Psychophisiological study of the working memory in relation to parallel processing

前额叶皮层在组织目标定向、目的性记忆中具有重要的功能。工作记忆是指在记忆过程中保持“在线”的信息，而这些信息是正确执行任务所必需的。在延迟反应任务中，前额叶神经元在延迟期内表现出活动变化（“延迟神经元”），其中一些显示空间特异性取决于线索的位置。本研究进行了是否前额叶神经元参与保持两种以上的不同类型的本实验采用三种不同类型的延迟反应任务，分别用不同的食物和液体奖励（1）、（2）和（3）对三只猴子进行训练。在50次试验中，任务的类型和奖励的种类通常是变化的。实验结果总结如下。(1)大约2/3的延迟神经元检查显示差异活动取决于它是一个右或左的审判，因此具有空间特异性。(2)约有一半的延迟神经元表现出不同的活动依赖于不同的奖励，从而具有奖励依赖性。(3)约80%的延迟神经元表现出不同的活动，这取决于不同的任务类型，从而具有任务依赖性。(4)具有空间特异性的延迟神经元中有相当一部分同时具有奖赏依赖和/或任务依赖，参与两种或三种不同的工作记忆。（5）这些前额叶神经元参与并行保留多种信息，被认为是需要并行处理的目标导向行为的基础。

The prefrontal cortex has important functions in organizig goal-directed, purposive hehavior.Working memory is the memory process of retaining the information "on-line" while that information is necessary for the correct performance.During the delayd response task, prefrontal neurons show activity changes during the delay period ("delay neurons") , some of them showing spatial specificity depending on the cue position.This study was conducted whether prefrontal neurons are involved in retaining more than two different kinds of information in parallel.Three monkeys were trained on three different typse of delayd response tasks with several kinds of food and liquid reward ; (1) Direct method food reward, (2) Indirect method food reward, and (3) Indirect method liquid reward.Type of task and kind of reward were changed usually in a block of 50 trials.The results of the experiment are summarized as follows.(1) About 2/3 of delay neurons examined showed differential activity depending on whether it was a right or left trial, and thus had spatial specificity.(2) About half of delay neurons showed differential activity depending on the difference of the reward, and thus had reward dependency.(3) About 80% of delay neurons showed differential activity depending on the difference of the type of the task, and thus had task dependency.(4) Substantial proportion of delay neurons with spatial specificity had reward dependency and/or task dependency as well, participating two or three different kinds of working memory.(5)These prefrontal neurons which are involved in retaining several kinds of information in parallel, are considered to be the basis of the goal-directed behavior where parallel processing is required.