title: [Context-dependent EEG spectral characteristics during performance of tasks].
abstract: Spatial and frequency EEG characteristics of two groups of healthy adult subjects were examined in two series of experiments, which differed in conditions of the second cognitive task in a trial. The first task was the same in the two series: subjects had to evaluate size relationship between two closely spaced circles. The second task successively presented in trials of the first series consisted in the recognition of words/pseudowords, and in the second series, subjects had to localize a target letter in a matrix. It was assumed that the cognitive performance in the first series predominantly involved the ventral visual system, whereas during task performance in the second series, predominant involvement of the ventral and dorsal visual systems alternated. Multichannel EEG fragments recorded prior to the presentation of the task pairs were analyzed. Analysis of variance of the EEG spectral power revealed the generalized significant effect of the factor of the second task in the pair for delta band and lower beta subband, the power being higher in the first series. Factor brain hemisphere had a significant effect for the alpha band in the occipital area, the spectral power being lower in the left hemisphere for both experimental series. The task x hemisphere interaction was significant in the temporal cortical areas for the EEG power in alpha2 band, i.e., the predominant involvement of the ventral visual system was associated with stronger asymmetry of alpha2 rhythm and lower spectral power in this band in the left temporal area. Thus, the character of the forthcoming cognitive activity was shown to be reflected in spatio-frequency characteristics of the preceding EEG.
authors.forename: N S
authors.initials: NS
authors.lastname: Kurova
authors.forename: E A
authors.initials: EA
authors.lastname: Cheremushkin
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D005556:Form Perception / Q000502:physiology; D006801:Humans; D008297:Male; D013028:Space Perception / Q000502:physiology