Brain mechanisms of the visual-pictorial thinking involved in performing tasks requiring mental manipulation of three-dimensional geometric bodies (and in particular role of temporal areas of the right and left hemispheres in the organization of corresponding thinking operations) have been studied. Dominance of the right hemisphere has been established which is likely connected with the fact that simultaneous synthesis of the incoming information mainly takes place there. Correlation between particular errors in performance and different neuropsychological symptoms of disturbed visual-spatial functions has also been established.