Biology subjects

Niedernhuber, M.

Publications and source records attributed to Niedernhuber, M..

8 recordsLinked to original sources

bioRxiv2025

Effective connectivity reveals a shift to left-hemisphere dominance for spatial attention with diminishing arousal

Spatial attention becomes biased toward the right side of space when alertness wanes, but the neural mechanisms underlying this shift remain unresolved. Competing theories propose that spatial attention depends either on a dominant right hemisphere, interhemispheric competition, or interactions between dorsal and ventral attention networks. Here, we used drowsiness as a model to investigate how diminishing alertness reshapes the cortical dynamics supporting auditory spatial attention. Thirty healthy participants completed a lateralised auditory localisation task while high-density EEG was recorded during wakefulness and drowsiness. Behaviourally, drowsiness selectively impaired localisation accuracy for left-sided stimuli, replicating the typical neglect-like rightward attentional bias observed with lower arousal in healthy people, and pathological attention deficits in brain injury patients. Using Dynamic Causal Modelling and Parametric Empirical Bayes, we identified a striking reconfiguration of effective cortico-cortical connectivity across arousal states. During wakefulness, spatial attention was characterised by reciprocal interhemispheric signalling between inferior frontal regions, consistent with balanced bilateral coordination. During drowsiness, this pattern shifted toward reduced right frontoparietal connectivity together with increased left-hemispheric parietofrontal connectivity. These findings suggest that waning alertness destabilises balanced interhemispheric control and allows left-hemispheric processing to dominate attentional processing. Rather than fully supporting existing theories of spatial attention, our results point toward a hybrid mechanism in which neglect-like spatial bias emerges from the interaction between right-hemispheric dysconnection and left-hemispheric dominance under low arousal. Diminishing alertness reshapes interhemispheric coordination rather than simply reducing right-hemisphere function.

neuroscience↗

bioRxiv2025

N, N-Dimethyltryptamine and harmine formulation shifts metastable topography sequences in the cortex

Classic serotonergic psychedelics are potent modulators of conscious awareness, yet the principles governing their effects on the temporal dynamics of brain activity remain unclear. Dominant theories propose that psychedelics increase the signal diversity and metastability of neural states, but whether this reflects a simple randomization of activity or a more structured reorganization is unknown. Here, we used high-density EEG (n=25) in a double-blind, placebo-controlled study to delineate the effects of an ayahuasca-inspired formulation (intranasal N,N-DMT and buccal harmine) on the syntax of whole-brain functional states. Using microstate analysis, we show that psychedelic states induced by DMT and harmine are characterized by a profound acceleration of neural dynamics, evidenced by a reduced microstate duration and an increased frequency of state transitions. Despite that, the sequence of microstates became less random, as indicated by a higher first-order Markov statistic. This syntactic restructuring involved a systematic de-prioritization of transitions into one state (M2) and a corresponding increase in the prevalence and accessibility of two other states (M3 and M5). These findings reveal that the psychedelic state leads to a syntactically reconfigured state of heightened metastability. By showing that psychedelics both lead to an accelerated exploration of an expanded repertoire of neural states governed by increased syntactic structure, our findings improve our understanding of neural metastability in psychedelic states.

neuroscience↗

bioRxiv2025

Sleep disturbance is associated with increased repetitive sensorimotor behaviour in autism but not in learning/intellectual disabilities or ADHD: A comparative study

The interplay of sleep and sensorimotor processing is a fundamental neurobiological process crucial for well-being. Individuals with neurodevelopmental conditions like autism, ADHD, and learning disabilities frequently experience both significant sleep disturbance and repetitive sensorimotor behaviours. Although a link between these domains is established, it is unclear whether this relationship and its functional impact are consistent across different neurodevelopmental conditions. In a cross-sectional dataset of individuals aged 5-21 (n = 212), we investigated whether the interplay between sleep disturbance and repetitive sensorimotor behaviours differs between individuals diagnosed with autism (IQ>70), ADHD, a learning disability (IQ<70), as well as typically developed controls. We also examined whether interactions between sleep and repetitive sensorimotor behaviours predicts distinct functional outcomes between neurodevelopmental groups. We found that individuals with autism (IQ>70) were most strongly affected by both sleep disturbance and repetitive sensorimotor behaviours. Crucially, we show that while a robust bidirectional link between sleep and repetitive sensorimotor behaviours exists across the entire sample, sleep problems amplify repetitive sensorimotor behaviours more strongly only in autistic people than in typical controls. Contrary to previous work, we found that learning disabled children and adolescents engaged in more repetitive sensorimotor behaviour but did not experience more sleep disturbance. Although the interaction between sleep problems and repetitive sensorimotor behaviours did not determine functional outcomes in autistic people, the interplay of sleep problems and repetitive sensorimotor behaviour impaired social awareness in people with ADHD. These findings challenge a transdiagnostic view that treats the reinforcement between sleep and sensorimotor problems as a general marker of neurodevelopmental conditions. Understanding the distinct pathways between sleep and waking behaviours is a critical step toward developing personalized, mechanistic interventions targeting specific sleep and sensory impairment profiles in different neurodevelopmental conditions.

neuroscience↗

bioRxiv2025

Sustained dynamics and modality-specific network reconfigurations define crossmodal prediction error

Predictive processing theories posit that the brain continuously generates expectations about incoming sensory inputs, updating them through prediction errors. While extensively studied within single modalities, it remains unclear how prediction errors unfold when expectations and violations occur across different senses. Using a local-global hierarchical oddball paradigm combined with high-density EEG in 47 participants, we contrasted unimodal and crossmodal prediction errors across auditory, visual, and somatosensory domains. We found that crossmodal violations elicit temporally sustained cortical responses which diverge from the transient, localised dynamics observed for unimodal prediction errors. Temporal decoding revealed that crossmodal effects maintain shared prolonged neural representations, suggestive of supramodal integration across all levels of cortical processing. Computational modelling further demonstrated that crossmodal prediction errors reorganize effective connectivity within and between sensory hierarchies, engaging distinct early cortical pathways depending on the sensory combination. Our findings refine hierarchical predictive coding for crossmodal transitions by demonstrating that, unlike unimodal prediction errors, crossmodal prediction errors recruit dedicated prolonged supramodal representations and flexibly adapted modality-specific networks.

neuroscience↗

bioRxiv2024

Reduced and Redundant: Information Processing of Prediction Errors during Sleep

During sleep, the human brain transitions to a sentinel processing mode, enabling the continued processing of environmental stimuli despite the absence of consciousness. Here, we employed advanced information-theoretic analyses, including mutual information (MI) and co-information (co-I), alongside event-related potential (ERP) and temporal generalization analyses (TGA), to characterize auditory prediction error processing across wakefulness and sleep. We hypothesized that a shared neural code would be present across sleep stages, with deeper sleep being associated with reduced information content and increased information redundancy. To investigate this, twenty-nine young healthy participants were exposed to an auditory local-global oddball paradigm during wakefulness and during an 8-hour sleep opportunity monitored via polysomnography in a cross-sectional study. We focused on local mismatch responses to a deviating fifth tone following four standard tones. ERP analyses showed that prediction error processing continued throughout all sleep stages (N1-N3, REM). Mutual information analyses revealed a substantial reduction in the amount of encoded prediction error information particularly during N3 and REM, although ERP amplitudes increased with deeper NREM sleep. In addition, we observed delayed information encoding during sleep and co-information analyses showed that neural dynamics became increasingly redundant with increasing sleep depth. Temporal generalisation analyses revealed a largely shared neural code between N2 and N3 sleep, although it differed between wakefulness and sleep. Here, we showed how the neural code of the sentinel processing mode changes from wake to light to deep sleep and REM, characterised by delayed processing, more redundant and less rich neural information in the human cortex as consciousness wanes. This altered stimulus processing reveals how neural information changes with the changes of consciousness states as we traverse the night.

neuroscience↗

bioRxiv2024

Supramodal neural information supports stimulus-driven attention across cortical levels

Predictive coding posits that the brain actively anticipates inputs from different senses, generating prediction errors when incoming information deviates from internal expectations. While much research has focused on prediction errors elicited by violations of single sensory features, natural environments frequently present more complex events deviating across multiple stimulus dimensions and sensory modalities. In this study, we employed a hierarchical oddball paradigm (n=30) manipulating auditory and somatosensory stimuli to violate one or two sensory features while high-density EEG was recorded. Temporal decoding revealed that while both single- and double-deviants evoked sustained supramodal activation patterns, double-deviants uniquely elicited a supramodal response starting at 100 ms after the oddball. Effective connectivity analyses identified shared interhemispheric interactions between inferior frontal gyri across modalities, as well as distinct modality-specific connectivity within early and associative sensory cortices. Our findings demonstrate that multi-feature prediction errors recruit both rapid supramodal integration mechanisms and hierarchically organized modality-specific pathways. These results advance our understanding of how the brain flexibly integrates multiple sensory expectation violations across different levels of cortical processing, providing new insights into the neural architecture supporting predictive perception. Author summaryThe brain constantly generates predictions about incoming sensory information. While many studies focus on simple violations of individual features, real-life events often involve simultaneous deviations across multiple sensory attributes. Our goal was to examine supramodal or modality-specific aspects of multi-feature prediction errors. Considering that the cortex needs to converge individual predictions from multiple pathways for multi-feature prediction, we hypothesised that multi-feature prediction errors rely on a mid-latency supramodal process in the inferior frontal cortex. In a high-density EEG study using a nested oddball paradigm, we examined neural responses to somatosensory and auditory stimulus deviations in one or two dimensions. Using temporal decoding, we revealed an early supramodal short-lived cortical process when double-deviants are detected. We also applied Parametric Empirical Bayes Modelling to show that multi-feature prediction errors not only rely on a common interhemispheric inhibition between inferior frontal gyri but also on various supramodal and modality-specific changes in effective connectivity across associative and modality-specific cortices.

neuroscience↗

bioRxiv2022

Light targeting the melanopic system suppresses melatonin, but does not alter sleepiness, vigilance, sensory processing, or sleep

Pre-sleep exposure to short-wavelength light suppresses melatonin and decreases sleepiness with activating effects extending to sleep. This has mainly been attributed to melanopic effects, but mechanistic insights are missing. Thus, we investigated whether two light conditions only differing in the melanopic effects (123 vs. 59 lux melanopic EDI) differentially affect sleep besides melatonin. Additionally, we studied whether the light differentially modulates sensory processing during wakefulness and sleep. Twenty-nine healthy volunteers (18-30 years, 15 women) were exposed to two metameric light conditions (high-vs. low-melanopic, {approx}60 photopic lux) for 1 hour ending 50 min prior to habitual bed time. This was followed by an 8-h sleep opportunity with polysomnography. Objective sleep measurements were complemented by self-report. Salivary melatonin, subjective sleepiness, and behavioural vigilance were sampled at regular intervals. Sensory processing was evaluated during light exposure and sleep on the basis of neural responses related to violations of expectations in an oddball paradigm. We observed suppression of melatonin by {approx}14 % in the high-compared to the low-melanopic condition. However, conditions did not differentially affect sleep, sleep quality, sleepiness, or vigilance. A neural mismatch response was evident during all sleep stages, but not differentially modulated by light. Suppression of melatonin by light targeting the melanopic system does not automatically translate to acutely altered levels of vigilance or sleepiness or to changes in sleep, sleep quality, or basic sensory processing. Given contradicting earlier findings and the retinal anatomy, this may suggest that an interaction between melanopsin and cone-rod signals needs to be considered. Statement of SignificanceMetameric light allows to mechanistically investigate the contribution of one specific retinal receptor. Using this approach, we here investigated the effects of high-vs. low-melanopic light for 1 hour in the evening at ecologically valid screen illuminance ({approx}60 photopic lux). Going beyond earlier research, we also investigated effects on sleep. We found that despite significant suppression of melatonin, other endpoints including sleep and sleep quality were not differentially affected. This underlines that melatonin suppression does not automatically translate to alterations of sleep, sleepiness, or vigilance. Further, it suggests that melanopsin effects may need to be studied in the context of cone-rod signals. Future research should thus investigate the relevance of such an interaction, which may vary between endpoints.

neuroscience↗

bioRxiv2022

Sensory target detection at local and global time scales dissociates modality-specific and supramodal dynamics in the cortical hierarchy

To ensure survival in a dynamic environment, the human neocortex monitors input streams forwarded from different sensory organs for important sensory events. Which principles govern whether different senses share common or modality-specific networks for sensory target detection? We examined whether complex targets evoke sustained supramodal activity while simple targets rely on modality-specific networks with short-lived supramodal contributions. In a series of hierarchical multisensory target detection studies (n=77, of either sex) using Electroencephalography, we applied a temporal cross-decoding approach to dissociate supramodal and modality-specific cortical dynamics elicited by rule-based global and feature-based local sensory deviations within and between the visual, somatosensory and auditory modality. Our data show that each sense implements a cortical hierarchy which orchestrates supramodal target detection responses operating on local and global timescales at successive processing stages. Across different sensory modalities, simple feature-based sensory deviations presented in temporal vicinity to a monotonous input stream triggered an MMN-like local negativity which decayed quickly and early whereas complex rule-based targets tracked across time evoked a P3b-like global ERP response which generalised across a late time window. Converging results from temporal cross-modality decoding analyses across different datasets, we reveal that global ERP responses are sustained in a supramodal higher-order network whereas local ERP responses canonically thought to rely on modality-specific regions evolve into short-lived supramodal activity. Taken together, our findings demonstrate that cortical organisation largely follows a gradient in which short-lived modality-specific as well as supramodal processes dominate local responses whereas higher-order processes encode temporally extended abstract supramodal information fed forward from modality-specific cortices. Sensory target detection at local and global timescales reveals a hierarchy of supramodal dynamics in the human cortex Significance statementEach sense supports a cortical hierarchy of processes tracking deviant sensory events at multiple timescales. Conflicting evidence produced a lively debate around which of these processes are supramodal. Here, we manipulated the temporal complexity of auditory, tactile, and visual targets to determine whether cortical local and global ERP responses to sensory targets share cortical dynamics between the senses. Using temporal cross-decoding, we found that temporally complex targets elicit a supramodal sustained response. Conversely, local responses to temporally confined targets typically considered modality-specific rely on early short-lived supramodal activation. Our finding provides evidence for a supramodal gradient supporting sensory target detection in the cortex, with implications for multiple fields in which these responses are studied (such as predictive coding, consciousness, and attention).

neuroscience↗