Characterization of the Community Structure of Large-Scale Functional Brain Networks During Ketamine-Medetomidine Anesthetic Induction

TL;DR

This study investigates how the community structure of large-scale brain networks changes during ketamine-medetomidine anesthesia in macaques, revealing significant reorganization associated with loss of consciousness.

Contribution

It provides empirical evidence of dynamic community structure changes in brain networks during anesthetic induction, linking neural modularity to consciousness states.

Findings

Community structure transitions within 1.5 minutes of anesthesia

Awake state shows large frontal-parietal clusters

Anesthetized state exhibits communities in visual and motor cortices

Abstract

One of the main goals of neuroscience is to understand how an organism's cognitive capacities or physiological states are potentially related to brain activities that involve the interaction of multiple brain structures and cortical areas. A key feature of functional brain networks is that they are modularly structured, and this modular architecture is regarded as accounting for a range of properties and functional dynamics. In the neurobiological context, communities may indicate brain regions involved in the same activity, representing neural-segregated processes. Several studies have demonstrated the modular character of the organization of brain activities. However, empirical evidence regarding its dynamics and relation to different levels of consciousness has not yet been reported. In this context, this research sought to characterize the community structure of functional brain networks during an anesthetic induction process. The experiment was based on intracranial recordings of the neural activities of an old-world macaque of the species Macaca fuscata during a Ketamine-Medetomidine anesthetic induction process. Changes were observed within approximately one and a half minutes after administering the anesthetics, revealing a transition in the community structure. The awake state was characterized by large clusters involving the frontal and parietal regions. In contrast, the anesthetized state was marked by the presence of communities in the primary visual and motor cortices, while the areas of the secondary associative cortex were the most affected. The results report the influence of general anesthesia on the structure of functional clusters, contributing to understanding some novel aspects of the neural correlates of consciousness.