Hemispherotomy leads to persistent sleep-like slow waves in the isolated cortex of awake humans.
PLoS biology October 1, 2025 Michele Angelo Colombo, Jacopo Favaro, Ezequiel Mikulan et al. 7 citations
After hemispherotomy surgery for epilepsy, which disconnects an entire brain hemisphere, the isolated cortex shows brainwave patterns typical of deep sleep or anesthesia, not wakefulness. In 10 pediatric patients, EEG recordings revealed prominent slow oscillations and a steeper spectral decay in the disconnected hemisphere, while the connected hemisphere maintained normal waking patterns. These sleep-like patterns persisted years after surgery, suggesting the isolated cortex likely lacks awareness.