The recording of neural signals from the brain of neonatal mice is of interest for the understanding of the functionality of the brain and its development processes. Treatments for certain forms of neural diseases like epilepsy are investigated with the help of neural recordings from mice [Marguet, Nature Medicine 21, 1436-1444, 2015]. For a systematic investigation of these processes, long term neural recordings of neonatal mice are needed. Neonatal mice have a weight of only 3 - 5 grams; commercially available recording systems are much too heavy and large for this application. To overcome this, an implantable neural recording system is proposed that can be placed inside a neonatal mouse (back, neck and head) and record Low Field Potentials (LFP) and Action Potentials (AP) from the brain.