Differential effects of prefrontal inhibitory tDCS on voluntary task selection
Joseph Orr1, Michael Imburgio1, Jesus Lopez1; 1Texas A&M University
Voluntary task selection (VTS) refers to the ability to guide task choices by one’s internal goals as opposed to external information. Previous fMRI studies have found conflicting results regarding which brain area underlies VTS. While some evidence suggests that the anterior cingulate cortex (ACC) underlies VTS, others suggest that the frontal pole (FP) is most important. However, fMRI studies yield correlational, not causal, conclusions. The current work utilized HD transcranial direct current stimulation to examine the effect of inhibiting the FP or ACC on VTS. Because prior work suggests that the FP is responsible for higher-level processing and the ACC is more involved in lower-level actions, it was predicted that inhibiting the FP would dampen top-down biases while inhibiting the ACC would dampen bottom-up biases. Forty-one participants were assigned to receive stimulation targeting either the FP or ACC, with both groups undergoing 20 minutes of inhibitory 2mA stimulation and sham stimulation in separate, counterbalanced sessions. After stimulation, participants were asked to voluntarily choose between two tasks, with instructions to choose the tasks randomly and equally often. Contrary to predictions, ACC inhibition caused participants to repeat tasks more often, suggesting an increased bottom-up bias. Similarly, inhibition of the FP caused participants to choose to switch tasks more often, indicating an increase in top-down bias. The current work may exemplify the propensity of cathodal stimulation to yield reverse effects at high intensities. The effects of anodal stimulation on VTS are currently being examined to assess the possibility of reversed effects.
Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching