Sparsification of neuronal activity in the visual cortex at eye-opening
Sparsification of neuronal activity in the visual cortex at eye-opening
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DOI：
10.1073/pnas.0907660106
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发表时间：
2009-09-01
影响因子：
11.1
通讯作者：
Konnerth, Arthur
中科院分区：
文献类型：
--
作者：
Rochefort, Nathalie L.;Garaschuk, Olga;Konnerth, Arthur
眼睛睁开代表了视觉皮层功能的转折点。在睁开眼睛之前，视觉皮层基本上没有感觉输入，神经元活动是内在产生的。睁开眼睛后，大脑皮层开始整合视觉信息。在此，我们利用在体双光子钙离子成像技术，通过分析小鼠视觉皮层持续的自发活动来探讨其发育变化。我们发现，在睁眼之前，第2/3层神经元的活动主要由慢波振荡组成。这些波在出生后第8天（P8）首次检测到。它们最初的极低频率（0.01 Hz）在发育过程中逐渐增加，成年后接近0.5 Hz。在睁眼之前，大部分神经元（>75%）在每个波期间都是活跃的。在睁开眼睛后的一天，这种密集的募集模式变成了稀疏模式，每个波只有36%的活跃神经元。随后在接下来的几周内逐渐减少，成人中每波活跃神经元的比例达到12%。通过分析黑暗饲养的小鼠，研究了视觉经验对稀疏化过程的可能作用。我们发现，稀疏化也发生在这些小鼠中，但从密集到稀疏的活动模式的转换与正常饲养的小鼠相比延迟了3-4天。这些结果揭示了在睁眼后的第一天，视觉体验的调节作用，但内在因素的整体主导作用。我们认为，网络活动从密集到稀疏的转变是睁眼时皮层功能改变的先决条件。
Eye-opening represents a turning point in the function of the visual cortex. Before eye-opening, the visual cortex is largely devoid of sensory inputs and neuronal activities are generated intrinsically. After eye-opening, the cortex starts to integrate visual information. Here we used in vivo two-photon calcium imaging to explore the developmental changes of the mouse visual cortex by analyzing the ongoing spontaneous activity. We found that before eye-opening, the activity of layer 2/3 neurons consists predominantly of slow wave oscillations. These waves were first detected at postnatal day 8 (P8). Their initial very low frequency (0.01 Hz) gradually increased during development to approximate to 0.5 Hz in adults. Before eye-opening, a large fraction of neurons (>75%) was active during each wave. One day after eye-opening, this dense mode of recruitment changed to a sparse mode with only 36% of active neurons per wave. This was followed by a progressive decrease during the following weeks, reaching 12% of active neurons per wave in adults. The possible role of visual experience for this process of sparsification was investigated by analyzing dark-reared mice. We found that sparsification also occurred in these mice, but that the switch from a dense to a sparse activity pattern was delayed by 3-4 days as compared with normally-reared mice. These results reveal a modulatory contribution of visual experience during the first days after eye-opening, but an overall dominating role of intrinsic factors. We propose that the transformation in network activity from dense to sparse is a prerequisite for the changed cortical function at eye-opening.