High acuity stereopsis emerges during an early postnatal critical period when binocular neurons in the primary visual cortex sharpen their receptive field tuning properties. We find that this sharpening is achieved by dismantling the binocular circuit present at critical period onset and building it anew. Longitudinal imaging of receptive field tuning (e.g., orientation selectivity) of thousands of neurons reveals that most binocular neurons present in layer 2/3 at critical period onset are poorly tuned and are rendered monocular. In parallel, new binocular neurons are established by conversion of well-tuned monocular neurons as they gain matched input from the other eye. These improvements in binocular tuning in layer 2/3 are not inherited from layer 4 but are driven by the experience-dependent sharpening of ipsilateral eye responses. Thus, vision builds a new and more sharply tuned binocular circuit in layer 2/3 by cellular exchange and not by refining the original circuit.

高敏立体视觉出现在出生后早期的关键时期，当时初级视觉皮层中的双眼神经元增强了它们的感受野调谐特性。我们发现这种锐化是通过拆除关键时期开始时存在的双目回路并重新构建它来实现的。数千个神经元的感受野调谐（例如，方向选择性）的纵向成像显示，在关键时期开始时存在于第 2/3 层的大多数双眼神经元调谐不佳并呈现单眼。同时，新的双眼神经元是通过转换调整良好的单眼神经元来建立的，因为它们从另一只眼睛获得匹配的输入。第 2/3 层中双目调谐的这些改进不是从第 4 层继承的，而是由同侧眼睛反应的经验依赖性锐化驱动的。因此，