0226 SLOW WAVE SLEEP ORCHESTRATES INPUT-SPECIFIC STRENGTHENING AND GLOBAL DOWNSCALING OF SYNAPSES IN THE HUMAN CORTEX

Abstract Introduction: Preclincial work suggests that sleep promotes the consolidation of synaptic long-term potentiation (LTP) of task-specific synapses (associative plasticity) and downscaling of overall synaptic strength (homeostatic plasticity). Methods: Here we use transcranial magnetic stimulation (TMS) and electroencephalography (EEG) as non-invasive indices of LTP-like plasticity and overall synaptic strength in humans before and after brief periods of daytime sleep and wakefulness (repeated measures sleep laboratory study, 14 healthy participants, 5 females, 9 males, 18–30 years). Results: We demonstrate indices of increased LTP-like plasticity (paired associative stimulation induced change in motor-evoked potential) and decreased overall synaptic strength (EEG theta activity) after sleep compared to wakefulness. The increase in LTP-like plasticity was positively correlated with EEG slow wave activity (1–4 Hz) over the respective motorcortical area (M1). Conclusion: Our study supports the notion that slow wave sleep orchestrates associative and homeostatic synaptic plasticity, believed to be the neural basis for adaptive behavior, in humans. Support (If Any): JGM and MK have received PhD grants provided by the FAZIT foundation.