielded stronger disruption by unexpected words, an effect that grew across the lifespan. We interpret this as reflecting a tightening of predictions formed from linguistic context - the less schizotypy-like the profile, and the older the reader, the more strongly incoming evidence is weighted against expectation. These effects remained robust under cross-validation. Our findings establish the Autism-Schizotypy Continuum as a dynamic, lifespan-sensitive framework for understanding how individuals differ in their responsiveness to incoming linguistic evidence. Significance StatementIndividual differences in perception are often framed as a trade-off between prior knowledge and sensory input, yet how these differences evolve with age and shape real-time language processing remains unclear. In a large adult lifespan sample, we show that cognitive-perceptual style shifts systematically with age and predicts sensitivity to lexical surprisal during reading. Our findings recast the Autism-Schizotypy Continuum as indexing sensitivity to incoming evidence and highlight the need for lifespan-sensitive, individualized models of predictive processing.

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bioRxiv2025

Dynamic Neural Encoding of Prior Expectations and Auditory Evidence Drive Perceptual Decision-Making

Perceptual decision-making has been studied extensively as the integration of evidence over time. Yet how moment-to-moment fidelity of sensory encoding interacts with prior expectations in shaping our choices remains poorly understood--particularly in the auditory domain. Here we quantify how priors act at the stage of sensory encoding and how these fluctuations predict behaviour. In a human model-based EEG study, we augmented a canonical click-train evidence accumulation task with probabilistic cues to shape prior expectations and analysed all activity with trial-resolved linear encoding models. Probabilistic cues drove alpha-oscillatory EEG patterns and induced symmetric shifts in response bias but did not change temporal integration dynamics. Neural encoding strength in lateralised auditory cortex uniquely predicted single-trial choice and confidence beyond what was explained by evidence strength or cueing alone. These findings identify sensory encoding fidelity as a mechanistic, behaviourally relevant link between priors and perceptual choice, offering new understanding how neural noise and expectations jointly shape decisions under uncertainty.

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bioRxiv2025

Prior Information Shapes Perceptual Evidence Accumulation Dynamics Differentially in Psychosis

Humans rely on prior information to navigate sensory uncertainty: Such priors could shape the decision process before sensory evidence is gathered (origin model), or could amplify sensory evidence dynamically (gain model). Dysfunctionalities in the utilisation of priors may underlie hallucinatory percepts and delusional ideation in psychosis, yet their impact on decision-making across sensory modalities has remained unclear. Using a perceptual target-detection task across auditory and visual domains in laboratory and online samples, we applied hierarchical drift diffusion modelling to examine how prior probabilities shape evidence accumulation in clinical and non-clinical populations. We show that in healthy individuals, prior information enhances sensory gain and decision flexibility, as represented by drift criterion and rate, consistent with the gain model. In contrast, individuals with psychosis exhibit diminished sensory gain, relying instead on pre-evidence biases, consistent with the origin model. Notably, greater positive symptom severity predicted a reduction in traditional criterion decision bias. These results suggest that sensory gain deficits may serve as a computational marker for psychosis progression, linking dysfunctional prior use to perceptual aberrancies. By demonstrating how prior information modulates evidence accumulation across sensory modalities, our study advances the understanding of psychotic perception and decision-making, offering insights for computational psychiatry and fine-tuned clinical diagnostics.

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bioRxiv2025

Attentional engagement with target and distractor streams predicts speech comprehension in multitalker environments

