Higher-order projections to sensory cortical areas converge on layer 1 (L1), the primary site for integration of top-down information via the apical dendrites of pyramidal neurons and L1 GABAergic interneurons. Here we investigated the contribution of early thalamic inputs onto L1 interneurons for establishment of top-down connectivity in the primary visual cortex. We find that bottom-up thalamic inputs predominate during L1 development and preferentially target neurogliaform cells. We show that these projections are critical for the subsequent strengthening of top-down inputs from the anterior cingulate cortex onto L1 neurogliaform cells. Sensory deprivation or selective removal of thalamic afferents blocked this phenomenon. Although early activation of the anterior cingulate cortex resulted in premature strengthening of these top-down afferents, this was dependent on thalamic inputs. Our results demonstrate that proper establishment of top-down connectivity in the visual cortex depends critically on bottom-up inputs from the thalamus during postnatal development.

对感觉皮层区域的高阶投射会聚在第 1 层 (L1)，这是通过锥体神经元和 L1 氨基丁酸能中间神经元的顶端树突整合自上而下信息的主要场所。在这里，我们调查了早期丘脑输入对 L1 中间神经元的贡献，以在初级视觉皮层中建立自上而下的连接。我们发现自下而上的丘脑输入在 L1 发育过程中占主导地位，并优先针对神经胶质细胞。我们表明，这些投射对于随后加强从前扣带皮层到 L1 神经胶质细胞的自上而下输入至关重要。感觉剥夺或选择性去除丘脑传入阻止了这种现象。尽管前扣带皮层的早期激活导致这些自上而下的传入神经过早增强，这取决于丘脑输入。我们的结果表明，在视觉皮层中正确建立自上而下的连接性关键取决于出生后发育过程中来自丘脑的自下而上的输入。