Arkadir David, Morris Genela, Vaadia Eilon, Bergman Hagai
Department of Physiology, Hadassah Medical School, The Hebrew University, Jerusalem 91120, Israel.
J Neurosci. 2004 Nov 10;24(45):10047-56. doi: 10.1523/JNEUROSCI.2583-04.2004.
Associating action with its reward value is a basic ability needed by adaptive organisms and requires the convergence of limbic, motor, and associative information. To chart the basal ganglia (BG) involvement in this association, we recorded the activity of 61 well isolated neurons in the external segment of the globus pallidus (GPe) of two monkeys performing a probabilistic visuomotor task. Our results indicate that most (96%) neurons responded to multiple phases of the task. The activity of many (34%) pallidal neurons was modulated solely by direction of movement, and the activity of only a few (3%) pallidal neurons was modulated exclusively by reward prediction. However, the activity of a large number (41%) of single pallidal neurons was comodulated by both expected trial outcome and direction of arm movement. The information carried by the neuronal activity of single pallidal neurons dynamically changed as the trial progressed. The activity was predominantly modulated by both outcome prediction and future movement direction at the beginning of trials and became modulated mainly by movement-direction toward the end of trials. GPe neurons can either increase or decrease their discharge rate in response to predicted future reward. The effects of movement-direction and reward probability on neural activity are linearly summed and thus reflect two independent modulations of pallidal activity. We propose that GPe neurons are uniquely suited for independent processing of a multitude of parameters. This is enabled by the funnel-structure characteristic of the BG architecture, as well as by the anatomical and physiological properties of GPe neurons.
将动作与其奖励价值相关联是适应性生物体所需的一项基本能力，需要边缘系统、运动系统和联合信息的汇聚。为了描绘基底神经节（BG）在这种关联中的参与情况，我们记录了两只猴子在执行概率性视觉运动任务时，苍白球外侧部（GPe）中61个分离良好的神经元的活动。我们的结果表明，大多数（96%）神经元对任务的多个阶段都有反应。许多（34%）苍白球神经元的活动仅受运动方向的调节，只有少数（3%）苍白球神经元的活动仅受奖励预测的调节。然而，大量（41%）单个苍白球神经元的活动同时受预期试验结果和手臂运动方向的共同调节。随着试验的进行，单个苍白球神经元的神经活动所携带的信息会动态变化。在试验开始时，活动主要受结果预测和未来运动方向的共同调节，而在试验结束时则主要受运动方向的调节。GPe神经元可以根据预测的未来奖励增加或降低其放电率。运动方向和奖励概率对神经活动的影响呈线性叠加，因此反映了苍白球活动的两种独立调节。我们认为，GPe神经元特别适合对多种参数进行独立处理。这是由BG结构的漏斗状结构特征以及GPe神经元的解剖和生理特性所实现的。
