[So-called slow posterior activity in the EEG and the sensori-motor reaction time. Results of re-examinations made after 5 years].

Six persons showing what is called slow posterior activity (4/s rhythm) in the electroencephalogram were reexamined after a period of five years. Sensorimotor reaction times were recorded in addition to the electroencephalogram which was analyzed for the frequency of LPA and for the degree of stability of time dependence. The frequency and distinctness of LPA were found to be stable after five years (r = 0.09 and 0.82, respectively; p less than 0.001), whereas the alpha rhythmus of the subjects had undergone considerable changes (r = 0.34; p greater than 0.05). The extension of reaction times to be observed under the influence of LPA was also seen to remain constant (r = 0.79; p less than 0.05). Accordingly, LPA proved an extremely stable characteristic which did not show any substantial variations in the course of five years.