Detection, characterization, and modulation of the infraslow fluctuation of sigma power

Project in brief: This line of work investigates the infraslow fluctuation of sigma power as a fundamental organizing principle of sleep. Across multiple projects, we examine its presence and properties in healthy development, its alteration in clinical populations such as schizophrenia, its relationship to functional markers of sleep and arousal, and its sensitivity to experimental manipulations including sleep deprivation and auditory stimulation.

Project description: The infraslow fluctuation of sigma power is a slow (~50 s) rhythm that structures periods of higher and lower arousability during sleep and reflects the temporal organization of sleep spindle activity. While this phenomenon has been demonstrated in humans, methodological approaches have been limited in their applicability to high-density EEG recordings and to developmental and clinical populations. To address this, we developed and applied an optimized framework for detecting and quantifying the infraslow fluctuation of sigma power across diverse datasets. Using this approach, we examined its presence across development and demonstrated that it is a robust feature of human sleep. We further extended this work to clinical populations, showing that the fluctuation is altered in schizophrenia-spectrum disorders, suggesting disruptions in the organization of sleep and arousal regulation. Building on these findings, ongoing work adopts an interventional perspective, investigating whether and how the infraslow fluctuation can be modulated through experimental manipulations such as sleep deprivation and closed-loop auditory stimulation, and how these interventions interact with its underlying dynamics.

Project goal: Our goal is to establish the infraslow fluctuation of sigma power as a unifying framework for understanding the temporal organization of sleep, linking microstructural sleep dynamics to arousal regulation, cognitive function, and neuropsychiatric conditions, and assessing its potential as a target for experimental modulation.

Group Leader: Prof. Dr. Reto Huber
PhD Students: Mary Eleni Dimitriades / Vanessa Isabel Kasties

Institutions:
Child Development Center
University Children's Hospital Zurich
University of Zurich

This grant was in part supported by the UZH Candoc Grant.