Inter and intrahemispheric EEG correlation as a function of sleep cycles

Abstract

Corsi-Cabrera, Maria, Miguel Angel Guevara, Consuelo Arce' and Julieta Ramos. Inter and intrahemispheric EEG correlation as a function of sleep cycles. Prog. Neuro-Psychopharmacol. & Biol. Psychiat., 1996, 20. 1. 1. Inter (INTERr) and intrahemispheric (INTRAr) EEG correlation were assessed in 8 young male adults during wakefulness (W) with eyes closed before going to sleep and during stage 2 (S2), stage 4 (S4) and paradoxical sleep (PS) of the first three sleep cycles during the second night spent at the laboratory. 2. 2. Pearson product-moment correlation were calculated between EEG signals of each pair of electrodes (C3, C4, F3, F4, T3, T4) for every 0.5 Hz from 1.5 to 15 Hz. 3. 3. INTERr and INTRAr of 1.5–6.5 and 11–15 Hz were significantly higher during stage 2 and 4, INTERr of 1.5–6.5 Hz was also higher during PS in cycle 1 and 2, whereas INTERr and INTRAr of 7–10.5 Hz were lower than during wakefulness. 4. 4. INTRAr of S2 and S4 approximated, whereas INTRAr of PS moved away from W over successive sleep cycles. 5. 5. These data show that cortical changes during sleep are also observed in functional differentiation between cortical sites. Inter and intrahemispheric differentiation is attenuated during stage 2 and 4 while during PS only interhemispheric differentiation is attenuated but intrahemispheric differentiation is accentuated compared to wakefulness. This pattern of cortical differentiation may be of relevance for the understanding of mental activity changes during sleep.