O efeito da omissão de reforço no repertório de ratos com lesão no complexo basolateral e no núcleo central da amígdala / The reinforcement omission effect on behavioral repertoire of rats with lesions in the basolateral complex and central nucleus of the amygdala

Reinforcement omission has been used as a procedure for the evaluation of attentional and motivational processes. Studies show that the activation of some amygdala nuclei may be involved in the modulation of these processes. This study examined the reinforcement omission effects on behavioral repertoire of rats with lesions in the central nucleus and basolateral complex of the amygdala, using classical conditioning and non-contingent reinforcement schemes. Each trial constituted of a 20 second tone, always followed by the delivery of water, in the 19th second. In the sessions involving omission, the water was delivered in half of the trials. The results showed that all groups responded to the omission and only the Basolateral group showed effect in the "Rearing" category, in the period after the omission. These results highlight the need to consider the involvement of a more complex neural network for evaluation of these effects.

A omissão de reforço tem sido usada como procedimento de avaliação dos processos atencionais e motivacionais. Estudos mostram que a ativação de alguns núcleos da amígdala pode estar envolvida na modulação destes processos. O presente trabalho examinou os efeitos da omissão do reforço no repertório comportamental de ratos com lesões no núcleo central e complexo basolateral da amígdala, utilizando-se de esquemas de condicionamento clássico e reforçamento não-contingente. Cada prática constituía de um sinal sonoro de 20 segundos, sempre seguido da liberação de água, no 19º segundo. Nas sessões que envolviam omissão, a água era liberada em metade das práticas. Os resultados mostraram que todos os grupos responderam à omissão e somente o grupo Basolateral apresentou efeito na categoria "Levantar-se", no período após a omissão. Estes resultados apontam a necessidade de se considerar o envolvimento de uma rede neural mais complexa para avaliação destes efeitos.

Effect of electrolytic and chemical lesion by ibotenic acid of the amygdala on salt intake

Sodium chloride intake was studied in male Holtzman rats weighing 250-300 g submitted to electrolytic and chemical lesion of the cell bodies, not fibers of the amygdaloid complex. Sodium chloride (1.5 percent) intake increased in animals with electrolytic lesion of the corticomedial nucleus of the amygdala. Sodium chloride (1.5 percent) intake increased after ibotenic acid injection into the corticomedial nucleus of the amygdala to a larger extent (26.6 + or - 9.2 to 147.6 + or - 34.6 ml/5 days). The results indicate that sodium inake response can be induced by lesions, which involved only cell bodies. The fibers of passage of the corticomedial nucleus of the amygdala produce a water intake less consistent than that induced by ibotenic acid, which is more acute. The results show that cell bodies of this region of the amygdala are involved in the control of sodium chloride intake