The neural representation of odor is modulated by the presence of a trigeminal stimulus during odor encoding
The neural representation of odor is modulated by the presence of a trigeminal stimulus during odor encoding
复制标题
DOI：
10.1016/j.clinph.2006.10.022
复制
发表时间：
2007-03-01
影响因子：
4.7
通讯作者：
Hummel, T.
中科院分区：
文献类型：
--
作者：
Bensafi, M.;Frasnelli, J.;Hummel, T.
目的：气味感知并不仅仅包括从转导到单一“真实”大脑表征的分层处理。在编码过程中，气味感觉可能被可用的感觉信息所调节。本研究旨在研究在气味编码过程中是否存在纯粹的三叉神经刺激可以在行为和皮层水平上调节气味感知。方法：参与者采用两阶段的受试者设计进行测试：首先，气味编码阶段包括一个延迟条件反射过程，在这个过程中，相对选择性的嗅觉刺激物（苯基乙醇或香兰素，条件刺激+，CS+）要么与二氧化碳脉冲一起呈现（非条件刺激，US），要么单独呈现（条件刺激-，CS-）；然后，在第二阶段，两种纯气味剂（CS+和CS-）单独呈现。在第二组实验中，同时记录并分析了Cz和Pz（已知分别对三叉神经和嗅觉刺激具有最大振幅的部位）等不同电极的嗅觉事件相关电位。每次试验结束后，受试者被要求对气味强度和愉悦感进行评分。结果：8例受试者CS+强度评分上升，6例受试者CS+强度评分下降。皮层P2振幅存在组效应，Cz时“CS+强度增加”组比“CS+强度降低”组增加（p < 0.05）， Pz时无组效应（p < 0.05）。结论：这一结果表明，在气味编码过程中，纯三叉神经刺激（CO2）的存在改变了纯气味的神经表征。意义：气味的神经表征不仅包括气味本身，还包括编码过程中呈现的上下文信息（在本例中为三叉神经）。(c) 2006年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objectives: Odor perception does not simply consist in hierarchical processing from transduction to a single "true" cerebral representation. Odor sensation may be modulated by available sensory information during encoding. The present study set out to examine whether the presence of a pure trigeminal stimulus during odor encoding may modulate odor perception at both behavioral and cortical levels.Methods: Participants were tested in a 2-session within-subject design: first, an odor encoding session included a delay conditioning procedure in which relatively selective olfactory stimulants (phenyl ethyl alcohol or vanillin, Conditioned Stimulus+, CS+) were presented either with a pulse Of CO2 (Unconditioned Stimulus, US), or alone (Conditioned Stimulus-, CS-); then, in the second session, both pure odorants (CS+ and CS-) were presented alone. During this second session, olfactory event-related potentials were simultaneously recorded and analyzed at different electrode sites including Cz and Pz (sites known to have maximal amplitudes for trigeminal and olfactory stimuli, respectively). After each trial, subjects were asked to rate odor intensity and hedonics.Results: The results showed that CS+ intensity ratings increased in 8 subjects and decreased in 6. Cortically, a group effect was observed for P2 amplitude, which increased in the "CS+ intensity increase" group vs. the "CS+ intensity decrease" group at Cz (p < 0.05) but not at Pz (p > 0.05).Conclusions: This result suggests that the presence of a pure trigeminal Stimulus (CO2) during odor encoding alters the neural representation of a pure odor.Significance: The neural representation of odors comprises not only the odor itself but also contextual information (trigeminal in the present case) presented during encoding. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.