Abstract
The Prefrontal Cortex (PFC) is thought to be hierarchically organized and to perform executive control functions such as planning and goal-directed behavior. Past experiments have found that representations that are abstract in temporal span (Desrochers et al., 2016) or degree of relation (Badre and D’Esposito, 2007) are processed in anterior regions of the PFC, which influence more posterior regions in order to implement proximal aspects of goal-oriented behavior, such as motor acts. Several researchers have even reported accurate classification of task set (Bode and Dylan-Haynes, 2009) or working memory content (Zhang et al., 2013) in various regions of PFC and also in parietal areas involved in the frontoparietal network. Notably, many of these tasks used visual stimuli that were at least partially confounded with the high-level representation that served as the target of classification. In the current experiment, participants performed a task that involved comparing visual stimuli at three levels of relational abstraction. Critically, the stimuli were the same across all three tasks. Each trial consisted of 4 configurations of stimuli that varied on 4 dimensions (number, shape, orientation, and luminance). Two comparison criteria for the stimuli (“is there exactly one match/mismatch”) were tested at each level of abstraction. After training to criterion on all levels of the task, participants performed the task during an MRI session. Whole-brain searchlight classification was performed to determine which areas contained task information encoding the difference in comparison criteria at each level of relational abstraction. Accurate classification was observed in frontoparietal areas for all levels, but most strongly for the most abstract level. While evidence for hierarchical organization of PFC was not observed in our experiment, our results replicate the finding that frontoparietal areas are critical for executive control, even when the stimuli are identical across tasks.