Neural broadening or neural attenuation? Investigating age-related dedifferentiation in the face network in a large lifespan sample.
Neural broadening or neural attenuation? Investigating age-related dedifferentiation in the face network in a large lifespan sample.
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DOI：
10.1523/jneurosci.4494-11.2012
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发表时间：
2012-02-08
期刊：
影响因子：
--
通讯作者：
Park DC
中科院分区：
文献类型：
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作者：
Park J;Carp J;Kennedy KM;Rodrigue KM;Bischof GN;Huang CM;Rieck JR;Polk TA;Park DC
先前的研究发现，随着人们年龄的增长，大脑皮层对不同刺激的反应变得不那么明显。这种与年龄相关的去分化可能反映了类别选择神经元调谐曲线的拓宽（拓宽假说），也可能是由于类别选择神经元激活的减少（衰减假说）。在这项研究中，我们在面部选择神经网络的背景下评估了这些假设。300多名年龄在20岁到89岁之间的参与者在功能性磁共振成像过程中观看了人脸、房屋和控制刺激的图像。在个体受试者中确定了核心面部网络和扩展面部网络内的区域。随着年龄的增长，许多这些区域的激活显著降低了面部选择性，证实了先前有关年龄相关去分化的报道。与拓宽假说一致，梭状面区（FFA）的去分化是由对房屋的激活增加所驱动的。相比之下，扩展面部网络的去分化是由对面部的激活减少驱动的，这与衰减假设一致。这些结果表明，与年龄相关的去分化反应了不同大脑区域的不同过程。更具体地说，FFA活动的去分化可能是由于面部选择神经元的调谐曲线变宽，而扩展面部网络的去分化反映了面部或情绪选择活动的减少。
Previous studies have found that cortical responses to different stimuli become less distinctive as people get older. This age-related dedifferentiation may reflect the broadening of the tuning curves of category-selective neurons (broadening hypothesis) or it may be due to decreased activation of category-selective neurons (attenuation hypothesis). In this study, we evaluated these hypotheses in the context of the face-selective neural network. Over 300 participants, ranging in age from 20 to 89 years, viewed images of faces, houses, and control stimuli in a functional magnetic resonance imaging session. Regions within the core face network and extended face network were identified in individual subjects. Activation in many of these regions became significantly less face-selective with age, confirming previous reports of age-related dedifferentiation. Consistent with the broadening hypothesis, this dedifferentiation in the fusiform face area (FFA) was driven by increased activation to houses. In contrast, dedifferentiation in the extended face network was driven by decreased activation to faces, consistent with the attenuation hypothesis. These results suggest that age-related dedifferentiation reflects distinct processes in different brain areas. More specifically, dedifferentiation in FFA activity may be due to broadening of the tuning curves for face-selective neurons, while dedifferentiation in the extended face network reflects reduced face- or emotion-selective activity.