DYNAMICS OF THE PARIETAL-OCCIPITAL ALPHA RHYTHM ACTIVITY DURING COMPARISON OF VISUAL STIMULI DURATIONS

Abstract

This research is aimed at studying the dynamics of the parietal-occipital alpha rhythm in its connection with the process of stimuli duration comparison. EEG study was conducted in which participants (n = 48) were asked to compare pairs of visual stimuli of different durations ranging from 3.2 to 6.4 s. The time-frequency analysis of the EEG was carried out in the range of 8–12 Hz. The power of alpha rhythm increases from the stimulus onset to the middle of its presentation, but then its dynamic depends on the stimulus duration: it further increases for short durations (3.2, 3.6, 4.0 s), stays the same for middle durations (4.4, 4.8, 5.2 s) and decreases for long durations (5.6, 6.0, 6.4 s). The relative decrease of alpha power for long stimuli in relation to the short ones was related to subjective perception of time. The results are discussed from the point of view of the “dual klepsydra” model: it is assumed that alpha rhythm acts as an electrophysiological correlate of the functioning of “neural accumulators” associated with the subjective passage of time.