Administration of Corticosterone After the First Downshift Trial Enhances Consummatory Successive Negative Contrast

BENTOSELA; RUETTI; MUZIO; MUSTACA; PAPINI

BEHAVIORAL NEUROSCIENCE.

Washington, D.C. : American Psychological Association

Lugar: Washington D.C., USA.; Año: 2006 vol. 120 p. 371 - 376

0735-7044

Rats given access to a 32% sucrose solution during ten 5-min daily trials spend more time in contact with the sipper tube than rats given access to a 4%  solution. However, a 32% to 4% downshift during the subsequent 5 trials results in less contact with the sipper tube than that exhibited by 4% unshifted controls. This phenomenon, called consummatory successive negative contrast, was found in Experiment 1 to be enhanced by a posttrial injection of corticosterone (3 mg/kg) administered immediately after the first downshifted trial (trial 11). Experiment 2 replicated this effect and further demonstrated the enhancing effect on negative contrast does not occur if corticosterone is administered 3 h after trial 11. These results support the hypothesis that corticosterone strengthens an aversive emotional component elicited by the surprising downshift in reward magnitude and present during the initial downshift trial.