Referential derivation of epidural electroencephalogram in El mice

Epidural EEG of 20 El mice is recorded under ketamine and xylazine anesthesia with epoxy coated silver balls as exploring electrodes. A stainless steel needle is placed subcutaneously near the nose as a reference electrode. Reproducibility of recording is remarkable. Multiple spike complex synchronizing on both frontal lobes is observed in 8 mice. Among them, small spikes preceding the multiple spike complex are also observed on the left frontal lead in 7 mice and on the right in 1 mouse. These spikes do not spread to occipital recordings. The discriminative ability of the recording is due to the coated electrode commonly employed with much larger animals and to suitable placement of the reference electrode. This simple and well known method permits the analysis of not yet satisfactorily explored the EEG of El mouse.