["Noise" in brain electrical activity. II. Age-related and clinical aspects]

The age-related changes of oscillatory periodic EEG-activity are well known. The aperiodic component of the EEG-activity, which so far has not been studied as intensively as the periodic one, progressively increases during aging which may play a role in the process of neural maturation. Even less data are available concerning the characteristics of neural noise in various diseases of neurology and psychiatry. As a common characteristic feature it may be noted that the efficiency of synchronization, essential for the realiza- tion of neural functions is biased by neural noise which may account for some clinical symptoms. In addition to its influence on synchronization, the measure of noise may provide information on the locally and/or globally prevailing ratio of excitatory/inhibi- tory processes which may also play a role in certain pathological processes.