The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project is to understand how conductivity in the brain is affected by anatomical variability between patients and, more importantly, to enable precise treatment of neurological diseases using transcranial Direct Current Stimulation (tDCS) and Transcranial Magnetic Stimulation (TMS) techniques. A number of studies have shown these techniques may be used, cost-effectively, to improve learning, working memory, as well as relieve chronic pain and the symptoms of depression, fibromyalgia, Parkinson's, and schizophrenia. However, current understanding of electromagnetic (EM) characteristics for the human head and state-of-the-art TMS and tDCS techniques suffer from the inability to precisely control the most appropriate excitation pathways in the brain to support a specified clinical objective. This can result in unexpected and sometimes ineffective or even detrimental outcomes. Models and TMS/tDCS treatment systems for implementation of excitation techniques are not validated to standards. A thorough understanding of pathways and development of validated mimics and phantom structures will enable development and clinical implementation of precisely controlled analytical models and protocols for effective, widely accessible, reliable and safe TMS/tDCS treatments. The proposed project will address gaps in current knowledge of intracranial electromagnetic characteristics and materials performance to develop reproducible head phantoms for clinical implementation of more precise, quantifiable tDCS and TMS techniques. This research will characterize solid, liquid and gel materials selected to comply with biomedical and commercialization criteria. Analyses will be used to develop formulations of combinations of materials that address the range of conductivity and anisotropy of the parts and interfaces of the human brain. These formulations will be experimentally evaluated and refined for producibility and accuracy. This will provide a database of materials solutions which will be used in Phase II and beyond. Traditional brain conductivity mimics are simple spherical shells consisting of a single agar based conductivity mimic, which lacks the complexity of the human brain. The challenges of developing an EM brain phantom include fabrication of the various materials for controlled and reproducible anisotropic conductivity values, shaping these materials to mimic anatomical features, and combining them to represent boundary interfaces and control gaps for accurate pathway performance. The proposed effort includes development of a shell mimic that incorporates applicable material formulations to validate extensibility to more sophisticated prototype phantoms during Phase II.
