How and when EEG reflects changes in neuronal connectivity due to time awake
Sophia Snipes,
Elias Meier,
Sarah Nadine Meissner,
Hans-Peter Landolt,
Reto Huber
Affiliations
Sophia Snipes
Child Development Center, University Children’s Hospital Zürich, University of Zürich, 8032 Zürich, Switzerland; Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zürich, 8092 Zürich, Switzerland; Corresponding author
Elias Meier
Child Development Center, University Children’s Hospital Zürich, University of Zürich, 8032 Zürich, Switzerland
Sarah Nadine Meissner
Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zürich, 8092 Zürich, Switzerland
Hans-Peter Landolt
Institute of Pharmacology and Toxicology, University of Zürich, Zürich, 8057 Zürich, Switzerland; Sleep & Health Zürich, University of Zürich, Zürich, 8006 Zürich, Switzerland
Reto Huber
Child Development Center, University Children’s Hospital Zürich, University of Zürich, 8032 Zürich, Switzerland; Sleep & Health Zürich, University of Zürich, Zürich, 8006 Zürich, Switzerland; Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital, University of Zürich, 8008 Zürich, Switzerland
Summary: Being awake means forming new memories, primarily by strengthening neuronal synapses. The increase in synaptic strength results in increasing neuronal synchronicity, which should result in higher amplitude electroencephalography (EEG) oscillations. This is observed for slow waves during sleep but has not been found for wake oscillations. We hypothesized that this was due to a limitation of spectral power analysis, which does not distinguish between changes in amplitudes from changes in number of occurrences of oscillations. By using cycle-by-cycle analysis instead, we found that theta and alpha oscillation amplitudes increase as much as 30% following 24 h of extended wake. These increases were interrupted during the wake maintenance zone (WMZ), a window just before bedtime when it is difficult to fall asleep. We found that pupil diameter increased during this window, suggesting the ascending arousal system is responsible. In conclusion, wake oscillation amplitudes reflect increased synaptic strength, except during the WMZ.
