States of productive and reproductive imagination reflected in the local synchronization of alpha and theta EEG frequencies

Abstract

Healthy subjects (n = 83) performed a task involving reproductive imagination (remembrances): they were asked to remember and to have an imaginary walk along a well-known road (a real walk, the reproductive imagination state, RIS). Then the subjects performed a task involving productive imagination: they were asked to imagine a city that does not actually exist and to have an imaginary walk through it (a fictitious walk, productive imagination state, PIS). The reference values were measured at rest with the eyes open (REO). Monopolar EEGs were recorded from 19 areas of the scalp surface (10–20 system). An increase in EEG power in the α₂ frequency range during RIS and even more pronounced increase during PIS as compared with REO were considered to reflect the internalization of attention. We also observed multidirectional dynamics of EEG power in the θ and α1 ranges during PIS and RIS as compared with REO, which suggests the dominance of free associative manipulation of visual images in PIS in contrast to RIS, where algorithmically ordered operations with visual images stored in the memory were dominant.