Enhancing cognitive control training with transcranial direct current stimulation: a systematic parameter study

Abstract

Background: Cognitive control (CC) is an important prerequisite for goal-directed behaviour and efficient information processing. Impaired CC is associated with reduced prefrontal cortex activity and various mental disorders, but may be effectively tackled by transcranial direct current stimulation (tDCS)enhanced training. However, study data are inconsistent as efficacy depends on stimulation parameters whose implementations vary widely between studies. Objective: We systematically tested various tDCS parameter effects (anodal/cathodal polarity, 1/2 mA stimulation intensity, left/right prefrontal cortex hemisphere) on a six-session CC training combined with tDCS. Methods: Nine groups of healthy humans (male/female) received either anodal/cathodal tDCS of 1/2 mA over the left/right PFC or sham stimulation, simultaneously with a CC training (modified adaptive Paced Auditory Serial Addition Task [PASAT]). Subjects trained thrice per week (19 min each) for two weeks. We assessed performance progress in the PASAT before, during, and after training. Using a hierarchical approach, we incrementally narrowed down on optimal stimulation parameters supporting CC. Longterm CC effects as well as transfer effects in a flanker task were assessed after the training period as well as three months later. Results: Compared to sham stimulation, anodal but not cathodal tDCS improved performance gains. This was only valid for 1 mA stimulation intensity and particularly detected when applied to the left PFC. Conclusions: Our results confirm beneficial, non-linear effects of anodal tDCS on cognitive training in a large sample of healthy subjects. The data consolidate the basis for further development of functionally targeted tDCS, supporting cognitive control training in mental disorders and guiding further development of clinical interventions.

Intensified electrical stimulation targeting lateral and medial prefrontal cortices for the treatment of social anxiety disorder: A randomized, double-blind, parallel-group, dose-comparison study

“…The rationale behind the protocol comes from a study showing that twice stimulation with 20 min interval leads to longer aftereffects on cortical excitability compared to nonrepeated stimulation or stimulation with long intervals, and resembles features of late-phase LTP [43,69], as well as a recent study demonstrating that 20 min of anodal stimulation-induced larger aftereffects for both 1 and 2 mA intensities, as compared to other durations (15 and 30 min) [70]. We chose specifically 1 and 2 mA stimulation intensities because results of previous studies show that the effects of stimulation on psychological processes are not in all cases larger with higher intensity [71,72]. Our findings showed that overall, both interventions in this intensified protocol significantly reduced SAD symptoms, worries, depressive states and emotion regulation after intervention.…”

Comparison of cortical network effects of high-definition and conventional tDCS during visuomotor processing

“…C. Log-RT by run during sham stimulation showing two SRTT blocks each consisting of 12 runs. Random runs [1,10] are indicated; all other runs used fixed sequences. D. RT by run during active stimulation.…”

Intensified stimulation targeting lateral and medial prefrontal cortices for the treatment of social anxiety disorder: A randomized, double-blind, parallel-group, dose-comparison study

“…The rationale behind the protocol comes from a study showing that twice stimulation with 20 min interval leads to longer aftereffects on cortical excitability compared to non-repeated stimulation or stimulation with long intervals, and resembles features of late-phase LTP, [43,69] as well as a recent study demonstrating that 20 min of anodal stimulation-induced larger aftereffects for both 1 and 2 mA intensities, as compared to other durations (15 and 30 min) [70]. We chose specifically 1 and 2 mA stimulation intensities because results of previous studies show that the effects of stimulation on psychological processes are not in all cases larger with higher intensity [71,72]. Our findings showed that overall, both interventions in this intensified protocol significantly reduced SAD symptoms, worries, depressive states and emotion regulation after intervention.…”