Date of Award


Document Type


Degree Name

Master of Science in Psychology



First Advisor

Crawford, Cynthia

Second Advisor

McDougall, Sanders

Third Advisor

Peacock, Jean


Examines whether the reinforcing properties of drugs of abuse were altered in adulthood by methylphenidate, more commonly known as Ritalin. Subjects were 108 rats of Sprague-Dawley descent (Harlan). Methylphenidate, or saline was administered daily to the subjects from the postnatal period (11-20 days old). The rats preference for morphine during early adulthood was measured using conditioned place preference. The number of dopamine D₂ receptors was measured in each rat and the correlation between receptor number and morphine preference was determined. Results indicate that rats pretreated with methylphenidate showed greater preference for morphine than saline pretreated rats and suggests that exposure to methylphenidate during the postnatal period increases the rewarding value of morphine.