Augmenting ideational fluency in a creativity task across multiple transcranial direct current stimulation montages

Abstract

Neuroimaging and transcranial direct current stimulation (tDCS) research has revealed that generating novel ideas is associated with both reductions and increases in prefrontal cortex (PFC) activity, and engagement of posterior occipital cortex, among other regions. However, there is substantial variability in the robustness of these tDCS‐induced effects due to heterogeneous sample sizes, different creativity measures, and methodological diversity in the application of tDCS across laboratories. To address these shortcomings, we used twelve different montages within a standardized tDCS protocol to investigate how altering activity in frontotemporal and occipital cortex impacts creative thinking. Across four experiments, 246 participants generated either the common or an uncommon use for 60 object pictures while undergoing tDCS. Participants also completed a control short-term memory task. We applied active tDCS for 20 min at 1.5 mA through two 5 cm × 5 cm electrodes over left or right ventrolateral prefrontal (areas F7, F8) or occipital (areas O1, O2) cortex, concurrent bilateral stimulation of these regions across polarities, or sham stimulation. Cathodal stimulation of the left, but not right, ventrolateral PFC improved fluency in creative idea generation, but had no effects on originality, as approximated by measures of semantic distance. No effects were obtained for the control tasks. Concurrent bilateral stimulation of the ventrolateral PFC regardless of polarity direction, and excitatory stimulation of occipital cortex did not alter task performance. Highlighting the importance of cross-experimental methodological consistency, these results extend our past findings and contribute to our understanding of the role of left PFC in creative thinking.

A meta-analysis of the effects of non-invasive brain stimulation on creative thinking

“…In recent years, research into the effects of NIBS and causal neural mechanisms underlying creative cognition is increasing rapidly. However, inconsistent findings in this research is also increasing, likely due to differences in experimental design, stimulation parameters, and creative measures (Chrysikou et al, 2021). For example, previous studies have shown that increasing excitability (via anodal tDCS) over the right inferior fronal gyrus (IFG) coupled with decreasing excitability (via cathodal tDCS) over the left IFG improved performance in a verbal divergent thinking task, and a deteriorative effect was observed with the reverse stimulation protocol (Hertenstein et al, 2019;Mayseless and Shamay-Tsoory, 2015).…”

“…Kleinmintz et al, (2018b) employed repetitive transcranial magnetic stimulation (rTMS) protocol with continuous theta-burst stimulation to inhibit the neural activation of left IFG and revealed a significant effect of stimulation that enhances originality scores in AUT. Conversely, some studies failed to find inhibitory activation of the left prefrontal cortex increased the generation of uncommon responses, but it works for appropriateness and fuency of participants' responses (Chrysikou et al, 2013;Chrysikou et al, 2021;Kenett et al, 2021). Moreover, the DLPFC was the most commonly used stimulation site and appears to work well for all-purpose cognitive enhancers.…”

“…For example, previous studies have shown that increasing excitability (via anodal tDCS) over the right inferior fronal gyrus (IFG) coupled with decreasing excitability (via cathodal tDCS) over the left IFG improved performance in a verbal divergent thinking task, and a deteriorative effect was observed with the reverse stimulation protocol (Hertenstein et al, 2019;Mayseless and Shamay-Tsoory, 2015). However, Chrysikou et al, (2021) failed to observe the beneficial effect of left IFG inhibition with concurrent excitation of the right IFG for originality of responses in the same verbal divergent thinking task. Besides, (Cerruti and Schlaug, 2009) found that anode tDCS over the left dorsal prefrontal cortex (DLPFC) improves the accuracy of remote associates test across two experiments, but a recent study failed to replicate these findings with the same experimental design and task (Xiang et al, 2021).…”

Non-invasive brain stimulation and neuroenhancement

“…This line of research suggests that stimulation may be “unleashing” creativity, mainly by modulating the bilateral temporal and prefrontal cortices. Placing the cathode over left and the anode over right cortical areas, in accordance with the hemispheric balance hypothesis, led to several studies finding positive results ( Chrysikou et al, 2021 , Hertenstein et al, 2019 , Ivancovsky et al, 2019 , Lifshitz-Ben-Basat and Mashal, 2021 , Mayseless and Shamay-Tsoory, 2015 ). According to this hypothesis, a shift in interhemispheric balance resulting in a predominance of the right over the left hemisphere promotes creativity.…”

Comparing transcranial direct current stimulation and transcranial random noise stimulation over left dorsolateral prefrontal cortex and left inferior frontal gyrus: Effects on divergent and convergent thinking

“…Results from transcranial stimulation studies mainly indicate that anodal tDCS over left DLPFC may increase DT (Colombo et al, 2015;Zmigrod et al, 2015;Peña et al, 2021) and CT (Cerruti and Schlaug, 2009;Metuki et al, 2012;Zmigrod et al, 2015;Peña et al, 2021Peña et al, , 2019. However, in separate studies, cathodal tDCS over the left IFG also found an increase in DT (Mayseless and Shamay-Tsoory, 2015;Kleinmintz et al, 2018;Hertenstein et al, 2019;Ivancovsky et al, 2019;Khalil et al, 2020;Chrysikou et al, 2021;Kenett et al, 2021).…”