Relation of Alpha Frequency to Amplitude Variability

Kleitman (4) has suggested that the frequency of the alpha EEG partern is related to level of consciousness. He presented studies which showed a decrease in alpha frequency during sensory isolation, an increase in alpha frequency in hyperthermia, a decrease in alpha frequency associated with hypothyroidism, and an association of alpha frequency and body temperature within the individual. Other evidence has suggested that the level of consciousness is related to the variability of the amplitude of the EEG (1, 2, 3, 5, 6). To investigate possible association of alpha frequency and amplitude variation of the normal EEG in a wakeful state was the aim of this study. The EEGs of 50 paid normal males (ages 17 to 62, inclusive), about high school educational level, were individually recorded. Each recording session was of 15 min. duration and held in a sound attenuated room with S in a supine position with closed eyes. A solidstate integrator and a Beckman-Offner Type R Polygraph were used to record the EEG from