嗅觉正常年轻人与老年人的功能性磁共振成像研究

Functional Magnetic Resonance Imaging Study of Normal Olfactory Young and Aged People

目的:应用功能性磁共振成像技术对正常嗅觉的年轻人和老年人进行对比研究,观察其嗅觉刺激后大脑功能活化区的区别,了解年龄对嗅觉中枢的影响。方法:对右利手、无嗅觉障碍的健康志愿者(年轻人10名,老年人9名)进行T&T主观嗅觉测试,然后应用苯乙醇对受试者进行嗅觉刺激,同时行功能性磁共振扫描获得图像数据,采用SPM5软件进行数据处理。利用视觉模拟量表对刺激气体进行气味强度和愉悦度评分,并将结果进行统计分析。结果:应用T&T嗅觉检查法测试老年人的嗅觉识别阈平均得分为0.22±1.20,这与年轻人的得分(-0.50±0.85)无显著差异(P>0.05)。两组受试者对于fMRI扫描期间所接受的刺激气体的主观气味强度评分(P<0.05)有统计学意义,而愉悦度评分(P>0.05)无差异。在年轻人组中,大脑活化区域位于额叶(包括眶额回)、岛叶、丘脑、扣带回、壳、杏仁体/梨状皮层,左侧顶下小叶、左侧中央前回、海马、海马旁回、苍白球、颞中回、右侧缘上回。而在老年人组中,除了左侧额上回、左侧中央前回、右侧缘上回,大脑活化区域包括上述大部分区域,但总活化像素较年轻人组明显减少(年轻人组1 578,老年人组852,P<0.01)。结论:我们观察到了年轻人和老年人主要嗅觉相关大脑区域的活化,而老年人的活化像素显著降低。这对于进一步研究嗅觉和老年化以及相关疾病的机制提供了必要的基础。

Objective：To explore the brain activation in normal olfactory young and aged people using functional magnetic resonance imaging（fMRI）,and to discuss the impact of aging on olfactory center.Methods：TT subjective smell test was used to test the smell function of 10 young and9aged healthy participants.Then subjects received olfactory stimuli of phenylethanol during functional magnetic resonance scanning.Odor intensity and valence was rated using visual analogue scale（VAS）,and the results were statistically analyzed.Results：The average score of TT subjective smell test of the aged people was（0.22±1.20）,which showed no significant difference from that of the young people（-0.50±0.85）（P〈0.05）.During the fMRI scanning,intensity scores（P〉0.05）were significantly different while pleasure scores（P〉0.05）had no differences between the two groups.In the young group,the brain activation was found in frontal（including orbitofrontal gyrus）,insula,thalamus,cingulate gyrus,putamen,amygdala/piriformcortex,the left inferior parietal lobule,the left precentral gyrus,hippocampus,parahippocampal,pallidum,middle temporal gyrus,and the right supramarginal gyrus.In the aged group,the brain activation area included most of the above areas except the left superior frontal gyrus,the left precentral gyrus,and the right supramarginal gyrus,and the gross voxels were significantly less（1 578 in young group versus 852 in aged group,P〈0.01）.Conclusion：We observed the young and aged people main olfactory-related brain activation,and the voxels of aged decreased significantly.This is important for further study of the mechanism of smell and aging-related diseases.