ABSTRACT
Even though the effects of overtraining and glucocorticoids on different phases of spatial memory are known, the interaction between these factors on the retrieval and extinction of spatial memory has not yet been described. Adult male Wistar rats received eight training trials per day in the Barnes maze for either one or two days. Twenty-four hours after the last training trial they were randomly assigned for receiving an intraperitoneal vehicle or corticosterone injection (0.125 or 0.5â¯mg/kg) and ten minutes later they were given a memory test, followed by seven extinction trials. Extinction retention was evaluated twenty-four hours after extinction. The second training session did not provoke significant changes regarding escape latency nor weighted errors, thereby showing that overtraining had been obtained. The overtrained animals performed better than the trained ones during the retrieval test. Corticosterone administration did not affect the overtrained animals' performance; by contrast, only the lower dose impaired trained animals' retrieval. Overtrained subjects acquired extinction more rapidly than those which received just one session, but corticosterone did not significantly modify extinction. However, whilst the spatial task remained extinguished in trained animals during the extinction retrieval test, spontaneous recovery occurred in overtrained animals. Such training intensity effects on extinction retrieval were reverted by corticosterone. Overall, these results suggested that overtraining modified the susceptibility of spatial memory's trace to the effects of corticosterone on retrieval and extinction.
Subject(s)
Corticosterone/administration & dosage , Extinction, Psychological/drug effects , Mental Recall/drug effects , Spatial Memory/drug effects , Animals , Male , Maze Learning , Rats, Wistar , Spatial LearningABSTRACT
El presente estudio evaluó si la escucha de música preferida por los participantes o la música relajante elegida por los investigadores previa al protocolo de estrés social modificado TSST (Trier Social Stress Test) afectaba el desempeño de las actividades realizadas durante el propio test, modulaba la respuesta de estrés que este induce, y en conjunto con el estresor, afectaba el desempeño en una tarea de atención en setenta y seis estudiantes universitarios asignados a uno de seis grupos: música relajante del investigador, música preferida por el participante y silencio, con o sin TSST Los resultados mostraron que la escucha de ambos tipos de música provocó una pendiente ascendente menos pronunciada en los niveles de cortisol en saliva luego del TSST, comparada con la que presentaron quienes no escucharon música, mientras que el aumento en la ansiedad-estado evaluada con el IDARE (Inventario de Ansiedad Rasgo-Estado) fue semejante en todos los grupos. No se encontraron diferencias debidas a la música en el desempeño de las tareas evaluadas. Se discute que la modulación de la escucha de música, independiente de la preferencia musical, tiene un efecto sobre la respuesta fisiológica de estrés posiblemente por la inducción de reacciones emocionales que esta provoca.
The present study examines the effects of listening to music selected by participants or relaxing music chosen by researchers before modified TSST (Trier Social Stress Test) on: 1) TSST tasks, 2) TSST-induced stress responses, and 3) one attention task with both music and TSST before it. Seventy six college students were randomly assigned to one of six groups: listening to relaxing music chosen by researchers, previously selected music by students, or silence, any of them with or without TSST Results showed that both relaxing or selected-by-participant music slowed salivary cortisol increase levels after TSST, whereas STAI (State-Trait Anxiety Inventory) increases were not significantly different. Listening to music has no significant effects on either TSST or attention tasks. Effects of listening to music on salivary cortisol levels due to possible emotional responses irrespective of music preference were discussed.
ABSTRACT
Long-Evans rats downshifted from 32% to 4% sucrose solution exhibit lower consummatory behavior during downshift trials than rats exposed only to 4% sucrose. In Experiment 1, this effect, called consummatory successive negative contrast (cSNC), was attenuated by administration of the benzodiazepine anxiolytic chlordiazepoxide (CDP, 5mg/kg, ip) before the second downshift trial (Trial 12), but was not affected when CDP was administered before the first downshift trial (Trial 11). In Experiment 2, CDP administered after Trial 11 actually enhanced the cSNC effect on Trial 12. This posttrial effect of CDP was reduced by delayed administration (Experiment 3). This CDP effect was not present in the absence of incentive downshift (Experiments 4-5), or when animals were tested with the preshift incentive (Experiment 6) or after complete recovery from cSNC (Experiment 7). The posttrial CDP effect was observed after an 8-day interval between Trials 11 and 12 (Experiment 8) and when administered after Trial 12, rather than Trial 11 (Experiment 9). Experiment 10 extended the effect to Wistar rats. Because CDP is a memory interfering drug, it was hypothesized that its posttrial administration interferes with the consolidation of the memory of the downshifted incentive, thus prolonging the mismatch between expected (32% sucrose) and obtained (4% sucrose) incentives that leads to the cSNC effect.
