Auditory tracking magnitude, temporal alignment, and anatomical distribution during wakefulness and propofol-based anesthesia in human sEEG

Abstract

General anesthesia attenuates auditory responses, but response magnitude alone does not describe how residual activity aligns with sound over time or varies across the brain. We jointly characterized these aspects of auditory tracking using stereoelectroencephalography (sEEG) in 13 patients with drug-resistant epilepsy during wakefulness and clinically defined unresponsiveness under propofol-based anesthesia. The same rhythmic humming sequences were presented at approximately 1.61 Hz in both sessions. During anesthesia, stimulus-rate power showed widespread reductions and phase alignment with the stimulus rhythm was less consistent, although responses remained detectable at some recording channels. During wakefulness, response strength decreased with cortical surface distance from posteromedial Heschl's gyrus; this distance-response relationship was weaker during anesthesia. In a contrastive learning analysis (CEBRA), low-dimensional embeddings derived from anesthesia recordings yielded lower acoustic-envelope decoding accuracy on held-out data and lower consistency across model fits. Together, these findings characterize how attenuated auditory tracking is expressed jointly in response magnitude, temporal alignment, and anatomical distribution.