Picture a patient lying motionless on an operating table in Houston, Texas. The anaesthetic has done its job. They feel nothing, know nothing, and will remember nothing. Yet deep inside their hippocampus, hundreds of neurons are quietly listening to a story — and guessing what comes next.

That discovery, published in Nature by researchers at Baylor College of Medicine, may be the strangest thing neuroscience has produced in years. The team, led by Dr. Sameer Sheth, a neurosurgery professor and McNair Scholar at Baylor, used a tool called Neuropixels probes to record the activity of individual neurons in patients undergoing epilepsy surgery. The hippocampus — a seahorse-shaped region buried deep in the brain and best known for its role in memory — had never been studied this way during full anaesthesia.

The technology gave scientists an unusually close look at what an unconscious mind actually does with the noise around it.