Neural signal propagation atlas of Caenorhabditis elegans

The dataset used in the paper "Randi, F., Sharma, A.K., Dvali, S. et al. Neural signal propagation atlas of Caenorhabditis elegans. Nature 623, 406–414 (2023)."

Establishing how neural function emerges from network properties is a fundamental problem in neuroscience. Here, to better understand the relationship between the structure and the function of a nervous system, we systematically measure signal propagation in 23,433 pairs of neurons across the head of the nematode Caenorhabditis elegans by direct optogenetic activation and simultaneous whole-brain calcium imaging. We measure the sign (excitatory or inhibitory), strength, temporal properties and causal direction of signal propagation between these neurons to create a functional atlas. We find that signal propagation differs from model predictions that are based on anatomy. Using mutants, we show that extrasynaptic signalling not visible from anatomy contributes to this difference. We identify many instances of dense-core-vesicle-dependent signalling, including on timescales of less than a second, that evoke acute calcium transients—often where no direct wired connection exists but where relevant neuropeptides and receptors are expressed. We propose that, in such cases, extrasynaptically released neuropeptides serve a similar function to that of classical neurotransmitters. Finally, our measured signal propagation atlas better predicts the neural dynamics of spontaneous activity than do models based on anatomy. We conclude that both synaptic and extrasynaptic signalling drive neural dynamics on short timescales, and that measurements of evoked signal propagation are crucial for interpreting neural function.

Read the paper at: https://www.nature.com/articles/s41586-023-06683-4

本研究所用数据集来自论文《Randi, F., Sharma, A.K., Dvali, S. 等. 秀丽隐杆线虫（Caenorhabditis elegans）神经信号传导图谱. Nature 623, 406–414 (2023).》

阐明神经功能如何由网络特性涌现而来，是神经科学领域的核心基础问题。为深入解析神经系统结构与功能的内在关联，本研究通过直接光遗传激活（optogenetic activation）结合同步全脑钙成像（whole-brain calcium imaging）技术，系统测定了秀丽隐杆线虫头部23,433对神经元之间的信号传导情况。我们量化了神经元间信号传导的极性（兴奋性或抑制性）、强度、时域特性及因果方向，以此构建了神经功能图谱。研究发现，实测的信号传导特性与基于解剖结构构建的模型预测结果存在显著差异。借助突变体实验，我们证实了解剖结构无法观测到的突触外信号传导（extrasynaptic signalling）是造成这一差异的关键因素。

我们鉴定出大量依赖致密核心囊泡（dense-core vesicle）的信号传导案例，其中包括时长不足1秒的快速信号传导事件，这类信号可诱发急性钙瞬变（calcium transients）——这类场景通常不存在直接的有线突触连接，但相关神经肽（neuropeptides）及其受体均有表达。据此我们提出，此类场景中突触外释放的神经肽发挥了与经典神经递质相似的功能。

最终，相较于基于解剖结构的模型，我们实测得到的信号传导图谱能更准确地预测自发活动的神经动力学（neural dynamics）。本研究结论表明，突触信号传导与突触外信号传导共同介导了短时程的神经动力学活动，而诱发式信号传导的实测数据对于解析神经功能至关重要。

可通过以下链接查阅原文：https://www.nature.com/articles/s41586-023-06683-4