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Akiko Ikkai, Sangita Dandekar, Clayton Curtis; Asymmetric alpha desynchronization during the maintenance of spatial attention. Journal of Vision 2011;11(11):243. doi: 10.1167/11.11.243.
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© ARVO (1962-2015); The Authors (2016-present)
In electrophysiological studies, persistent desynchronization in the alpha (8–12 Hz) frequency band has been considered to be a signature of maintenance of spatial information. However, simple comparisons between contralateral and ipsilateral representations fail to explain the detailed profile of the spatial representation in attentional control, particularly hemispheric asymmetry indicated in hemineglect patients. Here, we tested the hypothesis that attention modulates neural oscillation in a spatially selective manner. Using magnetoencephalography (MEG), we measured the alpha power while subjects’ attention was endogenously oriented to the peripheral visual field. We found posterior alpha desynchronization in sensors contralateral to the attended visual field. This desynchronization and spatial selectivity persisted throughout the delay period. These findings suggest that spatial attention modulates neural synchrony in a spatially biased manner. The decrease in alpha synchronization may cause the excitation of the task-related cortical regions for enhanced visual information processing. Moreover, we found that the left sensors showed greater contralateral bias than the right sensors in the lower alpha band. This is consistent with the theory that the right parietal cortex represents both visual fields, whereas the left parietal cortex predominantly represents the right visual field. The asymmetry in the neural oscillatory pattern offers an indication for the neural mechanism that underlies the hemineglect symptoms observed after right hemisphere lesions.
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