Methamphetamine (MA) and other psychostimulants target the motive circuit of the brain, which is involved in reward, behavioral sensitization, and relapse to drug-seeking/taking behavior. In spite of this fact, the data regarding the effective connectivity (EC) in this circuit among MA users is scarce. The present study aimed to assess resting-state EC in the motive circuit of MA users during abstinence using the fMRI technique. Seventeen MA users after abstinence and 18 normal controls were examined using a 3 T Siemens fMRI scanner. After extracting time series of the motive circuit, EC differences in the motive circuit were analyzed using dynamic causal modeling (DCM). The findings revealed that abstinent MA users had an enhanced EC from the prefrontal cortex (PFC) to the ventral palladium (VP) (PFC→VP) and on the mediodorsal thalamus (MD) self-loop (MD→MD), but they showed a decreased connectivity on the VP self-loop (VP→VP) compared to healthy controls. The findings suggest that abstinent MA users may suffer from a limited pathology in connectivity within the motive circuit involved in reward, behavioral sensitization, and relapse. The enhanced PFC→VP seems to be a compensatory mechanism to control or regulate the subcortical regions involved in reward and behavioral sensitization. Furthermore, the enhanced connectivity on the MD self-loop and the decreased connectivity on the VP self-loop in abstinent MA users may, at least partially, affect the output of the limbic system, which can be seen in the behavioral sensitization and relapse processes. Nonetheless, further investigation in this area is strongly recommended to elucidate the exact mechanisms involved.

中文翻译：

---

甲基苯丙胺使用者的运动回路中的静止状态有效连通性：病例对照功能磁共振成像研究。

甲基苯丙胺（MA）和其他精神刺激药的目标是大脑的运动回路，该回路参与奖励，行为敏锐度和吸毒/服药行为的复发。尽管有这个事实，但MA用户之间有关该电路中有效连接（EC）的数据仍然很少。本研究旨在使用功能磁共振成像技术评估禁食期间MA使用者运动回路中的静止状态EC。使用3 T Siemens fMRI扫描仪检查了禁欲后的17名MA使用者和18名正常对照。提取动力电路的时间序列后，使用动态因果模型（DCM）分析动力电路中的EC差异。研究结果表明，戒酒的MA使用者从前额叶皮层（PFC）到腹侧钯（VP）（PFC→VP）以及中腹丘脑（MD）自环（MD→MD）的EC均得到增强，但他们发现与健康对照组相比，VP自环（VP→VP）上的连通性降低。研究结果表明，节制的MA用户可能会受到与奖赏，行为敏感性和复发有关的动力回路内连通性的局限性病理影响。增强的PFC→VP似乎是控制或调节参与奖励和行为敏化的皮层下区域的补偿机制。此外，禁欲的MA用户在MD自环上增强的连接性和在VP自环上减小的连接性可能至少部分地影响边缘系统的输出，这可以从行为敏感性和复发过程中看出。但是，强烈建议对该领域进行进一步研究，以阐明涉及的确切机制。