Anodal tDCS over the right parietal but not frontal cortex enhances the ability to overcome task set inhibition during task switching

Abstract

Switching between tasks requires individuals to inhibit mental representations of the previous task demands and to activate representations of the new task demands. The inhibition of the executed task remains active for a while so that when the inhibited task set must be reactivated shortly after, the need to overcome residual task set inhibition leads to behavioral costs. In a sham-controlled balanced-order within-subjects experimental design we investigated whether applying right anodal/left cathodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal or parietal cortex modulated the ability to overcome persistent task inhibition during task switching. Results showed that right anodal/left cathodal tDCS over the parietal cortex improves performance selectively when switching back to a recently inhibited task that requires previous inhibition to be overcome. Right Anodal/left cathodal tDCS over the prefrontal cortex improves performance during task switching in general, either when re-engaging in a inhibited task or when engaging in a noninhibited task. Results suggest a different contribution of prefrontal and parietal regions to task switching, with parietal cortex being selectively involved in overcoming persistent task inhibition and prefrontal cortex being more generally involved in the control of task set during task switching.

Cognitive Neural Mechanism of Backward Inhibition and Deinhibition: A Review

“…The findings of Sdoia et al (2020) were obviously different from that of Dreher and Berman (2002) . The discrepancy of the conclusion could be due to the methodological differences, such as stimuli and experimental procedure between these two studies ( Sdoia et al, 2020 ).…”

“…While this expectation is rationally unfounded, the brain does, making it more difficult to respond to task A when it occurs unexpectedly. As found in the findings from the studies on oddball (i.e., unexpected items), both the frontal and occipital lobes of the brain were generally observed to be highly activated when unanticipated and rare stimuli were presented ( Brazdil et al, 2007 ; Hooi et al, 2018 ), which is overlapped with regions of brain activation found during deinhibition ( Dreher and Berman, 2002 ; Picazio et al, 2020 ; Sdoia et al, 2020 ).…”

“…However, there was no change in the BI effect when only the prefrontal lobe was stimulated. Sdoia et al (2020) observed improved performance of the CB A sequence, indicating that the stimulation of the prefrontal lobe not only improved the ability of deinhibition but also improved the ability to switch tasks. When only the parietal cortex was stimulated, the BI effect disappeared due to the fact that the performance of the CB A sequence remained unchanged.…”

“…Although the parietal cortex is known to play an important role in inhibitory control and cognitive flexibility ( Hedden and Gabrieli, 2010 ; Fedorenko et al, 2013 ; Tang et al, 2016 ; Tschentscher et al, 2017 ; Hartung et al, 2021 ), the role of the parietal cortex in BI is unclear. Sdoia et al (2020) used transcranial direct current stimulation (tDCS) to stimulate the prefrontal or parietal area and assessed the potential ability of deinhibition reflected as the N-2 task repetition cost. In the frontal stimulation condition, the anode was placed over the right dorsolateral prefrontal cortex (F4 according to 10–20 EEG International System), whereas the cathode electrode was placed over the left dorsolateral prefrontal cortex (F3).…”

Task switching ability is compromised after cross-hemispheric tDCS over the parietal cortex

“…Interestingly enough, a recent study applied crosshemispheric tDCS over the prefrontal and parietal cortex, and showed that task switching performance increased only when it was required to overcome a previous inhibition in order to switch back to a recently inhibited task (Sdoia, Zivi, & Ferlazzo, 2020). As task switching depends on an extensive brain network, it is not surprising to consider that specific regions may be also responsible for specific functions that underlie the general cognitive ability.…”