Finite element simulation of transcranial current stimulation in realistic rat head model

Transcranial current stimulation (tCS) is a method for modulating neural excitability and is used widely for studying brain function. Although tCS has been used on the rat, there is limited knowledge on the induced electric field distribution during stimulation. This work presents the finite element (FE) simulations of tCS in a realistic rat head model derived from MRI data. We simulated two electrode configurations and analyzed the spatial focality of the induced electric field for three implantation depth scenarios : (1) electrode implanted at the surface of the skull, (2) halfway through the skull and (3) in contact with cerebrospinal fluid. We quantitatively show the change in focality of stimulation with depth. This work emphasizes the importance of performing FE analysis in realistic models as a vital step in the design of tCS rat experiments. This can yield a better understanding of the location and intensity of stimulation, and its correlation to brain function.