Clewett David, Bachman Shelby, Mather Mara
Neuroscience Graduate Program, University of Southern California.
Neuroscience Undergraduate Program, University of Southern California.
Neuropsychology. 2014 Jul;28(4):631-42. doi: 10.1037/neu0000060. Epub 2014 Mar 17.
A current neuroanatomical model of anxiety posits that greater structural connectivity between the amygdala and ventral prefrontal cortex (vPFC) facilitates regulatory control over the amygdala and helps reduce anxiety. However, some neuroimaging studies have reported contradictory findings, demonstrating a positive rather than negative association between trait anxiety and amygdala-vPFC white matter integrity. To help reconcile these findings, we tested the regulatory hypothesis of anxiety circuitry using aging as a model of white matter decline in the amygdala-vPFC pathway.
We used probabilistic tractography to trace connections between the amygdala and vPFC in 21 younger, 18 middle-aged, and 15 healthy older adults. The resulting tract estimates were used to extract 3 indices of white-matter integrity: fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). The relationship between these amygdala-vPFC structural connectivity measures and age and State-Trait Anxiety Inventory (STAI) scores were assessed.
The tractography results revealed age-related decline in the FA (p = .005) and radial diffusivity (p = .002) of the amygdala-vPFC pathway. Contrary to the regulatory hypothesis, we found a positive rather than negative association between trait anxiety and right amygdala-vPFC FA (p = .01).
These findings argue against the notion that greater amygdala-vPFC structural integrity facilitates better anxiety outcomes in healthy adults. Instead, our results suggest that white matter degeneration in this network relates to lower anxiety in older adults.
当前关于焦虑的神经解剖学模型认为，杏仁核与腹侧前额叶皮层（vPFC）之间更强的结构连接性有助于对杏仁核进行调节控制，并有助于减轻焦虑。然而，一些神经影像学研究报告了相互矛盾的结果，表明特质焦虑与杏仁核 - vPFC白质完整性之间存在正相关而非负相关。为了调和这些发现，我们以衰老作为杏仁核 - vPFC通路白质衰退的模型，测试了焦虑神经回路的调节假说。
我们使用概率纤维束成像技术追踪了21名年轻、18名中年和15名健康老年人杏仁核与vPFC之间的连接。所得的纤维束估计值用于提取白质完整性的3个指标：各向异性分数（FA）、径向扩散率（RD）和轴向扩散率（AD）。评估了这些杏仁核 - vPFC结构连接性测量值与年龄和状态 - 特质焦虑量表（STAI）得分之间的关系。
纤维束成像结果显示，杏仁核 - vPFC通路的FA（p = .005）和径向扩散率（p = .002）存在与年龄相关的下降。与调节假说相反，我们发现特质焦虑与右侧杏仁核 - vPFC的FA之间存在正相关而非负相关（p = .01）。
这些发现反对了杏仁核 - vPFC结构完整性越高，健康成年人焦虑结果越好这一观点。相反，我们的结果表明，该网络中的白质退化与老年人较低的焦虑水平有关。
