Functional Connectivity and Anesthesia.

Various anesthetic agents at various concentrations have been studied as described above. The analysis techniques for the BOLD fMRI data are also institution and investigator dependent. Despite this variability there seems to be some common patterns in the connectivity effect of various anesthetics/sedatives when the endpoint is LOC. Anesthesia in lower doses does not affect lower-order sensory/motor networks. Anesthetic agents primarily affect cortico-cortical and within-network connectivity. Higher-order networks (such as DMN, ECN, and the salience) are more sensitive to anesthesia.38 Salience network (the term “salience” meaning dominant, important) coordinates the function of the DMN and ECN network. The communication and information processing between the lowerorder networks and the higher-order networks (related to association cortices) is disrupted by anesthesia, leading to LOC. Connectivity in the precuneus, PCC, and posterior inferior parietal cortex (3 regions that are among the most active regions in the awake state) decreases with LOC.