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Anil Bollimunta, Amarender Bogadhi, David Leopold, Richard Krauzlis; Attention-related BOLD modulation with and without superior colliculus inactivation. Journal of Vision 2016;16(12):1305. doi: https://doi.org/10.1167/16.12.1305.
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The superior colliculus (SC) contributes to visual spatial attention through mechanisms that can be dissociated from the classic attention-related modulation in visual cortex (Zenon & Krauzlis, 2012). To identify brain regions that might be part of the SC attention network, we have conducted fMRI in a monkey performing a spatial attention task, with and without SC inactivation. Imaging runs contained three types of blocks: Baseline (B), Foveal Attention (FA) and Peripheral Attention (PA), indicated to the monkey by the color of the fixation spot. In B block trials, the relevant stimulus was a central fixation point that dimmed at randomized times. FA block trials were similar to B block trials but added a peripheral motion-change stimulus as an irrelevant distracter. In PA block trials, the fixation point did not dim and the peripheral motion-change was the relevant stimulus. The monkey's task, in each block, was to maintain central fixation and to report the relevant stimulus change by releasing a lever to get a juice reward. In each anatomically defined ROI, we identified voxels with significant differences between PA and B blocks, and calculated an attention modulation index (AMI) for each of these voxels based on the %change in BOLD for PA and FA blocks. During SC inactivation, several cortical areas (V1, MT/MST, LIP and FEF) showed significant attentional modulation, with computed AMIs comparable to control values, despite the presence of significant performance deficits in the attention task. However, attention-related modulation was abolished in cortical area FST in the superior temporal sulcus, and dramatically reduced in the caudate, a subcortical input nucleus for the basal ganglia. The results suggest that the SC contributes to attention through a circuit involving cortical area FST and parts of the basal ganglia, highlighting the possible role of subcortical decision-making mechanisms in the control of attention.
Meeting abstract presented at VSS 2016
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