Para-chlorophenylalanine: Its effects on auditory discrimination.

The effects of Para-chlorophenylalanine (P-CPA) on the discrimination of a low intensity tone were evaluated. Three rats were trained in a two-lever operant chamber to press the right lever to terminate a tone and to press the left lever when the tone was off for food reinforcement. Errors, consisting of left-lever responses when the tone was on or right-lever responses when the tone was off, were recorded and used to determine the percent of the total responses that were correct. After training to essentially errorless performance, the tone intensity was lowered until the rats were performing at about 75% correct responses. After each rat achieved a stability criterion, it was treated P. O. with 150 mg/kg of P-CPA in mineral oil or with mineral oil alone. Each rat received P-CPA at least twice and mineral oil alone at least once. P-CPA consistently elevated the percent of correct responses while depressing the over-all response rate. Mineral oil had no effect on either measure. [ABSTRACT FROM AUTHOR]