The impact of prefrontal tDCS on conflict resolution and its phenomenological dynamics: a HD-tDCS/EEG randomized sham-controlled novel approach based on Drift Diffusion Modeling

Abstract

When humans are faced with conflict resolution tasks, performance is usually impaired. The effects of applying non-invasive brain stimulation techniques on conflict resolution performance is still an open question under debate. In this study we will address this issue by assessing the cognitive and physiological effects of applying anodal and cathodal high-definition transcranial direct current stimulation (HD-tDCS) over bilateral dorsolateral prefrontal cortex (DLPFC) on conflict resolution by using a 30-min flanker task. Moreover, the effects of the stimulation on phenomenological constructs such as mind-wandering, boredom, perceived cognitive effort and arousal over the course of the task will be addressed. In a pre-registered, randomized, sham-controlled, parallel study, we will assign participants to one of the three groups of stimulation: anodal, cathodal, and sham. A pre-post resting state EEG and the task-related oscillatory activity during the first and last 6-min temporal blocks of the task will be measured. Stimulation will be applied online from the second to the fourth block of trials (18 minutes). Right after, participants will be asked to report their temporal experience tracing (TET), a method that captures relevant aspects of their phenomenological experiences over a continuous period of time by drawing their headway in the task between two axes. Behavioral data will be analyzed by applying a drift diffusion modelling that enables statistical separation of different components of a speeded binary decision process. This novel approach will allow us to get a more thorough understanding of cognitive processes and electrophysiological mechanisms underlying the effects of cathodal and anodal stimulation on conflict resolution. As far as we know, this will be the most comprehensive piece of work within this research topic.