Biology subjects

Niedernhuber, M.

Publications and source records attributed to Niedernhuber, M..

3 recordsLinked to original sources

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↗