Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany.
Rhinology. 2011 Oct;49(4):458-63. doi: 10.4193/Rhino11.110.
So-called bimodal odorants are able to stimulate the intranasal trigeminal system at relatively low concentrations. Using them as stimuli, the current study focused on the interaction between the olfactory and trigeminal systems at a cerebral level. In the experiment, menthol was used at two concentrations, low and high, and these were delivered to two groups of subjects, a healthy control group and an anosmic group who were unable to perceive smells. A computer-controlled olfactometer based on principles of air-dilution was used to deliver the stimuli, while the brain functions were assessed by a functional magnetic resonance imaging (fMRI) technique. SPM5 was used for data analysis. The results showed that normosmic subjects exhibited activation in the anterior cingulate cortex (ACC) and posterior cingulate cortex (PCC), prefrontal cortex (PFC), and cerebellum. Whilst anosmic subjects activated the same area inside the anterior cingulate; moreover a cluster of activation was found in the left parahippocampal gyrus. In controls, an effect of stimulus intensity was localized between the anterior cingulated, the medial frontal gyrus and the cerebellum; such areas could not be found in anosmic subjects. These results suggest that the olfactory system modifies trigeminally mediated information causing an evident effect in the differentiation between stimulus intensities.
所谓双模态气味物质能够以相对较低的浓度刺激鼻内三叉神经系统。本研究使用这些物质作为刺激物，关注的是嗅觉和三叉神经系统在大脑层面的相互作用。在实验中，薄荷醇以低浓度和高浓度两种浓度使用，并将其输送给两组受试者，一组是健康对照组，另一组是无法感知气味的嗅觉丧失组。使用基于空气稀释原理的计算机控制嗅探器来输送刺激物，同时通过功能磁共振成像（fMRI）技术评估大脑功能。使用 SPM5 进行数据分析。结果表明，正常嗅觉的受试者在前扣带皮层（ACC）和后扣带皮层（PCC）、前额叶皮层（PFC）和小脑显示出激活。而嗅觉丧失的受试者在扣带前区激活了相同的区域；此外，在左侧海马旁回发现了一个激活簇。在对照组中，刺激强度的影响定位于前扣带、内侧额回和小脑之间；在嗅觉丧失的受试者中找不到这些区域。这些结果表明，嗅觉系统改变了三叉神经介导的信息，导致在刺激强度的区分上产生明显的影响。
