Structure and Dynamics of Brain Lobes Functional Networks at the Onset of Anesthesia Induced Loss of Consciousness

Anesthetic agents are neurotropic drugs able to induce dramatic alterations in the thalamo-cortical system, promoting a drastic reduction in awareness and level of consciousness. There is experimental evidence that general anesthesia impacts large scale functional networks leading to alterations in the brain state. However, the way anesthetics affect the structure assumed by functional connectivity in different brain regions have not been reported yet. Within this context, the present study has sought to characterize the functional brain networks respective to the frontal, parietal, temporal and occipital lobes. In this experiment, electro-physiological neural activity was recorded through the use of a dense ECoG-electrode array positioned directly over the cortical surface of an old world monkey of the species Macaca fuscata. Networks were serially estimated over time at each five seconds, while the animal model was under controlled experimental conditions of an anesthetic induction process. In each one of the four cortical brain lobes, prominent alterations on distinct properties of the networks evidenced a transition in the networks architecture, which occurred within about one and a half minutes after the administration of the anesthetics. The characterization of functional brain networks performed in this study represents important experimental evidence and brings new knowledge towards the understanding of neural correlates of consciousness in terms of the structure and properties of the functional brain networks.