Inter and intrahemispheric EEG correlation as a function of sleep cycles

Area of Science:

• Neuroscience
• Sleep Science
• Electroencephalography (EEG)

Background:

• Brain functional connectivity varies between wakefulness and sleep stages.
• Understanding cortical differentiation during sleep is crucial for cognitive function.

Purpose of the Study:

• To investigate changes in interhemispheric and intrahemispheric EEG correlation during different sleep stages.
• To explore the relationship between cortical functional differentiation and mental activity during sleep.

Main Methods:

• EEG signals were recorded from 8 young males during wakefulness and sleep stages (S2, S4, PS).
• Pearson correlation was calculated for EEG signals across electrode pairs (C3, C4, F3, F4, T3, T4) in frequency bands from 1.5 to 15 Hz.
• Interhemispheric (INTERr) and intrahemispheric (INTRAr) correlations were analyzed across sleep cycles.

Main Results:

• EEG correlation in lower (1.5-6.5 Hz) and higher (11-15 Hz) frequencies was higher during S2 and S4 compared to wakefulness.
• Interhemispheric correlation (1.5-6.5 Hz) was also elevated during early paradoxical sleep (PS).
• Correlation in the 7-10.5 Hz range decreased during sleep compared to wakefulness, with intrahemispheric correlation diverging during PS over cycles.

Conclusions:

• Cortical functional differentiation patterns change significantly across sleep stages.
• Interhemispheric and intrahemispheric differentiation are attenuated in S2 and S4, while PS shows attenuated interhemispheric but accentuated intrahemispheric differentiation.
• These findings suggest that altered cortical differentiation during sleep may underlie changes in mental activity.