Chaos In Wavelet Components Of Auditory Evoked EEG For Infantile Spasms

Infantile spasms is a special form of epilepsy which occurs during infancy, the pathogenesis of infantile spasms is not known. However, when infantile spasms is associated with structural damage to the brain, it is difficult to completely control the seizures and intellectual disability is very likely to be present. One of current hypothesis about the pathogenesis of IS is that brainstem is the responsible structure of IS. But this hypothesis can not be proved by traditional neurophysiological method. In this study, the pathogenesis of IS is investigated with the point of view of of information science, with the help of the wavelet and chaos theory.In this article, 3 groups' (IS group, normal group and temporal epilepsy group) evoked EEG are recorded with the auditory stimulation. After pre-process and Maxihat wavelet transform performed, the EEG signal is decomposed into different components in 7 scales, and their correlation dimensions(Dc) are calculated. The results show that the normal group's DC in 3 and 4 scales are significantly lower than that in the IS, in other scales no significant difference found. The freedom degree of brain activity becomes lower and the coupling among the components in brainstem reinforces when DC declining. In the IS group, the pathway of information in brain stem is in bad condition. This makes the coupling more difficult. So DC in the IS shows higher than that in the normal in 3,4 scales. Meanwhile, the 3,4 scales are in the high frequency range, which is relative to the brain cognition function. From informatics this research may explain why IS infants have cognition impairment.Our research proves that there is a brain stem disfunction in IS infants by analysis of wavelet and correlation dimension, verify the hypothesis that brainstem is the responsible structure of IS.