The effect of normal aging on the coupling of neural activity to the bold hemodynamic response
The effect of normal aging on the coupling of neural activity to the bold hemodynamic response
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DOI：
10.1006/nimg.1999.0444
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发表时间：
1999-07-01
期刊：
影响因子：
5.7
通讯作者：
Rypma, B
中科院分区：
文献类型：
--
作者：
D'Esposito, M;Zarahn, E;Rypma, B
使用功能性神经成像来检验关于认知过程的神经基质中与年龄相关的变化的假设依赖于关于神经活动与神经成像信号的耦合的假设。只有当这种耦合不随年龄变化时，年轻受试者和老年受试者之间的神经成像信号响应的差异才能直接映射到神经响应的差异。在这里，我们研究的空间和时间特性的BOLD功能磁共振成像血流动力学反应在初级感觉运动皮层在年轻和老年受试者在一个简单的反应时间任务的性能。我们发现，75%的老年受试者（n = 20）表现出可检测的体素明智的关系，在这个区域的行为范例相比，100%的年轻受试者（n = 32），在年轻受试者的阈上体素的中位数是老年受试者的四倍以上。与老年受试者相比，年轻受试者的每体素信号噪声比略高，这归因于老年受试者的每体素噪声水平更高。证据不支持老年人中观察到的较大头部运动是这种较大体素噪声的原因的观点。两组之间在血流动力学反应的形状或其组内变异性方面没有显著差异，尽管前者证明了接近显著的趋势。神经活动和BOLD功能磁共振成像信号之间的血液动力学耦合的某些方面随年龄变化的总体发现，对简单的解释比较年轻和老年受试者的成像研究的结果提出了警告。(C)北京：科学出版社.
The use of functional neuroimaging to test hypotheses regarding age-related changes in the neural substrates of cognitive processes relies on assumptions regarding the coupling of neural activity to neuroimaging signal, Differences in neuroimaging signal response between young and elderly subjects can be mapped directly to differences in neural response only if such coupling does not change with age. Here we examined spatial and temporal characteristics of the BOLD fMRI hemodynamic response in primary sensorimotor cortex in young and elderly subjects during the performance of a simple reaction time task. We found that 75% of elderly subjects (n = 20) exhibited a detectable voxel-wise relationship with the behavioral paradigm in this region as compared to 100% young subjects (n = 32), The median number of suprathreshold voxels in the young subjects was greater than four times that of the elderly subjects. Young subjects had a slightly greater signal:noise per voxel than the elderly subjects that was attributed to a greater level of noise per voxel in the elderly subjects. The evidence did not support the idea that the greater head motion observed in the elderly was the cause of this greater voxel-wise noise, There were no significant differences between groups in either the shape of the hemodynamic response or in its the within-group variability although the former evidenced a near significant trend. The overall finding that some aspects of the hemodynamic coupling between neural activity and BOLD fMRI signal change with age cautions against simple interpretations of the results of imaging studies that compare young and elderly subjects. (C) 1999 Academic Press.