Distinct Neural Representation in the Dorsolateral, Dorsomedial, and Ventral Parts of the Striatum during Fixed- and Free-Choice Tasks
Distinct Neural Representation in the Dorsolateral, Dorsomedial, and Ventral Parts of the Striatum during Fixed- and Free-Choice Tasks
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DOI：
10.1523/jneurosci.1962-14.2015
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发表时间：
2015-02-25
影响因子：
5.3
通讯作者：
Doya, Kenji
中科院分区：
文献类型：
--
作者：
Ito, Makoto;Doya, Kenji
纹状体是基底神经节的主要输入部位，在决策过程中起着至关重要的作用。以往的研究表明，纹状体的不同亚区具有不同的作用：背外侧纹状体(DLS)在习惯性动作中起作用，背内侧纹状体(DMS)在目标定向动作中起作用，腹侧纹状体(VS)在动机中起作用。为了阐明纹状体亚区在决策中的独特功能，我们系统地研究了DLS、DMS和VS中相活动神经元所代表的信息。大鼠完成两种类型的选择任务：固定选择任务和自由选择任务。在这两个任务中，大鼠都被要求在提示音呈现后向左或右鼻孔戳鼻子。根据所提供的线索和所选动作，以概率方式递送食物颗粒。在固定选择任务中，奖赏概率是固定的，而在自由选择任务中，奖赏概率是成组变化的。我们发现：(1)当大鼠开始任务时，大多数VS神经元的放电频率增加，有关任务类型和状态值的信息在VS中最强；(2)在动作选择过程中，动作和动作值信息在DMS中最强；(3)在DLS和DMS中，固定选择任务中的动作命令信息(动作选择前的动作表征)比自由选择任务中的强；(4)动作命令信息在DLS中最强，尤其是在相同的选择重复时。我们提出了基底节分层强化学习的假设，以连贯地解释这些结果。
The striatum is a major input site of the basal ganglia, which play an essential role in decision making. Previous studies have suggested that subareas of the striatum have distinct roles: the dorsolateral striatum (DLS) functions in habitual action, the dorsomedial striatum (DMS) in goal-directed actions, and the ventral striatum (VS) in motivation. To elucidate distinctive functions of subregions of the striatum in decision making, we systematically investigated information represented by phasically active neurons in DLS, DMS, and VS. Rats performed two types of choice tasks: fixed-and free-choice tasks. In both tasks, rats were required to perform nose poking to either the left or right hole after cue-tone presentation. A food pellet was delivered probabilistically depending on the presented cue and the selected action. The reward probability was fixed in fixed-choice task and varied in a block-wise manner in free-choice task. Wefound the following: (1) when rats began the tasks, a majority of VS neurons increased their firing rates and information regarding task type and state value was most strongly represented in VS; (2) during action selection, information of action and action values was most strongly represented in DMS; (3) action-command information (action representation before action selection) was stronger in the fixed-choice task than in the free-choice task in both DLS and DMS; and (4) action-command information was strongest in DLS, particularly when the same choice was repeated. Wepropose a hypothesis of hierarchical reinforcement learning in the basal ganglia to coherently explain these results.