Computer Analyses of Clinical Electroencephalographic Ink Tracings with the Aid of a High-Speed Automatic Curve Reader

Computer analyses of clinical electroencephalographic (EEG) ink tracings, which were reconverted to their electrical form with the aid of a newly developed multichannel automatic curve reader, are illustrated. On-line and off-line (via the intermediary of a magnetic tape recording) analyses by a variety of methods (frequency analysis, autocorrelation and crosscorrelation, and averaging of EEG responses evoked by sensory stimulation) were made of EEG tracings (some recorded 16 years previously) from a variety of different clinical conditions. Comparison, in some instances, of the data obtained by means of the curve reader with those computed from a magnetic tape recording made simultaneously with the original ink recording showed that the results of the two were essentially indistinguishable, within the limitations of the frequency response of the original ink tracing, and that of the scanning principle of the curve reader.