Structure and Dynamics of Brain Lobe's Functional Networks at the Onset of Anesthesia-Induced Loss of Consciousness
arXiv Preprint Archive – November 15, 2016
Source: arXiv
Summary
When consciousness fades under anesthesia, the brain's communication networks undergo dramatic changes within just 90 seconds. Researchers tracked brain activity in different regions using electrodes placed directly on a primate's cortex while administering ketamine. The analysis revealed distinct shifts in how brain areas connect and communicate, particularly in the frontal, parietal, temporal, and occipital regions. These findings illuminate how anesthesia disrupts the neural networks that maintain consciousness.
Abstract
Anesthetic agents are neurotropic drugs capable of inducing significant alterations in the thalamocortical system, promoting a profound decrease in awareness and level of consciousness. There is experimental evidence that general anesthesia affects large-scale functional networks, leading to alterations in the brain's state. However, the specific impact on the network structure assumed by functional connectivity locally in different cortical regions has not yet been reported. Within this context, the present study has sought to characterize the functional brain networks relative to the frontal, parietal, temporal, and occipital lobes. In this study, electrophysiological neural activity was recorded using a dense ECoG-electrode array placed directly on the cortical surface of an old-world monkey of the species Macaca fuscata. Networks were estimated serially over time every five seconds, while the animal model was under controlled experimental conditions of a Ketamine-Medetomidine anesthetic induction. In each of the four cortical brain lobes, noticeable alterations in distinct properties of the networks evidenced a transition in the network's architecture, which occurred within approximately one and a half minutes after administering the anesthetics. The characterization of functional brain networks performed in this study provides relevant experimental evidence that expands our understanding of the neural correlates of consciousness in terms of the structure and properties of the functional brain networks.