Smell & Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
Department of Food Science, Institute of Agriculture, University of Tennessee, Knoxville, TN, 37996, USA.
Sci Rep. 2021 Feb 17;11(1):4043. doi: 10.1038/s41598-021-83621-2.
Olfactory impairment after a traumatic impact to the head is associated with changes in olfactory cortex, including decreased gray matter density and decreased BOLD response to odors. Much less is known about the role of other cortical areas in olfactory impairment. We used fMRI in a sample of 63 participants, consisting of 25 with post-traumatic functional anosmia, 16 with post-traumatic hyposmia, and 22 healthy controls with normosmia to investigate whole brain response to odors. Similar neural responses were observed across the groups to odor versus odorless stimuli in the primary olfactory areas in piriform cortex, whereas response in the frontal operculum and anterior insula (fO/aI) increased with olfactory function (normosmia > hyposmia > functional anosmia). Unexpectedly, a negative association was observed between response and olfactory perceptual function in the mediodorsal thalamus (mdT), ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (pCC). Finally, connectivity within a network consisting of vmPFC, fO, and pCC could be used to successfully classify participants as having functional anosmia or normosmia. We conclude that, at the neural level, olfactory impairment due to head trauma is best characterized by heightened responses and differential connectivity in higher-order areas beyond olfactory cortex.
头部创伤后嗅觉障碍与嗅皮层变化有关，包括灰质密度降低和对气味的 BOLD 反应降低。关于其他皮质区域在嗅觉障碍中的作用知之甚少。我们在 63 名参与者的样本中使用 fMRI，其中包括 25 名创伤后功能性嗅觉丧失者、16 名创伤后嗅觉减退者和 22 名嗅觉正常的健康对照者，以研究大脑对气味的整体反应。在嗅球皮层的初级嗅觉区域，各组对气味与无味刺激的相似神经反应，而在额骨瓣和前岛叶（fO/aI）的反应则随着嗅觉功能（嗅觉正常>嗅觉减退>功能性嗅觉丧失）而增加。出乎意料的是，在中背侧丘脑（mdT）、腹内侧前额叶皮层（vmPFC）和后扣带回皮层（pCC）中观察到与嗅觉知觉功能呈负相关。最后，vmPFC、fO 和 pCC 组成的网络内的连通性可用于成功将参与者分类为功能性嗅觉丧失或嗅觉正常。我们得出结论，在神经水平上，头部创伤引起的嗅觉障碍的特征是嗅皮层以外的高级区域的反应增强和差异连接。
