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The spectral characteristics of the EEG were studied in the period immediately preceding slow eye-closures associated with the self-induction of epileptiform activity. Power levels were compared with similar spontaneous eye-closures not associated with paroxysmal activity, with eye closures performed to command, and with EEG preceding eye-blinks. A transient rise in EEG power at low frequencies 1-2 seconds before the slow eye-closure was found to be reliably associated with the subsequent occurrence of paroxysmal activity. This finding suggests that eye-closure may not be initial event in the sequence culminating in paroxysmal activity.

Properly functioning domestic television sets may induce seizures in epileptic patients (TV epilepsy). We investigated the effects of different types of visual stimuli on paroxysmal electroencephalographic (EEG) activity in 32 patients known to be sensitive to intermittent photic stimulation (stroboscopic light). We monitored sensitivity to patterns of horizontal and vertical lines, both stationary and vibrated (pattern sensitivity), and to normal broadcasts on a domestic, black and white (405- or 625-line) TV receiver (TV sensitivity). Twenty-three of the 32 patients were sensitive to pattern. Twenty-two were sensitive to vibrated patterns, and 11 to static patterns (P less than 0-01), All patients sensitive to pattern were also sensitive to TV; The association between sensitivity to pattern and to TV was significant. Clinical history of TV epilepsy (16 out of 32 patients) and laboratory evidence of pattern or TV sensitivity were not significantly associated. The high incidence of pattern sensitivity among flicker-sensitive patients and its association with TV sensitivity suggests that linear patterns produced by the raster of a black and white set as it scans, or "line-jitter" produced by the raster in areas of low TV-signal strength may contribute to the epileptogenic effect of TV.