Poster D39, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Causal evidence for learning-dependent frontal lobe contributions to cognitive control
Paul Muhle-Karbe1, Jiefeng Jiang1,2, Tobias Egner1; 1Duke University, 2Stanford University
The prefrontal cortex (PFC) is essential for controlling attention to amplify processing of task-relevant information. Although such control is of fundamental importance in pursuing goals, it can also be costly when deployed excessively. Efficient behavior therefore requires a careful regulation of PFC-based cognitive control to align it with changing external demands. This regulation can be observed in the Stroop task, where participants typically adapt their attentional selectivity based on the recent (trial-wise adaptation) or frequent (block-wise adaptation) experience of conflict. We have recently shown that both effects are captured by a volatility-driven reinforcement-learning model that learns to predict forthcoming control demand. Moreover, activity in the lateral PFC tracked learning-based adjustments in behavior (Jiang et al., 2015, Nat Comm). Here, we present a follow-up transcranial magnetic stimulation (TMS) study that probed the causal relevance of this region in learning-based engagement of control. Participants completed a Stroop task with dynamically changing conflict probabilities, and TMS was given on each trial just prior to stimulus onset (5 pulses, 10 Hz, 60% of stimulator output), either over the lateral PFC or over a control site. Results show that, in the control condition, participants adapted their performance to changing demands, as reflected by adaptation effects at both time scales. In contrast, no evidence for behavioral adaptation was found at either time scale during the PFC session. These preliminary results suggest a causal role for the PFC in implementing learning-dependent changes in cognitive control over stimulus processing. Additional, model-based analyses will be presented at the meeting.
Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching