Illusory Jitter Perceived at the Frequency of Alpha Oscillations

Neural oscillations, such as alpha (8-13 Hz), beta (13-30 Hz), and gamma (30-100 Hz), are widespread across cortical areas, and their possible functional roles include feature binding [1], neuronal communication [2, 3], and memory [1, 4]. The most prominent signal among these neural oscillations is the alpha oscillation. Although accumulating evidence suggests that alpha oscillations correlate with various aspects of visual processing [5-18], the number of studies proving their causal contribution in visual perception is limited [11, 16-18]. Here we report that illusory visual vibrations are consciously experienced at the frequency of intrinsic alpha oscillations. We employed an illusory jitter perception termed the motion-induced spatial conflict [19] that originates from the cyclic interaction between motion and shape processing. Comparison between the perceived frequency of illusory jitter and the peak alpha frequency (PAF) measured using magnetoencephalography (MEG) revealed that the inter- and intra-participant variations of the PAF are mirrored by an illusory jitter perception. More crucially, psychophysical and MEG measurements during amplitude-modulated current stimulation [20] showed that the PAF can be artificially manipulated, which results in a corresponding change in the perceived jitter frequency. These results suggest the causal contribution of neural oscillations at the alpha frequency in creating temporal characteristics of visual perception. Our results suggest that cortical areas, dorsal and ventral visual areas in this case, are interacting at the frequency of alpha oscillations [2, 3, 21-27].