Spatial Properties of Cutaneous Temperature Sensitivity

描述(申请人提供)：这个项目的长期目标是了解热刺激是如何在皮肤的感觉系统内和之间整合的。这项拟议的研究将检验三个假说，这些新发现对当前的热接受理论提出了质疑：第一，当热纤维也受到刺激时，皮肤冷纤维可能会导致热感，其中许多冷纤维在高温下也会“矛盾地”释放；第二，在31摄氏度至25摄氏度之间的温和降温会在静态接触冷却时产生刺痛和/或灼伤的痛感(“无害-寒冷伤害感觉”)；第三，较大刺激接触皮肤最敏感部位的可能性更高，这在很大程度上可以解释冷热总和。提出的实验将利用专门设计的热刺激器来测试以下假设：(1)当热纤维也被刺激时，由于冷刺激被编码为热，甚至热痛，所以发生热烧烤错觉(合成热)；(2)通过使用线性热模式阵列来研究合成热和悖论热来确定这些温冷相互作用的时空特性；(3)测试通过与皮肤动态接触产生的触觉刺激来抑制无伤感-冷伤害感的假设，并研究其与合成热和悖论热相关的伤害性感觉的关系；以及(4)使用一种独特的手持式热刺激器对空间总和的“敏感部位”解释进行进一步测试，该刺激器将能够在模拟触觉探测温度的条件下研究整个手部的热知觉和整合。除了增加我们对正常温度敏感性如何依赖于温度、触觉和痛觉之间的相互作用的了解外，拟议的研究结果还可能有助于解释温度引发的神经性疼痛，如冷痛和痛觉过敏，是如何由一个或多个皮肤感觉的传入处理中断引起的。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how thermal stimulation is integrated within and among the sensory systems of the skin. The proposed research will test hypotheses stemming from three new findings during the present funding period that raise questions about current theories of thermoreception: First, that cutaneous cold fibers, many of which also discharge 'paradoxically' at high temperatures, may contribute to sensations of heat whenever warm fibers are also stimulated; second, that mild cooling between 31degrees -25 degrees C can produce nociceptive sensations of stinging and/or burning ('innocuous-cold nociception') during static, but not dynamic, contact cooling; and third, that much of summation of warmth and cold can be accounted for by the higher probability that larger stimuli will contact the most sensitive sites in the skin. Experiments are proposed that will take advantage of specially designed thermal stimulators to (1) test the hypothesis that the Heat Grill Illusion (Synthetic Heat) occurs because cool stimulation is encoded as heat, and even heat pain, when warm fibers are also stimulated; (2) determine the spatiotemporal properties of these warm-cold interactions via studies of Synthetic Heat and Paradoxical Heat using a linear thermode array; (3) test the hypothesis that 'innocuous-cold nociception' is suppressed by tactile stimulation produced by dynamic contact with the skin, and investigate its relationship to the nociceptive sensations associated with Synthetic Heat and Paradoxical Heat; and (4) provide further tests of the 'sensitive-site' explanation of spatial summation using a unique, handgrip thermal stimulator that will enable studies of thermal perception and integration throughout the hand under conditions that mimic haptic exploration of temperature. In addition to increasing our knowledge of how normal temperature sensitivity depends upon interactions among the senses of temperature, touch, and pain, the results of the proposed studies may help to explain how neuropathic pains that are triggered by temperature, such as cold dysesthesias and hyperalgesias, can arise from disruption of afferent processing in one or more of the cutaneous senses.