Institute of Neuroscience, Key Laboratory of Primate Neurobiology, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2022 Jul 30;13(1):4426. doi: 10.1038/s41467-022-32210-6.
Decision making often entails evidence accumulation, a process that is represented by neural activities in a network of multiple brain areas. Yet, it has not been identified where exactly the accumulation originates. We reason that a candidate brain area should both represent evidence accumulation and information that is used to compute evidence. Therefore, we designed a two-stage probabilistic reasoning task in which the evidence for accumulation had to be first determined from sensory signals orthogonal to decisions. With a linear encoding model, we decomposed the responses of posterior parietal neurons to each stimulus into an early and a late component that represented two dissociable stages of decision making. The former reflected the transformation from sensory inputs to accumulable evidence, and the latter reflected the accumulation of evidence and the formation of decisions. The presence of both computational stages indicates that evidence accumulation signal in the parietal cortex is computed locally.
决策通常需要证据积累，这个过程由多个大脑区域的神经网络中的神经活动来表示。然而，尚未确定积累的确切起源位置。我们认为，候选脑区应该既能表示证据积累，又能表示用于计算证据的信息。因此，我们设计了一个两阶段概率推理任务，其中必须首先从与决策正交的感觉信号中确定积累的证据。通过线性编码模型，我们将后顶叶神经元对每个刺激的反应分解为早期和晚期成分，它们分别代表决策的两个可分离阶段。前者反映了从感觉输入到可积累证据的转换，后者反映了证据的积累和决策的形成。两个计算阶段的存在表明，顶叶皮层中的证据积累信号是在局部计算的。
