Volen Center and Biology Department, Brandeis University, Waltham, Massachusetts, United States of America.
PLoS Comput Biol. 2013;9(1):e1002857. doi: 10.1371/journal.pcbi.1002857. Epub 2013 Jan 10.
The crab Cancer borealis undergoes large daily fluctuations in environmental temperature (8-24°C) and must maintain appropriate neural function in the face of this perturbation. In the pyloric circuit of the crab stomatogastric ganglion, we pharmacologically isolated the pacemaker kernel (the AB and PD neurons) and characterized its behavior in response to temperature ramps from 7°C to 31°C. For moderate temperatures, the pacemaker displayed a frequency-temperature curve statistically indistinguishable from that of the intact circuit, and like the intact circuit maintained a constant duty cycle. At high temperatures (above 23°C), a variety of different behaviors were seen: in some preparations the pacemaker increased in frequency, in some it slowed, and in many preparations the pacemaker stopped oscillating ("crashed"). Furthermore, these crashes seemed to fall into two qualitatively different classes. Additionally, the animal-to-animal variability in frequency increased at high temperatures. We used a series of Morris-Lecar mathematical models to gain insight into these phenomena. The biophysical components of the final model have temperature sensitivities similar to those found in nature, and can crash via two qualitatively different mechanisms that resemble those observed experimentally. The crash type is determined by the precise parameters of the model at the reference temperature, 11°C, which could explain why some preparations seem to crash in one way and some in another. Furthermore, even models with very similar behavior at the reference temperature diverge greatly at high temperatures, resembling the experimental observations.
北方滨蟹经历着环境温度（8-24°C）的大幅日波动，必须在面对这种干扰时保持适当的神经功能。在北方滨蟹的口胃神经节的贲门电路中，我们通过药理学方法分离出起搏器核心（AB 和 PD 神经元），并描述了它们在温度从 7°C 升高到 31°C 时的行为。对于中等温度，起搏器显示的频率-温度曲线与完整电路的曲线在统计学上无法区分，并且与完整电路一样保持恒定的占空比。在高温（高于 23°C）下，会出现各种不同的行为：在一些准备中，起搏器的频率增加，在一些准备中，起搏器的频率减慢，而在许多准备中，起搏器停止振荡（“崩溃”）。此外，这些崩溃似乎分为两种不同的定性类别。此外，高温下动物间频率的变异性增加。我们使用一系列 Morris-Lecar 数学模型来深入了解这些现象。最终模型的生物物理组件具有与自然界相似的温度敏感性，并且可以通过两种与实验观察到的相似的定性不同的机制崩溃。崩溃类型由参考温度（11°C）下模型的精确参数决定，这可以解释为什么一些准备似乎以一种方式崩溃，而另一些则以另一种方式崩溃。此外，即使在参考温度下具有非常相似行为的模型在高温下也会有很大的差异，类似于实验观察。
