Abstract
Discussion and Conclusion
The results of the present experiments, clearly indicate a retardation in the acquisition of an alternating pattern of immediate and delayed reward. This became evident after the 15th day of the trials in both the 2,500 and 5,000 rad groups (Fig. 1 and 2). This learning deficit is ascribed to the effects of ionizing radiation directed to the forebrain and not due to abscopal effects or motivational factors which affect performance. All animals ran equally well on the immediately rewarded trials. There were no significant differences in the learning curves of the 2,500 and 5,000 rad groups which was not surprising since light microscope examination of the nervous tissue revealed, in general, only minor neuropathological differences in the reaction of the neuronal, glial and blood vascular structures to the 2,5′00 and 5,000 rad doses.
Nearly all areas of the forebrain were irradiated. The beam included the hippocampus, thalamus, hypothalamus, basal ganglia and all of the cerebral cortex except the most rostral part. Aside from the two brains with large necrotic lesions the remainder of the irradiated brains evhibited moderate alterations in blood vessels and to a limited extent in the underlying white matter. Astroglial hypertrophy was a consistent finding in all irradiated brains.
Get full access to this article
View all access options for this article.