En route from the retina to the cortex, visual information passes through the dorsolateral geniculate nucleus (dLGN) of the thalamus, where extensive corticothalamic (CT) feedback has been suggested to modulate spatial processing. How this modulation arises from direct excitatory and indirect inhibitory CT feedback pathways remains enigmatic. Here, we show that in awake mice, retinotopically organized cortical feedback sharpens receptive fields (RFs) and increases surround suppression in the dLGN. Guided by a network model indicating that widespread inhibitory CT feedback is necessary to reproduce these effects, we targeted the visual sector of the thalamic reticular nucleus (visTRN) for recordings. We found that visTRN neurons have large RFs, show little surround suppression and exhibit strong feedback-dependent responses to large stimuli. These features make them an ideal candidate for mediating feedback-enhanced surround suppression in the dLGN. We conclude that cortical feedback sculpts spatial integration in the dLGN, likely via recruitment of neurons in the visTRN.

在从视网膜到皮质的途中，视觉信息通过丘脑的背外侧膝状体核 (dLGN)，其中广泛的皮质丘脑 (CT) 反馈被认为可以调节空间处理。这种调节是如何从直接兴奋性和间接抑制性 CT 反馈通路中产生的仍然是个谜。在这里，我们表明在清醒的小鼠中，视网膜局部组织的皮质反馈会增强感受野 (RF) 并增加 dLGN 中的环绕抑制。在网络模型的指导下，表明广泛的抑制性 CT 反馈对于重现这些影响是必要的，我们针对丘脑网状核 (visTRN) 的视觉区域进行记录。我们发现 visTRN 神经元具有较大的 RF，显示出很少的环绕抑制，并且对大刺激表现出强烈的反馈依赖性反应。这些特性使它们成为在 dLGN 中调节反馈增强环绕声抑制的理想候选者。我们得出结论，皮质反馈塑造了 dLGN 中的空间整合，可能是通过在 visTRN 中招募神经元。