Poster B36, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Assessing the role of norepinephrine in attentional flexibility: A pupillometry study
Rebecca D. Calcott1, Jason Hubbard1, Elliot T. Berkman1; 1University of Oregon
Activity of the locus coeruleus-norepinephrine (LC-NE) system adjudicates the tradeoff between exploiting the current resource (stability) and exploring the environment for other opportunities (flexibility). In particular, large phasic LC-NE responses to task-relevant stimuli indicate exploitation mode, whereas high tonic LC-NE activity indicates exploration mode. The present study examined the role of phasic LC-NE activity on the ability to shift attentional focus, which is currently unknown. Subjects’ (N=67) pupil size was tracked continuously to measure LC-NE function during an attention shifting task. Subjects responded to a letter in a target color and ignored a distractor letter. Periodically, the color of the target letter switched from the previous trial, and these switch trials were contrasted with non-switch trials to index attentional flexibility. Switch trials occurred in blocks of two types: On Perseveration-Inhibition blocks, switches involved the distractor color becoming the new target color and vice-versa, whereas on Pure Updating blocks, switches involved both target and distractor becoming novel colors. Phasic pupil dilation was indexed by the task-evoked change in pupil size from baseline. Overall, pupil dilation was larger for non-switch trials compared to switch trials. Additionally, on Perseveration-Inhibition blocks, reaction time switch costs were greatest on trials with large pupil dilations, whereas the opposite pattern emerged on Pure Updating blocks, where switch costs were larger on trials with smaller pupil dilations. These findings suggest that the task context determines whether large phasic pupil dilations facilitate attentional shifts. A follow-up experiment will explore the effects of tonic (pre-trial) pupil size on attentional flexibility.
Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching