Centre for Engineering-Led Brain Research, School of Mechatronic Systems Engineering, Simon Fraser University, Surrey, British Columbia V3T 0A3, Canada.
Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario M6J 1A8, Canada.
J Neurosci. 2024 Sep 25;44(39):e0782242024. doi: 10.1523/JNEUROSCI.0782-24.2024.
Understanding how spontaneous brain activity influences the response to neurostimulation is crucial for the development of neurotherapeutics and brain-computer interfaces. Localized brain activity is suggested to influence the response to neurostimulation, but whether fast-fluctuating (i.e., tens of milliseconds) large-scale brain dynamics also have any such influence is unknown. By stimulating the prefrontal cortex using combined transcranial magnetic stimulation (TMS) and electroencephalography, we examined how dynamic global brain state patterns, as defined by microstates, influence the magnitude of the evoked brain response. TMS applied during what resembled the canonical Microstate C was found to induce a greater evoked response for up to 80 ms compared with other microstates. This effect was found in a repeated experimental session, was absent during sham stimulation, and was replicated in an independent dataset. Ultimately, ongoing and fast-fluctuating global brain states, as probed by microstates, may be associated with intrinsic fluctuations in connectivity and excitation-inhibition balance and influence the neurostimulation outcome. We suggest that the fast-fluctuating global brain states be considered when developing any related paradigms.
理解自发性脑活动如何影响神经刺激的反应对于神经治疗学和脑机接口的发展至关重要。局部脑活动被认为会影响神经刺激的反应，但快速波动（即数十毫秒）的大规模脑动力学是否也有任何影响尚不清楚。通过使用经颅磁刺激（TMS）和脑电图联合刺激前额叶皮层，我们研究了由微状态定义的动态全局脑状态模式如何影响诱发脑反应的幅度。与其他微状态相比，TMS 在类似于典型微状态 C 的状态下施加时，被发现可诱发高达 80ms 的更大诱发反应。这种效应在重复的实验过程中存在，在假刺激期间不存在，并且在独立的数据集上得到了复制。最终，由微状态探测到的持续和快速波动的全局脑状态可能与连接和兴奋抑制平衡的固有波动有关，并影响神经刺激的结果。我们建议在开发任何相关范式时考虑快速波动的全局脑状态。
