Dimensional complexity and power spectral measures of the EEG during functional versus predicative problem solving

Electroencephalograms were recorded in 22 men while solving tasks of visual -pattern completion and during mental relaxation. They were primed (by fore going trials) to solve these tasks either in a predicative or functional mo de of thinking. Predicative thinking required that in order to complete the pattern the subject had to get involved with the logic of the static struc ture of the pattern and therefore had to recognize the recurrence of certai n features of the elements (e.g., shape, color., and size). Functional thin king required involvement in a dynamic reading of the logic of the pattern and therefore to search for operations and actions to be performed on the p attern elements (e.g., pushing, mirroring, and rotating). The EEG complexit y during predicative thinking decreased in comparison to functional thinkin g and mental relaxation, with this reduction being most pronounced over the right parietal cortex. A reduction ih dimensional complexity during functi onal thinking as com pared to mental relaxation, which was concentrated ove r the left central cortex, although significant, was less clear. The reduce d EEG complexity during predicative thought, dominant over the right hemisp here, could reflect increased competitive inhibition among respective corti cal neuron assemblies in association with the visual analysis of static ele ment features, converging upon those predicates relevant for the solution. (C) 2000 Academic Press.