Considerações sobre o modelo de seleção pelas consequências: o que mudou em 28 anos ? / Considerations about the selection by consequences model: what was changed in 28 years ?

Este artigo compara dois conjuntos de textos publicados no Brasil, em 1 988 e 201 6, focados na análise domodelo de seleção pelas consequências proposto por Skinner. São apresentados os contextos acadêmicosem que os dois conjuntos foram produzidos, um breve resumo das principais contribuições de cada texto,fazendo uma comparação entre eles para vislumbrar a evolução que se deu na comunidade de analistas decomportamento no Brasil ao longo dos últimos 28 anos. No final, sugere-se que novas publicaçõespossam analisar dados experimentais recentes e sua compatibilidade com o nível ontogenético de seleçãopor consequências, complementando as considerações teórico-filosóficas aqui apresentadas em relação àseleção nos níveis filogenético e cultural(AU)

Learned helplessness: effects of response requirement and interval between treatment and testing.

Three experiments investigated learned helplessness in rats manipulating response requirements, shock duration, and intervals between treatment and testing. In Experiment 1, rats previously exposed to uncontrollable or no shocks were tested under one of four different contingencies of negative reinforcement: FR 1 or FR 2 escape contingency for running, and FR1 escape contingency for jumping (differing for the maximum shock duration of 10s or 30s). The results showed that the uncontrollable shocks produced a clear operant learning deficit (learned helplessness effect) only when the animals were tested under the jumping FR 1 escape contingency with 10-s max shock duration. Experiment 2 isolated of the effects of uncontrollability from shock exposure per se and showed that the escape deficit observed using the FR 1 escape jumping response (10-s shock duration) was produced by the uncontrollability of shock. Experiment 3 showed that using the FR 1 jumping escape contingency in the test, the learned helplessness effect was observed one, 14 or 28 days after treatment. These results suggest that running may not be an appropriate test for learned helplessness, and that many diverging results found in the literature might be accounted for by the confounding effects of respondent and operant contingencies present when running is required of rats.

Opioid nature of learned helplessness and stress induced analgesia observed without re-exposure to shock.

It has been shown that uncontrollable shocks that produce learned helplessness also produce long-term opioid analgesia if th animal is re-exposed to shock immediately before the test. The present study was conducted in order to investigate if this effect can be observed 24h after the uncontrollable shock treatment without re-exposure to shock, and if it is opioid mediated. Long-term analgesia was found in the absence of re-exposure to shock, and was prevented by an i.p. injection of naloxone (10mg/kg) administered 10min before the test. The learned helplessness effect produced by the same shock treatment was prevented by the administration of 10 and 20mg/kg of naloxone 10min before the shuttlebox test, but not by a lower naloxone dose (5mg/kg). These findings suggest that the shock re-exposure requirement proposed in previous studies is not crucial in determining the long-term analgesia, and that both the long-term analgesia and the learned helplessness effect produced by this shock treatment were opioid mediated.

Effects of ipsapirone and BAY R 1531 on learned helplessness

The effects of the 5-hydroxytryptamine-1A (5-HT1A) receptor agonists on the learned helplessness test were investigated. Rats were submited to a single session of 60 uncontrollable shocks (10-s duration, 1.0 mA, every 60 + or - 40 s) and then treated twice daily with ip ijections of either ipsapirone (13 mg/kg daily) or BAY R 1531 (0.375 mg/kg daily) for four consecutive days. On the last day, the animals were submitted to an escap test. The results showed that both drug treatments blocked the deficit in the escape learning (helplessness effect). These data suggest that drugs which stimulate 5-HT1A receptors have an antidepressant-like activity in this animal model of depression