Reduced neural feedback signaling despite robust neuron and gamma auditory responses during human sleep

We recorded single-unit spiking (713 clusters), microwire LFPs and iEEG from 13 patients implanted with depth electrodes while playing sounds (click-trains, words, music) during wakefulness and sleep, studying auditory responses (observed mainly in lateral temporal lobe). Amplitude of spike and gamma responses was similar in wake and NREM sleep, with modest or no attenuation in A1 and moderate attenuation beyond A1. Even responses outside A1 were highly robust and informative about the stimulus during sleep, but alpha-beta (10-30Hz) power decrease induced by auditory stimulation, often termed ABD (Alpha Beta Desynchronization), was reduced during sleep, even during REM sleep when we often dream but remain largely disconnected from the environment. Our results suggest that the “feedforward sweep” is intact during sleep, but feedback signaling is impaired.