Nonlinear dynamical analysis of developmental changes in hippocampal REM sleep EEG

Nonlinear dynamics analysis of the ontogeny of the hippocampal REM sleep EEG was performed using data recorded from electrodes implanted at two primary sites that generate the theta rhythm-the pyramidal cell layer at CA1 and the granule cell layer at the dentate gyrus. The hippocampal EEG data were collected from rats of 15 and 90 days of age. The correlation dimension of EEG was estimated using a modified Grassberger-Procaccia method. Our study has shown that the correlation dimension estimates of the hippocampal REM sleep EEG recorded from the dentate gyrus are significantly larger than those of CA1 in rats of 15 days of age, whereas the difference diminishes as rats mature at 90 days of age.