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Zhouyuan Sun, Linan Shi, Peng Zhang, Sheng He; Frequency and phase-specific direct interaction in visual cortex between visually evoked and tACS induced neuronal signals. Journal of Vision 2017;17(10):591. doi: 10.1167/17.10.591.
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© ARVO (1962-2015); The Authors (2016-present)
Recently, evidence has emerged that tACS (transcranial alternating current stimulation) can modulate neural oscillations and affect visual perception. However, it remains unclear whether there is frequency and phase-specific direct interaction between visually evoked signals and tACS induced neuronal activities in the human visual cortex. Here, we investigated whether tACS can produce visible "beats" with a luminance flicker when their temporal frequencies were slightly different: a signature of frequency and phase-specific interaction between the two neural signals in the visual cortex. The visual stimulus was a uniform flickering disk with its luminance modulated at 10Hz. In a two-interval forced-choice paradigm, the 10Hz luminance flicker was presented in both intervals, each for 10 seconds separated by 4 seconds. During these two intervals, tACS stimulation was applied to the occipital pole of subjects, at 10Hz for in one interval and at 12Hz for the other. Subjects made forced-choice response to indicate which interval contained 2Hz visual beats. Results showed that subjects could consistently (accuracy 67.5%, 75%, 77.05%, 95% from 4 subjects, respectively) detect the 2Hz visual beats in the interval with the 12Hz tACS. Control experiments ruled out the possibility that subjects could detect which interval had the 12Hz tACS alone without the visual flicker. This finding suggests that there is direct frequency and phase-specific interaction between visually evoked and tACS induced neuronal signals in the visual cortex.
Meeting abstract presented at VSS 2017
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