Default-mode network activity is retained in the isolated hemisphere of people after hemispherotomy.
Brain communications January 1, 2026 Tobias Bauer, Charlotte Gauvry, Sebastian Markett et al.
Default-mode network activity persists in brain hemispheres surgically isolated from the rest of the nervous system by hemispherotomy for severe epilepsy, meeting a necessary condition for consciousness. In connected hemispheres, default-mode network patterns were preserved and similar to controls. Isolated hemispheres showed preserved positive default-mode network connectivity, but negative connectivity was significantly reduced. In two patients scanned before and after surgery, the default-mode network remained detectable but divided between isolated and connected hemispheres. These findings indicate that default-mode network activity alone does not confirm conscious awareness, encouraging further study of neural correlates of consciousness in isolated hemispheres.