Chaotic Dynamics in Tracing BAEP and its Application on Investigating Brainstem Malfunction

The purpose of this study is to investigate the chaotic dynamics of tracing (dynamic) brainstem auditory evoked potential (BAEP), then to investigate the brainstem malfunction via dynamic characteristics of tracing BAEP. The radial basis function neural network (RBFNN) technique in combination with the moving window average (MWA) method was employed in order to extract the tracing BAEP from strong noise background. Data of noisy BAEP were collected from the infantile spasm (IS) group with brainstem malfunction and the tester group respectively. The chaotic dynamics of tracing BAEP were analyzed using phase projection and correlation dimension techniques. The results of this study have demonstrated: (1) there is a much stronger determination in BAEP than in noisy BAEP shown by more deterministic phase projections and lower D₂ in BAEP; (2) trajectories of BAEP never repeat and the value of correlation dimension is fractal; (3) the phase projection of BAEP for brainstem malfunction group shows more chaotic and has higher D ₂ than those for the tester group. The conclusions of this investigation suggest that BAEP is chaotic not deterministic and there is rich dynamics in BAEP; tracing BAEP is much more useful than noisy BAEP in describing brainstem malfunction because BAEP shows determination corresponding to brainstem function; BAEP in brainstem malfunction has more non-order dynamics than that in the tester