Electrocorticographic telemetric recording in unrestrained mouse pups.

BACKGROUND: Early onset epileptic encephalopathies are rare paediatric diseases, with seizures resistant to drugs and impacting development of cognitive and motor functions. Many of them show monogenic aetiology and engineered animal models are crucial to understand the underlying mechanisms and propose treatment trials. These models have mostly been explored in vitro or in vivo under anaesthesia. This may affect the occurrence of epileptic activities and their clinical expression. These study conditions perturb social skills and are limited in time.

NEW METHOD: We developed a technique using telemetric recordings by means of the Data Science International (DSI) mouse transmitter to study long lasting electro-cortical activity in freely moving mice younger than three weeks, trying to minimally affect social interactions and development RESULTS: We describe how to implant telemetry EEG devices in mice aged P13 to P18, weighing 7-10 g, including the surgical procedure and the recovery phase. Normal EEG data and epileptic activities can be recorded up to 2 months after implantation in normally behaving animals.

COMPARISONS WITH EXISTING METHODS: Electrocorticographic studies of mouse pups are rare, and few devices allow EEG recording at these ages. Here, the telemetry devices used for adult mice were implanted in mouse pups. The surgical procedure was well tolerated. An adapted recovery protocol allowed EEG recording during the period of interest.

CONCLUSION: This technique was developed with currently used devices to enable better understanding of the pathophysiology of epileptic encephalopathies, chronic recording of seizures and helping the development of new therapies using chronic trials in the young animal.