Understanding speech while ignoring competing speech streams in the surrounding environment is challenging. Previous studies have demonstrated that attention shapes the neural representation of speech features. Attended streams are typically represented more strongly than unattended ones, suggesting either enhancement of the attended or suppression of the unattended stream. However, it is unclear how these complementary processes support attentional filtering and speech comprehension on different hierarchical levels. In this study, we used multivariate temporal response functions to analyze the EEG signals of 43 young adults (24 women), examining the relationship between the neural tracking of acoustic and higher-level linguistic features and a fine-grained speech comprehension measure. We show that the neural tracking of word and phoneme onsets and word-level linguistic features in the attended stream predicted comprehension at the individual single-trial level. Moreover, acoustic tracking of the ignored speech stream was positively correlated with comprehension performance, whereas word level linguistic neural tracking of the ignored stream was negatively correlated with comprehension. Collectively, our results suggest that attentional filtering during speech comprehension requires target enhancement as well as distractor suppression at different hierarchical levels. Significance StatementIn social settings, speech comprehension is often challenged by the presence of multiple speakers talking simultaneously. The ability to focus on a relevant stream while ignoring irrelevant speech information in the background is crucial for successful and efficient interpersonal interactions. However, the precise neural mechanisms underlying this selective filtering process remain unclear. We establish the interplay of acoustic and higher-level information as objective markers of attentional selection and comprehension success.

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bioRxiv2025

Neural Tracking of the Maternal Voice in the Infant Brain

Infants preferentially process familiar social signals, but the neural mechanisms underlying continuous processing of maternal speech remain unclear. Using EEG-based neural encoding models based on temporal response functions, we investigated how 7-month-old human infants track maternal vs. unfamiliar speech and whether this affects simultaneous face processing. Infants (13 boys, 12 girls) showed stronger neural tracking of their mothers voice, independent of acoustic properties, suggesting an early neural signature of voice familiarity. Furthermore, central encoding of unfamiliar faces was diminished when infants heard their mothers voice and face-tracking accuracy at central electrodes increased with earlier occipital face tracking, suggesting heightened attentional engagement. However, we found no evidence for differential processing of happy vs. fearful faces, contrasting previous findings on early emotion discrimination. Our results reveal interactive effects of voice familiarity on multimodal processing in infancy: while maternal speech enhances neural tracking, it may also alter how other social cues, such as faces, are processed. The findings suggest that early auditory experiences shape how infants allocate cognitive resources to social stimuli, emphasizing the need to consider cross-modal influences in early development. Significance statementHow infants continuously process familiar social signals and how this familiarity shapes perception has remains unknown. Here we demonstrate that infants brains preferentially track maternal speech over unfamiliar voices, highlighting the early tuning of the auditory system to socially relevant signals. Moreover, the maternal voice modulates the neural encoding of concurrently presented faces without eliciting emotion-specific differences. These findings underscore the role of caregiver signals in shaping multisensory integration during early development.

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bioRxiv2025

Endogenous auditory and motor brain rhythms predictindividual speech tracking

Slow, endogenous brain rhythms in auditory cortex are hypothesized to track acoustic amplitude modulations during speech comprehension. Temporal predictions from the motor system are thought to enhance this tracking. However, direct evidence for the involvement of endogenous auditory and motor brain rhythms is lacking. Combining magnetoencephalographic recordings with behavioral data, we here show that endogenous peak frequencies of individuals resting-state theta rhythm in superior temporal gyrus predict speech tracking during comprehension. Importantly, endogenous rates of speech motor areas predicted auditory-cortical speech tracking only in individuals with high auditory-motor synchronization profiles. Higher rates in the supplementary motor area, and lower rates in inferior frontal gyrus, predicted stronger tracking. These findings align with participants behavioral data and provide compelling support for oscillatory accounts of auditory-motor interactions during speech perception. Interestingly, working memory capacity predicted speech comprehension performance particularly in individuals with low auditory-motor synchronization profiles. The findings highlight two partially independent speech processing routes across individuals: an auditory-motor route, related to enhanced comprehension performance, and an auditory working-memory route.

