Level of response suppression and amphetamine effects on negatively punished adjunctive licking

Abstract

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.

Intromisión de una sesión de beber inducido por el programa en un perido de 24 horas

“…dado que en todos los experimentos de BiP se observó el consumo de agua exclusivamente durante las sesiones, sesiones de BeBeR inducido en PeRíodos de 24 hoRas los investigadores llegaron a ciertas conclusiones que posiblemente fueron engañosas. Por ejemplo, desde el estudio en el que falk (1961) reportó por primera vez la ocurrencia del BiP hasta estudios recientes (e.g., Pérez-Padilla & Pellón, 2006) varios autores concluyeron que no existía una razón aparente para que las ratas bebieran agua consistentemente. Esta afirmación se basó en el supuesto de que dado que las ratas tenían una botella con agua disponible continuamente en sus cajas habitación, las ratas no estaban privadas de agua (cf.…”