Animals and humans share similar mechanisms of pain detection and similar brain areas involved in pain processing. Also, they show similar pain behaviors, such as reflexed sensation to nociceptive stimuli. Pain is often described in sensory discrimination (algosity) and affective motivation (unpleasantness) dimensions. Both basic and clinical findings indicate that individuals with chronic pain usually suffer more from pain-associated affective disturbances than from the actual pain sensations per se. Although the neural systems responsible for the sensory component of pain have been studied extensively, the neural mechanisms underlying negative affective component are not well understood. This is partly due to the relative paucity of animal paradigms for reliable examination of each component of pain. In humans, the experience of pain and suffering can be reported by language, while in animals, pain can only be inferred through physical and behavioral reactions. Animal behaviors, cognitive psychology and functional brain imaging have made it possible to assess pain affection and pain memory in animals. Animals subjected to either neuropathic injury or inflammatory insult display significant conditioned place aversion to a pain-paired environment in behaviors. The present review aims to summarize the common methods of affective unpleasantness assessment in rats.
动物和人有着类似的痛感知机制和参与疼痛加工的大脑脑区。 他们也会表现出相似的痛行为, 譬如对伤害性刺激的反射性感觉。 疼痛常用感觉(感觉质量)维度和情感动机(不愉快)维度来描述。 基础和临床研究都显示, 慢性痛患者经常遭受比实在的痛感觉更多的、 与疼痛有关的情绪痛苦。 虽然介导痛感觉的神经机制已经被广泛研究, 但是痛负面情绪的神经机制还没有得到很好的了解, 这主要归因于目前相对模糊的检测疼痛不同成分的行为学方法。 人可以用语言来表达疼痛和痛苦的经历, 而动物只能依靠其行为学反应来体现疼痛。 动物行为学、 认知心理学和脑功能成像技术使得检测动物的痛情绪和痛记忆成为可能。 遭受神经病理性痛或炎性痛伤害后, 动物会在行为上表现出对痛配对环境的条件位置性躲避。 本文主要对目前常用的大鼠痛厌恶情绪的检测方法进行综述。