Abstract

In our previous study, we reported that chronic morphine exposure changes neuronal response properties in rat somatosensory cortex. In this study, we investigated the effect of chronic morphine treatment on tactile learning behavior in rats. Morphine sulfate was dissolved in tap water, and was administered for 21 days. Tactile learning was assessed using the novel object recognition test (NORT) in a dark room. The chronic morphine treated group exhibited a learning impairment; the discrimination ratio was significantly lower as compared to the control group. These findings suggest that chronic exposure to morphine impaired the tactile learning in rats as the discrimination ratio was decreased following morphine administration.

Key words: Morphine, tactile learning, rat.