Primary visual cortex in ferrets is a model system for studying the plasticity and development of neuronal feature maps, such as maps of retinotopy, orientation and spatial frequency. Previous studies examining the nature of these maps and their relationships have primarily utilized optical imaging of intrinsic signals, and have focused on the superficial layers of V1 (Sharma et al., 2000; Yu et al., 2005). To extend our understanding to the deep layers of V1 and to other cortical areas, we have developed chronic, non-invasive procedures to measure visual feature maps in anesthetized, paralyzed ferrets using high-resolution functional magnetic resonance imaging (fMRI). Central to our measurements is a skull implant that has allowed us to precisely place a small coil (1.0-1.5 cm diameter) to ensure consistent coil position and coverage across imaging sessions. We have made three types of measurements in normal ferrets. First, we measured fMRI responses to gratings (~0.1 cpd, 1 Hz) compared to blank, using a 1-shot spin-echo EPI sequence with 0.5 mm iso-voxel resolution (TE: 30 ms, TR: 2.4 s, 14 slices). Robust responses (>1% amplitude, p <0.01) could be readily observed across the visual cortex within just 3 minutes of imaging time. Next, we measured fMRI responses to a single bar presented at a series of visual locations using the same EPI sequence, and obtained maps of visual elevation and azimuth that were found to be comparable to those from optical imaging. Third, fMRI responses to gratings in a series of orientations (0, 45, 90, 135 degrees) were measured using spin-echo EPI (TE: 30 ms) in 1-shot (TR: 2.4 s, 0.3X0.3X0.6 mm) or 2-shot (TR: 2 s, 0.2X0.25X0.6 mm) with 6 slices tangential to cortical surface. Data averaged from 1 hour of imaging time showed clusters of voxels with weak but reliable orientation-selective responses (0.5% amplitude, p < 0.05). Systematic and detailed investigation of these maps of retinotopy and orientation across the different visual areas in ferret brain are underway. Similar procedures were applied to image visual responses in auditory cortex of "rewired" ferrets (Sharma et al., 2000). Robust visual responses were found in some areas of rewired auditory cortex in response to high contrast grating stimuli.