An EEG system to detect brain signals from multiple adult zebrafish.

Zebrafish has been widely used as an experimental animal in many biological processes to study brain functions, neurological disorders and drug toxicity. Electroencephalogram (EEG), which directly measures brain activities, has been used to diagnose and study neurological disorders. Previous studies have recorded EEG signals from adult zebrafish, but the recordings have been only possible from a single individual. In this study, we developed a system to record EEG of multiple adult zebrafish simultaneously. To secure multiple zebrafish in a stable condition for a certain time, perfusion and recording systems were mechanically separated, which allowed effective immobilization of the fish. We recorded EEG signals from pentylenetetrazole (PTZ)-induced seizure models and valproic acid (VPA)-treated models to demonstrate the performance of the developed system in validation of the effect of anti-epileptic drugs. The developed system effectively measured individual EEG signals from more than three zebrafish out of four simultaneously on average. Seizure induction by PTZ and seizure suppression by VPA were successfully detected through EEG recording. The scheme of the EEG recording system developed in this study has a potential for expansion and could be further applied to mass drug screening in a short time.