McDowell Angela L, Heath Kathryn M, Garraghty Preston E
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA ; Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA ; Postdoctoral Associate, Department of Medicine, University of Pittsburgh, 628 NW MUH, 3459 5th Avenue, Pittsburgh, PA 15213, USA.
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.
Neurosci J. 2013;2013:893126. doi: 10.1155/2013/893126. Epub 2013 Feb 28.
Chronic stress has been shown to impact learning, but studies have been sparse or nonexistent examining sex or task differences. We examined the effects of sex and chronic stress on instrumental learning in adult rats. Rats were tested in an aversive paradigm with or without prior appetitive experience, and daily body weight data was collected as an index of stress. Relative to control animals, reduced body weight was maintained across the stress period for males (-7%, P ≤ .05) and females (-5%, P ≤ .05). For males, there were within-subject day-by-day differences after asymptotic transition, and all restrained males were delayed in reaching asymptotic performance. In contrast, stressed females were facilitated in appetitive and aversive-only instrumental learning but impaired during acquisition of the aversive transfer task. Males were faster than females in reaching the appetitive shaping criterion, but females were more efficient in reaching the appetitive tone-signaled criterion. Finally, an effect of task showed that while females reached aversive shaping criterion at a faster rate when they had prior appetitive learning, they were impaired in tone-signaled avoidance learning only when they had prior appetitive learning. These tasks reveal important nuances on the effect of stress and sex differences on goal-directed behavior.
慢性应激已被证明会影响学习，但研究性别或任务差异的研究很少或不存在。我们研究了性别和慢性应激对成年大鼠工具性学习的影响。大鼠在有或没有先前食欲体验的厌恶范式中进行测试，并收集每日体重数据作为应激指标。相对于对照动物，雄性（-7%，P≤0.05）和雌性（-5%，P≤0.05）在整个应激期体重均持续下降。对于雄性，在达到渐近线后存在个体内逐日差异，所有受限制的雄性达到渐近线表现均延迟。相比之下，应激雌性在仅涉及食欲和厌恶的工具性学习中得到促进，但在厌恶转移任务的习得过程中受损。雄性在达到食欲塑造标准方面比雌性更快，但雌性在达到食欲音调信号标准方面更有效。最后，任务效应表明，虽然雌性在有先前食欲学习时达到厌恶塑造标准的速度更快，但只有在有先前食欲学习时，她们在音调信号回避学习中才会受损。这些任务揭示了应激和性别差异对目标导向行为影响的重要细微差别。
