Neonatal Operant Conditioning in 5-day old rats: Changes in Milk Self-administration Patterns.

ARIAS, C; MOLINA, A; SPEAR, N.E.; MOLINA, J.C.

Atlanta, EEUU

Congreso; 39th Annual Meeting of the International Society for Developmental Psychobiology; 2006

International Society for Developmental Psychobiology

 Recent studies show that the newborn rat is capable of obtaining milk and other reinforcers by attaching to a surrogate nipple. Neonatal behaviors elicited by a nutritive surrogate nipple comprise suckling as well as head and forelimb movements similar to those observed during lactation. In this study the probability of occurrence of these behaviors was analyzed as a function of their contingency with intraoral infusions of milk. Neonates were positioned in a smooth surface texture having access to a tactil sensor. Physical contact with the sensor by means of head and/or forelimb movements activated an infusion pump which delivered milk intraorally. Yoked controls received the reinforcer whenever the paired counterpart activated the circuit. The contingency under analysis significantly modified the number of responses emitted after two (Experiment 1) or one 15 min. conditioning trials (Experiment 2). Moreover, paired newborns exhibited heightened levels of contacts with the sensor during an extinction test. Intake of the reinfocer did not differ between groups. Pups appeared to learn the contingency in only 15 minutes. These studies validate prior observations regarding the influence of operant-mediated behaviors during the suckling process. More importantly, the technique here developed, comparable to the one presented by Johanson & Hall (1981), allows to examine self-administration patterns of potential reinforcers within a minimum framework of time and hence to control intervening variables such as excessive maternal deprivation, nutritional deficits and fatigue.