Level of response suppression and amphetamine effects on negatively punished adjunctive licking.
The purpose of the present study was to investigate whether the level of response suppression is a major determinant of the effect of D-amphetamine on negatively punished adjunctive drinking. Rats were initially exposed to a multiple fixed-time (FT) 30-s FT 30-s food delivery schedule. They were then divided into two groups and subjected to one of two different multiple schedules, FT 30-s FT 45-s or FT 30-s FT 90-s. The FT 45-s and FT 90-s components were signalled by a tone. Comparably high levels of adjunctive licking were observed in both FT 30-s components, intermediate licking levels in the FT 45-s component, and little licking in the FT 90-s component. Licking during the FT 30-s components was subsequently punished by lick-contingent signalled delays (by a blackout) in food delivery. The duration of such delays was adjusted to reduce licking to levels obtained in the FT 45-s or FT 90-s components, respectively for each of the two groups. Punished licking was increased by 0.3 and 1.0 mg/kg of D-amphetamine, an effect that was greater in the FT 30-s FT 90-s group. No increase in licking was observed in the FT 45-s component, but the 1.0 mg/kg dose also increased responding in the FT 90-s component. In general, no statistically significant differences were found between the effects of D-amphetamine on punished and unpunished schedule-induced licking. As licking decreased during the FT 90-s component when the punishment contingency was introduced in the alternate component, the punishment procedure and FT 30-s component were entirely removed. On this occasion, D-amphetamine failed to increase licking induced by the FT 90-s schedule. These results indicate that the level of response suppression might be a good indicator of the degree to which D-amphetamine shows antipunishment effects on adjunctive licking reduced by negative punishment procedures.
Pérez-Padilla
Angeles
A
Animal Behaviour Laboratories, Department of Basic Psychology I, Faculty of Psychology, National University for Distance Learning, Madrid, Spain.
Pellón
Ricardo
R
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D001245:Association Learning / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003913:Dextroamphetamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D007266:Inhibition, Psychological; D008297:Male; D011678:Punishment; D051381:Rats; D017208:Rats, Wistar; D012055:Reinforcement Schedule
D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine