Effects of Anesthesia on Effective Connectivity in the Brain

Abstract

The brain constitutes a formidably complicated structural network. There are three main types of connectivity used to describe neuronal networks, which reflect three parallel levels of investigation: anatomical connectivity, functional connectivity and effective connectivity. Effective connectivity indicates the direct influence that a node exerts on another, and in the context of neuronal circuits, a causal relationship between the activities of two nodes. Since its definition, effective connectivity analysis has been used to describe causal relationship across multiple spatial scales in PET imaging, fMRI, electroencephalography (EEG) and magnetoencephalography (MEG), singleunit, and local field potential. There are diverse literatures which probe the anesthetized state using effective connectivity analysis over the past two decades. The examination of effective connectivity in the anesthetized state is of relevance to both anesthesiologists and neuroscientists, as it has the potential to elucidate still unclear mechanisms of anesthesia while offering insight into intrinsic functional activity in the brain. The present review attempts to examine, elucidate, and integrate the insight that effective connectivity analysis of the anesthetized state has generated thus far.

Differential modulation of thalamo-parietal interactions by varying depths of isoflurane anesthesia

“…In order to be able to perform surgery associated with highly noxious stimuli, general anesthetics should have hypnotic, amnesic, and analgesic effect. Although the mechanism of unconsciousness during anesthesia has been extensively investigated in previous studies [1–3], the neurophysiological mechanisms of the analgesic effect induced by anesthesia have attracted little interest.…”