Environmental cues attain the ability to guide behavior via learned associations. As predictors, cues can elicit adaptive behavior and lead to valuable resources (e.g., food). For some individuals, however, cues are transformed into incentive stimuli and elicit motivational states that can be maladaptive. The goal-tracker/sign-tracker animal model captures individual differences in cue-motivated behaviors, with reward-associated cues serving as predictors of reward for both phenotypes but becoming incentive stimuli to a greater degree for sign-trackers. While these distinct phenotypes are characterized based on Pavlovian conditioned approach behavior, they exhibit differences on a number of behaviors relevant to psychopathology. To further characterize the neurobehavioral endophenotype associated with individual differences in cue-reward learning, neuroendocrine and behavioral profiles associated with stress and anxiety were investigated in male goal-tracker, sign-tracker, and intermediate responder rats. It was revealed that baseline corticosterone increases with Pavlovian learning, but to the same degree, regardless of phenotype. No significant differences in behavior were observed between goal-trackers and sign-trackers during an elevated plus maze or open field test, nor were there differences in corticosterone response to the open field test or physiological restraint. Upon examination of central markers associated with stress-reactivity, we found that sign-trackers have greater glucocorticoid receptor mRNA expression in the ventral hippocampus, with no phenotypic differences in the dorsal hippocampus or prelimbic cortex. These findings demonstrate that goal-trackers and sign-trackers do not differ on stress- and anxiety-related behaviors, and suggest that differences in neuroendocrine measures between these phenotypes can be attributed to distinct cue-reward learning styles.

中文翻译：

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雄性目标跟踪器和体征跟踪器大鼠应激反应的神经内分泌和行为测量

环境提示可以通过学会的关联来指导行为。作为预测因子，线索可以引起适应性行为并导致有价值的资源（例如食物）。但是，对于某些人来说，提示会转变为激励刺激并引发可能具有不良适应能力的激励状态。目标跟踪器/符号跟踪器动物模型捕获提示动机行为中的个体差异，与奖励相关的线索充当两种表型的奖励预测因子，但在更大程度上成为标志跟踪器的激励刺激。虽然这些独特的表型是基于巴甫洛夫条件式进场行为来表征的，但它们在许多与心理病理学相关的行为上表现出差异。为了进一步表征与线索奖励学习中的个体差异相关的神经行为内表型，在雄性目标追踪者，体征追踪者和中级反应者大鼠中研究了与压力和焦虑相关的神经内分泌和行为特征。结果表明，基线巴氏皮质激素随着巴甫洛夫式学习而增加，但是无论其表型如何，其皮质酮水平都相同。在高架迷宫或野外测试期间，目标追踪器和体征追踪器之间的行为没有显着差异，皮质酮对野外测试或生理限制的反应也没有差异。通过检查与应激反应相关的中心标志物，我们发现体征追踪者在腹侧海马中具有更大的糖皮质激素受体mRNA表达，而在背侧海马或前肢皮层中没有表型差异。