Biology subjects

Kotz, S. A.

Publications and source records attributed to Kotz, S. A..

At least 19 recordsLinked to original sources

bioRxiv2026

Temporal Progression of Prior Precision, Surprisal, Model Updating and Tone Adaptation in Human Auditory Cortices

Auditory perception emerges from the continuous integration of incoming acoustic signals with statistical predictions, a process complemented by simpler local adaptation. Yet, how all these concurrent mechanisms unfold in time remains underexplored. Using magnetoencephalography (MEG) in participants listening to stochastic tone sequences with periodically shifting inferential statistics, we modelled the temporal, spatial, and spectral dynamics of stimulus-specific repetition suppression, surprisal, model updating, and prior precision. By concurrently tracking these computational parameters within this dynamic auditory environment, we revealed a distinct chronological hierarchy governing predictive and adaptive processing. Prior precision states - reflecting expectations - emerged earliest, followed by rapid and concurrent repetition suppression and surprisal - reflecting local acoustic attenuation and global mismatch detection. These initial dynamics culminated in subsequent, distributed model updates within fronto-parietal networks. Spectrally, these components mapped onto diverging oscillatory fingerprints, ranging from theta-alpha modulation during adaptation to beta suppression during surprisal and broad spectral dampening during precision weighting. Together, these findings demonstrate that the brain navigates uncertain auditory environments through a cascade of neural processes, where fast, local sensory gating and mismatch signals precede the hierarchical revision of internal models.

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bioRxiv2026

Distinct nigral and brainstem pathology markers map onto separable subthalamic electrophysiological signatures in Parkinson's disease

Subthalamic local field potentials (LFPs) are increasingly used as physiomarkers of the symptomatic state in Parkinsons disease, but their relationship to the underlying neurodegenerative pathology remains unclear. Here, we combined OFF-medication subthalamic LFP recordings with quantitative MRI markers of nigral and brainstem pathology in 33 people with Parkinsons disease. Distinct pathological markers mapped onto dissociable electrophysiological components. Substantia nigra pars compacta susceptibility was associated with increased occupancy, duration and rate of low-{beta} bursts, whereas nigral free water was associated with greater low-frequency aperiodic offset and a steeper slope. Pedunculopontine nucleus free-water- corrected axial diffusivity was selectively associated with high-frequency aperiodic activity, and this relationship strengthened with increasing nigral susceptibility, consistent with dopaminergic-state- dependent influences of extranigral pathology on subthalamic physiology. Only low-frequency aperiodic offset was also associated with contralateral bradykinesia. These findings indicate that the subthalamic LFP is not a unitary readout of dopamine loss or motor state, but an integrated physiological signal in which pathology across interconnected systems is expressed through separable oscillatory and aperiodic components. Chronically implanted devices may therefore provide physiological readouts of underlying disease biology alongside control signals for adaptive therapy.

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bioRxiv2026

A body-brain-behavioral cross-frequency architecture links biological and behavioral periodicities

Spontaneous behaviors, e.g., walking and speaking, are thought to rely on an internal sense of time that provides a scaffold for precise temporal coordination. Yet the endogenous rates of many behavioral processes often diverge from the arbitrarily defined unit of objective time (Chronos), raising a fundamental question: what temporal reference frame coordinates behavior? Recent theoretical work (Buzsaki, 2026) proposed the rich repertoire of subjective time (Kairos) to fluctuate in function of a dynamic cross-frequency architecture linking body-brain periodicities along a lognormal linear progression in the frequency domain. Withing this framework, an emergent sense of time may regulate the rate of semi-periodic behaviors. Using high temporal resolution multimodal recordings, we show that endogenous body-brain periodicities - including pupil fluctuations, saccadic eye movements, respiration, cardiac activity and neural oscillations - as well as spontaneous behaviors such as tapping, walking, and speaking, are organized as an arithmetic progression in a natural logarithmic frequency space. This observation suggests that a unified scaling law may coordinate complex, multi-scale interactions across biological and behavioral timescales. We propose that such organization may provide an emergent temporal reference frame that scaffolds perception and action.

