Biology subjects

Markusfeld, G.

Publications and source records attributed to Markusfeld, G..

2 recordsLinked to original sources

bioRxiv2024

Neural Correlates of the Embodied Sense of Agency

The Sense of Agency (SoA) is the subjective experience that I am in control of my actions. Recent accounts have distinguished two levels in the formation of SoA - early implicit sensorimotor processes (feeling of agency) and later explicit higher-level processes, incorporating ones thoughts and beliefs (judgment of agency). Even though SoA is fundamental to our interactions with the external world and the construct of the self, its underlying neural mechanism remains elusive. In the current pre-registered electroencephalography (EEG) study, we used time-frequency analysis and Multivariate Pattern Analysis (MVPA) to investigate the electrophysiological characteristics associated with SoA. We used an established embodied virtual reality paradigm in which visual feedback of a movement is modulated to examine the effect of conflicts between the predicted and perceived sensory feedback. Participants moved their finger and were shown a virtual hand that either mimicked their movement or differed anatomically (different finger) or spatially (angular shift), then judged their SoA over the observed movement while their brain activity was recorded. In accordance with our pre-registered hypothesis, we found that a reduction of SoA is associated with decreased attenuation in the alpha frequency band. Increased power in the theta frequency band was also associated with SoA reduction. Importantly, we show that trials containing a sensorimotor alteration vs. trials containing no alteration can reliably be decoded with up to 68% accuracy starting around 200ms after the movement onset. Finally, cross-decoding analyses revealed similar neural patterns for reduced SoA in the anatomical and spatial conditions, starting around 500ms after the movement onset. Together, our results reveal a cortical signature of loss of SoA and provide neural evidence supporting the hypothesis of a two-level formation of SoA - an early domain-specific component, possibly the equivalent of the implicit feeling of agency, and a late domain-general component, possibly the equivalent of the explicit judgment of agency.

neuroscience↗

bioRxiv2020

Context Sensitivity Across Multiple Time and Frequency Scales

Everyday auditory streams are complex, including spectro-temporal content that varies at multiple time scales. Using EEG, we investigate the sensitivity of human auditory cortex to the content of past stimulation in unattended sequences of equiprobable tones. In 3 experiments including 82 participants overall, we found that neural responses measured at different latencies after stimulus onset were sensitive to frequency intervals computed over distinct time scales. Importantly, early responses were sensitive to a longer history of stimulation than later responses. To account for these results, we tested a model consisting of neural populations with frequency-specific but broad tuning that undergo adaptation with exponential recovery. We found that the coexistence of neural populations with distinct recovery rates can explain our results. Furthermore, the adaptation bandwidth of these populations depended on spectral context - it was wider when the stimulation sequence had a wider frequency range. Our results provide electrophysiological evidence as well as a possible mechanistic explanation for dynamic and multi-scale context-dependent auditory processing in the human cortex. SIGNIFICANCE STATEMENTIt has become clear that brain processing of sensory stimuli depends on their temporal context, but context can be construed at time scales from the recent millisecond to life-long. How do different contextual time scales affect sensory processing? We show that auditory context is integrated across at least two separate time scales, and that at both of these time scales responses dynamically adapt to a varying frequency stimulation range. Using computational modeling, we develop a rigorous methodology to estimate the time and frequency scales of context integration for separate response components. Our robust results replicated across 3 EEG experiments, and contribute to the understanding of neural mechanisms supporting complex and dynamic context integration.

neuroscience↗