Anatomical details affect electric field predictions for non-invasive brain stimulation in non-human primates

• Published in: NeuroImage (Orlando, Fla.) Vol. 279; p. 120343
• Main Authors: Mantell, Kathleen E., Perera, Nipun D., Shirinpour, Sina, Puonti, Oula, Xu, Ting, Zimmermann, Jan, Falchier, Arnaud, Heilbronner, Sarah R., Thielscher, Axel, Opitz, Alexander
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2023; Elsevier Limited; Elsevier
• Subjects: Animal models; Animals; Anisotropy; Automation; Brain; Computer Simulation; Conductivity; Electric fields; Electricity; Finite element method modeling; Humans; Magnetic fields; Medical imaging; Noninvasive brain stimulation (NIBS); Primates; Scanners; Transcranial electric stimulation (TES), Non-human primate; Transcranial magnetic stimulation; Transcranial magnetic stimulation (TMS); Translation; Ultra-high field imaging; Visual field; Transcranial magnetic stimulation (TMS); Ultra-high field imaging; Finite element method modeling; Noninvasive brain stimulation (NIBS); Transcranial electric stimulation (TES), Non-human primate
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2023.120343

•We created non-human primate FEM head models from MR data that includes one high-resolution model created by 10.5 t MRI.•We ran TES and TMS simulations to evaluate the effects of muscle and head field of view on the induced electric fields.•We simulated both isotropic and anisotropic muscle conductivities.•Incorporating muscle tissue increases electric field strength by up to 22% in realistic modeling for TES, but not for TMS.•We observed appreciable effects for full vs. cropped models for TES (increase up to 24.8%) and TMS (decrease up to 24.6%).
Non-human primates (NHPs) have become key for translational research in noninvasive brain stimulation (NIBS). However, in order to create comparable stimulation conditions for humans it is vital to study the accuracy of current modeling practices across species. Numerical models to simulate electric fields are an important tool for experimental planning in NHPs and translation to human studies. It is thus essential whether and to what extent the anatomical details of NHP models agree with current modeling practices when calculating NIBS electric fields. Here, we create highly accurate head models of two non-human primates (NHP) MR data. We evaluate how muscle tissue and head field of view (depending on MRI parameters) affect simulation results in transcranial electric and magnetic stimulation (TES and TMS). Our findings indicate that the inclusion of anisotropic muscle can affect TES electric field strength up to 22% while TMS is largely unaffected. Additionally, comparing a full head model to a cropped head model illustrates the impact of head field of view on electric fields for both TES and TMS. We find opposing effects between TES and TMS with an increase up to 24.8% for TES and a decrease up to 24.6% for TMS for the cropped head model compared to the full head model. Our results provide important insights into the level of anatomical detail needed for NHP head models and can inform future translational efforts for NIBS studies.