A novel approach to studying the neurobiology of decision-making: modeling cognitive effort in rats

认知神经科学和行为神经科学的首要目标之一是了解我们选择特定选项的机制，以及不同的因素如何影响这一决定。在基于实验室的范例中，决策框架内的特定因素（延迟/概率/努力）是系统变化的，这为我们提供了大量关于潜在神经系统的信息，在某种程度上，神经化学系统涉及不同形式的决策。通过将这些任务转化为非人类动物模型，有可能测试由人类数据提出的因果关系，并进一步描述选择过程的药理学和分子调控。考虑到这个世界上的大多数决定都需要认知努力的分配，我们的建议解决了老鼠在做决定时是否对精神紧张的维度敏感，以及在执行这些判断时可能涉及哪些神经生物学过程的问题。为此，我们开发了一种新的范例——大鼠认知努力任务（R-CET）——在这项任务中，大鼠选择是执行一项需要注意力的任务，在这项任务中，它们必须检测到非常短暂的光刺激的空间位置，还是执行一项更容易的任务，在这项任务中，刺激被照亮的时间更长，因此更容易定位。正确执行更困难的选择将获得更大的奖励。有趣的是，动物在选择难度较大的实验时，个体差异显著，这导致了动物被分为“勤奋”和“懒惰”两类。这种分类与动物进行困难或简单试验的能力无关，也就是说，不管刺激持续时间如何，工作的动物和偷懒的动物在检测视觉目标时都一样准确。因此，我们似乎可以将付出认知努力的意愿与完成更费力任务的能力区分开来。本提案中概述的实验旨在建立我们对这一新颖决策任务的初步描述，并确定涉及的大脑区域、化学物质和分子信号通路。

Understanding the mechanism by which we come to prefer a particular option, and how different factors can influence that decision, is one of the overarching goals of both cognitive and behavioural neuroscience. Laboratory-based paradigms in which a particular factor within a decision frame (delay/ probability/ effort) is systematically varied have provided us with a wealth of information regarding the potential neural, and to some extent, neurochemical systems implicated in different forms of decision-making. By translating these tasks into non-human animal models, it is possible to test the causative relationships suggested by human data, and delineate further the pharmacological and molecular regulation of the choice process. Given that most decisions in this world require allocation of cognitive effort, our proposal addresses the question of whether rats are sensitive to the dimension of mental strain when making decisions, and what neurobiological processes may be involved in the execution of such judgements. To this end, we have developed a novel paradigm- the rat cognitive effort task (R-CET)- in which rats choose whether to perform an attentional demanding task, in which they have to detect the spatial location of a very brief light stimulus, or an easier task, in which the stimulus is illuminated for longer and is therefore easier to localise. 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 accurate at detecting the visual target, regardless of the stimulus duration. Hence, it would appear that we can separate willingness to exert cognitive effort from the ability to perform a more effortful task. The experiments outlined in this proposal aim to build on our initial characterisation of this novel decision-making task, and determine the brain areas, chemicals and molecular signalling pathways involved.