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bioRxiv2026

Emergent Entrainment and Predictive Dynamics in Bio-Inspired Spiking Neural Networks

Rhythm is a key building block of human music, speech and numerous other human activities. Understanding the computational substrates of rhythm perception requires models that bridge algorithmic function with biological implementation. We propose a physiologically grounded spiking neural network (SNN) framework to investigate the emergent representation and interpretation of auditory rhythms. Utilizing a recurrent SNN architecture trained on an auditory entrainment task, we characterize the networks latent dynamics through the analysis of firing rates and membrane potential fluctuations. Our results demonstrate that simulated neural populations exhibit phase-locking to the stimulus beat, with endogenous oscillations driven by rhythmic input. We further show that anticipatory dynamics--characterized by pre-stimulus depolarization--emerge naturally from the networks synaptic plasticity and temporal integration properties, rather than from explicitly defined oscillators. By treating network layers as functional analogs of cortical populations, this framework allows for the application of spectral and information-theoretic analyses typical of empirical electrophysiology. More in general, this approach establishes SNNs as robust exploratory tools for uncovering how predictive coding and rhythmic entrainment arise from the inherent constraints of biological neural computation.

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bioRxiv2025

Reduced belief updating impairs adaptive step initiation in older adults

Ageing is associated with declines in mobility and balance that threaten independence and increase fall risk. Although these changes are often attributed to deterioration of muscular and sensory systems, growing evidence suggests that age-related alterations in cognitive control also contribute to postural instability and gait impairments. Here, we examined whether shifts in cognitive control strategy underlie impaired gait initiation in older adults by modelling how individuals update beliefs about upcoming actions. Older and younger adults performed a choice-stepping go/no-go task in which step likelihood was manipulated across trials. We measured anticipatory postural adjustments (APAs), the preparatory weight shifts preceding stepping and modelled age-related differences in APA onset using a hierarchical Bayesian framework. Older adults initiated slower APAs, particularly after repeated go trials. Computational modelling revealed reduced learning rates and heightened sensitivity to uncertainty in older adults, identifying altered belief updating as a cognitive mechanism shaping age-related changes in adaptive stepping.

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bioRxiv2025

Distinct Roles of Deep and Superficial Cortical Layers in Tone Prediction, Comparison, and Adaptation in Human Auditory Cortex

Auditory perception relies on prior sensations both to form expectations about upcoming sounds and to adapt to repeated inputs. Yet, how these processes interact with bottom-up frequency-specific stimulus drive, and how they are organised across cortical depth, remains unclear. Using ultra-high-field functional magnetic resonance imaging (7T fMRI), participants listened to stochastic tone sequences whose repetition structure and predictability varied over time. For each voxel independently, we used computational modelling to estimate responses for stimulus drive, repetition suppression, and expectations. We then partitioned the unique and shared variance of these components to estimate their relative importance in modulating BOLD activity across cortical layers in auditory cortices. Expectation-related signals explained most unique variance in deep (infagranular) layers, in line with accounts that place internal model representations and belief updates in deeper cortical populations. Variance jointly explained by stimulus drive and expectation was instead strongest in superficial layers, consistent with these compartments expressing computations that combine bottom-up input with top-down predictions, such as prediction error signalling. Finally, repetition suppression accounted for variance uniformly across depth, suggesting an adaptation-like mechanism that modulates responsiveness without a clear laminar bias. Together, the data suggest that deep layers contain content-specific predictive models, superficial layers register prediction-input alignment, and repetition suppression provides a depth-invariant, local gain control that complements predictive processing.

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bioRxiv2025

Lesions in the cerebellum impact cross-modal temporal predictions

The cerebellum (CE) supports the encoding of the precise sensory event timing and the generation of temporal predictions. Here we investigated whether focal CE lesions impact temporal predictions in a cross-modal context. Individuals with CE lesion (n=9) and healthy-matched controls (HC) were presented with visuo-auditory stimulus pairs, presented in a temporally regular (predictable) or irregular (unpredictable) manner while EEG was recorded. We hypothesized cross-modal temporal predictions to be mediated by pre-stimulus cerebello-cortical beta-band (12-25Hz) activity. In turn, we expected HC, but not CE patients, to show a modulation of pre-stimulus beta power as a function of temporal prediction. HC showed greater pre-stimulus beta-band suppression in anticipation of sound onsets, and stronger post-stimulus delta- and theta-band (1-4Hz; 4-8Hz) power in the predictable than the unpredictable condition. Furthermore, they displayed a significant modulation of pre-stimulus delta-beta cross-frequency coupling as a function of temporal prediction. These effects were not observed in the CE group. Results confirm that cerebellar lesions impair the generation of temporal predictions in cross-modal (visuo-auditory) stimulus processing, extending the role of cerebellar predictive timing from sensorimotor to motor-independent cross-modal perception.

