Neuronal circuitry related to working memory in the prefrontal cortex

为了研究前额叶神经元如何保持多个空间位置的信息，记录了两只猴子在执行两项任务时的前额叶皮层神经元活动；在延迟顺序到达任务中，猴子被要求保留两个线索位置及其呈现顺序，而在延迟到达任务中，猴子只被要求保持一个位置。在138个任务相关神经元中，72个表现出显著的延迟期活动。通过比较两个任务的活动，将延迟期的活动分为四组。19个神经元只有在视觉线索呈现在特定位置时才表现出延迟期活动；在6个神经元中，线索位置对于激发活动是重要的，而13个神经元只有当视觉线索以特定顺序呈现在特定位置时才表现出活动。39个神经元只有在视觉线索呈现…时才表现出延迟期活动更多的是两个特定的位置；13个无论线索呈现的时间顺序如何都表现出这种活动，而26个只有当视觉线索以特定的时间顺序呈现时才表现出这种活动。其余14个则表现为无差别活动或杂项活动。本实验表明，新出现的延迟期活动保留了线索呈现的多个位置和时间顺序，即配对依赖和时间顺序依赖的活动。依赖于对的延迟期活动可能是一种同时保留多位空间信息并通过单个神经元有效地连接这些信息的机制。具有时间顺序依赖性的活动的存在表明，主体周围区域在计划和执行顺序行为方面发挥了作用，而保留呈现的位置和时间顺序可能是保留和连接多比特信息的另一种有效策略。较少

To investigate how information for multiple spatial positions is retained by prefrontal neurons, neuron activity was recorded from the prefrontal cortex of two monkeys while they performed two tasks ; in the delayd sequential reaching task, monkeys were required to retain two cue locations and the order of their presentation, while in the delayd reaching task, monkeys were required to retain only one location. Among 138 task-related neurons, 72 showed statistically significant delay-period activity. By comparing the activity across both tasks, the delay-period activity were classified into four groups. 19 neurons exhibited delay-period activity only when the visual cue was presented at a particular position ; in 6 neurons, the cue position was important for eliciting the activity, whereas 13 exhibited the activity only when the visual cues were presented at a particular position in a particular order. 39 neurons exhibited delay-period activity only when the visual cues were presented a … More t two particular positions ; 13 exhibited this activity regardless of the temporal order of cue presentation, whereas 26 exhibited the activity only when the visual cues were presented in a particular temporal order. The remaining 14 exhibited either non-differential activity or miscellaneous activity. The present experiment shows that the new class of delay-period activity emerged to retain multiple positions and the temporal order of cue presentation ; pair-dependent and temporal order-dependent activity. Pair-dependent delay-period activity could be a mechanism for simultaneously retaining multiple bits of spatial information and for effectively interconnecting these information by a single neuron. The presence of the activity with temporal order-dependency suggests that the periprincipal area plays a role in planning and executing sequential behaviors and that retaining both the positions and the temporal order of the presentation could be an another effective strategy for retaining and interconnecting multiple bits of information. Less