Stimulation of Dorsolateral Prefrontal Cortex Enhances Adaptive Cognitive Control: A High-Definition Transcranial Direct Current Stimulation Study

Abstract

Conflict adaptation is a hallmark effect of adaptive cognitive control and refers to the adjustment of control to the level of previously experienced conflict. Conflict monitoring theory assumes that the dorsolateral prefrontal cortex (DLPFC) is causally involved in this adjustment. However, to date, evidence in humans is predominantly correlational, and heterogeneous with respect to the lateralization of control in the DLPFC. We used high-definition transcranial direct current stimulation (HD-tDCS), which allows for more focal current delivery than conventional tDCS, to clarify the causal involvement of the DLPFC in conflict adaptation. Specifically, we investigated the regional specificity and lateralization of potential beneficial stimulation effects on conflict adaptation during a visual flanker task. One hundred twenty healthy participants were assigned to four HD-tDCS conditions: left or right DLPFC or left or right primary motor cortex (M1). Each group underwent both active and sham HD-tDCS in crossover, double-blind designs. We obtained a sizeable conflict adaptation effect (measured as the modulation of the flanker effect as a function of previous response conflict) in all groups and conditions. However, this effect was larger under active HD-tDCS than under sham stimulation in both DLPFC groups. In contrast, active stimulation had no effect on conflict adaptation in the M1 groups. In sum, the present results indicate that the DLPFC plays a causal role in adaptive cognitive control, but that the involvement of DLPFC in control is not restricted to the left or right hemisphere. Moreover, our study confirms the potential of HD-tDCS to modulate cognition in a regionally specific manner.

Monitoring and control in multitasking

“…In fMRI, activation in the dorsal anterior cingulate cortex (ACC) is observed when response conflict is high (e.g., Botvinick, Nystrom, Fissell, Carter, & Cohen, 1999). The second component, control adjustment, is on a neural level linked to the dorso-lateral prefrontal cortex (dlPFC; Egner & Hirsch, 2005;Gbadeyan, McMahon, Steinhauser, & Meinzer, 2016;Kerns et al, 2004;MacDonald, Cohen, Stenger, & Carter, 2000), which is assumed to be involved in cognitive control functions in general (e.g., Badre & D'Esposito, 2007;Cieslik et al, 2013;Koechlin & Summerfield, 2007;Miller & Cohen, 2001).…”

No Evidence for Enhancing Prospective Memory with Anodal Transcranial Direct Current Stimulation Across Dorsolateral Prefrontal Cortex

“…a 4 x 1 montage) and which has been thought to increase focality. Gbadeyan, McMahon, Steinhauser, & Meinzer (2016) report significant effects using HD-tDCS. Also, multiple session tDCS has also been found to be effective in enhancing cognitive demands over time, which may provide another option for future research on this topic.…”

tDCS modulates behavioral performance and the neural oscillatory dynamics serving visual selective attention

“…Despite this interference effect, participants generally have high accuracy rates, and this is thought to reflect successful utilization of visual selective attention functions, as participants are able to focus on the target and ignore the flanking stimuli. Several behavioral studies have already used tDCS to modulate attention and performance during flanker tasks (Gbadeyan, McMahon, Steinhauser, & Meinzer, ; Karuza et al, ; Nozari, Woodard, & Thompson‐Schill, ; Zmigrod, Zmigrod, & Hommel, ), but these studies have had mixed results, with some showing improved performance and others showing decrements following tDCS. Of course, some of this variability reflects methodological differences (e.g., tDCS montage, duration/amplitude of tDCS, online/offline, etc.)…”

“…Several behavioral studies have already used tDCS to modulate attention and performance during flanker tasks (Gbadeyan, McMahon, Steinhauser, & Meinzer, 2016;Karuza et al, 2016;Nozari, Woodard, & Thompson-Schill, 2014;Zmigrod, Zmigrod, & Hommel, 2016), but these studies have had mixed results, with some showing improved performance and others showing decrements following tDCS. Of course, some of this variability reflects methodological differences (e.g., tDCS montage, duration/amplitude of tDCS, online/offline, etc.)…”