Psychophysical and behavioral characteristics of olfactory adaptation
Psychophysical and behavioral characteristics of olfactory adaptation
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DOI：
10.1093/chemse/25.4.487
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发表时间：
2000-08-01
期刊：
影响因子：
3.5
通讯作者：
Dalton, P
中科院分区：
文献类型：
--
作者：
Dalton, P
感觉适应允许生物体与周围环境达到行为平衡，并主要对刺激的变化做出反应。考虑到嗅觉系统的功能重要性，嗅觉系统的适应表现出许多与包括视觉在内的其他感觉系统的适应相同的特征也就不足为奇了。重复或长时间暴露于气味剂通常会导致对该气味剂的嗅觉敏感性的刺激特异性降低，但在没有进一步暴露的情况下，敏感性会随时间恢复。心理物理学分析表明，嗅觉适应的结果在气味阈值的升高和降低反应阈上刺激。此外，减少的幅度以及适应和恢复的时间过程取决于气味的浓度和暴露的持续时间。人们普遍认为，嗅觉适应可以发生在嗅觉系统的多个层次，可以涉及外周（受体水平）和更中央（后受体）的组件。外周和中枢参与的证据来自于研究，表明单嗅刺激导致同侧和对侧脊髓的适应，尽管同侧脊髓的适应程度更深，恢复更慢。中枢参与的其他证据来自研究，这些研究发现，尽管感知强度大幅降低，但重复刺激后外周反应相对较小。然而，大多数关于适应的心理物理学研究并没有区分外周过程和中枢过程。虽然数量相对较少，但脊椎动物（如大鼠）和无脊椎动物（如果蝇、秀丽隐杆线虫）动物模型中嗅觉适应的参数特征研究似乎复制了成年人心理物理学研究中的发现。尽管嗅觉适应与其他感觉系统的适应有着广泛的整体相似性，但嗅觉适应仍表现出一些独特的特征。嗅觉的适应在某些情况下是非常持久的，并且可能受到前神经事件和气味分子的物理化学性质的影响，这些气味分子控制扩散到受体部位和受体后清除。
Sensory adaptation allows organisms to reach behavioral equilibrium with the ambient environment and respond primarily to changes in stimulation. Given its functional significance, it is not surprising that adaptation in the olfactory system exhibits many of the same characteristics as adaptation in other sensory systems, including vision. Repeated or prolonged exposure to an odorant typically leads to stimulus-specific decreases in olfactory sensitivity to that odorant, but sensitivity recovers over time in the absence of further exposure. Psychophysical analysis shows that olfactory adaptation results in elevations in odor thresholds and in reduced responsiveness to suprathreshold stimulation. Further, the magnitude of the decrease and the time course of adaptation and recovery are dependent on the concentration of the odor and on the duration of exposure. It is generally agreed that olfactory adaptation can occur at multiple levels in the olfactory system and can involve both peripheral (receptor level) and more central (post-receptor) components. Evidence for peripheral and central involvement comes from studies showing that monorhinal stimulation results in adaptation in both the ipsilateral and contralateral nostril, although the degree of adaptation in the ipsilateral nostril is more profound and recovery is slower. Additional evidence for central involvement comes from studies that have found relatively small decreases in peripheral response following repeated stimulation despite substantial reductions in perceived intensity. Most psychophysical studies of adaptation, however, have not differentiated the peripheral and central processes. Although relatively few in number, studies of the parametric features of olfactory adaptation in both vertebrate (e.g. rat) and invertebrate (e.g. Drosophila, Caenorhabditis elegans) animal models appear to replicate the findings in psychophysical studies of adult humans. Despite the broad overall similarity of olfactory adaptation to adaptation in other sensory systems, olfactory adaptation exhibits some unique features. Adaptation in olfaction has been shown to be very long-lasting in some cases and may be modulated by the contribution of pre-neural events and physico-chemical properties of the odorant molecules that govern diffusion to receptor sites and post-receptor clearance.