Effects of Online Repetitive Transcranial Magnetic Stimulation on the Frequency of Insights During Anagram Solving

Insight is the sudden unpredictable appearance of a problem’s solution. The solution of anagrams is one of the tasks available for studying insight. Repetitive transcranial magnetic stimulation (rTMS) allows the detection of a causal relationship between the activity of a cerebral cortex area and the studied cognitive phenomenon. During online-rTMS, the presentation of a short train of stimuli causes a so-called “virtual lesion” - a disruption of the task performance in which this area is involved. We aimed to study online effects of rTMS over left and right dorsolateral prefrontal cortex (DLPFC) on insight solution of anagrams. Healthy volunteers aged 18 to 55 years who did not have contraindications for magnetic resonance imaging (MRI) and rTMS were included. Each volunteer underwent 3 sessions of rTMS of left DLPFC, right DLPFC and Vertex (Control region) in a randomized order with intersession interval not less than 48 h. The presentation and solving of anagrams was synchronized to the rTMS train. During each session, 35 anagrams were presented with the intertrain intervals not less than 26 s. We assessed the total number and frequency of insight problem solving, mean duration of an insight solution and the percentage of correct answers. The data of 16 healthy volunteers were analyzed. No significant differences were observed depending on the stimulation zone when comparing the studied parameters for the three stimulation protocols and in pairwise comparisons between them. These results may be associated with a high degree of interindividual variability of the insight rate and a relatively low total number of insights. Further studies in this area are needed patients.