How and when EEG reflects changes in neuronal connectivity due to time awake

Area of Science:

• Neuroscience
• Sleep Science
• Cognitive Neuroscience

Background:

• Neuronal synapse strengthening underlies memory formation during wakefulness.
• Increased synaptic strength should elevate electroencephalography (EEG) oscillation amplitudes, but this is not observed during wakefulness.
• Traditional spectral power analysis may obscure changes in oscillation amplitude versus occurrence.

Purpose of the Study:

• To investigate changes in EEG oscillation amplitudes during extended wakefulness.
• To determine if wake oscillation amplitudes reflect synaptic potentiation.
• To examine the impact of the wake maintenance zone (WMZ) on these oscillations.

Main Methods:

• Utilized cycle-by-cycle analysis of EEG data.
• Extended wakefulness for 24 hours in participants.
• Measured pupil diameter as an indicator of arousal.

Main Results:

• Theta and alpha EEG oscillation amplitudes increased by up to 30% after 24 hours of extended wakefulness.
• These amplitude increases were suppressed during the wake maintenance zone (WMZ).
• Increased pupil diameter was observed during the WMZ, suggesting arousal system involvement.

Conclusions:

• Wake EEG oscillation amplitudes positively correlate with synaptic strength.
• The wake maintenance zone (WMZ) disrupts the reflection of synaptic strength in wake oscillations.
• The ascending arousal system likely influences this disruption during the WMZ.