「领域快报」是AiBrain筹备的特别栏目，是由海内外知名高校的一线青年科研工作者(博士后、PI）精选的领域科研动态，旨在为学科融合、交叉合作提供平台和机遇。
「领域快报」注意与决策
Current Biology
抽象决策中的感觉信息整合
IF=10.834
研究感知决策有利于了解我们如何整合感官经验，从而做出决策。当猴子知道与当前决策对应的运动动作时，那些参与该动作的神经元便会将动作的内容进行整合表征。然而，当决策对应的运动方向未知时（例如，任务要求用眼跳报告决策结果，但眼跳方向未知），猴子会如何做出决策（这种情况称为抽象决策abstract decision-making），目前仍然知之甚少。
哥伦比亚大学Michael Shadlen团队训练猕猴根据点阵的运动方向，眼跳至不同颜色的靶点（比如点阵向右运动则眼跳至黄色靶点，点阵向左运动则眼跳至蓝色靶点）。两种颜色的靶点在屏幕上出现的位置是随机的，因此在眼跳靶点出现前（go signal之前），与决策对应的眼跳运动方向对猕猴来说是未知的。电生理结果显示，在眼跳靶点出现之后，LIP神经元才开始整合感觉信息，并出现了决策相关的分化。此外，由于该任务中做出选择前刺激已经消失，LIP神经元需要从短期记忆中提取相关感觉信息，才能完成信息整合，因此短时记忆中存储的是对运动点阵的采样，而不是当前决策对应的眼跳靶点的颜色。
本文采用的抽象决策行为范式能够很好地分离决策过程中感觉信息编码和运动选择两个主要成分，并且发现抽象决策中LIP神经元需要从短时记忆中提取信息，才能整合感觉信息；并且信息整合的过程与运动选择的过程耦合。
该成果于2022年3月29日发表于《Current Biology》。
关键词：
decision making, abstraction, short-term memory, area LIP, macaque monkey
文章链接 ：
Sequential sampling from memory underlies action selection during abstract decision-making: Current Biology (cell.com)
Abstract
The study of perceptual decision-making in monkeys has provided insights into the process by which sensory evidence is integrated toward a decision. When monkeys make decisions with the knowledge of the motor actions the decisions bear upon, the process of evidence integration is instantiated by neurons involved in the selection of said actions. It is less clear how monkeys make decisions when unaware of the actions required to communicate their choice—what we refer to as ‘abstract’ decisions. We investigated this by training monkeys to associate the direction of motion of a noisy random-dot display with the color of two targets. Crucially, the targets were displayed at unpredictable locations after the motion stimulus was extinguished. We found that the monkeys postponed decision formation until the targets were revealed. Neurons in the parietal association area LIP represented the integration of evidence leading to a choice, but as the stimulus was no longer visible, the samples of evidence must have been retrieved from short-term memory. Our results imply that when decisions are temporally unyoked from the motor actions they bear upon, decision formation is protracted until they can be framed in terms of motor actions
Neuron
外侧顶内区失活会导致短暂的知觉决策偏差
IF=17.173
知觉决策产生于将感觉信息作为证据（evidence）进行整合，并转化为运动计划（plan of action）的过程。这种转化可能涉及与工作记忆、注意和计划相关的脑区。外侧顶内区（Lateral Intraparietal area, LIP）的神经元在这些功能中发挥作用，并且大部分关于决策的神经生物学研究都涉及到LIP及其网络。然而LIP的因果作用仍然存在争议。
哥伦比亚大学Michael Shadlen团队采用药理学和化学遗传学方法失活猕猴的单侧LIP，结果发现失活导致了短暂的决策偏差，这种偏差会随着时间减弱至消失，作者推断可能是由于未失活的区域对此产生了补偿作用。这些发现解决了前人研究中的争议，并为大脑功能局部的扰动提供了解释。
本文发现抑制LIP神经元可以产生决策行为的改变，为LIP参与决策行为提供因果性证据。
该成果于2022年4月13日发表于《Neuron》杂志。
关键词：
perceptual decision making parietal cortex area LIP inactivation muscimol chemogenetics Macaca mulatta
文章链接 ：
Deficits in decision-making induced by parietal cortex inactivation are compensated at two timescales: Neuron (cell.com)
Abstract
Perceptual decisions arise through the transformation of samples of evidence into a commitment to a proposition or plan of action. Such transformation is thought to involve cortical circuits capable of computation over timescales associated with working memory, attention, and planning. Neurons in the lateral intraparietal area (LIP) play a role in these functions, and much of what is known about the neurobiology of decision-making has been influenced by studies of LIP and its network of connections. However, the causal role of LIP remains controversial. In this study, we used pharmacological and chemogenetic methods to inactivate LIP in one brain hemisphere of four rhesus monkeys. This inactivation produced biases in decisions, but the effects dissipated despite persistent neural inactivation, implying compensation by unaffected areas. Compensation occurred rapidly within an experimental session and more gradually across sessions. These findings resolve disparate studies and inform the interpretation of focal perturbations of brain function.
Neuron
额叶和顶叶在探索-利用决策中的分工编码
IF=17.173
灵活的决策要求动物放弃即时奖励去尝试新颖的选项，以发现其他更好的选择。新墨西哥大学Jeremy Hogeveen团队首先采用相同的任务和部分可观察的马尔可夫决策过程（a partially observable Markov decision process, POMDP）模型来量化选择的价值，并确定猴子和人类对于探索-利用的权衡是相似的。随后，作者使用了fMRI来确定在人脑中哪些脑区编码选项的直接价值和未知价值。
结果显示前额叶和顶叶区域（包括额极皮层）分别编码及时奖赏（reward value）和不确定性（uncertainty）（与猕猴研究结果一致），此外在动机相关脑区（包括杏仁核，腹侧纹状体和眶额皮层）也存在并行编码。上述结果表明前额叶回路和动机回路之间的相互作用，并且该结果支持了人类和非人类灵长类动物在探索-利用决策上存在的相似性。
本文一方面阐明了前额叶和动机环路在探索性决策中的共享，另一方面可以启发未来更多关于人类和非人灵长类的研究。
该成果于2022年4月6日发表于《Neuron》杂志。
关键词：
reward, decision-making, exploration, fMRI, computational modeling, frontopolar cortex, explore-exploit dilemma, amygdala, striatum, reinforcement learning
文章链接：
The neurocomputational bases of explore-exploit decision-making: Neuron (cell.com)
Abstract
Flexible decision-making requires animals to forego immediate rewards (exploitation) and try novel choice options (exploration) to discover if they are preferable to familiar alternatives. Using the same task and a partially observable Markov decision process (POMDP) model to quantify the value of choices, we first determined that the computational basis for managing explore-exploit tradeoffs is conserved across monkeys and humans. We then used fMRI to identify where in the human brain the immediate value of exploitative choices and relative uncertainty about the value of exploratory choices were encoded. Consistent with prior neurophysiological evidence in monkeys, we observed divergent encoding of reward value and uncertainty in prefrontal and parietal regions, including frontopolar cortex, and parallel encoding of these computations in motivational regions including the amygdala, ventral striatum, and orbitofrontal cortex. These results clarify the interplay between prefrontal and motivational circuits that supports adaptive explore-exploit decisions in humans and nonhuman primates.
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