Omer Sharon, M.Sc.

Former student at Dr. Yuval Nir's laboratory

Research title
Attenuated fast steady-state visual evoked potentials during natural human sleep


Research project

During sleep, external sensory events rarely elicit a behavioral response or affect perception. However, how sensory processing differs between wakefulness and sleep remains unclear. Most human electroencephalogram (EEG) research compared brain responses to brief auditory stimuli, but the occurrence of non-specific K-complexes in non-rapid-eye movement (NREM) sleep limits interpretation. Here, we propose a novel approach by intermittingly delivering periodic visual flicker stimulation through closed eyes across sleep and wakefulness while recording high-density EEG. Such stimulation does not disturb sleep, elicits robust responses without requiring participants to perform a task, and is associated with high a signal-to-noise ratio (SNR) where responses are evident in individual trials. Moreover, this paradigm effectively separates onset/offset responses from steady-state visual evoked potentials (SSVEPs) that are specific for the stimulation frequency and selectively observed over visual cortex. We find that onset responses are largest in NREM sleep, but that sustained/SSVEPs show frequency dependent effects. While SSVEP in response to fast (8/10Hz) stimulation is substantially stronger in wakefulness than in both NREM and REM sleep, SSVEP response to slow (3/5Hz) stimulation is stronger in both NREM and REM sleep. Analysis of single-trial amplitude and phase effects reveal that stronger fast SSVEPs in wakefulness are primarily driven by consistent EEG phase entrainment. The results suggest that the sleeping brain is unable to effectively synchronize large neuronal populations in response to rapid sensory stimulation. This paradigm can be used to study sensory processing across other unresponsive states in clinical settings.


Meetings

  • Sharon O, Nir Y. (2016) Attenuated fast steady-state visual evoked potentials during human sleep The fourth Conference on Cognition Research of the Israeli Society for Cognitive Psychology (Akko, Israel

  • Sharon O, Nir Y. (2016) Attenuated fast steady-state visual evoked potentials during human sleep The 25th Annual meeting of the Israeli society for Neuroscience (EIlat, Israel) .

  • Sharon O, Nir Y. (2015) Comparing cortical responses to periodic steady-state visual stimulation across wakefulness and sleep using scalp EEG in humans. The Jerusalem Conference on Conscious and Unconscious Processes (Jerusalem, Israel.

  • Sharon O, Nir Y. (2015) Comparing cortical responses to periodic 'strobe' steady-state visual stimulation across sleep ans wakefulness using high-density EEG in humans. The 7th world congress of the world sleep federation (Istanbul, Turkey) .

  • Sharon O, Nir Y. (2015) Comparing cortical responses to periodic steady-state visual stimulation across wakefulness and sleep using scalp EEG in humans. The 24th Annual meeting of the Israeli society for Neuroscience (Eilat, Israel)


Publications

  • Sharon O, Nir Y. (2017) Attenuated fast steady-state visual evoked potentials during human sleep, Cereb Cortex 2017 1-15.


Awards

  • 2016 - Msc with great honors

  • 2015 – The Adams Super Center for Brain Studies travel award.


Contact
omerxsharon@gmail.com


Research Categories: Cognitive neuroscience, System Neuroscience