Computer analysis of the telemetered EEG in the study of epilepsy and schizophrenia.

Computation of power spectra from averaged brief epochs of spike free scalp EEG coincident with the subcortical spike has revealed a distinctive spectral configuration characterized by smooth monotonic decline in power from lowest to highest frequencies. Nine out of 10 patients with epilepsy display similar patterns preceeding long latency responses to a verbal motor reaction time task. Although subcortical spike activity has been recorded from the parasental region of patients with schizophrenia by several investigators half of our patients with schizophrenia displayed a different pattern which resembles a "white noise" spectrum during the delayed reaction time of incorrect response trials. Power spectra derived from 24-hour telemetered scalp EEGs from patients with epilepsy and schizophrenia are also sharply differentiated by similar criteria. These non-invasive methods for analysis of the scalp EEG in relation to careful and controlled behaviour observations may give useful information regarding subcortical activity when intracranial electrodes cannot be utilized.