Radiofrequency current density imaging of kainate-evoked depolarization

The purpose of this study was to examine whether radiofrequency current den sity imaging (RF-CDI) can quantitatively monitor depolarizations evoked by excitatory amino acids in a rat's brain. To evoke depolarization, a glutama te receptor agonist, kainate, was administered into the right lateral ventr icle. First, electroencephalographic activity was recorded in a basal condi tion and after the application of kainate, Complex behavioral patterns were observed. Second, impedance measurements were performed to assess the chan ge in conductivity of the brain due to kainate at the Larmor frequency of t he imager, Calculated changes were about 17%, Third, a set of current densi ty images was obtained with RF-CDI before and after the administration of k ainate, Kainate-induced excitatory changes were observed on current density images as brighter regions, mainly in the hippocampal area compared with t he same area in the basal condition. Magn Reson Med 42:136-140, 1999. (C) 1 999 Wiley-Liss, Inc.