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Janneke Jehee, Devin Brady, Frank Tong; Attentional enhancement of orientation responses in human visual cortex depends on task. Journal of Vision 2009;9(8):95. doi: https://doi.org/10.1167/9.8.95.
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© ARVO (1962-2015); The Authors (2016-present)
When spatial attention is directed to a stimulus, are all of the features contained in that stimulus more strongly encoded in the visual system, or are feature-selective responses strengthened only for those features that are relevant to the task performed by the subject? We used functional MRI in combination with pattern-based analyses to address these questions. Subjects performed either an orientation discrimination task or a contrast discrimination task involving one of two laterally presented gratings. Attention was directed to one or the other grating by a central cue, and task difficulty was manipulated using an adaptive staircase procedure. With both tasks, much stronger BOLD responses were observed for attended stimulus locations than unattended locations in early visual areas. To test whether this also improved the strength of orientation-selective responses, we used a pattern-based analysis to decode the presented stimulus orientation from cortical activity in these regions. In the orientation discrimination task, we found significantly better decoding performance in the attended condition as compared to the unattended condition in areas V1, V2 and V3. However, this attentional enhancement of cortical responses to orientation was not found in the contrast discrimination task. We conclude that while the overall BOLD amplitude increases with attention regardless of task, attentional enhancement of feature-selective responses depends on the task performed.
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