Cortical feedback pathways are proposed to guide cognition and behavior according to context and goal-direction. At the cellular level, cortical feedback pathways target multiple excitatory and inhibitory populations. However, we currently lack frameworks that link how the cellular mechanisms of cortical feedback pathways underlie their cognitive/behavioral functions. To establish this link, we expand on the framework of signal routing, the ability of cortical feedback pathways to proactively modulate how feedforward signals are propagated throughout the cortex. We propose that cortical feedback modulates routing through multiple mechanisms: preparing intended motor representations, setting the trigger conditions for evoking cortical outputs, altering coupling strengths between cortical regions, and suppressing expected sensory representations. In developing this framework, we first define the anatomy of cortical feedback pathways and identify recent advances in studying their functions at high specificity and resolution. Second, we review the diverse functions of cortical feedback pathways throughout the cortical hierarchy and evaluate these functions from the framework of signal routing. Third, we review the conserved cellular targets and circuit impacts of cortical feedback. Fourth, we introduce the concept of the “cortical landscape,” a graphical depiction of the routes through cortex that are favored at a specific moment in time. We propose that the cortical landscape, analogous to energy landscapes in physics and chemistry, can capture important features of signal routing including coupling strength, trigger conditions, and preparatory states. By resolving the cortical landscape, we may be able to quantify how the cellular processes of cortical feedback ultimately shape cognition and behavior.

中文翻译：

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塑造皮质景观：自上而下的皮质反馈通路的功能和机制

提出了皮质反馈通路，以根据上下文和目标方向来指导认知和行为。在细胞水平上，皮层反馈通路针对多个兴奋性和抑制性群体。然而，我们目前缺乏将皮层反馈通路的细胞机制如何作为其认知/行为功能基础的框架。为了建立这种联系，我们扩展了信号路由的框架，即皮层反馈通路主动调节前馈信号如何在整个皮层传播的能力。我们建议皮层反馈通过多种机制调节路由：准备预期的运动表征、设置诱发皮层输出的触发条件、改变皮层区域之间的耦合强度以及抑制预期的感觉表征。在开发这个框架时，我们首先定义了皮层反馈通路的解剖结构，并确定了以高特异性和分辨率研究其功能的最新进展。其次，我们回顾了整个皮层层次结构中皮层反馈通路的不同功能，并从信号路由的框架中评估了这些功能。第三，我们回顾了皮质反馈的保守细胞目标和电路影响。第四，我们引入了“皮层景观”的概念，这是对通过皮层的路线的图形描述，这些路线在特定时刻受到青睐。我们建议皮质景观类似于物理和化学中的能量景观，可以捕捉信号路由的重要特征，包括耦合强度、触发条件和准备状态。通过解析皮质景观，