Early reactivation of medial temporal lobe neurons during emergence from propofol anesthesia in neurosurgical patients

Although much is known about the molecular and cellular effects of general anesthetics, the neural mechanisms underlying loss and recovery of consciousness during anesthesia remain elusive. We provide the first report of human single neuron activity recorded throughout emergence from general anesthesia. Following cessation of propofol infusion, emergence was assessed as motor response to verbal command (RC). In most cells, firing rates increased during the course of emergence. Analysis of pooled firing rate changes indicated a shift towards criticality during emergence and attractor states during and immediately following anesthesia and immediately after RC. Changes in activity in some regions occurred prior to overt RC, with shortest latencies in the hippocampus, parahippocampal gyrus, and amygdala, followed by cingulate and then insular cortex. This work reveals that brain activity in medial temporal regions may presage restoration of responsiveness in humans following general anesthesia.