Role of context in the extinction paradigm in preweanlig rats

REVILLO DAMIÁN; TREBUCQ GASTÓN; PAGLINI GABRIELA; ARIAS CARLOS

San Sebastían

Congreso; 48th annual meeting of the International Society for Developmental Psychobiology; 2015

Society for Developmental Psychobiology

While Pavlovian extinction has been widely studied in adult organisms,only few studies have focused on this effect during infancy. Although it iscurrently accepted that the extinction effect reflects new ?context-dependent-learning, this is not so clear during infancy, because some studies didnot find recovery of the extinguished CR before postnatal day (PD) 21.The authors concluded that extinction during infancy erases the CS-USassociation. However, we have recently reported evidences of renewal,more rapid reacquisition, reinstatement and spontaneous recovery of anextinguished CR in preweanling rats. The present study analyzed thepossibility of recovering an extinguished CR with a reinstatementprocedure in a fear conditioning paradigm, on PD17 (Experiment 1?4)and on PD23 (Experiment 5). At the same time, it was explored the roleof context salience as a procedural variable that may affect extinctionduring the preweanling period. In accordance with previous studies formour laboratory, results shown that preweanling rats expressed a previouslyextinguished CR after a single experience with an unsignaled US(Experiments 2 and 4a). Furthermore, this result was only found whensubjects were trained and tested in salient contexts, but not in standardones (Experiments 3 and 4b). Finally, Experiment 5 demonstrated thereinstatement effect on PD23 in a standard context. These results are inagreement with previous findings showing that the extinction effect duringinfancy shares features with extinction learning in adult organisms.[BID-PICT 0892 to G. Paglini and C. Arias]