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Yasaman Bagherzadeh, Daniel Baldauf, Benjamin Lu, Dimitrios Pantazis, Robert Desimone; Alpha and gamma neurofeedback reinforce control of spatial attention. Journal of Vision 2017;17(10):385. doi: https://doi.org/10.1167/17.10.385.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have shown that alpha synchrony is linked with suppression of information processing, whereas gamma frequency is associated with attention to targets. To determine whether alpha and gamma synchrony play a causal role in the control of spatial attention, we designed a MEG neurofeedback task to train subjects to increase an asymmetry of oscillatory power between the left and right parietal cortex (alpha in Exp1 or gamma in Exp2). During neurofeedback trials a Gabor pattern was presented in the center of the screen, with its contrast modulated according to a real time measure of the hemispheric asymmetry in the alpha (or gamma) range. We tested the effects of these oscillatory changes on both behavioral performance in a free viewing task and on visual evoked potentials recorded from visual cortex. Twenty healthy subjects participated in the study. They were divided into two groups, a left and a right training group, depending on the feedback direction of the hemispheric asymmetry. We found that subjects were able to control the asymmetry between the left and right hemispheres in the frequency range of interest in both training directions. Increasing alpha in one hemisphere lead to reduced visually evoked responses (Exp1) while increasing gamma in one hemisphere lead to enhanced evoked responses (Exp2). Hemispheric asymmetry in the alpha band resulted in attentional bias in the free viewing task by reducing the number of fixations in the contralateral hemifield. The results support the idea that alpha and gamma synchrony play reciprocal roles in the control of spatially directed attention.
Meeting abstract presented at VSS 2017
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