EL ESTRÉS AGUDO INTERFIERE CON LA EVOCACIÓN Y PROMUEVE LA EXTINCIÓN DE LA MEMORIA ESPACIAL EN EL LABERINTO DE BARNES. Acute Stress Impairs Evocation and Promotes Extinction of Spatial Memory in the Barnes Maze.

To evaluate the effects of acute stress on evocation and extinction of a spatial memory task, we used rats trained in the Barnes circular maze. The training protocol consisted of eight acquisition trials (intertrial interval, ITI; 5 min) where animals must learn to find an escape box placed under one of these eighteen holes of the maze. All animals learned the spatial memory task as indicated by diminished escape latency and weighted errors along the eight acquisition trials. Twenty four hours after training spatial memory evocation and extinction were tested (one trial with escape box, and seven consecutive trials without escape box, ITI: 5 min). One hour and a half before memory evaluation session half of the animals underwent movement restriction during one hour (one hour stress, 1H) and were allowed 30 min to recover, while the other half stayed in their home cage without manipulation (control, C). Stressed animals displayed a significant increase both in escape latency and in weighted errors during the trial with scape box. These results indicate that movement restriction-induced stress deteriorates the spatial memory evocation. Moreover, movement restriction-induced stress during one hour facilitates extinction, showed by the non-persistence in the exploration of the escape hole during the trials without escape box.