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bioRxiv2025

Heightened Sensitivity to Voice Loudness Changes in Parkinson's Disease

Parkinsons disease (PD) affects voice and speech production, often resulting in reduced vocal intensity and monotonous speech. Recent studies have suggested that these changes can be partially explained by altered sensory feedback processing when producing speech. Individuals with PD (IwPD) may fail to monitor sensory feedback from their own voice, impairing their ability to adjust voice and speech when sensory input differs from expectations. In this study, we investigated sensory feedback processing in PD by looking at the sensory attenuation typically observed in event-related responses (ERP) to the self-generated voice. When sensory feedback processing is intact, the P50, N100, and P200 ERP responses to the self-generated voice are more attenuated than to an externally-generated voice. Twenty-three IwPD and 23 healthy controls (HCs) participated in a voice playback study that comprised three conditions: self-generated voice (auditory-motor condition; AMC), externally-generated voice (auditory-only condition; AOC), and motor-only. The AMC and AOC conditions also included an amplitude modulation of the voice (0/+15dB). Linear mixed models assessed group differences in ERP morphology. While groups did not differ in their P50 and P200 responses, there was a significant group-condition- loudness interaction for the N100. Follow-up analyses showed that IwPD displayed much larger N100 error responses for unexpected loudness modulations as compared to HC. This observation suggests that IwPD may process voice modulations differently than HC. The hypersensitivity to loudness changes may underlie IwPDs difficulties in processing and adapting their voice acoustics.

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bioRxiv2024

Not enough pleasure? Influence of hallucination proneness on sensory feedback processing of positive self-voice

Ample research explored changes in sensory feedback processing of the self-voice as well as the control of attention allocation in voice hearers, including both non-clinical voice hearers and voice hearers with a psychotic disorder. While the attentional bias toward negative emotional information in voice hearers with a psychotic disorder due to heightened sensitivity towards threat/danger is well established, it remains unclear how positive emotion captures or controls attention. Manipulating the certainty of sensory feedback to the self-voice, transitioning from fully neutral to entirely positive (100% neutral, 60-40% neutral-pleasure, 50-50% neutral-pleasure, 40-60% neutral-pleasure, 100% pleasure), provides an opportunity to investigate attentional control and sensory feedback processing in positive self-voice as a function of hallucination proneness (HP). Participants with different HP scores self-generated and passively listened to their own voices during EEG recordings. N100 or P200 responses to self-generated and externally-generated self-voices did not differ. Further, HP did not modulate N100/P200 responses. These null findings might result from the minimal perceptual discriminability among the five types of voices varying in pleasure content. This might have led to less variation in certainty regarding the sensory feedback to self-voice, and consequently a lack of differential engagement of attentional resources. The lack of a global N100 suppression effect prompts inquiry into the association of sense of ownership/agency and pleasure.

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bioRxiv2024

Differentiating hallucination proneness dimensions through resting state alpha dynamics

