Rai Narayan, Hipolito Maria Mananita, VanMeter John W, Seth Riya, Adenuga Ayokunnumi, Shelby Myeshia, Misiak-Christian Magdalena, Nwaokobia Charles, Manaye Kebreten F, Obisesan Thomas O, Nwulia Evaristus
Department of Psychiatry and Behavioral Sciences, Howard University, Washington DC, USA.
Department of Neurology, Center for Functional and Molecular Imaging, Georgetown University Medical Center, Washington DC, USA.
Neuropsychiatr Dis Treat. 2021 Apr 30;17:1279-1288. doi: 10.2147/NDT.S298303. eCollection 2021.
This study evaluated human Blood Oxygen Level-Dependent (BOLD) responses in primary and higher-order olfactory regions of older adults, using odor memory and odor identification tasks. The goal was to determine which olfactory and memory regions of interest are more strongly engaged in older populations comparing these two odor training tasks.
Twelve adults 55-75 years old (75% females) without intranasal or major neurological disorders performed repetitive odor memory and identification tasks using a 3-tesla magnetic resonance scanner. Odors were presented intermittently at 10-second bursts separated by 20-second intervals of odorless air. Paired -tests were used to compare differences in the degree of activation between odor identification and odor memory tasks within individuals. An FDR cluster-level correction of <0.05 was used for multiplicity of tests (with a cluster-defining threshold set at <0.01 and 10 voxels).
Odor identification compared to memory (ie, odor identification > odor memory) contrasts had several areas of significant activation, including many of the classical olfactory brain regions as well as the hippocampus. The opposite contrast (odor memory > odor identification) included the piriform cortex, though this was not significant. Both tasks equally activated the piriform cortex, and thus when the two tasks are compared to each other this area of activation appears to be either absent (OI > OM) or only weakly observed (OM > OI).
These findings from a predominantly African American sample suggest that odor identification tasks may be more potent than memory tasks in targeted olfactory engagement in older populations. Furthermore, repetitive odor identification significantly engaged the hippocampus - a region relevant to Alzheimer's disease - more significantly than did the odor memory task. If validated in larger studies, this result could have important implications in the design of olfactory training paradigms.
本研究利用气味记忆和气味识别任务，评估了老年人初级和高阶嗅觉区域的血氧水平依赖（BOLD）反应。目的是确定在比较这两种气味训练任务时，老年人群中哪些感兴趣的嗅觉和记忆区域参与度更高。
12名年龄在55 - 75岁之间（75%为女性）、无鼻内或重大神经系统疾病的成年人，使用3特斯拉磁共振扫描仪进行重复性气味记忆和识别任务。气味以10秒的脉冲间歇性呈现，间隔20秒的无气味空气。配对t检验用于比较个体内气味识别和气味记忆任务之间激活程度的差异。对多个测试采用错误发现率（FDR）聚类水平校正，校正后的P值<0.05（聚类定义阈值设置为<0.01且10体素）。
与记忆相比（即气味识别>气味记忆），气味识别对比有几个显著激活区域，包括许多经典的嗅觉脑区以及海马体。相反的对比（气味记忆>气味识别）包括梨状皮层，不过这并不显著。两项任务均同等程度地激活了梨状皮层，因此当将这两项任务相互比较时，该激活区域似乎不存在（气味识别>气味记忆）或仅微弱观察到（气味记忆>气味识别）。
这些来自以非裔美国人为主的样本的研究结果表明，在老年人群中，气味识别任务在有针对性的嗅觉参与方面可能比记忆任务更有效。此外，重复性气味识别比气味记忆任务更显著地激活了与阿尔茨海默病相关的海马体区域。如果在更大规模的研究中得到验证，这一结果可能对嗅觉训练范式的设计具有重要意义。
