Code and data

Decision-making requires processing of sensory information, comparing the gathered evidence to make a judgement, and performing the action to communicate it. How neuronal representations transform during this cascade of representations remains a matter of debate. Here, we studied the succession of neuronal representations in the primate prefrontal cortex. We trained monkeys to judge whether a pair of sequentially presented displays had the same number of items. We used a combination of single neuron and population-level analyses and discovered a sequential transformation of represented information with trial progression. While numerical values were initially represented with high precision and in conjunction with detailed information such as order, the decision was encoded in a low-dimensional subspace of neural activity. This decision encoding was invariant to both retrospective numerical values and prospective motor plans, representing only the binary judgment of 'same number' versus 'different number,' thus facilitating the generalization of decisions to novel number pairs. We conclude that this transformation of neuronal codes within the prefrontal cortex supports cognitive flexibility and generalizability of decisions to new conditions.决策过程需历经感官信息处理、比对采集到的证据以形成判断，以及执行动作以传达判断结果这一系列环节。在这一表征级联过程中，神经元表征的转变机制至今仍存争议。本研究聚焦灵长类前额叶皮层（prefrontal cortex）内的神经元表征序列展开探究。我们训练猕猴完成一项数量判断任务：依次呈现两组视觉刺激，要求其判断两组刺激包含的物品数量是否一致。我们采用单神经元（single neuron）与群体水平（population-level）分析相结合的手段，发现随着试次推进，表征信息会发生有序的阶段性转变。尽管数值信息最初以高精度形式被表征，且与刺激顺序等细节信息绑定，但最终的决策会被编码至神经活动的低维子空间（subspace）中。该决策编码不受回溯性数值信息与前瞻性运动计划的干扰，仅对“数量相同”与“数量不同”这一二元判断进行编码，由此可助力决策泛化至全新的数对组合场景。综上，前额叶皮层内神经元编码的这一转变过程，支撑了认知灵活性以及决策在新情境下的泛化能力。