Euphoric responses toward the decrease of an aversive reward

SUAREZ, A.

Ciudad Autónoma de Buenos Aires

Congreso; II Congress of the Federation of Latin-American and Caribbean Societies for Neuroscience (FALAN); 2016

Sociedad Argentina de Neurociencias

The consummatory Sucessive Positive Contrast effect (cSPC) consist in a significant increase of consummatory responses toward an appetitive reward, after consecutively obtaining a low-magnitude reinforcer. Performance is compared to a control group that during the whole training received a high-magnitude reward. This phenomenon has been scarcely reported, probably due to methodological limitations inherent to the experimental protocols available, such as the ceiling effect. Likewise, evaluation of this phenomenon during ontogeny is nonexistent. The purpose of this study was to evaluate CPSc contrast effect in 14-17 days-old rats by manipulating the concentration of an aversive solution. Preweanling rats were exposed to 0.1% or 0.01% quinine solution during 4, 10-min, trials (pre-shift phase). All animals were then given two trials of exposure to 0.01% quinine (post-shift phase). The animals that shifted from a 0.1% to 0.01% quinine solution exhibited significantly greater intake of 0.01% quinine, along with a reduction in the emission of paw treading and enhancement of paw licking, an appetitive response, compared to the control group. Altogether, this evidence suggests the emergence of consummatory successive positive contrast during the second week of life of the rat. To our knowledge, this is the first evidence of positive contrast using an aversive solution.