A study of the interhemispheric correlation during sleep in elderly subjects.

The interhemispheric relationship during sleep in elderly subjects was studied throughout the night by a minute-by-minute computation of two linear correlation coefficients between right and left EEG activities. One of these coefficients (X delta) related to the 1-4-Hz band activity, and the other (X sigma) to the 12.5-14.5-Hz band activity. For five of the six subjects examined, it was found that the rapid-eye-movement (REM) mean values of both coefficients were significantly different from the nonrapid-eye-movement (NREM) values. A comparison between this elderly group and a control group of young subjects, examined previously, did not reveal any significant shift, either for the REM or for the NREM mean values of the coefficients.