The effect of different types of cognitive tasks on postural sway fluctuations in older and younger adults: A nonlinear study.

BACKGROUND: There are numerous types of cognitive tasks classified as mental tracking (MT), working memory (WM), reaction time (RT), discrimination and decision-making and verbal fluency (VF). However, limited studies have investigated the effects of cognitive task type on postural control in older adults. PURPOSE: s: The aim of this study was to investigate the effect of aging and several types of cognitive tasks on postural control in terms of nonlinear analysis. METHOD: Postural control was investigated under 6 conditions (single task and dual-task with RT; easy and difficult VF; easy and difficult WM; easy and difficult MT. Outcome measurements were the max Lyapunov, entropy, and correlation dimension at anteroposterior (AP) and mediolateral (ML) directions. RESULTS: The results revealed that within the older group, the AP & ML max Lyapunov at dual-task with difficult WM and MT was significantly higher than all other conditions. In addition, the older group had lower AP entropy at dual-task with easy VF, difficult WM, and easy as well as difficult MT. CONCLUSION: The results can be useful to understand the postural control mechanisms and to detect the alterations following aging and applying different types of cognitive tasks. In addition, the investigated parameters can be a basis for identifying postural control deficiencies.

Study on Point-wise Correlation Dimension of Electroencephalogram Nonlinear Analysis in Patients with Stagnation of Liver-Qi Syndrome / 中国康复理论与实践

@#Objective To investigate the changes of non-linear dynamics characteristics of electroencephalogram(EEG) in patients with the stagnation of Liver-Qi syndrome.Methods 15 Liver-Qi stagnation syndrome patients and 15 normal persons were paired by sex and age.The data of EEG under three states(eyes closed,eyes opened,and mental arithmetic with eyes opened) were analyzed by the parameter of point-wise correlation dimension(PD2).Results PD2 of the stagnation of Liver-Qi syndrome group increased significantly compared with that of the healthy control group and always maintain high level.The difference of PD2 between two groups was gradually reduced along with the increase of stimulated condition.Conclusion Non-linear dynamic analysis is more appropriate for the study of mental functions changes of stagnation of Liver-Qi syndrome and can be used to investigate the brain mechanism of the stagnation of Liver-Qi syndrome.