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In order to determine possible effects of exposure to nuclear magnetic resonance imaging (MRI) on cognitive processes, the performance of imaged, sham exposed, and control rats on a spatial memory task was examined. This particular task was chosen because, under some conditions, animals use the magnetic field as a compass when navigating. The rats were required to collect food from eight different locations before returning to an already chosen location. All three groups of rats achieved a high level of performance, and there were no differences between groups in any of the performance measures examined. These results indicate that the MRI procedure has no significant effect on spatial memory processes in rats.

The effect of exposure to the magnetic and radio-frequency fields associated with Nuclear Magnetic Resonance Imaging (MRI) on two standard animal behavior tests, was examined in rats. In the first experiment male rats were given a baseline open-field test and 48 hrs later exposed for 22.5 min to a MRI procedure, a sham imaging procedure, or a control condition. Immediately after this exposure period a second open-field test was administered. All animals were given 4 more daily exposures to their respective treatment conditions and after the last exposure period a third open-field test was given. Analysis of open-field ambulation, rearing, and defecation responses indicated no significant effect of exposure to MRI on these behaviours. In a second experiment rats were conditioned in a step-down passive avoidance task and then exposed for 23.2 min (48 hrs later) to MRI, sham imaging, or control conditions. Retention tests for the passive avoidance response were administered after the first and fifth daily exposure to the experimental treatment conditions. No significant effects of the treatment conditions on retention of the avoidance response were obtained and a third retention test 3 months after the second test, also failed to provide any evidence for treatment effects. These results fail to provide any evidence for short or long term behavioral changes in animals exposed to MRI.