Modeling transcranial electric stimulation in mouse: A high resolution finite element study

Mouse models are widely used in studies of various forms of transcranial electric stimulation (TES). However, there is limited knowledge of the electric field distribution induced by TES in mice, and computational models to estimate this distribution are lacking. This study examines the electric field and current density distribution in the mouse brain induced by TES. We created a high-resolution finite element mouse model incorporating ear clip electrodes commonly used in mouse TES to study, for example, electroconvulsive therapy (ECT). The electric field strength and current density induced by an ear clip electrode configuration were computed in the anatomically realistic, inhomogenous mouse model. The results show that the median electric field strength induced in the brain at 1 mA of stimulus current is 5.57 V/m, and the strongest field of 20.19 V/m was observed in the cerebellum. Therefore, to match the median electric field in human ECT at 800 mA current, the electrode current in mouse should be set to approximately 15 mA. However, the location of the strongest electric field in posterior brain regions in the mouse does not model well human ECT which targets more frontal regions. Therefore, the ear clip electrode configuration may not be a good model of human ECT. Using high-resolution realistic models for simulating TES in mice may guide the establishment of appropriate stimulation parameters for future in vivo studies.