Existence of multiple transitions of the critical state due to anesthetics.
Nature communications – August 15, 2024
Source: PubMed
Summary
Anesthetics don't just make us unconscious - they can trigger multiple distinct patterns in brain activity. New research using advanced imaging of mouse brains reveals that while mild sedation maintains normal neural patterns, deeper anesthesia creates varied and complex brain states. Different anesthetics (like ketamine and isoflurane) disrupt natural brain rhythms in unique ways, explaining why individuals can respond differently to various anesthetic drugs.
Abstract
Scale-free statistics of coordinated neuronal activity, suggesting a universal operating mechanism across spatio-temporal scales, have been proposed as a necessary condition of healthy resting-state brain activity. Recent studies have focused on anesthetic agents to induce distinct neural states in which consciousness is altered to understand the importance of critical dynamics. However, variation in experimental techniques, species, and anesthetics, have made comparisons across studies difficult. Here we conduct a survey of several common anesthetics (isoflurane, pentobarbital, ketamine) at multiple dosages, using calcium wide-field optical imaging of the mouse cortex. We show that while low-dose anesthesia largely preserves scale-free statistics, surgical plane anesthesia induces multiple dynamical modes, most of which do not maintain critical avalanche dynamics. Our findings indicate multiple pathways away from default critical dynamics associated with quiet wakefulness, not only reflecting differences between these common anesthetics but also showing significant variations in individual responses. This is suggestive of a non-trivial relationship between criticality and the underlying state of the subject.