Abstract
We have previously described newly-developed EEG derivation method from the free moving mouse. Briefly, EEG derived between an electrode placed on the dura mater through a burr hole on the skull and a reference electrode placed subcutaneously near the nose. This EEG derivation recording technique for conscious mice has enabled us to detect both EEG and sleeping status as baseline fluctuations caused by respiration. In the El-mouse, an established epilepsy model, maintained by sib-matings at the Department of Veterinary Physiology, Nippon Veterinary and Animal Science University, Tokyo, Japan, we have noted frequent appearance of spike discharges on EEG during sleep without ictal phenotype. Sleeping status was further monitored by animal's quinsence at the place with closed eyes and unawareness to environmental stimuli. These spikes resembled to those seen in interictal EEG and the pattern changed with age of mice. Thus, to reveal the nature of the spikes in sleeping EEG of El mice, we examined changes in power spectrum density (PSD) at different ages. And the wavelet decomposition was applied to EEG to identify the temporal changes of spikes and several components. PSD analysis indicated that the character of spike frequencies shifted toward higher frequencies with age of El-mice. And wavelet decomposition could assign spike discharges, ECG, respiration and body movement, respectively.
