Neuroscience Graduate Program.
Undergraduate Program in Neuroscience.
eNeuro. 2021 May 6;8(3). doi: 10.1523/ENEURO.0384-20.2021. Print 2021 May-Jun.
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 (GT)/sign-tracker (ST) 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 STs. While these distinct phenotypes are characterized based on Pavlovian conditioned approach (PavCA) 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 GT, ST, and intermediate responder (IR) rats. It was revealed that baseline corticosterone (CORT) increases with Pavlovian learning, but to the same degree, regardless of phenotype. No significant differences in behavior were observed between GTs and STs during an elevated plus maze (EPM) or open field test (OFT), nor were there differences in CORT response to the OFT or physiological restraint. Upon examination of central markers associated with stress reactivity, we found that STs have greater glucocorticoid receptor (GR) mRNA expression in the ventral hippocampus, with no phenotypic differences in the dorsal hippocampus or prelimbic cortex (PrL). These findings demonstrate that GTs and STs do not differ on stress-related and anxiety-related behaviors, and suggest that differences in neuroendocrine measures between these phenotypes can be attributed to distinct cue-reward learning styles.
环境线索通过学习关联获得指导行为的能力。作为预测因子，线索可以引发适应性行为，并引导人们获得有价值的资源（例如食物）。然而，对于某些人来说，线索会转变为激励刺激，并引发可能适应不良的动机状态。目标追踪器（GT）/信号追踪器（ST）动物模型捕捉到了线索驱动行为的个体差异，奖励相关的线索既是两种表型的奖励预测因子，但对 ST 来说，更像是激励刺激。虽然这些不同的表型是基于条件反射接近（PavCA）行为来定义的，但它们在许多与精神病理学相关的行为上存在差异。为了进一步描述与线索奖励学习个体差异相关的神经行为表型，研究了雄性 GT、ST 和中间反应者（IR）大鼠的神经内分泌和与应激和焦虑相关的行为特征。结果表明，基础皮质酮（CORT）随着条件反射学习而增加，但无论表型如何，增加程度相同。在高架十字迷宫（EPM）或旷场测试（OFT）中，GT 和 ST 之间没有观察到行为上的显著差异，也没有观察到 CORT 对 OFT 或生理限制的反应有差异。在检查与应激反应相关的中枢标志物时，我们发现 ST 在腹侧海马体中的糖皮质激素受体（GR）mRNA 表达更高，而在背侧海马体或前额叶皮层（PrL）中没有表型差异。这些发现表明，GT 和 ST 在与应激和焦虑相关的行为上没有差异，并表明这些表型之间神经内分泌测量值的差异可以归因于不同的线索奖励学习方式。