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bioRxiv2025

Neural and Behavioral Adaptation to Listening with a Unilateral Cochlear Implant (CI)

The human auditory system must distinguish relevant sounds from noise. Severe hearing loss can be treated with cochlear implants (CIs), but how the brain adapts to electrical hearing remains unclear. This study examined adaptation to unilateral CI use in the first and seventh month after CI-activation using speech comprehension measures and electroencephalography (EEG) recordings, both during passive listening and an active spatial listening task. Neural phase-locking to amplitude-modulated (AM) sounds interacted with time, such that phase-locking longitudinally increased stronger for 40 compared with 4 Hz. In the spatial listening task, the benefit of performing the task with the CI on vs. off was most pronounced when the CI ear was primarily exposed to target speech. Lateralized alpha oscillations ([~]10 Hz) reliably marked CI users focus of spatial attention. Stronger alpha modulation in the hemisphere opposite to the non-implanted ear indicates an attentional bias toward the acoustically hearing ear. Our findings suggest that adaptation to hearing with a CI is accomplished by dynamic changes in auditory phase-locking and a bias in auditory spatial attention. Data availabilityAll data are available from the corresponding author upon request. A table including data for most important behavioural and neural outcome measures is available at https://osf.io/tkurz/.

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bioRxiv2024

Predicting the irrelevant: Neural effects of distractor predictability depend on load

Distraction is ubiquitous in human environments. Distracting input is often predictable, but we do not understand when or how humans can exploit this predictability. Here we ask whether predictable distractors are able to reduce uncertainty in updating the internal predictive model. We show that utilising a predictable distractor identity is not fully automatic but in part depends on available resources. In an auditory spatial n-back task, listeners (n = 33) attended to spoken numbers presented to one ear and detected repeating items. Distracting numbers presented to the other ear either followed a predictable (i.e., repetitive) sequence or were unpredictable. We used electroencephalography (EEG) to uncover neural responses to predictable versus unpredictable auditory distractors, as well as their dependence on perceptual and cognitive load. Neurally, pairs of targets and unpredictable distractors induced a sign-reversed lateralization of pre-stimulus alpha oscillations ([~]10 Hz) and larger amplitude of the stimulus-evoked P2 event-related potential component. Under low versus high memory load, distractor predictability increased the magnitude of the frontal negativity component. Behaviourally, predictable distractors under low task demands (i.e., good signal-to-noise ratio and low memory load) made participants adopt a less biased response strategy. We conclude that predictable distractors decrease uncertainty and reduce the need for updating the internal predictive model. In turn, unpredictable distractors might mislead proactive spatial attention orientation, elicit larger neural responses, and put higher demand on memory.

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bioRxiv2024

Limited cognitive resources reduce the language predictability benefit across the adult lifespan

Humans routinely anticipate upcoming language, but whether such predictions come at a cognitive cost remains debated. In this study, we demonstrate the resource-dependent nature of predictive mechanisms in language comprehension across the lifespan: Experimentally limiting executive resources through a concurrent task reduces the effect of language predictability on reading time. Participants (N=175, replication N=96) read short articles presented word-by-word while completing a secondary font colour n-back task, thus varying cognitive demand. Language predictability was indexed by word surprisal as derived from a pre-trained large language model (GPT-2). Across two independent samples, our findings reveal that language predictions are not cost-free: They draw on executive control resources, and this dependency becomes more pronounced with age (18-85 years). These results help resolve the debate over cognitive demands in language comprehension and highlight prediction as a dynamic, resource-dependent process across the lifespan.

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bioRxiv2024

Neurophysiology of effortful listening: Decoupling motivational modulation from task demands

In demanding listening situations, a listeners motivational state may affect their cognitive investment. Here, we aim to delineate how domain-specific sensory processing, domain-general neural alpha power, and pupil size as a proxy for cognitive investment encode influences of motivational state under demanding listening. Participants performed an auditory gap-detection task while pupil size and the magnetoencephalogram (MEG) were simultaneously recorded. Task demand and a listeners motivational state were orthogonally manipulated through changes in gap duration and monetary-reward prospect, respectively. Whereas task difficulty impaired performance, reward prospect enhanced it. Pupil size reliably indicated the modulatory impact of an individuals motivational state. At the neural level, the motivational state did not affect auditory sensory processing directly but impacted attentional post-processing of an auditory event as reflected in the late evoked-response field and alpha power change. Both pre-gap pupil dilation and higher parietal alpha power predicted better performance at the single-trial level. The current data support a framework wherein the motivational state acts as an attentional top-down neural means of post-processing the auditory input in challenging listening situations. Significance StatementHow does an individuals motivational state affect cognitive investment during effortful listening? In this simultaneous pupillometry and MEG study, participants performed an auditory gap-detection task while their motivational state was manipulated through varying prospect of a monetary reward. The pupil size directly mirrored this motivational modulation of the listening demand. The individuals motivational state also enhanced top-down attentional post-processing of the auditory event but did neither change auditory sensory processing nor pre-gap parietal alpha power. These data suggest that a listeners motivational state acts as a late attentional top-down effect on auditory neural processes in challenging listening situations.

