Learning and language in the unconscious human hippocampus.
bioRxiv : the preprint server for biology April 9, 2025 Kalman A Katlowitz, Shraddha Shah, Melissa C Franch et al. 11 citations preprint
Learning, semantic processing, and online prediction persist in the human hippocampus during general anesthesia-induced loss of consciousness. Using high-density Neuropixels microelectrodes to record neural activity while playing tones to anesthetized patients, hippocampal neurons reliably detected oddball tones, and this effect grew over about ten minutes, consistent with learning. A recurrent neural network model showed that learning and oddball representation emerge from flexible tone discrimination. When language stimuli were played, single units and ensembles carried information about semantic and grammatical features of natural speech, even predicting semantic information about upcoming words. These results indicate that complex sensory processing occurs in the hippocampus even in the unconscious state.