Abstract: ObjectiveTo investigate the changes of non-linear dynamics characteristic of electroencephalogram (EEG) under three states (eyes closed, mental arithmetic with eyes closed and orientation test with eyes closed), and the application of non-linear dynamic analysis for cognitive function research.MethodsEEG was recorded in 30 healthy young volunteers at three stages. The correlation dimension (D₂) and approximate entropy (ApEn) were calculated for all subjects.ResultsD₂ and ApEn increased significantly during mental tasks as compared to the rest state with eyes closed (P<0.01). In different mental tasks, the complexity of mental functions and the regions involved in the cognitive task were different.ConclusionNon-linear analysis methods are appropriate for the study of cognitive functions and can help to understand the working mechanism of brain during mental activities.

Key words: electroencephalogram (EEG), non-linear dynamics, cognitive function