Analysis of Electroencephalogram of Autism Spectrum Disorder Using Correlation DimensionChanges in brain Map

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects information processing in the nervous system and the procedure of natural brain evolution. Therefore, the processing and analysis of the brain function of these patients have captivated the attention of many researchers. Qualitative electroencephalography (EEG) is an evaluation method for determining functional brain abnormalities that is different from quantitative EEG. Chaotic tools are used in qualitative EEG whereas linear and nonlinear methods are applied in quantitative EEG. The purpose of the present study is to compare qualitative EEG findings of healthy and autistic subjects.

In this study, 19 channels of brain signals (Cz, C4, F4, Fz, F3, C3, P3, Pz, P4, T4, F8, Fp2, Fp1, F7, T3, T5, O1, O2, T6) of 6 healthy and 5 autistic subjects were evaluated in two phases. At first 5-minutes with closed eyes and then 5-minutes with opened eyes, the subjectchr('39')s EEG was recorded. After removing the artifacts, the correlation dimension of the signals was calculated, and brain maps were plotted to analyze the changes of correlation dimension on the scalp surface.

By comparison of the brain maps of the healthy and autistic groups between the opened and closed eyes periods, we found there was a difference between the brain function of the groups, especially in the T3 and T4 regions of the temporal regions as well as frontal and posterior areas.

Using brain maps, correlation dimension mapping on the brain surface provides a better understanding of brain dynamics in autistic subjects.