BackgroundHallucination-like experiences (HLEs) are untriggered sensory perceptions linked to externalizing bias - the misattribution of self-generated sensory experiences to an external source. The vulnerability to HLEs, i.e., hallucination proneness (HP), is typically assessed by the Launay-Slade Hallucination Scale (LSHS). A recent LSHS factor analysis revealed four distinct HP dimensions: Multisensory HLEs, Auditory daydreaming, Vivid thoughts and inner speech, and Personified HLEs. The current study assesses whether these HP dimensions map onto distinct patterns of resting state brain dynamics in the alpha frequency band due to its modulatory role in attention and perception. MethodsWe used a Hidden semi-Markov Model to segment continuous RS alpha activity into nine recurrent brain states and extracted the total number of transitions (TT) and the number of visits per state (SV). We assessed how the HP dimensions relate to these metrics, calculated across the entire 3-minute recording and within shorter sliding windows to capture finer temporal changes. ResultsAll HP dimensions and increased RS time correlated with increased TT. Increased Personified HLEs scores linked to different time-dependent changes of SV in two states (SV to state 5 decreased over time, while visits to state 9 increased), highlighting distinct alpha dynamics in high- and low-hallucination prone individuals. ConclusionsIncreased TT could indicate frequent attentional switches between internal and external states. Different SV patterns related to higher Personified HLEs scores suggest unstable source monitoring, potentially inducing an externalizing bias. These findings provide novel predictors of HP dimensions, revealing distinct neural profiles associated with different vulnerability profiles.

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bioRxiv2024

Audio-visual concert performances synchronize an audience's heart rates

People enjoy engaging with music. Live music concerts provide an excellent option to investigate real-world music experiences, and at the same time, use neurophysiological synchrony to assess dynamic engagement. In the current study, we assessed engagement in a live concert setting using synchrony of cardiorespiratory measures, comparing inter-subject, stimulus-response, correlation, and phase coherence. As engagement might be enhanced in a concert setting by seeing musicians perform, we presented audiences with audio-only (AO) and audio-visual (AV) piano performances. Only correlation measures were above chance level. In comparing time-averaged synchrony across conditions, AV performances evoked higher inter-subject correlation of heart rate (ISC-HR). However, self-reported engagement did not correspond to synchrony when averaged across music pieces. On the other hand, time-resolved analyses show that synchronized deceleration-acceleration heart rate (HR) patterns, typical of an orienting response (an index of directed attention), occurred within music pieces at salient events of section boundaries. That is, seeing musicians perform heightened audience engagement at structurally important moments in Western classical music. Overall, we could show that multisensory information shapes dynamic engagement. By comparing different synchrony measures, we further highlight the advantages of timeseries analysis, specifically ISC-HR, as a robust measure of holistic musical listening experiences in naturalistic concert settings.

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bioRxiv2024

Ageing impacts basic auditory and timing processing

Deterioration in the peripheral and central auditory systems is common in older adults and often leads to hearing and speech comprehension difficulties. Even when hearing remains intact, electrophysiological data of older adults frequently exhibit altered neural responses along the auditory pathway, reflected in variability in phase alignment of neural activity to speech sound onsets. However, it remains unclear whether these challenges in speech processing in aging stem from more fundamental deficits in auditory and timing processes. Here, we investigated if and how aging individuals encoded temporal regularities in isochronous auditory sequences presented at 1.5Hz, and if they employed adaptive mechanisms of neural phase alignment in anticipation of next sound onsets. We recorded EEG in older and young individuals listening to simple isochronous tone sequences. We show that aging individuals displayed increased amplitudes and variability in time-locked responses to sounds, an increased 1/F slope, but reduced phase-coherence in the delta and theta frequency-bands. These observations suggest a lack of repetition-suppression and inhibition when processing repeated and predictable sounds in a sequence and altered mechanisms of continuous phase-alignment to expected sound onsets in aging. Given that deteriorations in these basic timing capacities may affect other higher-order cognitive processes (e.g., attention, perception, and action), these results underscore the need for future research examining the link between basic timing abilities and general cognition across the lifespan. HighligthsO_LIAging individuals (HO) show increased cortical excitability as compared to younger adults (HY); C_LIO_LIHOs neural responses to fully predictable isochronous tones were larger and more variable than HY; C_LIO_LIHO showed reduced phase coherence in delta- and theta-band oscillations during listening to auditory sequence; C_LIO_LIAltogether, these results show altered sensory and timing processes in aging. C_LI

