MRI Localization of Extracellular Electrodes using Metallic Deposition at 1.5T J. S. Pezaris and D. J. Dubowitz Computation and Neural Systems California Institute of Technology, Pasadena, CA 91125, U.S.A. Introduction Extracellular electrodes are widely used in neuroscience applications for electrophysiological recordings from cerebral cortex. Spatial localization of the exact recording site has traditionally relied on accurate stereotaxic positioning and histological confirmation of areas of gliosis at the end of the study. A novel technique described in rats by Fung et al involves electrodeposition of a small amount of iron along the electrode tract, to be later localized with high-field MRI. We investigated a similar approach at conventional (1.5T) field strengths, allowing neuroscience centers studying larger animal models, or without recourse to dedicated high field systems, to use more readily available conventional scanners, and thus avoid unnecessary histology. Fetch PDF of paper Fetch postscript of paper John Pezaris, Caltech, Mail Code 216-76, Pasadena, CA 91125, john@pezaris.com, 8 January 1999.