纹状体神经元对空间和事件的任务依赖性编码取决于神经亚型。

Task-dependent encoding of space and events by striatal neurons is dependent on neural subtype.

作者信息

Schmitzer-Torbert N C, Redish A D

机构信息

Department of Psychology, Wabash College, Crawfordsville, IN 47933, USA.

出版信息

Neuroscience. 2008 May 2;153(2):349-60. doi: 10.1016/j.neuroscience.2008.01.081. Epub 2008 Mar 4.

Abstract

The dorsal striatum plays a critical role in procedural learning and memory. Current models of basal ganglia assume that striatal neurons and circuitry are critical for the execution of overlearned, habitual sequences of action. However, less is known about how the striatum encodes task information that guides the performance of actions in procedural tasks. To explore the striatal encoding of task information, we compared the behavioral correlates of striatal neurons tested in two tasks: a multiple T-maze task in which reward delivery was entirely predictable based on spatial cues (the Multiple-T task), and a task in which rats ran on a rectangular track, but food delivery depended on the distance traveled on the track and was not dependent solely on spatial location (the Take-5 task). Striatal cells recorded on these tasks were divisible into three cell types: phasic-firing neurons (PFNs), tonically firing neurons (TFNs), and high-firing neurons (HFNs) and similar proportions of each cell type were found in each task. However, the behavioral correlates of each cell type were differentially sensitive to the type of task rats were performing. PFNs were responsive to specific task-parameters on each task. TFNs showed reliable burst-and-pause responses following food delivery and other events that were consistent with tonically active neurons (TANs) on the Take-5 (non-spatial) task but not on the Multiple-T (spatial) task. HFNs showed spatial oscillations on the Multiple-T (spatial) task but not the Take-5 (non-spatial) task. Reconstruction of the rats' position on the maze was highly accurate when using striatal ensembles recorded on the Multiple-T (spatial) task, but not when using ensembles recorded on the Take-5 (non-spatial) task. In contrast, reconstruction of time following food delivery was successful in both tasks. The results indicated a strong task dependency of the quality of the spatial, but not the reward-related, striatal representations on these tasks. These results suggest that striatal spatial representations depend on the degree to which spatial task-parameters can be unambiguously associated with goals.

摘要

背侧纹状体在程序性学习和记忆中起着关键作用。当前的基底神经节模型认为,纹状体神经元和神经回路对于执行过度学习的习惯性动作序列至关重要。然而,关于纹状体如何编码指导程序性任务中动作执行的任务信息,我们所知甚少。为了探究纹状体对任务信息的编码,我们比较了在两项任务中测试的纹状体神经元的行为相关性:一项多T迷宫任务,其中奖励发放完全基于空间线索是可预测的(多T任务),以及一项大鼠在矩形轨道上奔跑的任务,但食物发放取决于在轨道上行驶的距离,而不仅仅取决于空间位置(5选1任务)。在这些任务中记录的纹状体细胞可分为三种细胞类型:相位发放神经元(PFN)、持续发放神经元(TFN)和高频发放神经元(HFN),并且在每项任务中发现每种细胞类型的比例相似。然而,每种细胞类型的行为相关性对大鼠执行的任务类型具有不同的敏感性。PFN对每项任务中的特定任务参数有反应。TFN在食物发放和其他事件后表现出可靠的爆发和暂停反应,这与5选1(非空间)任务中的持续活动神经元(TAN)一致,但在多T(空间)任务中则不然。HFN在多T(空间)任务中表现出空间振荡,但在5选1(非空间)任务中则没有。当使用在多T(空间)任务中记录的纹状体神经元集群时,大鼠在迷宫上的位置重建非常准确,但使用在5选1(非空间)任务中记录的集群时则不然。相比之下,在两项任务中食物发放后的时间重建都很成功。结果表明,在这些任务中,空间纹状体表征的质量存在强烈的任务依赖性,但奖励相关的纹状体表征则不然。这些结果表明,纹状体空间表征取决于空间任务参数与目标明确关联的程度。

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