Wise Paul M, Canty Thomas M, Wysocki Charles J
Monell Chemical Senses Center, Philadelphia, Pennsylvania, 19104-3308, USA.
Toxicol Sci. 2005 Sep;87(1):223-31. doi: 10.1093/toxsci/kfi229. Epub 2005 Jun 23.
Two experiments examined integration of perceived irritation over short-term (approximately 100-4000 ms) delivery of ammonia into the nasal cavity of human subjects. Experiment 1 examined trade-offs between time and concentration at threshold level by means of nasal lateralization, a common measure of irritation threshold. Within experimental sessions, the duration of a fixed-concentration stimulus varied to determine the shortest, detectable pulse. Subjects could lateralize increasingly weaker concentrations with longer stimulus presentations. Experiment 2 examined an analogous trade-off for supra-threshold irritation. Subjects rated irritation from presentations of ammonia that varied both in concentration and in duration. Rated intensity for a given concentration increased with stimulus duration. Hence integration occurred at both threshold and supra-threshold levels. However, more than a twofold increase in duration was required to compensate for a twofold decrease in concentration to maintain threshold lateralization or a fixed level of perceived intensity. These results suggest that an imperfect mass-integrator model may be able to describe short-term integration of nasal irritation from ammonia at both the threshold and supra-threshold levels.
两项实验研究了在向人类受试者鼻腔短期（约100 - 4000毫秒）输送氨气过程中，感知到的刺激的整合情况。实验1通过鼻腔偏向化这一常用的刺激阈值测量方法，研究了阈值水平下时间与浓度之间的权衡。在实验过程中，固定浓度刺激的持续时间会发生变化，以确定最短的可检测脉冲。随着刺激呈现时间延长，受试者能够区分出越来越弱的浓度。实验2研究了超阈值刺激下类似的权衡。受试者对不同浓度和持续时间的氨气刺激进行刺激程度评级。对于给定浓度，评级强度随刺激持续时间增加。因此，在阈值和超阈值水平均发生了整合。然而，要补偿浓度减半以维持阈值偏向化或固定的感知强度水平，持续时间需要增加两倍以上。这些结果表明，一个不完美的质量积分模型或许能够描述氨气引起的鼻腔刺激在阈值和超阈值水平的短期整合情况。
