Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, Canada, T1K 6T5.
Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, 4401 University Drive West, Lethbridge, AB, Canada, T1K 6T5.
Neuroscience. 2019 Aug 10;413:169-182. doi: 10.1016/j.neuroscience.2019.06.019. Epub 2019 Jun 21.
Decision-making in the mammalian brain typically involves multiple brain structures within the midbrain, thalamus, striatum, limbic system, and cortex. Although task specific contributions of each brain region have been identified, neurons responding to reinforcement have been found throughout these structures. We sought to determine if any brain area, or cluster of areas, are the source of information, and if the fidelity of information varies among the areas. We recorded simultaneous field potentials (FPs) in rats from seven brain regions as they completed a binary choice task. The FPs of a 0.5 s window following reinforcement were given as input to a classifier that attempted to predict whether or not the rat received reward on each trial. The classifier correctly categorized reward on 77% of trials. Any region-specific signal could be omitted without lowering accuracy. Frequencies above 40 Hz and signals recorded later than 0.25 s following reinforcement were necessary to achieve this accuracy. Further, the classifier was able to predict reinforcement outcome above chance levels when using FPs from any single recorded brain region. Some combinations of structures, however, were more predictive than others. Analysis of FPs prior to reward revealed most regions reflected the prior probability of reward. Lastly, analyses of information flow suggested reinforcement information does not originate within a single structure of the network, within the resolution afforded by FP recordings. These data suggest reward delivery information is rapidly distributed non-uniformly across the network, and there is no canonical flow of information about reward events in the recorded structures.
哺乳动物大脑中的决策通常涉及中脑、丘脑、纹状体、边缘系统和皮层中的多个脑区。尽管已经确定了每个脑区在特定任务中的作用，但在这些结构中都发现了对强化有反应的神经元。我们试图确定是否有任何脑区或脑区集群是信息的来源，以及信息的保真度是否在不同的脑区之间有所不同。我们在大鼠完成二选一任务时，同时记录来自七个脑区的场电位 (FP)。在强化后 0.5 秒的窗口中，FP 被输入到分类器中，该分类器试图预测大鼠在每次试验中是否获得奖励。分类器在 77%的试验中正确地对奖励进行了分类。如果不降低准确性，可以省略任何特定区域的信号。需要超过 40 Hz 的频率和强化后 0.25 秒后的信号才能达到这一准确性。此外，当使用任何单个记录的脑区的 FP 时，分类器能够在高于机会水平的情况下预测强化结果。然而，并非所有结构的组合都具有预测能力。在奖励之前对 FP 的分析表明，大多数区域反映了奖励的先验概率。最后，信息流的分析表明，强化信息不是在网络的单个结构内产生的，而是在 FP 记录提供的分辨率内。这些数据表明，奖励传递信息在网络中迅速非均匀地分布，并且在记录的结构中，关于奖励事件的信息没有标准的流向。
