Singh Teghpal, Jones Joshua L, McDannald Michael A, Haney Richard Z, Cerri Domenic Hayden, Schoenbaum Geoffrey
Program in Neuroscience, University of Maryland School of Medicine Baltimore, MD, USA.
Front Aging Neurosci. 2011 Mar 29;3:4. doi: 10.3389/fnagi.2011.00004. eCollection 2011.
Normal aging is associated with deficits in cognitive flexibility thought to depend on prefrontal regions such as the orbitofrontal cortex (OFC). Here, we used Pavlovian reinforcer devaluation to test whether normal aging might also affect the ability to use outcome expectancies to guide appropriate behavioral responding, which is also known to depend on the OFC. Both young and aged rats were trained to associate a 10-s conditioned stimulus (CS+) with delivery of a sucrose pellet. After training, half of the rats in each age group received the sucrose pellets paired with illness induced by LiCl injections; the remaining rats received sucrose and illness explicitly unpaired. Subsequently, responding to the CS+ was assessed in an extinction probe test. Although aged rats displayed lower responding levels overall, both young and aged rats conditioned to the CS+ and developed a conditioned taste aversion following reinforcer devaluation. Furthermore, during the extinction probe test, both young and aged rats spontaneously attenuated conditioned responding to the cue as a result of reinforcer devaluation. These data show that normal aging does not affect the ability to use expected outcome value to appropriately guide Pavlovian responding. This result indicates that deficits in cognitive flexibility are dissociable from other known functions of prefrontal - and particularly orbitofrontal - cortex.
正常衰老与认知灵活性缺陷有关，这种缺陷被认为依赖于前额叶区域，如眶额叶皮质（OFC）。在此，我们使用巴甫洛夫式强化物贬值来测试正常衰老是否也可能影响利用结果预期来指导适当行为反应的能力，而这种能力也已知依赖于眶额叶皮质。年轻和老年大鼠均接受训练，将10秒的条件刺激（CS +）与蔗糖颗粒的递送相关联。训练后，每个年龄组的一半大鼠接受与注射氯化锂诱导的疾病配对的蔗糖颗粒；其余大鼠接受蔗糖和疾病明确不配对的处理。随后，在消退探测测试中评估对CS +的反应。尽管老年大鼠总体上表现出较低的反应水平，但年轻和老年大鼠对CS +进行了条件化，并在强化物贬值后形成了条件性味觉厌恶。此外，在消退探测测试期间，年轻和老年大鼠均因强化物贬值而自发减弱了对该线索的条件反应。这些数据表明，正常衰老不会影响利用预期结果值来适当指导巴甫洛夫式反应的能力。这一结果表明，认知灵活性缺陷与前额叶（特别是眶额叶）皮质的其他已知功能是可分离的。
