2021/08/01 by Eduardo C. Padovani, Padovani, Eduardo C.
Neuroscience · #Neural dynamics and brain function #EEG and Brain-Computer Interfaces #Functional Brain Connectivity Studies
paper · pdf · doi:10.48550/arxiv.2108.00371
Propofol, when administered for general anesthesia, induces oscillatory\ndynamic brain states that are thought to underlie the drug's pharmacological\neffects. Despite the elucidation of propofol's mechanisms of action at the\nmolecular level, its effects on neural circuits and overall cortical\nfunctioning, which eventually lead to unconsciousness, are still unclear. To\nidentify possible mechanisms, the spatial-temporal patterns of functional\nconnectivity established among specialized cortical areas in anesthetized\nsubjects need to be described. Within this context, the present research\ninvolved the analysis of dense sub-dural ECoG electrode array recordings from\nmacaques under propofol anesthetic induction. Granger causality methodology was\nused to infer functional connectivity interactions in five physiological\nfrequency bands serially over time, every five seconds throughout the\nexperiment. The time-resolved networks obtained permitted us to observe the\nunfolding of the anesthetic induction and compare the networks obtained under\ndifferent experimental conditions. About one minute after administering\npropofol, functional connectivity started to increase for 4-5 minutes, then\ndecreased until the LOC was achieved. A predominant Granger causality flow from\nthe occipital and temporal areas towards the frontal and parietal regions was\nalso evidenced during the transition. During general anesthesia, the local\nconnectivity of the occipital lobe increased, as did the interactions between\nthe occipital and temporal lobes. Conversely, the functional connectivity from\nthe frontal and parietal lobes toward the temporal and occipital regions was\nmainly impaired. The research is one of the first studies to describe the\ndynamics of the functional connectivity during the transitional state that\nprecedes the LOC.\n