Cerebellum and Habit

项目摘要 我们的很多行为都是习惯性的。习惯被定义为自动启动的行为，以响应 刺激，这意味着行为的可能结果的神经表征（例如，奖励）不 控制这些行为。习惯学习和行为表现的神经机制具有临床意义 相关性，因为强迫症，如强迫症和毒瘾，很可能 涉及习惯和目标导向的行为控制之间的不平衡。最突出的理论是 刺激-行为关联--激活习惯行为的刺激的神经表征-- 形成的结果多巴胺介导的强化学习和可塑性皮质纹状体电路。 尽管对背侧纹状体的损伤、失活和药理学研究支持这一观点， 神经生理学证据表明背侧纹状体神经元代表刺激-动作关联。 在这里，我们提出了一个新的假设：习惯学习是一种技能学习形式，就像其他形式的技能一样， 学习，是依赖于感觉预测错误为基础的可塑性在小脑。技能是动作序列 快速准确地完成。像习惯一样，熟练的动作序列的表现并不需要 奖励结果的神经表示（尽管熟练的动作序列可以由这种动作序列激活）。 表示）。熟练的动作序列学习取决于根据以下因素调整正在进行的和未来的动作： 所执行的操作与前一个操作所预测的操作之间的差异，或者 刺激。这些差异表现为小脑的感觉预测错误， 在学习过程中，小脑输出神经元开始代表动作-动作和刺激-动作的关联。的 这些神经元的活动在序列内的正确时间产生准确的运动。我们提出 将刺激连接到动作序列，使得动作在刺激之后自动执行， 呈现-即，学习一种刺激-行动习惯-需要同样的小脑回路和监督 学习算法学习动作序列本身。 拟议中的实验验证了这一假设的有力预测，即小脑功能的破坏将 破坏刺激行为习惯的形成和表现，并且深层神经元的放电 小脑核将反映刺激-动作关联的形成。此外，根据解剖学 研究表明，小脑和边缘下神经之间的相互单突触和多突触连接， 大脑皮层是习惯行为所需的结构，我们将专门研究这些投射是否有助于 to habit习惯learning学习and performance性能.建立小脑在习惯学习中的作用是一致的 越来越多的文献表明，小脑参与的认知功能远远超过运动功能， 行为最重要的是，证明一个合理的候选小脑机制的习惯学习， 构成了我们对习惯是如何学习和控制的理解的范式转变。

Project Summary Much of our behavior is habitual. Habits are defined as behaviors that are initiated automatically in response to stimuli, which means that neural representations of the likely outcome of the behavior (e.g., a reward) do not control these behaviors. The neural mechanisms underlying habit learning and performance are of clinical relevance because compulsive disorders, such as obsessive-compulsive disorder and drug addiction, are likely to involve imbalances between habit and goal-directed control over behavior. The most prominent theories posit that stimulus-action associations – neural representations of the stimulus that activate the habit action – are formed as a consequence of dopamine-mediated reinforcement learning and plasticity in corticostriatal circuits. Although lesion, inactivation and pharmacology studies of the dorsal striatum support this view, there is little neurophysiological evidence that dorsal striatal neurons represent stimulus-action associations. Here, we propose a novel hypothesis: that habit learning is a form of skill learning that, like other forms of skill learning, is dependent on sensory prediction error-based plasticity in the cerebellum. Skills are action sequences that are performed rapidly and accurately. Like habits, performance of skilled action sequences does not require a neural representation of the reward outcome (although skilled action sequences can be activated by such representations). Skilled action sequence learning depends on adjusting ongoing and future actions based on the difference between the action performed and the action predicted by the immediately-preceding action or stimulus. These differences are represented as sensory prediction errors in the cerebellum and, during skill learning, cerebellar output neurons come to represent action-action and stimulus-action associations. The activity of these neurons produces accurate movements at the correct time within the sequence. We propose that connecting a stimulus to an action sequence so that the action is performed automatically after stimulus presentation – i.e., learning a stimulus-action habit – requires the same cerebellar circuitry and supervised learning algorithm as learning the action sequence itself. The proposed experiments test the strong predictions of this hypothesis that disruption of cerebellar function will disrupt the formation and performance of stimulus-action habits, and that the firing of neurons in the deep cerebellar nuclei will reflect the formation of stimulus-action associations. Furthermore, based on anatomical studies that show reciprocal mono- and polysynaptic connections between the cerebellum and the infralimbic cortex, a structure required for habit behavior, we will specifically investigate whether these projections contribute to habit learning and performance. Establishing a role for the cerebellum in habit learning would be consistent with a growing literature indicating that the cerebellum participates in cognitive functions far beyond motor behavior. Most importantly, demonstrating a plausible candidate cerebellar mechanism for habit learning would constitute a paradigm shift in our understanding of how habits are learned and controlled.