Attenuation of x-ray-induced taste aversions by olfactory-bulb or amygdaloid lesions

These experiments used Sprague-Dawley derived rats to study the effects of either olfactory-bulb or amygdaloid lesions on x-ray-induced taste aversions. Sham-operated and normal subjects exposed to 60 roentgens of x-radiation following saccharin ingestion developed marked saccharin aversions while sham-irradiated controls maintained strong saccharin preferences. Olfactory-bulb lesions supported reports that bulbectomies can partially disrupt the acquisition of x-ray-induced saccharin aversions. Suggestive evidence of similar aversion disruption was also observed following amygdaloid lesions. A second experiment which produced stronger aversions showed that amygdaloid lesions can impair the acquisition of x-ray-induced saccharin aversions. This experiment also confirmed that bulbectomized subjects do develop significant aversions under appropriate conditioning parameters. Olfactory-bulb lesions approximated total bulbectomies while amygdaloid lesions were centered in the corticomedial amygdala with some damage to basolateral nuclei. Bulbectomy results are discussed in relation to nonsensory contributions of the olfactory bulbs. Amygdaloid lesions are related to possible contributions of different amygdaloid regions.