Variations in EEG coherence as an index of the affective content of dreams from REM sleep: relationships with face imagery.

EEG coherence was examined in relation to four measures of socioemotional dream content, including a new measure--the proportional representation of a character's face. Twenty-four healthy subjects, recorded for sleep stages and EEG activity, were awakened from REM sleep to report dream mentation and to rate it on these variables. Coherence scores were calculated for homologous interhemispheric electrode pairs (Fp1-Fp2, F3-F4, F7-F8, C3-C4, P3-P4, O1-O2, T3-T4, T5-T6) and for left and right intrahemispheric pairs for delta, theta, alpha, beta1, and beta2 frequencies. These were correlated with the mentation measures. Positive correlations were found between average interhemispheric coherence in most bands and the character face measure. A breakdown by gender revealed that this relationship was most evident for women, whereas for men positive correlations were observed between coherence and negative self-feeling. That similar relationships also obtained for both left and right intrahemispheric coherence is consistent with the hypothesis that dreamed socioemotional interactions reflect the integrative functioning of many brain regions in both hemispheres.