Wiring stability of the adult Drosophila olfactory circuit after lesion
Wiring stability of the adult Drosophila olfactory circuit after lesion
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DOI：
10.1523/jneurosci.4941-05.2006
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发表时间：
2006-03-29
影响因子：
5.3
通讯作者：
Luo, LQ
中科院分区：
文献类型：
--
作者：
Berdnik, D;Chihara, T;Luo, LQ
据报道，在成人神经系统的许多部分，神经元对经验或损伤的反应是可塑性的。例如，视觉或躯体感觉皮质图可以对周围病变做出显著重组，但一定程度的稳定性对于神经元回路执行其特定功能是必不可少的。以前对损伤诱导的神经元重组的研究主要集中在使用连续神经映射的系统上。在这里，我们评估了以成年果蝇嗅觉回路为代表的离散神经图谱中的连线可塑性。使用毒素的条件表达，我们从基因上消融了特定类别的神经元，并检查了对它们的突触伙伴或成年触角叶中相邻类别的影响。我们没有发现嗅觉感受器神经元(ONS)与其突触后靶点投射神经元(PNS)之间的联系特异性改变。消融一个ORN类可以保持肾小球边界内的PN树突，正常情况下支配邻近靶点的ORN轴突不会扩张。同样，消融PN类不会改变其伙伴ORN轴突的连通性。有趣的是，对侧ORN轴突终末密度的增加是对竞争同侧ORN移除的反应。因此，这个回路的可塑性可以发生，但仅限于肾小球内，从而保留了ONS和PNS的连接特异性。我们的结论是，尽管成年嗅觉神经元可以在失去竞争的情况下发生可塑性变化，但在这个离散的映射中，嗅觉回路在保留分离的信息通道方面总体上是极其稳定的。
Neuronal wiring plasticity in response to experience or injury has been reported in many parts of the adult nervous system. For instance, visual or somatosensory cortical maps can reorganize significantly in response to peripheral lesions, yet a certain degree of stability is essential for neuronal circuits to perform their dedicated functions. Previous studies on lesion-induced neuronal reorganization have primarily focused on systems that use continuous neural maps. Here, we assess wiring plasticity in a discrete neural map represented by the adult Drosophila olfactory circuit. Using conditional expression of toxins, we genetically ablated specific classes of neurons and examined the consequences on their synaptic partners or neighboring classes in the adult antennal lobe. We find no alteration of connection specificity between olfactory receptor neurons (ORNs) and their postsynaptic targets, the projection neurons (PNs). Ablating an ORN class maintains PN dendrites within their glomerular borders, and ORN axons normally innervating an adjacent target do not expand. Likewise, ablating PN classes does not alter their partner ORN axon connectivity. Interestingly, an increase in the contralateral ORN axon terminal density occurs in response to the removal of competing ipsilateral ORNs. Therefore, plasticity in this circuit can occur but is confined within a glomerulus, thereby retaining the wiring specificity of ORNs and PNs. We conclude that, although adult olfactory neurons can undergo plastic changes in response to the loss of competition, the olfactory circuit overall is extremely stable in preserving segregated information channels in this discrete map.