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bioRxiv2024

Characterizing directional dynamics of semantic prediction based on inter-regional temporal generalization

The event-related potential/field component N400(m) has been widely used as a neural index for semantic prediction. It has long been hypothesized that feedback information from inferior frontal areas plays a critical role in generating the N400. However, due to limitations in causal connectivity estimation, direct testing of this hypothesis has remained difficult. Here, magnetoencephalography (MEG) data was obtained during a classic N400 paradigm where the semantic predictability of a fixed target noun was manipulated in simple German sentences. To estimate causality, we implemented a novel approach based on machine learning and temporal generalization to estimate the effect of inferior frontal gyrus (IFG) on temporal areas. In this method, a support vector machine (SVM) classifier is trained on each time point of the neural activity in IFG to classify less predicted (LP) and highly predicted (HP) nouns and then tested on all time points of superior/middle temporal sub- regions activity (and vice versa, to establish spatio-temporal evidence for or against causality). The decoding accuracy was significantly above chance level when the classifier was trained on IFG activity and tested on future activity in superior and middle temporal gyrus (STG/MTG). The results present new evidence for a model predictive speech comprehension where predictive IFG activity is fed back to shape subsequent activity in STG/MTG, implying a feedback mechanism in N400 generation. In combination with the also observed strong feedforward effect from left STG/MTG to IFG, our findings provide evidence of dynamic feedback and feedforward influences between IFG and temporal areas during N400 generation.

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bioRxiv2024

Does amplitude compression help or hinder attentional neural speech tracking?

Amplitude compression is an indispensable feature of contemporary audio production and especially relevant in modern hearing aids. The cortical fate of amplitude-compressed speech signals is not well-studied, however, and may yield undesired side effects: We hypothesize that compressing the amplitude envelope of continuous speech reduces neural tracking. Yet, leveraging such a compression side effect on unwanted, distracting sounds could potentially support attentive listening if effectively reducing their neural tracking. In this study, we examined 24 young normal-hearing (NH) individuals, 19 older hearing-impaired (HI) individuals, and 12 older normal-hearing individuals. Participants were instructed to focus on one of two competing talkers while ignoring the other. Envelope compression (1:8 ratio, loudness-matched) was applied to one or both streams containing short speech repeats. Electroencephalography (EEG) allowed us to quantify the cortical response function and degree of speech tracking. With compression applied to the attended target stream, HI participants showed reduced behavioural accuracy, and compressed speech yielded generally lowered metrics of neural tracking. Importantly, we found that compressing the ignored stream resulted in a stronger neural representation of the uncompressed target speech. Our results imply that intelligent compression algorithms, with variable compression ratios applied to separated sources, could help individuals with hearing loss suppress distraction in complex multi-talker environments. Significant statementAmplitude compression, integral in contemporary audio production and hearing aids, poses an underexplored cortical challenge. Compressing the amplitude envelope of continuous speech is hypothesized to diminish neural tracking. Yet, capitalizing on this compression side effect for distracting sounds might enhance attentive listening. Studying normal-hearing (NH), older hearing-impaired (HI), and older normal hearing individuals in dual-talker scenarios, we applied envelope compression to speech streams. Both NH and HI participants showed diminished neural tracking with compression on the speech streams. Despite weaker tracking of a compressed distractor, HI individuals exhibited stronger neural representation of the concurrent target. This suggests that adaptive compression algorithms, employing variable ratios for distinct sources, could aid individuals with hearing loss in suppressing distractions in complex multi-talker environments.

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