We analyze unidirectional and reciprocally connected pairs of neurons in the chemical connectomes of the male and hermaphrodite Caenorhabditis elegans, using recently published data. Our analysis reveals that reciprocal connections provide communication between most neurons with chemical synapses, and comprise on average more synapses than both unidirectional connections and the entire connectome. We further reveal that the C. elegans connectome is wired so that afferent connections onto neurons with large numbers of presynaptic neighbors (in‐degree) comprise an above‐average number of synapses (synaptic multiplicity). Notably, the larger the in‐degree of a neuron the larger the synaptic multiplicity of its afferent connections. Finally, we show that the male forms two times fewer reciprocal connections between sex‐shared neurons than the hermaphrodite, but a large number of reciprocal connections with male‐specific neurons. These observations provide evidence for Hebbian structural plasticity in the C. elegans.

中文翻译：

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秀丽隐杆线虫连接组中单向和相互化学连接的统计分析

我们使用最近发表的数据来分析雄性和雌雄同体秀丽隐杆线虫的化学连接体中的单向和相互连接的神经元对。我们的分析表明，相互连接为大多数神经元之间的化学突触提供了交流，并且平均而言，与单向连接和整个连接组相比，突触的连接更多。我们进一步揭示了秀丽隐杆线虫连接器是有线连接的，因此到具有大量突触前邻居（in-度）的神经元的传入连接构成高于平均水平的突触（突触多重性）。值得注意的是，神经元的度数越大，其传入连接的突触多样性就越大。最后，我们证明，与雌雄同体相比，雄性形成的性别共享神经元之间的相互联系要少两倍，但与雄性特定的神经元之间的相互联系却要多得多。这些观察结果为线虫中的Hebbian结构可塑性提供了证据。