Abstract
This experiment was designed to test the effects of a 7 mg/kg dose of morphine sulfate on the extinction of a conditioned escape response in rats. Ten male albino rats were conditioned to escape a 30-v AC electric shock by running out of a start box, down a 3-ft runway and into a goal box. During extinction trials half the animals received 7 mg/kg of morphine sub-cutaneously (s.c.) and half received a subcutaneous (s.c.) injection of physiological saline as a placebo. The morphine group took a significantly greater number of trials to extinguish the escape response. It was concluded that morphine increased the resistance to extinction.
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This research was conducted at the NIMH Addiction Research Center, Lexington, Kentucky.
The author wishes to express his appreciation to the Staff at the NIMH Addiction Research Center and gratefully acknowledge their assistance in conducting this research.
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Collins, L.G. Effects of morphine sulfate on the extinction of conditioned escape behavior in the rat. Psychon Sci 3, 31–32 (1965). https://doi.org/10.3758/BF03343002
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DOI: https://doi.org/10.3758/BF03343002