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bioRxiv2024

Striatal Dopamine Modulates Temporal Surprise P3a

Dopamine is vital in forming mental models of "what" and "when" sensory events occur that essentially guide goal-directed behaviour. However, it remains largely unknown how variations in temporal predictability are incorporated into such mental models. A better understanding of the underlying mechanisms is important, considering dopaminergic depletion in diseases such as Parkinsons Disease and Schizophrenia, where abnormal temporal processing is observed. Some electroencephalographic (EEG) studies indicate that noradrenergic mechanisms, as reflected in the P3b event-related potential, are modulated by temporal predictability, whereas others indicate that dopaminergic mechanisms as reflected in the P3a, underlie surprise. In this study, resting-state and task-dependent EEG was recorded from 24 healthy participants who were administered a selective D2 agonist or antagonist before they performed a pure tone auditory "oddball" task. Two oddball sequences included either partially predictable, with inter-stimulus intervals (ISIs) of 400ms/1200ms; or fully temporally predictable tones, with a consistent ISI of 600ms. Tones following 400ms ISIs were perceived as surprising, or "early", as shown in an enhanced P3a response; tones following a 1200ms ISIs showed a much reduced P3a response ("late"). The agonist accentuated the "late" effect, demonstrating that drugs targeting D2 receptors modulate temporal prediction. These findings differentiate the role of the dopaminergic system in temporal processing and model-based auditory predictions.

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bioRxiv2024

Entrainment Echoes in the Cerebellum

Historically, researchers have considered the cerebellum a coordinator of motor programs that ensures precise timing of movements and their adaptation to external events1. However, it has become increasingly clear that this role is not restricted to the motor system2. Rather, the cerebellum seems to play an important role in temporal prediction in general, as shown in its involvement in multiple functions that rely on precise event timing3. Although previous work suggested that the cerebellum exclusively predicts the interval between two events4, rather than tracking a global rhythm, it is also active when a rhythmic stimulus changes in rate5. The latter finding is in line with a cerebellar role in speech processing6 that entails frequent rate changes7. Neural mechanisms underlying the cerebellums involvement in speech processing, however, remain poorly understood. Moreover, there is a lack of studies contrasting speech and non-speech stimuli to establish speech-specificity of the observed effects8. In a re-analysis of magnetoencephalography (MEG) data9, we found that activity in the cerebellum aligned to rhythmic sequences of noise-vocoded speech, irrespective of its intelligibility. We then tested whether these "entrained" responses persist, and how they interact with other brain regions, when the rhythmic stimulus stopped and temporal predictions had to be updated. We found that only intelligible speech produced rhythmic responses in the cerebellum that outlasted the stimulus. During this "entrainment echo", but not during rhythmic speech itself, cerebellar activity was coupled with that in the left inferior frontal gyrus (IFG), and specifically at rates corresponding to the preceding stimulus rhythm. This finding represents unprecedented evidence for specific cerebellum-driven temporal predictions in speech processing and their relay to cortical regions.

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bioRxiv2024

Neural and behavioral dynamics of encoding, production and synchronization with external rhythms in subcortical lesion patients

Acting in and adapting to a dynamically changing environment necessitates precise encoding of the timing of unfolding sensory events in our environment, and to time of our own (re-)actions to them. Cerebellar (CE) and basal ganglia (BG) circuitries play fundamental and complementary roles in timing processes. While the CE seems to encode the precise timing of sensory events (when an event occurs), the BG engage in generating temporal predictions (when a next event occurs). However, their contributions are rarely investigated in combination, as it is generally difficult to record data from respective patient groups in parallel. Here we investigated the causal roles of CE and BG in sensory and sensorimotor timing processes. Healthy controls and patients with CE or BG lesions listened to isochronous auditory sequences while their EEG was recorded and later performed a tapping synchronization task. We assessed intra- and inter-individual variabilities, as well as group differences, using event-related responses, delta-band inter-trial phase-coherence and acceleration dynamics while tuning to the stimulation frequency (Sf). CE and BG lesions increased variability in ERP latency and reduced the coherence of delta-band activity. CE but not BG lesions further impacted the stability of delta-band oscillations while tuning to the Sf. These findings show a causal link between subcortical lesions and the capacity to encode and synchronize ongoing neural activity with temporal regularities in the acoustic environment, but do not fully dissociate the specific contributions of the BG and the CE to processing sound in isochronous contexts.

