[The functional significance of alpha activity in the visual cortex for the recognition of images and movement].

The idea of the EEG alpha-waves as a rhythmically spreading scanning process was tested in 27 subjects. The stimuli presentation was not synchronised with the alpha-wave phase in control. In experimental group, recognition of different-shape figures and size coincided with one of four phases of the EEG alpha-wave in occipital area. Under flicker stimulation through closed eyes with the alpha-frequency, 11 of the 12 subjects perceived distinct illusory visual objects. The optimal stimulation frequency was always within the alpha-range and closely correlated with the individual predominant alpha-frequency. The data obtained corroborate the theory that the alpha-wave in the visual cortex reflects a uniformity of the spreading scanning process which plays a major part in the process of visual recognition.