Jackson J B, Scrivener C L, Correia M M, Mada M, Woolgar A
MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge CB2 7EF, UK.
MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge CB2 7EF, UK; School of Philosophy, Psychology and Language Sciences, University of Edinburgh, Edinburgh, UK.
J Neurosci Methods. 2025 Oct;422:110513. doi: 10.1016/j.jneumeth.2025.110513. Epub 2025 Jun 6.
Transcranial magnetic stimulation (TMS) concurrent with functional magnetic resonance imaging (fMRI) can provide insights into the causal relationships between brain activity and behaviour. TMS pulses can cause artifacts in fMRI data, but these can be avoided if they are presented in short gaps between MRI slice acquisitions (interslice TMS-fMRI).
We collected TMS-fMRI data to provide 1) guidance on the gap required and 2) a higher-level framework and code for researchers to test their own protocols. We quantified signal dropout and temporal signal-to-noise ratio in fMRI data (spherical phantom) for TMS pulses presented from up to 100 ms before and after slice excitation. We delivered up to 3 pulses per volume with interslice gaps of 37.5 ms/100 ms (slice time 62.5 ms), two 7-channel TMS-dedicated surface coils, and a multiband sequence (factor=2), on a Siemens 3 T Prisma scanner. We repeated a subset of parameters with a human participant.
We observed minimal data contamination when pulses were applied at least -20 ms/+ 50ms from slice excitation, and confirmed this approach can be used with 10 Hz TMS.
Compared to other strategies that avoid TMS pulse-related artifacts, interslice allows for greater flexibility in terms of timing of the TMS pulse, MRI read out and any stimulus presentation.
A 10 Hz TMS interslice protocol is possible with minimal data contimination. A stimulation frequency faster than 10 Hz would require a shorter gap or shorter slice acquisition times. Further, stimulator intensity, slice orientation, and the number of TMS pulses affected data quality and are important considerations for researchers when setting up their own protocol.
经颅磁刺激（TMS）与功能磁共振成像（fMRI）同步进行能够深入了解大脑活动与行为之间的因果关系。TMS脉冲会在fMRI数据中产生伪影，但如果在MRI切片采集的短暂间隔（层间TMS-fMRI）中施加这些脉冲，就可以避免产生伪影。
我们收集了TMS-fMRI数据，以提供1）所需间隔的指导，以及2）一个更高级别的框架和代码，供研究人员测试他们自己的方案。我们对在切片激发前后最多100毫秒施加的TMS脉冲，量化了fMRI数据（球形模型）中的信号丢失和时间信噪比。在西门子3T Prisma扫描仪上，我们使用两个7通道TMS专用表面线圈和多频段序列（因子=2），以37.5毫秒/100毫秒的层间间隔（切片时间62.5毫秒），每体积最多施加3个脉冲。我们对一名人类受试者重复了部分参数。
当在距切片激发至少-20毫秒/ +50毫秒处施加脉冲时，我们观察到数据污染最小，并证实该方法可用于10赫兹的TMS。
与其他避免TMS脉冲相关伪影的策略相比，层间方法在TMS脉冲的时间安排、MRI读出和任何刺激呈现方面具有更大的灵活性。
以最小的数据污染实现10赫兹的层间TMS方案是可行的。高于10赫兹的刺激频率将需要更短的间隔或更短的切片采集时间。此外，刺激器强度、切片方向和TMS脉冲数量会影响数据质量，是研究人员在制定自己的方案时需要重点考虑的因素。