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bioRxiv2023

Revisiting Alpha Resting State Dynamics Underlying Hallucinatory Vulnerability: Insights from Hidden Semi-Markov Modeling

Resting state (RS) brain activity is inherently non-stationary. Hidden Semi-Markov Models (HsMM) can characterize the continuous RS data as a sequence of recurring and distinct brain states along with their spatio-temporal dynamics. Recent explorations suggest that EEG brain state dynamics in the alpha frequency link to auditory hallucination proneness (HP) in non-clinical individuals. The present study aims to replicate these findings to elucidate robust neural correlates of hallucinatory vulnerability. Specifically, we aimed to investigate the reproducibility of HsMM states across different data sets and within-data set variants as well as the replicability of the association between alpha brain state dynamics and HP. We found that most brain states are reproducible in different data sets, confirming that the HsMM characterized robust and generalizable EEG RS dynamics. Brain state topographies and temporal dynamics of different within-data set variants showed substantial similarities and were robust against reduced data length and number of electrodes. However, the association with HP was not directly reproducible across data sets. These results indicate that the sensitivity of brain state dynamics to capture individual variability in HP may depend on the data recording characteristics and individual variability in RS cognition, such as mind wandering. We suggest that the order in which eyes-open and eyes-closed RS data are acquired directly influences an individuals attentional state and generation of spontaneous thoughts, and thereby might mediate the link to hallucinatory vulnerability.

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bioRxiv2023

Exploring Neural Dynamics in Self-Voice Processing and Perception: Implications for Hallucination Proneness.

Altered sensory feedback processing and attention control are assumed to contribute to auditory verbal hallucinations, which are experienced by the general population and patients with psychosis, implying a continuum of hallucination proneness (HP). However, the interaction of altered sensory feedback processing and attention control along this HP continuum remains unclear. Manipulating the level of certainty of sensory feedback by changing self-voice quality (100% neutral, 60-40% neutral-angry, 50-50% neutral-angry, 40-60% neutral-angry, 100% angry) in individuals varying in HP, we tested this interaction using electroencephalography while participants self-generated or passively listened to their voices. Regardless of voice quality, HP modulated the N100 and P200 suppression effects. High HP individuals showed an increased N100 response to the self-generated voices and an increased P200 response for externally-generated voices. This may indicate increased error awareness and attention allocation in high HP individuals for self-voice generation stemming from altered sensory feedback processing, and/or attentional control. The current findings suggest that alterations of the sensory feedback processing in self-voice production are a fundamental characteristic of the continuum of HP, regardless of the clinical status of voice hearers. HighlightsO_LIAltered N100 voice suppression in high HP, regardless of the clinical status. C_LIO_LIHigh HP associated with altered sensory feedback processing and attentional control. C_LIO_LICurrent findings support a neurophysiological continuum of HP. C_LI

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bioRxiv2023

Hallucination proneness alters sensory feedback processing in self-voice production

BackgroundSensory suppression occurs when hearing ones self-generated voice, as opposed to passively listening to ones own voice. Quality changes of sensory feedback to the self-generated voice can increase attentional control. These changes affect the self-other voice distinction and might lead to hearing non-existent voices in the absence of an external source (i.e., auditory verbal hallucinations (AVH)). However, it is unclear how changes in sensory feedback processing and attention allocation interact and how this interaction might relate to hallucination proneness (HP). Study DesignParticipants varying in HP self-generated and passively listened to their voice that varied in emotional quality and certainty of recognition -- 100% neutral, 60-40% neutral-angry, 50-50% neutral-angry, 40-60% neutral-angry, 100% angry, during EEG recordings. Study ResultsThe N1 auditory evoked potential was more suppressed for the self-generated than externally generated voices. Increased HP was associated with (i) an increased N1 response to the self-compared to externally generated voices, (ii) a reduced N1 response for angry compared to neutral voices, and (iii) a reduced N2 response to unexpected voice quality in sensory feedback (60-40% neutral-angry) compared to neutral voices. ConclusionsThe current study highlights an association between increased HP and systematic changes of the emotional quality and certainty in sensory feedback processing (N1) and attentional control (N2) in self-voice production in a non-clinical population. Considering that voice hearers also display these changes, these findings support the continuum hypothesis. However, additional research is needed to validate this conclusion.

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