Artículos de revistas
Learned helplessness and immunization with different escape responses in rats
Desamparo aprendido e imunizaçáo com diferentes respostas de fuga
Autor
Yano, Yuristella
Leite Hunziker, Maria Helena
Institución
Resumen
Two experiments were conducted in order to test the learned helplessness and the immunization effects as a function of the activity level of the escape responses: the jumping and the nose poking, classified as active and passive responses, respectively In experiment 1, rats were divided in four groups exposed to two sessions. On the first session, the rats were submitted to uncontrollable shocks or no shocks treatment, followed by the second session where they were exposed to an escape procedure with the jumping or the nose poking responses. In experiment 2, six groups of rats were exposed to three sessions. On the first session, some rats had the opportunity to escape the electric shocks by performing the nose poking response, others received uncontrollable shocks or no-shocks. On the second session, half of animals from each group was exposed to uncontrollable shocks and half was exposed to no-shocks. On the third session all rats were tested for escape shocks by performing the jumping response. The results showed that the learned helplessness effect was equally observed with active or passive responses, and that the training with a low activity response immunized the rats against the learned helplessness. These results are discussed considering the learned helplessness and the learning inactivity hypotheses. Foram realizados dois experimentos com o objetivo de investigar o desamparo aprendido e a imunizaçâo, em ratos, em funçâo do nível de atividade motora da resposta a ser aprendida: "saltar" e "focinhar", classificadas como de alta e baixa atividade, respectivamente. No experimento 1, os animáis foram subrnetidos a duas sesssões, sendo na primeira expostos a choques incontroláveis ou nenhum choque, e na segunda submetidos a urna contingéncia de fuga com as respostas de saltar ou focinhar. No experimento 2, os sujeitos foram submendos a trĕs sessões: na pnmeira receberam choques controláveis (resposta de focinhar), choques incontroláveis ou nenhum choque; na sesssâo seguinte, metade dos animais de cada grupo foi exposta a choques incontroláveis e metade a nenhum choque; na terceira sesssâo, todos os animais foram submetidos a urna contingĕncia de fuga com a resposta. de saltar. Os resultados mostraram dificuldade de aquisiçáo da resposta de fuga em todos os grupos previamente expostos a choques incontroláveis (desamparo), mas a primeira experiĕncia prévia com controle impediu o aparecimento deste efeito (imunizaçáo). Os resultados mostraram igual nível de desamparo nos testes com respostas de alta e baixa atividade motora. Além disso, o treino de fuga com resposta pouco ativa imunizou os sujeitos contra o desamparo. Estes resultados sâo discutidos considerando-se as hipóteses do desamparo aprendido e da inatividade aprendida