Oscillatory brain activity during anagram solving: the effect of cognitive strategy

Introduction: Anagram is a word formed by rearranging the letters of another word. Anagrams solving is a useful model to study the cognitive strategies because anagrams can be solved in two different ways at least: by conscious manipulation of letters or with insight. However, it is still an open question whether brain mechanisms underlying these two strategies are different, and if so what neuronal features underlay the insight. To study this issue we have examined changes in oscillatory brain activity during anagram solving in healthy adult participants.

Method: 14 healthy right-handed subjects aged from 20 to 34 participated in the study. Each person took part in the experiment five times in three weeks. Subjects were solving nine different 6-letters anagrams in each of five experimental series. 40 seconds were given to solve one anagram. After each correct solution participants indicated, whether anagrams were solved with or without insight. In the control series, subjects were looking at 6-letter words (one at a time) for 30 seconds, memorized them, and named them later. 19-chanal EEG was recorded during anagram solving and control sessions. The input EEG was filtered between 0.53 Hz and 30 Hz. One participant was excluded from the experimental sample because of the large number of artifacts.  EEG spectral power was calculated in five frequency bands: theta (4–7.5 Hz), alpha1 (7.5–9.5 Hz), alpha2 (9.5–12.5 Hz), beta1 (12.5–18 Hz), and beta2 (18–30 Hz). In each band the spectral power before and after the analytical solution, before and after the insight solution, and default spectral power was compared using the Kruskal-Wallis one-way analysis of variance.

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