Role for frontal cortex neurons in absolute time coding

本研究的目的是探讨额叶皮层神经元活动在绝对时间编码中的作用。为了回答这一问题，我们首先记录了猴子在执行时间段创造任务时，额叶皮层辅助运动区（SMA）和前辅助运动区（pre-SMA）的神经元活动。（Macaca fuscata）被训练以创建三个不同的时间段（2、4或8秒）。通过按下连接在前肢支架末端的保持键开始每次试验。按键后1 - 2秒，三个指示灯中的一个亮起2秒，每个指示灯指示灯亮起至保持键释放之间的最短等待时间。黄灯、红灯和绿色灯分别表示2秒、4秒和8秒的最短等待时间。此外，我们还应用了颠倒规则，其中绿色和红色灯的含义是颠倒的。即，绿色灯表示8秒的最小等待时间，红色灯表示4秒。日 ...更多信息 该任务以块方式执行。每个区组由5个试验组成。在新的区块开始之前，通过灯随机闪烁2秒来指示反向规则。在SMA和pre-SMA中，约70%的任务相关神经元在光开始和运动开始之间的间隔期间活跃。许多pre-SMA神经元在光开始后立即显示出显著的活动增加或在整个等待期间相对恒定的活动。与此相反，大多数SMA神经元表现出逐渐增加的活动对运动开始。大量的前SMA神经元表现出不同的活动之间的2，4，和8个等待期。在某些前SMA神经元中，4秒和8秒等待期内的活动幅度在相同等待期内呈相反的规律。只有少数SMA神经元表现出这种特性。这些观察结果表明，SMA前而不是SMA在执行需要创建不同时间段的任务中起着重要作用。少

The purpose of the present study was to examine how neuronal activity in the frontal cortex is involved in the absolute time cording, For the first step to answer this question, we recorded neuronal activity in the supplementary motor area (SMA) and pre-supplementary (pre-SMA) motor area during the performance of time period creation task.The monkey (Macaca fuscata) was trained to create the three different time periods (2, 4 or 8 sec). Each trial was started by pressing the hold key attached at the end of the forelimb brace. One to two seconds after the key press, one of the three lights was turned on for 2 sec, each of which indicating the minimum waiting period between the light onset to the hold key release. Yellow, red and green lights means 2, 4 and 8 sec of minimum waiting period, respectively. In addition, we also applied reversed rule, where the meaning of green and red lights was reversed. That is, green light indicated 8 sec of minimum waiting period and red light, 4 sec. Th … More is task was performed in a block manner. Each block consisted of 5 trials. Reversed rule was indicated by the lights flashed randomly for 2 sec, before the start of new block. The correct movement was rewarded with a drop of fruit juice (0.1 ml).In both SMA and pre-SMA, about 70% of task-related neurons were active during the interval between the light onset and the initiation of movement Many pre-SMA neurons showed marked increased activity just after the light onset or relatively constant activity throughout the waiting period. In contrast, majority of the SMA neurons showed gradually increased activity toward the movement onset. A substantial number of pre-SMA neurons showed different activity between 2, 4, and 8 waiting periods. In some pre-SMA neurons, the magnitude of activity in 4 or 8 sec waiting period was different in the same waiting period in reversed rule. Only small number of SMA neurons showed such properties. These observations indicate that the pre-SMA rather than SMA plays a important role in the execution of this task requiring to create the different time periods. Less