Are all reinforcers the same? A memory consolidation perspective

增强剂的“记忆增强”假说产生了三个可检验的预测。首先，不同的增强剂应该通过对记忆巩固的重叠神经化学系统的作用来加强行为。其次，因为这些神经化学系统是重叠的，所以不同的增强剂之间应该存在行为上的相互作用。最后，在哺乳动物的大脑中，相互作用的神经化学系统汇聚成巩固记忆的主要“途径”。 为了测试这些预测，将训练Spraogue-Dawley大鼠将特定动作(自我给药时按下杠杆)或环境刺激(放置条件时的白色小室)与各种增强剂的提供联系起来。在训练之后，将通过评估学习的行动的持久性或在没有增强剂的情况下接近环境刺激的频率来衡量这些联系的记忆。 研究1-9将使用药理学和神经生物学方法来研究糖精、果糖、葡萄糖、羟考酮和可卡因参与的记忆巩固系统。之所以选择这些增强剂，是因为尽管它们对身体和大脑有不同的影响，但它们都是由大鼠自行给药的。这些“甜食”将自行口服，药物将静脉注射。在研究10中，大鼠将接受双重自我给药程序的训练，并将在存在或不存在一种或两种增强剂的情况下，在各种测试中表征行为交互作用。最后，研究11-13将使用神经药理学方法来探索多巴胺和去甲肾上腺素之间的相互作用，这两个系统可能有助于通过所有增强刺激激活记忆巩固的途径。 这个创新的研究项目调查心理学和神经科学中长期存在的基本问题。在记忆巩固的背景下，还没有系统地探讨不同增强剂对神经和行为的影响。而且，解决各种增强剂如何促进学习的问题，不仅是理解行为的核心，而且也与人类健康(例如肥胖和物质依赖)直接相关。

The “memory enhancing” hypothesis of reinforcers generates three testable predictions. First, different reinforcers should strengthen behavior through actions on overlapping neurochemical systems of memory consolidation. Second, because these neurochemical systems overlap, there should be behavioural interactions between different reinforcers. Finally, in the mammalian brain, interacting neurochemical systems converge into a primary “pathway” of memory consolidation. To test these predictions, Sprague-Dawley rats will be trained to associate particular actions (pressing a lever during self-administration) or environmental stimuli (a white chamber during place conditioning), with the delivery of various reinforcers. Following training, the memories of these associations will be measured by assessing the persistence of the learned actions, or the frequency of approach to the environmental stimuli, in the absence of reinforcers. Studies 1-9 will employ pharmacological and neurobiological methods to study systems of memory consolidation engaged by saccharin, fructose, glucose, oxycodone and cocaine. These reinforcers have been selected because, although they have different effects on the body and on the brain, they are all self-administered by rats. The “sweets” will be self-administered intraorally and the drugs intravenously. In Study 10, rats will be trained in a dual self-administration procedure, and behavioural interactions will be characterized during various tests in the presence and absence of one or both reinforcers. Finally, Studies 11-13 will employ neuro-pharmacological methods to explore the interaction between dopamine and noradrenaline; two systems that likely contribute to a pathway of memory consolidation activated by all reinforcing stimuli. This innovative program of research investigates long-standing, basic questions in psychology and neuroscience. There have been no systematic explorations of the neural and behavioral effects produced by different reinforcers in the context of memory consolidation. And, addressing the question of how various reinforcers promote learning, is not only central to the understanding of behavior, but it is also of direct relevance to human health (e.g., obesity and substance dependence).