EFMouse: a Matlab toolbox to model stimulation-induced electric fields in the mouse brain.

Compared to the rapidly growing literature on transcranial electrical stimulation (tES) in humans, research into the mechanisms underlying neuromodulation by tES using in-vivo animal models is growing but still relatively rare. Such research, however, is key to overcome experimental limitations in humans and essential to build a detailed understanding of the in-vivo consequences of tES that can ultimately lead to development of targeted and effective therapeutic applications of non-invasive brain stimulation. The sheer difference in scale and geometry between animal models and the human brain contributes to the complexity of designing and interpreting animal studies. Here, we introduce EFMouse, a toolbox that extends previous approaches to model intracranial electric fields and is optimized to generate predictions that can be tested with in-vivo intracranial recordings in mice. Although the EFMouse toolbox has general applicability and could be used to predict intracranial fields for any electrical stimulation study using mice, we illustrate its usage by comparing fields in a tES high-density multi-electrode montage with a more traditional two-electrode montage. Our simulations show that both montages can produce strong focal homogeneous electric fields in targeted areas. However, the high-density montage produces a field that is more perpendicular to the visual cortical surface, which is expected to result in larger changes in neuronal excitability. The EFMouse toolbox is publicly available at https://github.com/klabhub/EFMouse.