Abstract
When sustaining attention to a task, performance fluctuates between stable/accurate and variable/error-prone periods. Such fluctuations are, in part, modulated by motivation as reward has been shown to both boost performance and alter neural responses in brain regions critical to sustaining attention. The link between these neural changes and enhanced performance, however, is poorly understood. Thus, the present research uses fMRI and Representational Similarity Analyses to measure the influence of reward on the flow of task-relevant visual information, specifically examining the fidelity and connectivity of stimulus representations within and across brain regions critical to sustaining attention. Participants (N=16) performed the gradual onset Continuous Performance Task during an fMRI scan. This entailed viewing a series of city or mountain scenes, responding to cities (90% of trials) and withholding responses to mountains (10%). Task runs were separated into unrewarded and rewarded blocks. Representational similarity matrices (RSMs), reflecting the similarity structure of the set of city exemplars (n=10), were computed for each participant within parahippocampal place area (PPA), dorsal attention network (DAN), and default mode network (DMN) ROIs. Representational fidelity (RF) and representational connectivity (RC) were quantified as the inter-participant reliability across the RSMs from given ROI (RF) and across a pair of ROIs (RC) and were computed separately for rewarded and unrewarded blocks. We found that reward was characterized by increased RF within the DMN (p ~ 0.05) and increased RC between the DAN and DMN (p < 0.01). In striking contrast, traditional functional connectivity (time series correlations) between the DAN and DMN decreased during rewarded blocks (p < 0.01) suggesting that reward inhibited overall DAN-DMN communication despite facilitating the communication of task-relevant information. These results further our understanding of how motivation boosts performance during sustained attention and implicate the DMN as having an active role in the processing task-relevant visual information.
Meeting abstract presented at VSS 2018