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Wiremu D Hohaia, Alan Johnston, Kielan Yarrow, Derek H Arnold; Adaptation-induced changes to the ‘intrinsic’ occipital alpha rhythm. Journal of Vision 2019;19(10):165. doi: https://doi.org/10.1167/19.10.165.
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© ARVO (1962-2015); The Authors (2016-present)
One of the longest-standing observations from human electroencephalographic (EEG) recordings has been that oscillatory power in the alpha frequency range (~7 to 13Hz) is enhanced when people close their eyes. This has been taken as evidence for a particular rhythm of activity intrinsic to visual cortex, which is disrupted by inhibitory interactions between input signals when people open their eyes. We have found that this effect can be modulated via motion adaptation. After adapting to radial motion, the increase in alpha power when people close their eyes is enhanced. This effect is broadly tuned, peaking for motion adaptation of ~10Hz, but it is robust for a range of adaptation frequencies about this value - ruling out a modulated frequency tag as a plausible explanation. The increase in alpha band activity is apparent when eyes are both open and closed. We also show that changes in alpha band activity while the eyes are closed predict the strength of ‘stored’ motion aftereffects, experienced when people reopen their’ eyes. Our data are consistent with activity in visual cortex being entrained at an intrinsic rhythm, which is disrupted by inhibitory interactions. Visual adaptation would reduce inhibition from neural populations responsive to the adaptor, and thereby exaggerate both the intrinsic alpha rhythm, and create the inhibitory imbalance that generates perceptual aftereffects.
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