Electroencephalography (EEG) is an indispensable neurological diagnostic tool in terms of fast time scale, portability, and cost efficiency. Improved spatial resolution of EEG measures would greatly benefit clinical and research applications, including stroke, epilepsy, and cognitive studies. Dense-array EEG recordings can be used to localize cortical function, providing a unique opportunity for monitoring brain activity both in space and time. Localizing brain function using EEG can be further optimized by use of realistic head models and incorporating accurate conductivity estimates for each tissue type of the head model. Lack of accurate skull conductivity information is particularly problematic given the variations in skull development from infancy through adolescence. The goal of this project is to develop technology for conductivity estimation to guide EEG source localization. This Phase I project will quantify systematic bias in EEG source localization due to conductivity misspecifications and structural uncertainties and demonstrate the feasibility of noninvasive conductivity estimation of major head tissues using parameterized electrical impedance tomography measurements and realistic head geometry in computational models. This will lead to development of a product that will be able to non- invasively determine tissue conductivities, and when coupled with dense-array EEG, will provide unique functional information about brain state. The product innovation proposed in this project would improve the utility of EEG to not only perform functional assessment of the brain but also to accurately localize brain function. This technology will be affordable and portable. Consequently, EEG will be applicable to the management of many neurological disorders, such as epilepsy and stroke, which require acute assessment as well as continuous brain monitoring. [unreadable] [unreadable] [unreadable]