Layer- and Cell-Type-Specific Subthreshold and Suprathreshold Effects of Long-Term Monocular Deprivation in Rat Visual Cortex
Layer- and Cell-Type-Specific Subthreshold and Suprathreshold Effects of Long-Term Monocular Deprivation in Rat Visual Cortex
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DOI：
10.1523/jneurosci.2951-11.2011
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发表时间：
2011-11-23
影响因子：
5.3
通讯作者：
Medini, Paolo
中科院分区：
文献类型：
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作者：
Medini, Paolo
连接性和树突特性是新皮层中特定于层和细胞类型的可塑性的决定因素。然而，经验依赖的可塑性在突触输入和尖峰输出水平的影响仍然不清楚沿着垂直皮层微电路。在这里，我比较了阈下和阈上的敏感性，以长期单眼剥夺（MD）大鼠双眼视皮层在第4层和第2/3层金字塔（4Ps和2/3 Ps）和厚簇和nontufted层5金字塔（5 TP和5 NP），这支配不同的外皮质的目标。在正常大鼠中，5 TP和2/3 Ps的突触输入最多，5 NP最少。所有5 TP的棘波反应是高度双眼，而2/3 Ps的主要由对侧或同侧的眼睛。MD显著改变了2/3 Ps和4Ps的视觉偏好，主要是通过抑制剥夺眼输入。第5层的可塑性有很大的不同。阈下眼偏好的转变是7倍小，因为在5 TP较小的抑郁症的剥夺输入结合了广泛的反应性损失，是无法检测到的5 NP。尽管他们温和的眼优势的变化，穗反应的5 TP一贯失去了他们典型的高双目在MD。对垂直微电路主要受影响的输出单元2/3 Ps和5 TPs的MD效应的比较表明，阈下可塑性并不是由初始的输入双目度唯一决定的。这些数据提出了一个问题，即在MD期间，5 TP是否仅由2/3 Ps驱动。两种细胞群体的不同阈上可塑性可能是弱视不同功能缺陷的基础。
Connectivity and dendritic properties are determinants of plasticity that are layer and cell-type specific in the neocortex. However, the impact of experience-dependent plasticity at the level of synaptic inputs and spike outputs remains unclear along vertical cortical microcircuits. Here I compared subthreshold and suprathreshold sensitivity to prolonged monocular deprivation (MD) in rat binocular visual cortex in layer 4 and layer 2/3 pyramids (4Ps and 2/3Ps) and in thick-tufted and nontufted layer 5 pyramids (5TPs and 5NPs), which innervate different extracortical targets. In normal rats, 5TPs and 2/3Ps are the most binocular in terms of synaptic inputs, and 5NPs are the least. Spike responses of all 5TPs were highly binocular, whereas those of 2/3Ps were dominated by either the contralateral or ipsilateral eye. MD dramatically shifted the ocular preference of 2/3Ps and 4Ps, mostly by depressing deprived-eye inputs. Plasticity was profoundly different in layer 5. The subthreshold ocular preference shift was sevenfold smaller in 5TPs because of smaller depression of deprived inputs combined with a generalized loss of responsiveness, and was undetectable in 5NPs. Despite their modest ocular dominance change, spike responses of 5TPs consistently lost their typically high binocularity during MD. The comparison of MD effects on 2/3Ps and 5TPs, the main affected output cells of vertical microcircuits, indicated that subthreshold plasticity is not uniquely determined by the initial degree of input binocularity. The data raise the question of whether 5TPs are driven solely by 2/3Ps during MD. The different suprathreshold plasticity of the two cell populations could underlie distinct functional deficits in amblyopia.