Biology subjects

Filipchuk, A.

Publications and source records attributed to Filipchuk, A..

5 recordsLinked to original sources

bioRxiv2025

Convergent information flows explain recurring firing patterns in cerebral cortex

Cortical population events, short-lived patterns of neuronal activity that recur with some consistency, are central to sensorimotor coordination. These reproducible firing patterns are often attributed to attractor dynamics, supported by strong mutual connectivity. However, using multi-modal datasets -- including 2-photon imaging, electrophysiology, and electron microscopy -- we show that these reproducible patterns do not involve strongly interconnected neurons. Instead, we show that cortical networks exhibit hierarchical modularity, with core neurons acting as high-information-flow nodes positioned at module interfaces. These cores funnel activity but lack structural signatures of pattern completion units expected in an attractor network. Using computational models, we find that distance-dependent connectivity is necessary and sufficient to generate the modularity and transient reproducible events observed in cortex. Our findings suggest that cortical networks are instead pre-configured to support sensorimotor coordination. This work redefines the structural and dynamical basis of cortical activity, highlighting the link between modular structure and function.

neuroscience↗

bioRxiv2025

The geometry of cortical sound processing in slow wave sleep

During wake, sound-evoked and spontaneous neural activity of the auditory cortex evolve in distinct subspaces whereas anesthesia disrupts sound responses and merges these spaces. To evaluate if similar modifications of the sound representation geometry explain sensory disconnection during sleep, we followed large neural populations of the mouse auditory cortex across slow wave sleep and wakefulness. We observed that sleep dampens sound responses but preserves the geometry of sound representations which remain separate from spontaneous activity. Moreover, response dampening was strongly coordinated across neurons and varied throughout sleep spanning from fully preserved response patterns to population response failures on a fraction of sound presentations. These failures are more common during high spindle-band activity and more rarely observed in wakefulness. Therefore, in sleep, the auditory system preserves sound feature selectivity up to the cortex for detailed acoustic surveillance, but concurrently implements an intermittent gating mechanism leading to local sensory disconnections.

neuroscience↗

bioRxiv2024

Enhanced Brain-Heart Connectivity as a Precursor of Reduced State Anxiety After Therapeutic Virtual Reality Immersion

State anxiety involves transient feelings of tension and nervousness in response to threats, which can escalate into anxiety disorders if persistent. Despite treatments, 30%-50% of individuals show limited improvement, and neurophysiological mechanisms of treatment responsiveness remain unclear, requiring the development of objective biomarkers. In this study, we monitored multimodal electrophysiological parameters: heart rate variability (high-frequency, low-frequency, LF/HF ratio), EEG beta and alpha relative power, and brain-to-heart connectivity in participants with real-life state anxiety. Participants underwent a therapeutic intervention combining virtual-reality immersion, hypnotic script, and a breath control exercise. Real-life state anxiety was captured using the STAI-Y1 scale before and after the intervention. We observed reduced anxiety immediately after the intervention in 16 out of 27 participants. While all participants, independently of their STAI-Y1 score, showed increased HRV low frequency power, only treatment-responders displayed increased overall autonomic tone (high and low frequency HRV), increased midline beta power and brain-to-heart connectivity. Notably, the LF/HF ratio showed a significant linear relationship with anxiety reduction, with higher ratios linked to greater therapeutic response. These findings suggest that increased cognitive regulation of brain-to-heart connectivity could serve as a biomarker for therapeutic efficacy, with elevated midline beta power facilitating improved cardiac tone in responders. Significance StatementElevated state anxiety can escalate into debilitating disorders, such as generalized anxiety disorder, yet treatment efficacy remains inconsistent, and reliable biomarkers predicting therapeutic outcomes are lacking. This study identifies key neural and physiological markers linked to effective anxiety reduction following a virtual reality-based non-pharmacological intervention in healthy participants with increased state anxiety. Anxiety reduction is associated with increased midline beta power, heightened heart rate variability (LF/HF ratio), and enhanced brain-to-heart connectivity. These findings highlight the role of brain-to-heart modulation and autonomic nervous system functioning in therapeutic response. By highlighting these biomarkers, this research aims at advancing our understanding of anxiety treatment mechanisms and offering insights into the development of biomarker-driven, scalable interventions.

neuroscience↗

bioRxiv2022

Core neurons are structural crossroads of cortical dynamics

Cortical activity often consists of recurring population events of correlated neuronal firing and highly reproducible firing patterns. Because of their resemblance with attractor dynamics, the attractor model prevails today, although it has not been firmly demonstrated. Here, we used a unique dataset, with co-registered two-photon calcium imaging and electron microscopy of the same cortical tissue, to test the central assumption of attractor networks: recurrently active "core" neurons should be strongly interconnected. We report that, contrary to the attractor paradigm, core neurons have fewer weaker connections compared to other neurons. Instead, core neurons funnel the flow of multiple connectivity pathways. Computational models give a mechanistic account of these features showing that distance-dependent connectivity forms converging-diverging motifs and, at their funneling centers, core neurons are found. Thus, reproducible cortical activity and connectivity can be explained without postulating underlying attractor networks but rather by the existence of overlapping information flows.

neuroscience↗

bioRxiv2021

Awake perception is associated with dedicated neuronal assemblies in cerebral cortex

Neural activity in sensory cortex combines stimulus responses and ongoing activity, but it remains unclear whether they reflect the same underlying dynamics or separate processes. Here we show that during wakefulness, the neuronal assemblies evoked by sounds in the auditory cortex and thalamus are specific to the stimulus and distinct from the assemblies observed in ongoing activity. In contrast, we observed in three different anesthesia, that evoked assemblies are indistinguishable from ongoing assemblies in the cortex. However, they remain distinct in the thalamus. A strong remapping of sensory responses accompanies this dynamical state change produced by anesthesia. Together, these results show that the awake cortex engages dedicated neuronal assemblies in response to sensory inputs, which we suggest is a network correlate of sensory perception.

neuroscience↗