Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, United States; Department of Radiology, Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.
Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, United States.
Neuroimage. 2021 Aug 15;237:118100. doi: 10.1016/j.neuroimage.2021.118100. Epub 2021 Apr 29.
The dynamic nature of resting-state functional magnetic resonance imaging (fMRI) brain activity and connectivity has drawn great interest in the past decade. Specific temporal properties of fMRI brain dynamics, including metrics such as occurrence rate and transitions, have been associated with cognition and behaviors, indicating the existence of mechanism distruption in neuropsychiatric disorders. The development of new methods to manipulate fMRI brain dynamics will advance our understanding of these pathophysiological mechanisms from native observation to experimental mechanistic manipulation. In the present study, we applied repeated transcranial direct current stimulation (tDCS) to the right dorsolateral prefrontal cortex (rDLPFC) and the left orbitofrontal cortex (lOFC), during multiple simultaneous tDCS-fMRI sessions from 81 healthy participants to assess the modulatory effects of stimulating target brain regions on fMRI brain dynamics. Using the rDLPFC and the lOFC as seeds, respectively, we first identified two reoccurring co-activation patterns (CAPs) and calculated their temporal properties (e.g., occurrence rate and transitions) before administering tDCS. The spatial maps of CAPs were associated with different cognitive and disease domains using meta-analytical decoding analysis. We then investigated how active tDCS compared to sham tDCS in the modulation of the occurrence rates of these different CAPs and perturbations of transitions between CAPs. We found that by enhancing neuronal excitability of the rDLPFC and the lOFC, the occurrence rate of one CAP was significantly decreased while that of another CAP was significantly increased during the first 6 min of stimulation. Furthermore, these tDCS-associated changes persisted over subsequent testing sessions (both during and before/after tDCS) across three consecutive days. Active tDCS could perturb transitions between CAPs and a non-CAP state (when the rDLPFC and the lOFC were not activated), but not the transitions within CAPs. These results demonstrate the feasibility of modulating fMRI brain dynamics, and open new possibilities for discovering stimulation targets and dynamic connectivity patterns that can ensure the propagation of tDCS-induced neuronal excitability, which may facilitate the development of new treatments for disorders with altered dynamics.
静息态功能磁共振成像 (fMRI) 脑活动和连接的动态性质在过去十年中引起了极大的兴趣。 fMRI 脑动力学的特定时间特性，包括发生率和转变等度量，与认知和行为相关，表明神经精神障碍存在机制破坏。开发新的方法来操纵 fMRI 脑动力学将推进我们从自然观察到实验机制操纵的这些病理生理机制的理解。在本研究中，我们应用重复经颅直流电刺激 (tDCS) 对 81 名健康参与者的多个同时 tDCS-fMRI 期间的右侧背外侧前额叶皮层 (rDLPFC) 和左侧眶额皮层 (lOFC)，以评估刺激目标大脑区域对 fMRI 脑动力学的调节作用。分别使用 rDLPFC 和 lOFC 作为种子，我们首先确定了两个重复出现的共同激活模式 (CAP)，并在进行 tDCS 之前计算了它们的时间特性 (例如发生率和转变)。使用元分析解码分析，将 CAP 的空间图与不同的认知和疾病领域相关联。然后，我们研究了在调节这些不同 CAP 的发生率和 CAP 之间转变的干扰方面，主动 tDCS 与假 tDCS 相比如何。我们发现，通过增强 rDLPFC 和 lOFC 的神经元兴奋性，在刺激的前 6 分钟内，一个 CAP 的发生率显著降低，而另一个 CAP 的发生率显著增加。此外，这些 tDCS 相关的变化在随后的三个连续测试会议中持续存在 (在 tDCS 期间以及前后)。主动 tDCS 可以干扰 CAP 之间和非 CAP 状态 (当 rDLPFC 和 lOFC 未被激活时) 之间的转变，但不能干扰 CAP 内的转变。这些结果证明了调节 fMRI 脑动力学的可行性，并为发现能够确保 tDCS 诱导的神经元兴奋性传播的刺激靶点和动态连接模式开辟了新的可能性，这可能有助于开发具有改变动力学的疾病的新治疗方法。
