Deciphering decision making: exploring the interactions between neural and neurochemical systems underlying the evaluation versus employment of cognitive effort in rats

大多数决定我们经济成功的关键决策都涉及在提供较低回报的简单决策与提供巨大回报的困难决策之间做出选择。 了解我们的大脑如何做出这样的决定是认知和行为神经科学学科的主要目标之一。 通过研究健康志愿者在实验室游戏中的决策过程，我们获得了很多有用的信息，但通常很难确定观察到的大脑活动和选择模式之间的关系是否表明大脑区域正在导致某人以某种方式行事，或者仅仅与行为相关。 通过将这些游戏转化为非人类动物（如实验室大鼠）的行为任务，可以直接测试大脑区域与决策之间因果关系的强度，因为可以以令人难以置信的精度和控制暂时关闭特定大脑区域的神经活动。 此外，通过给予大鼠不同的药物，如纯化形式的大麻，并评估这些化合物是否真的改变认知，以及在什么样的时间尺度上，可以确定哪些大脑化学物质参与决策。 这些影响是否立即出现，如果反复给药，它们会如何变化？ 为了尝试回答这些问题，我们开发了大鼠认知努力任务（rCET）。 在这个任务中，大鼠选择是否执行一个需要注意力的任务，在这个任务中，它们必须正确地发现一个非常短暂的光刺激，或者一个更容易的任务，在这个任务中，灯打开的时间更长，因此更容易定位。 正确地完成一个更难的选择会带来更大的回报。 有趣的是，动物选择更难的试验的程度存在明显的个体差异，导致动物被分为“工作者”或“懒汉”。 这种分类与动物进行困难或简单试验的能力无关，即工作者和懒汉在检测视觉目标方面都一样好，不管这有多难。 因此，看来，愿意发挥认知努力是不同的，并可以变化，不管，执行一个更努力的任务的能力。 我们现在想用这个行为游戏来研究老鼠的大脑区域和大脑化学物质调节决策，以及改变工作意愿的药物实际上对大脑内的神经元产生了什么影响，从而产生了行为效应（它们是激活了某些大脑区域，还是减少了细胞与细胞的交流？） 从长远来看，我们想知道是什么让一些老鼠自然地更有可能选择更难，但更有价值的选择，而一些老鼠则想“偷懒”。这就是本研究计划的目标。

Most of the key decisions that determine our economic success involve the choice between something easy that provides lower returns, or something difficult that, should we succeed, provides great reward. Understanding how our brains make such decisions is one of the primary goals of the academic disciplines of cognitive and behavioural neuroscience. A lot of useful information is obtained from studying the decision making of healthy volunteers in laboratory-based games, but it is often hard to determine whether relationships observed between, say, brain activity and choice patterns indicate that a brain region is causing someone to act a certain way, or simply correlates with behavior. By translating these games into behavioral tasks for non-human animals, such as laboratory rats, it is possible to directly test the strength of causal relationships between brain regions and decision making, as it is possible to temporarily shut down neural activity in a particular brain region with incredible precision and control. Furthermore, it is possible to determine what kinds of brain chemicals are involved in decision making by giving rats different drugs, such as purified forms of cannabis, and evaluating whether such compounds really do alter cognition, and over what kind of timescale. Are the effects present right away, and how do they change if the drugs are given repeatedly? To try and answer such questions, we have developed the rat cognitive effort task (rCET). In this task, rats choose whether to perform an attentionally demanding task, in which they have to correctly spot a very brief light stimulus, or an easier task, in which the light is turned on for longer and is therefore easier to locate. Correct performance of a more difficult option leads to a greater amount of reward. Interestingly, there are marked individual differences in the degree to which animals select the harder trials, leading to the classification of animals as either “workers” or “slackers”. This classification is independent of animals' ability to perform the hard or easy trials i.e. both workers and slackers are just as good at detecting the visual target, regardless of how difficult that is. Therefore, it would appear that willingness to exert cognitive effort is distinct from, and can vary regardless of, the ability to perform a more effortful task. We now want to use this behavioral game for rats to figure out which brain regions and brain chemicals regulate decision making, and what drugs that alter willingness to work actually do to the neurons inside the brain to produce their behavioral effects (do they activate certain brain areas, or reduce cell-to-cell communication?) In the long term, we want to find out if we can tell what makes some rats naturally more likely to choose harder, but more rewarding options, and some to want to “slack off”. These are the goals of this research program.