抄録
In patients who were at rest, awake or subjected to cyclic photic stimulation, time lapse contour maps were made by recording the contour of the power spectrum using the EEG frequency as the horizontal axis and time as the vertical axis. Frequency response contour maps were made by recording the contour of the power spectrum using the EEG frequency as the horizontal axis and the frequency of stimulation as the vertical axis. Although the subjects studied had cerebral arteriosclerosis or a hemiplegia as a sequela to cerebral apoplexy, at a glance they did not exhibit EEG abnormalities including asymmetrical EEGs. The results obtained were as follows:
1) The time lapse contour map in the patients with a hemiplegia as a sequela to the cerebral apoplexy showed comparatively stable active response peaks on the part of the dominant EEG frequency both at rest and awake, and the map was simple in comparison with that of normal adults. The frequency response contour map was not the same as that of a normal adult, because there was a discontinuity in range between the peak of facilitation and the trough of occlusion. Thus, the damaged hemisphere tended to exhibit EEG abnormalities.
2) In the patient with a hemiplegia as a sequela to the cerebral apoplexy, there were differences in effects between one eye and twye stimulation as regards the peaks and the troughs. Otherwise there were no differences.
3) The time lapse contour map of the patient with cerebra arteriosclerosis showed that, in addition to the peak in the alpha range, there appeared another peak peculiar to the frequency of stimulation. The map was stable, like those of cerebral apoplexy sequela patients. Even in the case of the patient whose clinical EEG did not reveal any abnormalities, the frequency response contour map was different from that of the normal adult : the contour was variable; in many cases there were EEG asymmetries.
4) By means of the frequency response contour map, it is possible to clarify the mechanism of EEG abnormalities in the case of cerebrovascular disorders in which, if the abovementioned analysis were not employed, it would be difficult to detect EEG abnormalities.
