Gradual progression from sensory to task-related processing in cerebral cortex.
Gradual progression from sensory to task-related processing in cerebral cortex.
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DOI：
10.1073/pnas.1717075115
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发表时间：
2018-07-24
影响因子：
11.1
通讯作者：
Miller EK
中科院分区：
文献类型：
--
作者：
Brincat SL;Siegel M;von Nicolai C;Miller EK
大脑皮层处理的最早阶段反映了感觉输入的相对忠实的副本，但智能行为需要抽象出与行为相关的概念和类别。我们通过比较猴子在三个视觉领域的六个大脑皮层区域的神经表现，研究了这种转换是如何在大脑皮层的多个层次进行的。我们发现，范畴抽象在整个大脑皮层层级中以一种渐进的方式发生，并在前额叶皮质达到顶峰。范畴编码不尊重大规模皮层组织的经典模型。随着这些代表性的变化，神经群体活动的维度也降低了。我们的结果揭示了原始感觉输入是如何转化为与行为相关的抽象概念的。在大脑皮层的某处，与行为相关的信息是从原始的感觉输入中提取出来的。我们通过比较猴子在三个视觉领域(形状、运动方向和颜色)中视觉、颞叶、顶叶和额叶皮质的神经表征，研究了这种转换是如何沿着层次结构的多个水平进行的。视区、中颞区和V4区的表征与外部感觉输入密切相关。相反，外侧前额叶皮质(PFC)在很大程度上代表了刺激(任务规则、运动类别和颜色类别)的抽象行为相关性。中间水平的区域，包括后颞下区(PIT)、外侧顶内区(LIP)和前部眼野(FEF)，表现出混合的表现。虽然感觉信息在不同区域的分布与经典的功能划分很好地一致(MT携带更强的运动信息，而V4和PIT携带更强的颜色和形状信息)，但范畴抽象没有，这表明这些区域可能参与了不同的刺激驱动和认知功能网络。与这些代表性差异平行的是，神经群体活动的维度从感觉到中间到额叶皮质依次递减。这显示了原始的感觉表征如何被转化为与行为相关的抽象概念，并表明高级皮质区域的神经活动的维度可能特定于他们当前的任务。
The earliest stages of processing in cerebral cortex reflect a relatively faithful copy of sensory inputs, but intelligent behavior requires abstracting behaviorally relevant concepts and categories. We examined how this transformation progresses through multiple levels of the cortical hierarchy by comparing neural representations in six cortical areas in monkeys categorizing across three visual domains. We found that categorical abstraction occurred in a gradual fashion across the cortical hierarchy and reached an apex in prefrontal cortex. Categorical coding did not respect classical models of large-scale cortical organization. The dimensionality of neural population activity was reduced in parallel with these representational changes. Our results shed light on how raw sensory inputs are transformed into behaviorally relevant abstractions. Somewhere along the cortical hierarchy, behaviorally relevant information is distilled from raw sensory inputs. We examined how this transformation progresses along multiple levels of the hierarchy by comparing neural representations in visual, temporal, parietal, and frontal cortices in monkeys categorizing across three visual domains (shape, motion direction, and color). Representations in visual areas middle temporal (MT) and V4 were tightly linked to external sensory inputs. In contrast, lateral prefrontal cortex (PFC) largely represented the abstracted behavioral relevance of stimuli (task rule, motion category, and color category). Intermediate-level areas, including posterior inferotemporal (PIT), lateral intraparietal (LIP), and frontal eye fields (FEF), exhibited mixed representations. While the distribution of sensory information across areas aligned well with classical functional divisions (MT carried stronger motion information, and V4 and PIT carried stronger color and shape information), categorical abstraction did not, suggesting these areas may participate in different networks for stimulus-driven and cognitive functions. Paralleling these representational differences, the dimensionality of neural population activity decreased progressively from sensory to intermediate to frontal cortex. This shows how raw sensory representations are transformed into behaviorally relevant abstractions and suggests that the dimensionality of neural activity in higher cortical regions may be specific to their current task.
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