小柯机器人

美国冷泉港实验室Adam Kepecs小组发现，额叶皮层神经元类型明确编码单个决策变量。 2019年12月4日，《自然》在线发表了这一成果。

研究人员表明，大鼠眶额皮质（OFC）的神经活动具有高度结构化：单个神经元活动与解释选择行为的计算模型中的各个变量共变量。为了表征跨较大行为空间的神经反应，研究人员对大鼠进行了一项结合知觉和价值导向的决策行为任务训练。无偏倚、无模型的聚类分析确定了OFC神经元的不同组，每个组在任务可变空间中具有特定的响应曲线。将简单的选择行为模型应用于这些分类响应情况，可以发现每个情况在数量上对应于特定的决策变量，例如决策信心。另外，研究人员证明了连通性定义的细胞类型，即投射到纹状体的眶额神经元，承载着一个决策变量的选择性和时间持续性表示：累积值。研究人员认为，与其他皮质区域一样，额叶皮层中的神经元会形成与该区域功能相关的特征的稀疏和过完整体现，并将这些信息选择性地分布到下游区域以支持行为发生。

据了解，目前已经发现许多皮质区域中的单个神经元编码与区域的功能有关的环境或身体的特定、可识别特征。然而，在涉及认知的额叶皮层中，神经反应显示出令人困惑的复杂性，携带感觉、运动和其他与任务相关的变量看似混乱的混合体。这种复杂性导致了这样的认知，即个体额叶神经元中的表示是随机混合的，只能在神经群体水平上才能理解。

附：英文原文

Title: Frontal cortex neuron types categorically encode single decision variables

Author: Junya Hirokawa, Alexander Vaughan, Paul Masset, Torben Ott, Adam Kepecs

Issue&Volume: 2019-12-04

Abstract: Individual neurons in many cortical regions have been found to encode specific, identifiable features of the environment or body that pertain to the function of the region13. However, in frontal cortex, which is involved in cognition, neural responses display baffling complexity, carrying seemingly disordered mixtures of sensory, motor and other task-related variables413. This complexity has led to the suggestion that representations in individual frontal neurons are randomly mixed and can only be understood at the neural population level14,15. Here we show that neural activity in rat orbitofrontal cortex (OFC) is instead highly structured: single neuron activity co-varies with individual variables in computational models that explain choice behaviour. To characterize neural responses across a large behavioural space, we trained rats on a behavioural task that combines perceptual and value-guided decisions. An unbiased, model-free clustering analysis identified distinct groups of OFC neurons, each with a particular response profile in task-variable space. Applying a simple model of choice behaviour to these categorical response profiles revealed that each profile quantitatively corresponds to a specific decision variable, such as decision confidence. Additionally, we demonstrate that a connectivity-defined cell type, orbitofrontal neurons projecting to the striatum, carries a selective and temporally sustained representation of a single decision variable: integrated value. We propose that neurons in frontal cortex, as in other cortical regions, form a sparse and overcomplete representation of features relevant to the regions function, and that they distribute this information selectively to downstream regions to support behaviour. Frontal cortex neurons can be grouped into categorical response types corresponding to particular decision variables, such as reward size, decision confidence, or value, and individual variables may be encoded in distinct projection populations; this suggests that, like  neurons in sensory cortex, frontal neurons form a sparse and overcomplete representation of important variables in the environment.

DOI: 10.1038/s41586-019-1816-9

Source:https://www.nature.com/articles/s41586-019-1816-9

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html