Responses of tonically discharging neurons in the monkey striatum to primary rewards delivered during different behavioral states
Responses of tonically discharging neurons in the monkey striatum to primary rewards delivered during different behavioral states
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DOI：
10.1007/pl00005773
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发表时间：
1997-10-01
影响因子：
2
通讯作者：
Trouche, E
中科院分区：
文献类型：
--
作者：
Apicella, P;Legallet, E;Trouche, E
在灵长类纹状体中，紧张性放电神经元对与奖赏相关的条件刺激作出反应。我们研究了这些神经元是否对奖赏本身做出反应，以及奖赏传递的行为环境的变化如何影响它们的反应。本研究观察了2只清醒猕猴尾状核和壳核内286个神经元的活动，并在3种行为情境下给予液体奖赏：（1）工具性任务，即视觉触发手臂运动后给予奖赏;（2）经典条件性任务，即视觉信号后1 s给予奖赏;（3）自由奖赏情境，即在条件作用任务之外，以不规则的时间间隔给予奖赏。猴子对奖励发放时间的不确定性是通过监测它们的嘴部运动来评估的。在自由奖赏情境中，对奖赏反应的神经元比例（86%）高于经典条件任务（57%）和工具任务（37%）。在所有情况下测试的神经元（n = 78）中，24%的神经元对奖励做出反应，而不管情况如何，65%的神经元只在一两种情况下做出反应。对一种特定情况的选择性反应只发生在免费奖励的情况下。在经典条件任务中，当奖励在视觉信号之后立即传递时，大多数神经元减少或完全失去了对奖励的反应，而其他神经元仍然保持反应。相反，神经元的反应总是坚持奖励后，视觉信号后1秒。这是第一个报告，紧张性纹状体神经元可能会直接显示初级奖励的反应。神经元的反应受到动物接受奖励的行为背景的强烈影响。一个重要的因素似乎是奖励的时机。因此，这些神经元可能有助于受试者对相关刺激的行为反应的一般方面。
In the primate striatum, the tonically discharging neurons respond to conditioned stimuli associated with reward. We investigated whether these neurons respond tcr the reward itself and how changes in the behavioral context in which the reward is delivered might influence their responsiveness. A total of 286 neurons in the caudate nucleus and putamen were studied in two awake macaque monkeys while liquid reward was delivered in three behavioral situations: (1) an instrumental task, in which reward was delivered upon execution of a visually triggered arm movement; (2) a classically conditioned task, in which reward was delivered 1 s after a visual signal; (3) a free reward situation, in which reward was delivered at irregular time intervals outside of any conditioning task. The monkeys' uncertainty about the time at which reward will be delivered was assessed by monitoring their-mouth movements. A larger proportion of neurons responsive to reward was observed in the free reward situation (86%) than in the classically conditioned (57%) and instrumental tasks (37%). Among the neurons tested in all situations (n = 78), 24% responded to reward regardless of the situation and 65% in only one or two situations. Responses selective for one particular situation occurred exclusively in the free reward situation. When the reward was delivered immediately after the visual signal in the classically conditioned task, most of the neurons reduced or completely lost their responses to reward, and other neurons remained responsive. Conversely, neuronal responses invariably persisted when reward was delivered later than 1 s after the visual signal. This is the first report that tonic striatal neurons might display responses directly to primary rewards. The neuronal responses were strongly influenced by the behavioral context in which the animals received the reward. An important factor appears to be the timing of reward. These neurons might therefore contribute to a general aspect of behavioral reactivity of the subject to relevant stimuli.