Cortical state change by auditory deviants: a mismatch response generation mechanism in unconsciousness

Mismatch negativity is an auditory-evoked biomarker for an array of neuropsychological disorders that occurs irrespective of consciousness, yet the generation mechanisms are still debated. Cortical slow oscillations occur during sleep or anesthesia and consist of reliable changes between “Up” and “Down” phases, characterised by high and low neural activity, respectively. Here we measure electrocorticography responses in the urethane-anesthetised rat and we demonstrate that during an auditory “oddball” paradigm, deviants trigger cortical Up phase initiations. Triggering of Up phases creates a mismatch response across the cortex, and when deviants fail to trigger Up phases, no mismatch response is present. We therefore propose triggering of cortical Up phases as a mechanism for mismatch negativity generation in unconscious states.