Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat.
Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat.
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DOI：
10.7554/elife.05457
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发表时间：
2015-04-14
期刊：
影响因子：
7.7
通讯作者：
Brody CD
中科院分区：
文献类型：
--
作者：
Erlich JC;Brunton BW;Duan CA;Hanks TD;Brody CD
许多大脑区域已被证明与逐渐积累决策证据的神经相关，但这些区域在由证据积累驱动的决策中的因果作用尚未确定。在这里，在执行听觉证据积累任务的大鼠中，我们停用了额叶定向场(FOF)和后顶叶皮质(PPC)，这两个大鼠皮质区域与积累证据的神经相关，并被认为是决策的中心。我们使用了决策过程的详细模型来分析灭活的影响。FOF的失活导致了实质性的性能损害，量化上最好的描述是具有长积分时间常数(>；240 ms)的证据累加器的输出路径中的损害。相反，我们发现PPC在通过积累听觉证据指导决策方面的作用很小，即使在内部指导的决策中PPC的作用很强。Http://dx.doi.org/10.7554/eLife.05457.001想象一下，你必须在开学前买一台电脑。你有几种选择，比如笔记本电脑或台式机，每种选择都有自己的优点和缺点。笔记本电脑相对轻便，而台式机内存更大，价格更便宜。你会逐渐积累支持和反对每一种选择的证据，但在开学之前，你必须做出决定。这种循序渐进的证据积累是许多形式决策中的一个重要因素。众所周知，大脑内许多区域的活动似乎代表着证据的积累，但人们对每个区域在决策过程中所起的因果作用知之甚少。现在，通过在老鼠身上进行一系列实验，Erlich等人。已经阐明了其中两个区域的确切作用：前额叶皮质的额叶定向场和后顶叶皮质。在实验中，老鼠听了两个扬声器发出的一系列滴答声，一个在左边，一个在右边，然后必须决定是左边的还是右边的扬声器发出更多的滴答声。老鼠通常使用所有积累的证据(最多1秒)来做出决定。当后顶叶皮质被沉默时(使用一种名为Muscimol的药物)，大鼠继续使用它们可以获得的所有证据。然而，当额叶定向场被静默时(同样使用了麝香酚)，决定只取决于最近积累的证据(只有几百毫秒)。因此，在计算机的例子中，如果没有正面定向场的帮助，如果最新的证据是笔记本电脑，你会选择笔记本电脑，即使更老的证据强烈支持台式机。这些结果表明，额叶定向场对于根据积累的证据做出决定是必要的，但进一步的实验表明，积累过程本身似乎发生在大脑的其他地方。另一组相关实验表明，后顶叶皮质参与了一种不同类型的决策，即在没有正确答案的情况下，老鼠在两个选项之间做出决定，比如从一堆相同的饼干中挑选一块饼干。DOI：http://dx.doi.org/10.7554/eLife.05457.002
Numerous brain regions have been shown to have neural correlates of gradually accumulating evidence for decision-making, but the causal roles of these regions in decisions driven by accumulation of evidence have yet to be determined. Here, in rats performing an auditory evidence accumulation task, we inactivated the frontal orienting fields (FOF) and posterior parietal cortex (PPC), two rat cortical regions that have neural correlates of accumulating evidence and that have been proposed as central to decision-making. We used a detailed model of the decision process to analyze the effect of inactivations. Inactivation of the FOF induced substantial performance impairments that were quantitatively best described as an impairment in the output pathway of an evidence accumulator with a long integration time constant (>240 ms). In contrast, we found a minimal role for PPC in decisions guided by accumulating auditory evidence, even while finding a strong role for PPC in internally-guided decisions. DOI: http://dx.doi.org/10.7554/eLife.05457.001 Imagine that you have to buy a computer before the start of the school year. You have a few options, such as a laptop or a desktop, each with its own advantages and disadvantages. A laptop is relatively light and portable, whereas a desktop has more memory and is cheaper. You will gradually accumulate evidence for and against each option, but before school starts, you have to make a decision. This gradual accumulation of evidence is an important element in many forms of decision making. It is known that the activity of many regions within the brain seem to represent accumulation of evidence, but relatively little is known about the causal role played by each region in the decision-making process. Now, by performing a series of experiments on rats, Erlich et al. have clarified the precise roles of two of these regions: the frontal orienting fields in prefrontal cortex and the posterior parietal cortex. In the experiments the rats listened to a series of clicks from two speakers, one to the left and one to the right, and then had to decide if more clicks came from the left or the right speaker. The rats normally used all of the accumulated evidence (up to 1 second) for their decision. When the posterior parietal cortex was silenced (using a drug called muscimol), the rats continued to use all of the evidence available to them. However, when the frontal orienting fields were silenced (again using muscimol), decisions were driven only by evidence accumulated over the most recent past (just a few hundred milliseconds). So in the computer example, without the help of the frontal orienting fields, you would choose the laptop if the most recent piece of evidence was for the laptop, even if older evidence argued strongly for the desktop. These results show that the frontal orienting fields are necessary for making decisions based on accumulated evidence, but further experiments suggested that the accumulation process itself seems to happen elsewhere in the brain. Another set of related experiments showed that the posterior parietal cortex is involved in a different type of decision making, namely ‘free choice’ decisions in which the rat decides between two options when there is no correct answer, such as picking a cookie from a pile of identical cookies. DOI: http://dx.doi.org/10.7554/eLife.05457.002