Biology subjects

Bruchmann, M.

Publications and source records attributed to Bruchmann, M..

5 recordsLinked to original sources

bioRxiv2025

Neural correlates of consciousness in an auditory no-report fMRI study

In the search for neural correlates of consciousness (NCC), prominent theories disagree about the role of sensory versus wide-spread fronto-parietal brain activity. Research on auditory awareness has been widely neglected, and isolating NCC from correlates of task-related post-perceptual processes (e.g., report) is an ongoing challenge. The present study addressed these issues using functional magnetic resonance imaging (fMRI) during a no-report inattentional deafness paradigm. Sixty-three participants performed an auditory distractor task while supra-threshold but task-irrelevant sounds were presented in the background. Whereas one group was aware of these stimuli, another group remained unaware. Comparing brain responses to the critical sounds between aware and unaware participants while controlling for correlates of sensory and postperceptual processing revealed that auditory awareness was associated with significantly increased activity in secondary auditory but not in fronto-parietal areas. These findings suggest a dominant role of stimulus-specific sensory processing rather than widespread fronto-parietal information broadcasting in conscious perception.

neuroscience↗

bioRxiv2025

Early neural responses to nonconscious fearful and neutral faces - an ERP study

Prioritized processing of fearful compared to neutral faces is reflected in differential event-related potentials (ERPs). There is an ongoing debate about the extent to which faces in general and fearful faces in particular enhance specific ERPs if they are not consciously perceived. Specifically, the N170 has been suggested as the most likely candidate for enhanced processing of nonconscious fearful faces. In this pre-registered study, we tested in a large sample based on sequential Bayesian sampling (N = 64) whether early components of the ERP (P1, N170, and early posterior negativity; EPN) discriminate between fearful faces, neutral faces, and non-facial control stimuli. Consciousness was manipulated by presenting stimuli for 17 ms in a backward masking design, with the mask following immediately or after a delay of 200 ms. Participants rated their subjective perception on a perceptual awareness scale in each trial. Importantly, only trials in which nothing but the mask was perceived were considered for the analysis of nonconscious effects. The results showed strong evidence for an increased N170 in response to nonconscious fearful compared to neutral faces; however, this difference was significantly smaller than in the conscious condition. Furthermore, we obtained strong evidence for N170 differences between nonconscious faces and no-faces. For P1 and EPN amplitudes, no significant effects were observed in the nonconscious conditions, although exploratory analyses of the P1 peak interval suggest nonconscious face-no-face differentiation. These results support the notion that nonconscious emotion and face processing are detectable in early neural responses and show that these nonconscious effects are considerably weaker than the corresponding conscious effects.

neuroscience↗

bioRxiv2021

The effects of emotional valence and intensity on cognitive and affective empathy after insula lesions

The insula plays a central role in empathy. However, the complex structure of empathic deficits following insular damage is not fully understood. While previous lesion research has shown variable deficits in patients with insular damage on basic discrimination tasks or self-report measures, it is unclear in how far patients with insular damage are impaired in cognitive (CE) and affective empathy (AE) functions depending on valence and arousal of stimuli using an ecologically valid paradigm. In the present study, patients with insular lesions (n = 20) and demographically-matched healthy controls (n = 24) viewed 16 videos (duration: 60 sec each) that varied in terms of valence and emotional intensity. The videos showed a person (target) reporting on a personal life event. In CE conditions, subjects continuously rated the affective state of the target, while in AE conditions they continuously rated their own affect. Mean Squared Error (MSE) assessed deviations between subject and target ratings (CE: deviation between targets and participants ratings of targets emotions; AE: deviation between targets and participants self-ratings of emotion). Patients differed from controls only in negative, low intensity AE, rating their own affective state less negative than the target rated his/her affect. This deficit was not related to trait empathy, neuropsychological or clinical parameters, or laterality of lesion. Our findings provide important insights into the profile of social cognition impairment after insular damage. Empathic functions may be widely spared after insular damage in a naturalistic, dynamic setting, potentially due to the intact interpretation of social context cues by residual networks outside the lesion. The particular role of the insula in AE for negative states may evolve specifically in situations that bear higher uncertainty, which points to a threshold role of the insula in online ratings of AE.

neuroscience↗

bioRxiv2021

Effects of awareness and task relevance on neurocomputational models of mismatch negativity generation

Detection of regularities and their violations in sensory input is key to perception. Violations are indexed by an early EEG component called the mismatch negativity (MMN) - even if participants are distracted or unaware of the stimuli. On a mechanistic level, two dominant models have been suggested to contribute to the MMN: adaptation and prediction. Whether and how context conditions, such as awareness and task relevance, modulate the mechanisms of MMN generation is unknown. We conducted an EEG study disentangling influences of task relevance and awareness on the visual MMN. Then, we estimated different computational models for the generation of single-trial amplitudes in the MMN time window. Amplitudes were best explained by a prediction error model when stimuli were task-relevant but by an adaptation model when task-irrelevant and unaware. Thus, mismatch generation does not rely on one predominant mechanism but mechanisms vary with task relevance of stimuli.

neuroscience↗

bioRxiv2020

Differential effects of prediction and adaptation along the cortical hierarchy during deviance processing

Neural mismatch responses have been proposed to rely on different mechanisms, including prediction error-related activity and adaptation to frequent stimuli. However, the cortical hierarchical structure of these mechanisms is unknown. To investigate this question, we used functional magnetic resonance imaging (fMRI) and an auditory oddball design with a suited control condition that enabled us to delineate the contributions of prediction error- or adaptation-related brain activation during deviance processing. We found that while prediction-error related processes increased with the hierarchical position of the brain area, adaptation declined. This suggests that the relative contribution of different mechanisms in deviance processing varies across the cortical hierarchy.

neuroscience↗