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Ada Le, Matthew T. Keough, Boge Stojanoski, Matthias Niemeier; Neural correlates of the right-brain dominance for spatial processes. Journal of Vision 2009;9(8):99. doi: 10.1167/9.8.99.
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© ARVO (1962-2015); The Authors (2016-present)
The right brain is dominant for spatial and attentional functions, and right-brain damage often results in spatial deficits such as spatial neglect. However, to date there is no comprehensive understanding of the underlying neural mechanisms because right-dominant asymmetries in healthy individuals are subtle and often inconsistent. We have recently introduced a relatively sensitive test of asymmetries, called gratingscales task that requires perceptual comparisons between two stimuli containing high and low spatial frequencies. Interestingly, people are leftward-biased in their perceptions when instructed to compare high spatial frequencies but not when comparing the low spatial frequencies of the same stimuli. Here we used this effect to narrow down the temporal-spatial structure of neural systems underlying the perceptual bias. We recorded the electrical event-related potentials of participants while they compared high or low spatial frequencies of the gratingscales task, or while they performed a control task on the same stimuli. We found that both tasks differed in similar ways from the control task. Both showed a greater negativity 150 ms after stimulus onset that originated from bilateral occipital electrodes and then migrated to electrodes over right parietal and right latero-occipital regions. This was followed by bilateral positivity over occipital and parieto-occipital regions at ∼200 ms. Importantly however, only for high spatial frequency judgments task differences traveled back to right latero-occipital electrodes, manifesting in a more pronounced N300 there. Our data offer novel insights into the interplay between perceptual, attentional, and potentially working memory functions involved in perceptual biases. Future research will specify locations and the functional role of these components in the right-brain dominance of spatial tasks.
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