Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), 203 East Cary Street, Suite 202, Richmond, VA 23219, USA; Department of Radiology, Virginia Commonwealth University (VCU), Richmond, VA, USA.
Institute for Drug and Alcohol Studies, Virginia Commonwealth University (VCU), 203 East Cary Street, Suite 202, Richmond, VA 23219, USA; Department of Psychiatry, Virginia Commonwealth University (VCU), Richmond, VA, USA.
Psychiatry Res Neuroimaging. 2018 Aug 30;278:21-34. doi: 10.1016/j.pscychresns.2018.05.010. Epub 2018 Jun 8.
Previous working memory (WM) studies found that relative to controls, subjects with cannabis use disorder (CUD) showed greater brain activation in some regions (e.g., left [L] and right [R] ventrolateral prefrontal cortex [VLPFC], and L dorsolateral prefrontal cortex [L-DLPFC]), and lower activation in other regions (e.g., R-DLPFC). In this study, effective connectivity (EC) analysis was applied to functional magnetic resonance imaging data acquired from 23 CUD subjects and 23 controls (two groups matched for sociodemographic factors and substance use history) while performing an n-back WM task with interleaved 2-back and 0-back periods. A 2-back minus 0-back modulator was defined to measure the modulatory changes of EC corresponding to the 2-back relative to 0-back conditions. Compared to the controls, the CUD group showed smaller modulatory change in the R-DLPFC to L-caudate pathway, and greater modulatory changes in L-DLPFC to L-caudate, R-DLPFC to R-caudate, and R-VLPFC to L-caudate pathways. Based on previous fMRI studies consistently suggesting that greater brain activations are related to a compensatory mechanism for cannabis neural effects (less regional brain activations), the smaller modulatory change in the R-DLPFC to L-caudate EC may be compensated by the larger modulatory changes in the other prefrontal-striatal ECs in the CUD individuals.
先前的工作记忆（WM）研究发现，与对照组相比，大麻使用障碍（CUD）患者在某些区域（例如左[L]和右[R]腹外侧前额叶皮层[VLPFC]，以及左背外侧前额叶皮层[L-DLPFC]）表现出更大的大脑激活，而在其他区域（例如右背外侧前额叶皮层[R-DLPFC]）表现出更低的激活。在这项研究中，应用有效连接（EC）分析对 23 名 CUD 患者和 23 名对照者（两组在社会人口统计学因素和物质使用史方面匹配）在执行 n-back WM 任务时采集的功能磁共振成像数据进行了分析，该任务包括交错的 2-back 和 0-back 期。定义了 2-back 减去 0-back 调制器，以测量对应于 2-back 相对于 0-back 条件的 EC 的调制变化。与对照组相比，CUD 组在 R-DLPFC 到 L-尾状核的通路中显示出较小的调制变化，而在 L-DLPFC 到 L-尾状核、R-DLPFC 到 R-尾状核以及 R-VLPFC 到 L-尾状核的通路中显示出更大的调制变化。基于先前的 fMRI 研究一致表明，更大的大脑激活与大麻神经效应的补偿机制有关（区域大脑激活减少），因此 R-DLPFC 到 L-尾状核的 EC 调制变化较小可能被 CUD 个体中其他前额叶-纹状体 EC 的更大调制变化所补偿。
