Dissociable Forms of Uncertainty-Driven Representational Change Across the Human Brain
Dissociable Forms of Uncertainty-Driven Representational Change Across the Human Brain
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DOI：
10.1523/jneurosci.1713-18.2018
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发表时间：
2019-02-27
影响因子：
5.3
通讯作者：
Kable, Joseph W.
中科院分区：
文献类型：
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作者：
Nassar, Matthew R.;McGuire, Joseph T.;Kable, Joseph W.
环境变化可能导致决策者在不同的行为模式之间迅速转变。这些行为变化可能伴随着神经网络放电模式的快速变化。然而，尚不清楚参与这种“网络重置”现象的神经元群体代表什么。在这里，我们研究了以下内容：（1）在行为快速变化期间，是否以及在何处可以通过功能磁共振成像观察到多元活动模式的快速变化，以及（2）什么类型的表征会引起这些现象。我们通过检查男性和女性人类受试者的 BOLD 活动的多体素模式的波动来做到这一点，并对部分可观察和不连续变化的变量的状态进行连续推断。我们发现，在顺序推理任务的背景下，许多皮质区域的多元活动模式包含在行为背景变化后的不确定时期变化更快的表征。在运动皮层中，这种现象表明行为输出的不连续变化，而在视觉区域中，通过跟踪显着的环境变化引发了相同的基本现象。在大多数其他皮质区域，包括背外侧前额叶和前扣带皮层，这种现象与直接编码不确定性程度最为一致。然而，在包括眶额皮层在内的其他一些区域，这种现象最好的解释是在快速学习期间变化更快的环境变化。这些表征可以为学习提供动态基础，有助于在变化期间快速脱离习得的反应。
Environmental change can lead decision makers to shift rapidly among different behavioral regimes. These behavioral shifts can be accompanied by rapid changes in the firing pattern of neural networks. However, it is unknown what the populations of neurons that participate in such "network reset" phenomena are representing. Here, we investigated the following: (1) whether and where rapid changes in multivariate activity patterns are observable with fMRI during periods of rapid behavioral change and (2) what types of representations give rise to these phenomena. We did so by examining fluctuations in multivoxel patterns of BOLD activity from male and female human subjects making sequential inferences about the state of a partially observable and discontinuously changing variable. We found that, within the context of this sequential inference task, the multivariate patterns of activity in a number of cortical regions contain representations that change more rapidly during periods of uncertainty following a change in behavioral context. In motor cortex, this phenomenon was indicative of discontinuous change in behavioral outputs, whereas in visual regions, the same basic phenomenon was evoked by tracking of salient environmental changes. In most other cortical regions, including dorsolateral prefrontal and anterior cingulate cortex, the phenomenon was most consistent with directly encoding the degree of uncertainty. However, in a few other regions, including orbitofrontal cortex, the phenomenon was best explained by representations of a shifting context that evolve more rapidly during periods of rapid learning. These representations may provide a dynamic substrate for learning that facilitates rapid disengagement from learned responses during periods of change.