Plasticity and language in the anaesthetized human hippocampus.
Kalman A Katlowitz, Eric R Cole, Elizabeth A Mickiewicz, Shraddha Shah, Melissa Franch, Joshua A Adkinson, James L Belanger, Raissa K Mathura, Domokos Meszéna, Matthew McGinley, William Muñoz, Garrett P Banks, Sydney S Cash, Chih-Wei Hsu, Angelique C Paulk, Nicole R Provenza, Andrew J Watrous, Ziv Williams, Alica M Goldman, Vaishnav Krishnan, Atul Maheshwari, Sarah R Heilbronner, Robert Kim, Nuttida Rungratsameetaweemana, Benjamin Y Hayden, Sameer A Sheth
Nature June 1, 2026 DOI: 10.1038/s41586-026-10448-0 (opens in new tab) via PubMed
Summary
AI-generated from the abstractHippocampal neurons and local field potentials in anaesthetized humans retain the ability to detect oddball tones, process semantic and grammatical features of speech, and predict upcoming words, indicating that complex sensory processing persists during unconsciousness. The effect of oddball detection grew over roughly 10 minutes, demonstrating representational plasticity. A recurrent neural network model showed that learning and oddball representation emerge from flexible tone discrimination. These results indicate that the hippocampus, distant from primary sensory cortices, performs complex stimulus processing even in the unconscious state.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Population | Anaesthetized patients |
| Intervention | general anaesthesia |
| Duration | Around 10 min |
| Key finding | Hippocampal neurons and local oscillations retained detection of oddball tones and carried information about semantic and grammatical features of natural speech during general-anaesthesia-induced loss of consciousness. |
Abstract
Consciousness is a fundamental component of cognition1, but the degree to which higher-order pattern recognition relies on it remains disputed2,3. Here we demonstrate the persistence of oddball discrimination, semantic processing and online prediction in individuals under general-anaesthesia-induced loss of consciousness4,5. Using high-density Neuropixels microelectrodes6 to record both single-unit and local-field-potential neural activity in the human hippocampus while playing a series of tones to anaesthetized patients, we found that hippocampal neurons and local oscillations retained some detection of oddball tones. This effect size grew over the course of the experiment (around 10 min), demonstrating representational plasticity. A biologically plausible recurrent neural network model showed that learning and oddball representation are an emergent property of flexible tone discrimination. Moreover, when we played language stimuli, single units and local field potentials carried information about the semantic and grammatical features of natural speech, even predicting semantic information about upcoming words. Together these results indicate that in the hippocampus, which is anatomically and functionally distant from primary sensory cortices7, complex processing of sensory stimuli occurs even in the unconscious state.