Billimoria Cyrus P, DiCaprio Ralph A, Birmingham John T, Abbott L F, Marder Eve
Volen Center, Biology Department, Brandeis University, Waltham, Massachusetts 02454, USA.
J Neurosci. 2006 May 31;26(22):5910-9. doi: 10.1523/JNEUROSCI.4659-05.2006.
The neuropeptide allatostatin decreases the spike rate in response to time-varying stretches of two different crustacean mechanoreceptors, the gastropyloric receptor 2 in the crab Cancer borealis and the coxobasal chordotonal organ (CBCTO) in the crab Carcinus maenas. In each system, the decrease in firing rate is accompanied by an increase in the timing precision of spikes triggered by discrete temporal features in the stimulus. This was quantified by calculating the standard deviation or "jitter" in the times of individual identified spikes elicited in response to repeated presentations of the stimulus. Conversely, serotonin increases the firing rate but decreases the timing precision of the CBCTO response. Intracellular recordings from the afferents of this receptor demonstrate that allatostatin increases the conductance of the neurons, consistent with its inhibitory action on spike rate, whereas serotonin decreases the overall membrane conductance. We conclude that spike-timing precision of mechanoreceptor afferents in response to dynamic stimulation can be altered by neuromodulators acting directly on the afferent neurons.
神经肽抑咽侧体素可降低两种不同甲壳类动物机械感受器对随时间变化的拉伸刺激的放电频率，这两种感受器分别是北方黄道蟹的胃幽门感受器2和肉球近方蟹的基节弦音器（CBCTO）。在每个系统中，放电频率的降低伴随着由刺激中的离散时间特征触发的尖峰时间精度的增加。这是通过计算对刺激的重复呈现做出反应而引发的单个识别尖峰时间的标准差或“抖动”来量化的。相反，血清素会增加放电频率，但会降低CBCTO反应的时间精度。来自该感受器传入神经的细胞内记录表明，抑咽侧体素会增加神经元的电导，这与其对放电频率的抑制作用一致，而血清素会降低整体膜电导。我们得出结论，直接作用于传入神经元的神经调质可以改变机械感受器传入神经对动态刺激的尖峰时间精度。
