Blocking of EEG alpha activity during visual performance in healthy adults. A quantitative study.

The reactivity of the electroencephalogram was studied in a group of 54 healthy adults (23 women and 31 men, aged 23-80 years). The amplitude ratio between the situation with eyes closed and that with eyes open (EC/EO ratio) was calculated from quantitative parameters for each subject. The whole group was further divided into two subgroups according to age (younger than 60 and older than 60 years). In the temporo-occipital bipolar derivations (T6-O2, T5-O1), a negative correlation was found between alpha amplitude ratio and age in the whole group and especially in the subjects older than 60 years.