Simulation of the electrical stimulation of the rat brain using sleep frequencies: A finite element modeling approach

•Finite element methods provide an exceptional tool to model current dynamics in the sleeping brain, to better understand the physiological mechanisms of the transcranial electrical stimulation. It also fosters the refinement of techniques, and the potential replacement of animals.•The stimulation of the current frequency is crucial in some studies in the field of neuroscience and concretely in sleep research; however, this parameter is hardly accounted in computational models using FEM to assess the behavior of the electrical current in the brain.•Stimulation frequency has comparative less impact on electric field than electrode configurations.•Subcranial screw anodes affect deeper brain areas and display higher current density and electric field across stimulation frequencies. Nevertheless, both modeled electrode setups (screw and plate) impose electric current to a wide portion of the brain.•The use of FEM to model and simulate current behavior in the brain is very relevant for neuroscience and concretely for sleep research. It not only allows for sophistication of the mechanistic explanations of the effect of electrical stimulation in the brain. A realistic rat brain model was used to simulate current density and electric field distributions under frequencies characteristic of sleeping states (0.8, 5, and 12 Hz). Two anode-electrode setups were simulated: plate vs. screws-anode, both with a cephalic cathode. Our simulations showed that these frequencies have limited impact on electric field and current density; however, the highest frequency evidenced higher values for both variables. The type of electrode setup had a greater effect on current distribution and induced fields. In that sense, the screws setup resulted in higher values of the modeled variables. The numeric results obtained are within the range of available data for rodent models using the finite elements method. These modeled effects should be analyzed regarding anatomical consequences (depth of penetration of the currents) and purpose of the experiment (i.e., entrainment of brain oscillations) in the context of sleep research.