Optical mapping of spatiotemporal emergence of functional synaptic connections in the embryonic chick olfactory pathway
Optical mapping of spatiotemporal emergence of functional synaptic connections in the embryonic chick olfactory pathway
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DOI：
10.1016/j.neuroscience.2006.11.019
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发表时间：
2007-02
期刊：
影响因子：
3.3
通讯作者：
K. Sato;M. Kinoshita;Y. Momose-Sato
中科院分区：
文献类型：
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作者：
K. Sato;M. Kinoshita;Y. Momose-Sato
为了理解中枢神经系统的功能成熟，有必要首先描述感觉处理的功能成熟。我们通过使用电压敏感染料成像跟踪与颅骨和脊髓感觉输入相关的神经回路形成的个体发育模式来探讨这个主题。在之前的研究中，我们描述了脑干/中脑神经回路中突触的功能成熟。在这里，我们通过研究与鸡胚嗅觉神经（N.I）相关的神经网络来阐明前脑回路的功能成熟。在分离的 N.I-嗅球-前脑准备中，对 N.I 应用电刺激在嗅球中引发兴奋性突触后电位 (EPSP) 相关的慢光信号。慢信号主要由谷氨酸介导，由于胚胎中枢神经系统突触的不成熟，很容易因重复刺激而疲劳。从个体发育角度来看，从 6 天胚胎阶段就检测到了慢信号，这表明 N.I 和嗅球之间的功能性突触连接在这个阶段出现。此外，从胚胎第8天开始，前脑内出现了另一个反应区域，对应于嗅觉通路的高级核。与我们之前关于胚胎脑干和中脑中其他脑神经相关感觉核的功能发育的研究相比，这些结果表明，嗅觉通路是在发育早期阶段功能性产生的，而与其他内脏和躯体感觉输入相关的神经网络也处于发育过程中。
In order to understand the functional maturation of the CNS, it is essential to first describe the functional maturation of sensory processing. We have approached this topic by following the ontogenetic patterning of neural circuit formation related to cranial and spinal sensory input using voltage-sensitive dye imaging. In previous studies, we have described the functional maturation of synapses in brainstem/midbrain neural circuits. Here, we elucidate the functional maturation of forebrain circuits by investigating neural networks related to the olfactory nerve (N. I) of chicken embryo. In the isolated N. I–olfactory bulb–forebrain preparation, application of electrical stimulation to N. I elicited excitatory postsynaptic potential (EPSP)–related slow optical signals in the olfactory bulb. The slow signal was mainly mediated by glutamate, and was easily fatigued with repetitive stimuli because of the immaturity of synapses in the embryonic CNS. Ontogenetically, the slow signal was detected from the 6-day embryonic stage, suggesting that functional synaptic connections between N. I and olfactory bulb emerge around this stage. In addition, from the 8-day embryonic stage, another response area was discriminated within the forebrain, which corresponded to the higher-ordered nucleus of the olfactory pathway. In comparison with our previous studies concerning the functional development of other cranial nerve-related sensory nuclei in the embryonic brainstem and midbrain, these results suggest that the olfactory pathway is functionally generated in the early stages of development when neural networks related to other visceral and somatic sensory inputs are also in the process of developing.