Acoustically evoked K-complexes are sufficient to boost verbal memory consolidation during sleep

The pivotal role of sleep in memory consolidation is widely acknowledged, yet which specific electrophysiological components drive this process remains a topic of intense debate. To unveil this process, a neuromodulation approach enabling the precise manipulation of specific oscillations is necessary. Here, we combined phase-targeted auditory stimulation (PTAS) during sleep in combination with high-density electroencephalography (hd-EEG) to specifically evoke K-complexes (KCs), a prominent oscillation during non-rapid-eye-movement (NREM) sleep. Over the course of two nights, one with PTAS, the other without, data from 14 young healthy adults were recorded. By targeting the down-phase of slow waves, auditory stimuli selectively evoked KCs. Strikingly, these evoked KCs were associated with improved verbal memory consolidation via enhanced cross-frequency coupling between slow waves and spindles in a right frontal region. This finding suggests that evoked KCs actively participate in the hippocampal-neocortical dialogue and thereby drive the consolidation of memories during sleep. ### Competing Interest Statement RH and WK are founders and shareholders of Tosoo AG, a company developing wearables for sleep electrophysiology monitoring and stimulation. Tosoo AG did not contribute in any form to the work presented in this manuscript. The remaining authors declare no competing interests.