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Xiaoli Zhang, Julie Golomb; Independent and overlapping neural representations of saccades, attention shifts, and reference frames. Journal of Vision 2017;17(10):522. doi: 10.1167/17.10.522.
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When changing our focus from one location to another, we can either move our eyes or shift our attention covertly. Previous research indicates that saccade execution and attention shifts might share underlying brain networks, including intraparietal sulcus (IPS) and frontal eye field (FEF) (Corbetta & Shulman, 2002). To further explore how neural representations of saccades and covert attention shifts interact, we acquired fMRI data during a combined saccade and covert attention task. Participants began each trial by fixating at one of two fixation points while covertly attending to one of three rapid serial visual presentation (RSVP) streams (left, center, right of screen). There were four critical conditions. On eyes-fixed trials, participants either held attention at the same initial location (hold eyes, hold attention) or shifted attention to another stream midway through the trial (hold eyes, shift attention). On eyes-move trials, participants made a saccade midway through the trial, while maintaining attention in one of two reference frames: (shift eyes, retinotopic attention) and (shift eyes, spatiotopic attention). The retinotopic condition involved holding attention at a fixation-relative location but shifting relative to the screen, whereas the spatiotopic condition involved holding attention on the screen-centered location but shifting relative to the eyes. We used multivariate pattern analysis (MVPA) to decode information about saccades (eyes-fixed vs. eyes-move), attention shifts (hold vs. shift attention), and reference frames (retinotopic vs. spatiotopic attention). Regions where saccade information could be decoded overlapped with those where attention shifts could be decoded, including parts of IPS, superior parietal lobe (SPL) and FEF, consistent with previous literature. Moreover, reference frame information could be decoded in additional regions (e.g., left SPL) that did not fully overlap with saccade-decoding or attention-shift-decoding regions. The reference frame results might reflect an integrated neural representation of saccades and covert attention shifts, beyond their independent and overlapping representations.
Meeting abstract presented at VSS 2017
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