A study of Fractal Dimension and Lyapunov exponent index in various age groups

Abstract

Fractal Dimension (FD) could be an index of correlation among variable parameters in non-linear chaotic signals. We tried to demonstrate that EEG wave is compatible with chaotic waves by measuring the Lyapunov exponent index and compared the difference in FD among various age groups (teens and 30's and 50's). We estimated the Lyapunov exponent index and the FD from digital EEG data from five normal individuals in each age group using the software programmed in our laboratory. Statistical analysis was done with SPSS for Windows 9.0. The statistical differences of the Lyapunov exponent index and FD between each electrode and each age group were determined with ANOVA and paired sample t-test. There was no statistical difference in the FD and Lyapunov exponent index between each electrode and age group. The power of theta wave band was significantly stronger statistically in teens than those in 30's and 50's, fast waves such as beta and gamma bands were shown more in 50's than in teens or 30's, and the value that was obtained by dividing the total power by each wave also showed the same result as that of the fast waves.