研究人员利用病毒工具来标记了来自皮层V4区针对早期视觉皮层（V1区）的反馈连接。当猴子执行视觉空间注意力任务时，在不改变局部皮质内和前馈输入的情况下，失活V1中的反馈轴突末端会减少单细胞的响应增益，并损害神经群体编码外部刺激的准确性。这些影响主要表现在V1的浅层，并向下游V4区域传播。注意以一种层依赖性的方式，通过特定地改变皮层反馈的强度来增强视觉皮层的感觉编码。
研究人员表示，注意力通过增强感觉信息的神经编码来改善知觉。一个长期存在的假设是，皮层反馈投射携带自上而下的信号来影响感觉编码。然而，这一假设从未被验证以建立因果关系。
附：英文原文
Title: Suppressing feedback signals to visual cortex abolishes attentional modulation
Author: Samantha R. Debes, Valentin Dragoi
Issue&Volume: 2023-02-03
Abstract: Attention improves perception by enhancing the neural encoding of sensory information. A long-standing hypothesis is that cortical feedback projections carry top-down signals to influence sensory coding. However, this hypothesis has never been tested to establish causal links. We used viral tools to label feedback connections from cortical area V4 targeting early visual cortex (area V1). While monkeys performed a visual–spatial attention task, inactivating feedback axonal terminals in V1 without altering local intracortical and feedforward inputs reduced the response gain of single cells and impaired the accuracy of neural populations for encoding external stimuli. These effects are primarily manifested in the superficial layers of V1 and propagate to downstream area V4. Attention enhances sensory coding across visual cortex by specifically altering the strength of corticocortical feedback in a layer-dependent manner.
DOI: ade1855
Source: https://www.science.org/doi/10.1126/science.ade1855