Alpha rhythm parameters and short-term memory span.

The study examined a statement from the neurophysiological model of A.N. Lebedev as to whether short-term memory span is related to a ratio of the alpha-rhythm frequency and parameters of step-type behaviour of wave processes in the EEG alpha range. Forty young healthy subjects performed a digit memory test. EEG signals were recorded from the occipital area during a resting period with eyes closed. As one of the parameters of step-type behaviour of alpha oscillations a mean value of the difference between periods of neighbouring peaks in the alpha spectra was calculated. A second parameter--the duration of alpha spindles, considered to be a superposition of alpha oscillations--was also measured. It was shown that the ratio of the alpha-rhythm frequency to parameters of the step-type behaviour of alpha oscillations positively correlated with memory performance.