The laminar development of direction selectivity in ferret visual cortex.
The laminar development of direction selectivity in ferret visual cortex.
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DOI：
10.1523/jneurosci.3399-12.2012
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发表时间：
2012-12-12
期刊：
影响因子：
--
通讯作者：
Van Hooser SD
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文献类型：
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作者：
Clemens JM;Ritter NJ;Roy A;Miller JM;Van Hooser SD
感觉体验在皮层回路的发育中起着至关重要的作用。在睁眼时，雪貂的视觉皮层神经元表现出方向选择性，但缺乏方向选择性，这是雪貂成熟皮层神经元的特征。方向选择性在眼睛睁开后的几天或几周内通过一个需要视觉经验的过程出现。然而，在方向选择性发展的基础上的电路机制仍然不清楚。在这里，我们使用微电极来检查眼睛睁开前后方向选择性发展的层流年表，以确定在这一过程中皮层回路中发生改变的位置。我们发现第4层和2/3层的神经元在自然睁眼之前表现出较弱的方向选择性。第4层神经元的方向选择性略有增加，但第2/3层细胞的方向选择性仍与睁眼前一样弱。睁眼且PND 35或以上的动物在第4层和第2/3层均表现出更高的方向选择性。平均而言，小于PND35的动物最初的方向选择性增加可以解释为对首选方向的反应增加，而PND35或更大的动物随后的方向选择性增加可以解释为对零方向的反应减少。这些结果表明，在经验依赖发育的早期阶段，所有皮质层都受到感觉刺激的影响。
Sensory experience plays a critical role in the development of cortical circuits. At the time of eye opening, visual cortical neurons in the ferret exhibit orientation selectivity, but lack direction selectivity, which is a feature of mature cortical neurons in this species. Direction selectivity emerges in the days and weeks following eye opening via a process that requires visual experience. However, the circuit mechanisms that underlie the development of direction selectivity remain unclear. Here, we used microelectrodes to examine the laminar chronology of the development of direction selectivity around the time of eye opening in order to identify the locations within the cortical circuit that are altered during this process. We found that neurons in layers 4 and 2/3 exhibited weak direction selectivity just prior to natural eye opening. Layer 4 neurons in animals that had opened their eyes but were younger than postnatal day (PND) 35 exhibited modestly increased direction selectivity, but layer 2/3 cells remained as weakly tuned as before eye opening. Animals that had opened their eyes and were PND 35 or older exhibited increased direction selectivity in both layers 4 and 2/3.On average, initial increases in direction selectivity in animals younger than PND 35 were explained by increases in responses to the preferred direction, while subsequent increases in direction selectivity in animals PND35 or older were explained by decreases in responses to the null direction. These results suggest that all cortical layers are influenced by sensory stimulation during early stages of experience-dependent development.