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Biomedical subjects

J B Overmier

Publications and source records attributed to J B Overmier.

At least 55 records · Page 3Linked to original sources
PubMed1979

Cranial irradiation of young rats impairs later learning and growth.

Young rats (26 days) were exposed to ionizing radiation of the head of 0, 1200, 2400, or 3000 rads total in 200 rads/day doses. The subsequent growth of irradiated rats was permanently impaired: such impairment was positively related to amount of irradiation. Beginning in adolescence, rats were trained on a horizontal/vertical visual discrimination in a runway task, and although all four groups mastered the discrimination, they differed in their patterns of acquisition. These results indicate long term effects are associated with a cranial irradiation regimen similar to that given to children suffering acute lymphocytic leukemia (ALL).

Animals↗
PubMed1979

On the mechanism of the post-asymptotic CR decrement phenomenon.

Three experiments with 49 dogs explored the decrease in CR magnitude that sometimes occurs when CS-US pairings are continued beyond those needed to reach maximum CR magnitude. The first experiment confirmed the existence of the phenomenon, obtaining less conditioned excitation after 300 CS-US trials than after 18 CS-US trials. The second experiment demonstrated that the phenomenon is not dependent upon paired CS-US presentations because 18 CS-US pairings yielded little excitation if preceded by, followed by, or intermixed with 282 US presentations. The third experiment indicated that in contrast to the decremental effects on excitatory conditioning, inhibitory conditioning was faciliated by large numbers of prior US exposures, suggesting explanation of the post-asymptotic decrement phenomenon by opponent-process theory.

Acoustic Stimulation↗