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Sarah C. Tyler, Samhita Dasgupta, Lorella Battelli, Sara Agosta, Emily D. Grossman; Spatial cueing and task difficulty effects on the temporal attention selective temporal parietal junction. Journal of Vision 2012;12(9):139. doi: 10.1167/12.9.139.
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Introduction. Patients with parietal damage often show spatial deficits that are commonly limited to the contralesional field, while temporal deficits are typically bilateral (Battelli et al., 2003). In a previous fMRI study, we found temporal parietal junction (TPJ) activation when subjects attended to temporal features of a dynamic quartet, with the left TPJ activated by attention to both hemifields. Here, we isolate the effects of cueing and task difficulty on the same tasks. Methods. In an event-related fMRI design, subjects viewed a quartet of disks (two per hemifield, 4 deg eccentric) flickering for 1000 ms, sandwiched in time between 350ms of textured disks in the same location. Subjects reported whether the two disks in a targeted hemifield were in phase (flicker task) or identical in contrast (texture task). Flicker rate and texture contrast were calibrated individually to yield 80% performance. Pre-cue trials were initiated by an arrow indicating the target hemifield. The arrow was shown after the stimulus in post-cue trials. In a second experiment, subjects performed the flicker task on an 8Hz flicker quartet with a singleton disk flickering 45, 90, or 180 degrees out of phase (all post-cued). Results. Group analysis revealed a main effect of task, with ventral TPJ regions more strongly responsive to flicker relative to more dorsal regions. This pattern was largely explained by cueing, with a similar TPJ task effect in the pre-cue trials only. For post-cue trials, TOJ selective activation was apparent only in the left hemisphere. The phase manipulation revealed increased activation in left TPJ for more difficult out-of-phase conditions, regardless of attended hemifield. Conclusions. Our findings support left TPJ involvement in attention directed to temporal features, particularly when spatial shifts of attention are controlled. It remains unclear how to reconcile these findings with the patient literature.
Meeting abstract presented at VSS 2012
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