Hunziker M H L, Dos Santos C V
Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Prof. Mello Moraes 1721, CEP 05508-030 - Cidade Universitária - São Paulo, Brazil.
Behav Processes. 2007 Nov;76(3):183-91. doi: 10.1016/j.beproc.2007.02.012. Epub 2007 Feb 16.
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.
三项实验研究了大鼠在应对反应要求、电击持续时间以及治疗与测试间隔方面的习得性无助。在实验1中，先前暴露于不可控电击或无电击的大鼠在四种不同的负强化条件之一进行测试：跑步的FR 1或FR 2逃避条件，以及跳跃的FR1逃避条件（最大电击持续时间为10秒或30秒）。结果表明，只有当动物在最大电击持续时间为10秒的跳跃FR 1逃避条件下进行测试时，不可控电击才会产生明显的操作性学习缺陷（习得性无助效应）。实验2将不可控性的影响与电击暴露本身的影响隔离开来，结果表明，使用FR 1逃避跳跃反应（电击持续时间为10秒）观察到的逃避缺陷是由电击的不可控性导致的。实验3表明，在测试中使用FR 1跳跃逃避条件时，在治疗后1天、14天或28天观察到了习得性无助效应。这些结果表明，跑步可能不是习得性无助的合适测试方法，并且文献中发现的许多不同结果可能是由于要求大鼠跑步时存在的应答性和操作性条件的混杂效应所致。
