Navegando por Assunto "Luz"

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Acesso aberto (Open Access)
Desamparo aprendido com o zebrafish (Danio rerio)
(Universidade Federal do Pará, 2014-05-23) NASCIMENTO, Gabriela Souza do; GOUVEIA JUNIOR, Amauri; http://lattes.cnpq.br/1417327467050274
Exposure to uncontrollable aversive events leads to difficulty in learning contingency relations, escape and/or avoidance. Such phenomenon was named learned helplessness and it has been correlated to depression and post-traumatic stress disorder. This thesis is composed by three studies that together have the aim of: producing learned helplessness in Danio rerio (Study I); investigating the effects of light on the escape test (Study II) and evaluating the effects imipramine have on learned helplessness when applied acutely in Danio rerio (Study III). In every experiment it was used an acrylic shutllebox (INSIGHT equipment) which contained a central area (removable) that enabled the isolation of the subjects. The general protocol consisted in two phases: 1) Treatment, each subject of the Uncontrollable shock (USH) treatment was subjected to 60 random and uncontrollable shocks (0.7 – 0.9V, lasting 30 seconds each), in this phase the subjects of the group that didn't receive treatment with electric shock (NSH) only remained in the central area for 60 minutes; and 2) Test, each subject from both groups was subjected to an escape session with 30 shocks (0.7 – 0.9V, maximum duration of 30 seconds each). In Study I, 3 groups were used, one experimental (EGUSH) and two controls, one remaining in the experimental aquarium for 60 minutes without shock (CG-NSH). In Study II, 4 groups were used, a pair from NSH and USH subjected to the light test, another pair (NSH and USH) underwent the test no light condition. In Study III 6 groups were used according to the concentration of imipramine administered during 10 minutes before the test session: 0.0 mg/l NCH; 0.0 mg/CHI; 1.0 mg/l NCH; 1.0 mg/l CHI; 2.0 mg/l NCH; e 2.0 mg/l CHI. The main results show that it is possible to create learned helplessness in Danio rerio (study I), considering light as a variable that can interfere directly in the acquisition of the phenomenon (study II), in addition, it was showed that acute imipramine in the doses administered here did not revert the learned helplessness in Danio rerio.
Acesso aberto (Open Access)
O jato de ar quente como estímulo aversivo: delineamento de sujeito único e sensibilização
(Universidade Federal do Pará, 2015-11-10) PUREZA, Heloisa Quaresma; CARVALHO NETO, Marcus Bentes de; http://lattes.cnpq.br/7613198431695463
Previous studies which tested the Hot Air Blast (HAB) as an alternative stimulus to electric shock only used between-groups designs although the single-subject designs also are appropriate to examine behavioral measures. One of this studies proposed that the presence of light during the experimental session would affect the aversive function of the HAB, making it more effective in suppressing operant bar-pressing response. The aim of this study was (a) evaluate the aversive function of JAQ on a single subject design and (b) to test the hypothesis about the increase of the suppressive function of HAB in the presence of light. To test this, 16 albino rats were divided into two groups and exposed to three experimental phases. In Pre-Punishment phase lasted a multiple schedule in which two components (light/dark) succeeded randomly every two minutes, both on a VI 30sec contingency. In Punishment phase, the same experimental conditions were maintained, but the aversive contingency (in FR1) was superimposed on the VI 30sec. during the light component, for group Punishment light (PL), and the dark component, for group Punishment Dark (PD). In the Post-Punishment phase, aversive contingency was suspended for both groups. The results showed that subjects emitted high rates of bar-pressure responses during the Pre-Punishment and Post-Punishment, but this behavior was suppressed during the punishment components in Punishment phase. The results also showed no differences in the suppression of operant bar-pressing response when the HAB was presented in the presence or absence of light (Punishment phase). Therefore, once again the HAB was effective as a punisher stimulus for operant responses and the presence or absence of light, under the manipulated conditions, did not change the aversive function of the HAB.