Breza Joseph M, Nikonov Alexandre A, Contreras Robert J
Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306-4301, USA.
J Neurophysiol. 2010 Apr;103(4):1771-84. doi: 10.1152/jn.00785.2009. Epub 2010 Jan 27.
The purpose of this study was to investigate the role of response latency in discrimination of chemical stimuli by geniculate ganglion neurons in the rat. Accordingly, we recorded single-cell 5-s responses from geniculate ganglion neurons (n = 47) simultaneously with stimulus-evoked summated potentials (electrogustogram; EGG) from the anterior tongue to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse solution and solvent for all stimuli [(0.5 M sucrose, 0.03-0.5 M NaCl, 0.01 M citric acid, and 0.02 M quinine hydrochloride (QHCl)], 0.1 M KCl as well as for 0.1 M NaCl +1 μM benzamil. Cluster analysis separated neurons into four groups (sucrose specialists, NaCl specialists, NaCl/QHCl generalists and acid generalists). Artificial saliva elevated spontaneous firing rate and response frequency of all neurons. As a rule, geniculate ganglion neurons responded with the highest frequency and shortest latency to their best stimulus with acid generalist the only exception. For specialist neurons and NaCl/QHCl generalists, the average response latency to the best stimulus was two to four times shorter than the latency to secondary stimuli. For NaCl-specialist neurons, response frequency increased and response latency decreased systematically with increasing NaCl concentration; benzamil significantly decreased NaCl response frequency and increased response latency. Acid-generalist neurons had the highest spontaneous firing rate and were the only group that responded consistently to citric acid and KCl. For many acid generalists, a citric-acid-evoked inhibition preceded robust excitation. We conclude that response latency may be an informative coding signal for peripheral chemosensory neurons.
本研究的目的是调查反应潜伏期在大鼠膝状神经节神经元对化学刺激辨别中的作用。因此，我们记录了膝状神经节神经元（n = 47）的单细胞5秒反应，同时记录了来自舌尖的刺激诱发的总和电位（电味觉图；EGG），以信号指示刺激何时接触舌上皮。人工唾液用作所有刺激物[（0.5 M蔗糖、0.03 - 0.5 M氯化钠、0.01 M柠檬酸和0.02 M盐酸奎宁（QHCl）]、0.1 M氯化钾以及0.1 M氯化钠 + 1 μM苯扎明的冲洗溶液和溶剂。聚类分析将神经元分为四组（蔗糖特异性神经元、氯化钠特异性神经元、氯化钠/盐酸奎宁通用型神经元和酸通用型神经元）。人工唾液提高了所有神经元的自发放电率和反应频率。通常，膝状神经节神经元对其最佳刺激的反应频率最高且潜伏期最短，酸通用型神经元是唯一的例外。对于特异性神经元和氯化钠/盐酸奎宁通用型神经元，对最佳刺激的平均反应潜伏期比对次要刺激的潜伏期短两到四倍。对于氯化钠特异性神经元，随着氯化钠浓度的增加，反应频率增加且反应潜伏期系统性缩短；苯扎明显著降低了氯化钠反应频率并增加了反应潜伏期。酸通用型神经元具有最高的自发放电率，并且是唯一对柠檬酸和氯化钾持续反应的组。对于许多酸通用型神经元，柠檬酸诱发的抑制先于强烈的兴奋。我们得出结论，反应潜伏期可能是外周化学感觉神经元的一个信息编码信号。
