Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri, USA.
J Neurophysiol. 2013 Sep;110(5):1117-29. doi: 10.1152/jn.00974.2012. Epub 2013 Jun 12.
Changes in oral temperature can influence taste perception, indicating overlap among mechanisms for taste and oral somesthesis. Medullary gustatory neurons can show cosensitivity to temperature, albeit how these cells process combined taste and thermal input is poorly understood. Here, we electrophysiologically recorded orosensory responses (spikes) from 39 taste-sensitive neurons in the nucleus tractus solitarii of anesthetized mice during oral delivery of tastants adjusted to innocuous cool (16 and 18°C), room (22°C, baseline), and warm (30 and 37°C) oral temperatures. Stimuli included (in mM) 100 sucrose, 30 NaCl, 3 HCl, 3 quinine, an umami mixture, and water. Although cooled water excited few cells, water warmed to 30 and 37°C significantly excited 33% and 64% of neurons, respectively. Warmth induced responses of comparable magnitude to room temperature tastants. Furthermore, warming taste solutions influenced the distribution of gustatory responses among neurons and increased (P < 0.05) neuronal breadth of tuning across taste qualities. The influence of warmth on response magnitude was stimulus specific. Across neurons, warming facilitated responses to sucrose and umami in a superadditive manner, as these responses exceeded (P < 0.05) the arithmetic sum of activity to warming alone and the taste stimulus tested at room temperature. Superadditive increases (P < 0.05) in responding were also noted in some cells for warmed HCl. Yet warming induced only simple additive or subtractive effects on responses to quinine and NaCl. Data show temperature is a parameter of gustatory processing, like taste quality and concentration, in medullary circuits for taste.
口腔温度的变化会影响味觉感知，表明味觉和口腔体感之间的机制存在重叠。延髓味觉神经元对温度表现出共敏感性，尽管这些细胞如何处理味觉和热输入的组合还知之甚少。在这里，我们在麻醉小鼠的孤束核中记录了 39 个味觉敏感神经元的口腔感觉反应（尖峰），这些神经元在口腔输送经调整至无害凉爽（16 和 18°C）、室温（22°C，基线）和温暖（30 和 37°C）的味觉刺激物时会产生反应。刺激物包括（mM）100 蔗糖、30 NaCl、3 HCl、3 奎宁、鲜味混合物和水。虽然冷却的水仅能激发少数细胞，但加热至 30 和 37°C 的水则分别显著激发了 33%和 64%的神经元。温暖的刺激引起的反应与室温味觉刺激相当。此外，加热会影响味觉反应在神经元之间的分布，并增加（P < 0.05）跨味觉品质的神经元调谐宽度。温暖对反应幅度的影响是刺激特异性的。对于整个神经元群体，加热会以超相加的方式促进蔗糖和鲜味的反应，因为这些反应（P < 0.05）超过了单独加热和在室温下测试的味觉刺激的算术和。在一些细胞中，加热还会引起 HCl 反应的超加性增加（P < 0.05）。然而，加热仅对奎宁和 NaCl 的反应产生简单的相加或相减效应。数据表明，温度是延髓味觉回路处理味觉的参数之一，就像味觉质量和浓度一样。
