New Insights into How the Brain Orchestrates Its Slowest Activity Waves

A recent groundbreaking study has shed light on the mechanisms behind the brain's slow oscillations, rhythmic electrical activities that persist even during deep sleep and anesthesia. Conducted by researchers from the Sensory-motor Processing by Subcortical Areas laboratory at the Institute for Neurosciences—affiliated with the Spanish National Research Council (CSIC) and Miguel Hernández University (UMH) of Elche—the study reveals that the direction of these slow waves is primarily governed by neuronal excitability rather than solely by anatomical structure.

Using advanced computational models that integrate analyses at both the local network level and across different brain regions, the scientists demonstrated that when multiple brain areas connect, their differences tend to synchronize, following the activity of the most excitable region. This phenomenon is akin to a classroom where students follow the trendsetters. This 'leader' concept helps explain the coordinated propagation of slow waves despite the diversity among brain regions.

Experimental validation in mice showed that increasing neuronal excitability in the occipital lobe caused the wave direction to reverse, moving contrary to normal patterns. Such oscillations are crucial during sleep and anesthesia, facilitating brain activity organization. However, disruptions in their regulation can lead to abnormal patterns seen in wakefulness or epilepsy.

Through simulations and real-data analysis, the team identified key factors influencing slow-wave activity at both local and global levels. Their modeling approach, grounded in the anatomy and physiology of mammalian brains, provides a realistic framework for understanding neural network behavior. This methodological advance opens doors for exploring scenarios difficult to reproduce experimentally.

Overall, this research underscores the importance of neuronal excitability in directing brain waves and offers insights into how neural activity is coordinated across the brain. It also provides a foundation for future studies investigating abnormal brain rhythms associated with neurological conditions.

Source: https://medicalxpress.com/news/2025-09-reveals-brain-slowest.html