High-sensitivity TMS/fMRI of the Human Motor Cortex Using a Dedicated Multichannel MR Coil

Lara, Lucia I. Navarro de; Tik, Martin; Woletz, Michael; Frass-Kriegl, Roberta; Moser, Ewald; Laistler, Elmar; Windischberger, Christian

doi:10.1016/j.neuroimage.2017.02.062

Cited by 46 publications

(48 citation statements)

References 36 publications

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“…When the TMS coil was aligned with the B 0 field, we found that image quality remained high with delay times exceeding 50 ms. This timing is consistent with a recent report that delays on the order of 50 ms are sufficient to avoid distortions in the images with the 100% TMS output intensity (Navarro de Lara et al, 2017). Notably, we observed a different spatiotemporal perturbation pattern when the TMS coil was perpendicular to the B 0 field (Fig.…”

Section: Discussionsupporting

confidence: 92%

“…We also observed BOLD signal changes associated with TMS even in the absence of motor performance in distributed brain regions. These activation patterns, found in sensorimotor cortex, parietal operculum, and auditory regions, are largely consistent with the results of previous TMS-fMRI studies targeting on motor cortex (Bestmann et al, 2004;Moisa et al, 2009;Shitara et al, 2011;Navarro de Lara et al, 2017;Yau et al, 2013). Importantly, the responses to TMS were characterized by robust and systematic temporal response profiles that closely resemble the response time courses related to motor performance.…”

Section: Discussionsupporting

confidence: 88%

“…We used the 4 th volume in the scan as the reference. Because magnetic fields produced by TMS decay over space and time, we computed the root mean square error (RMSE) between corresponding slices in the reference and comparison volumes for each TMS pulse time, as done previously (Navarro de Lara et al, 2017). Note that we excluded data from a single slice measurement from the analysis because its signal intensity differed from the mean of the other 9 slices acquired under identical conditions by -33 times the standard deviation across the 9 slices.…”

Section: Discussionmentioning

confidence: 99%

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EPI distortion correction for simultaneous human brain stimulation and imaging at 3T

Kim

Yau

2019

Preprint

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Transcranial magnetic stimulation (TMS) can be paired with functional magnetic resonance imaging (fMRI) in simultaneous TMS-fMRI experiments. These multimodal experiments enable causal probing of network architecture in the human brain which can complement alternative network mapping approaches. Critically, merely introducing the TMS coil into the scanner environment can sometimes produce substantial magnetic field inhomogeneities and spatial distortions which limit the utility of simultaneous TMS-fMRI. We assessed the efficacy of point spread function corrected echo planar imaging (PSF-EPI) in correcting for the field inhomogeneities associated with a TMS coil at 3T. In phantom and brain scans, we quantitatively compared the coil-induced distortion artifacts measured in PSF-EPI scans to artifacts measured in conventional echo-planar imaging (EPI) and a simultaneous multi-slice sequence (SMS)-EPI. While we observed substantial coil-related artifacts in the data produced by the conventional EPI and SMS sequences, PSF-EPI produced data that had significantly greater signal-to-noise and less distortions. In phantom scans with the PSF-EPI sequence, we also characterized the temporal profile of dynamic artifacts associated with TMS delivery and found that image quality remained high as long as the TMS pulse preceded the RF excitation pulses by at least 50ms. Lastly, we validated the PSF-EPI sequence in human brain scans involving TMS and motor behavior as well as resting state fMRI scans. Our collective results demonstrate the superiority of PSF-EPI over conventional EPI and SMS sequences for simultaneous TMS-fMRI when coil-related artifacts are a concern. The ability to collect high quality resting state fMRI data in the same session as the simultaneous TMS-fMRI experiment offers a unique opportunity to interrogate network architecture in the human brain.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

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EPI distortion correction for simultaneous human brain stimulation and imaging at 3T

Kim

Yau

2019

Preprint

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“…The data from the resting state scan were not analyzed for the purposes of the current paper. The finger tapping run was intended as a control task that can be used to evaluate the power of our setup to detect brain activations, as done in previous concurrent TMS-fMRI studies (Bestmann et al, 2003, 2005; Navarro de Lara et al, 2017a; Vink et al, 2018b). During that run subjects were asked to tap with their right index finger once every second for 10 seconds, followed by a 10-second break with no finger movement.…”

Section: Methodsmentioning

confidence: 99%

TMS alters multivoxel patterns in the absence of overall activity changes

Rafiei

Safrin

Wokke

et al. 2020

Preprint

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Transcranial magnetic stimulation (TMS) has become one of the major tools for establishing the causal role of specific brain regions in perceptual, motor, and cognitive processes. Nevertheless, a persistent limitation of the technique is the lack of clarity regarding its precise effects on neural dynamics. Here, we examined the effects of TMS intensity and frequency on concurrently recorded blood-oxygen level-dependent (BOLD) signals at the site of stimulation in dorsolateral prefrontal cortex. In Experiment 1, we delivered a series of pulses at high (100% of motor threshold) or low (50% of motor threshold) intensity, whereas in Experiment 2, we always used high intensity but delivered stimulation at four different frequencies (5, 8.33, 12.5, and 25 Hz). We found that the TMS intensity and frequency could be reliably decoded using multivariate analysis techniques even though TMS had no effect on overall BOLD activity at the site of stimulation in either experiment. These results provide important insight into the mechanisms through which TMS influences neural activity.

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“…To separate the EF into three orthogonal components, we calculated the depth vector field d( r) that points from r to the nearest point on the inner surface of the skull. In addition, we calculated the outer normal vector n of the grey matter at the hand knob MNI coordinate (40, −20, 52) (Yousry et al, 1997;Cárdenas-Morales et al, 2014;Navarro de Lara et al, 2017). d( r) and n were used to determine the posterior-anterior, medial-lateral, and depth (E PA = u PA · E, E ML = u ML · E, and E D = u D · E) components as follows:…”

Section: Electric Field Modellingmentioning

confidence: 99%

Electric field dependent effects of motor cortical TDCS

Laakso

Mikkonen

Koyama

et al. 2018

Preprint

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Transcranial direct current stimulation (TDCS) can modulate motor cortical excitability. However, its after-effects are highly variable between individuals. Individual cranial and brain anatomy may contribute to this variability by producing varying electric fields in each subject's brain. Here we show that these fields are related to excitability changes following anodal TDCS of the primary motor cortex (M1). We found in two experiments (N=28 and N=9) that the after-effects of TDCS were proportional to the individual electric field in M1, calculated using MRI-based models. Individuals with the lowest and highest local electric fields in M1 tended to produce opposite changes in excitability. Furthermore, the effect was field-direction dependent and non-linear with stimulation duration or other experimental parameters. The electric field component pointing into the brain was negatively proportional to the excitability changes following 1 mA 20 min TDCS of right M1 (N=28); the effect was opposite after 1 mA 10 min TDCS of left M1 (N=9). Our results demonstrate that a large part of variability in the after-effects of motor cortical TDCS is due to inter-individual differences in the electric fields. We anticipate that individualized electric field dosimetry could be used to control the neuroplastic effects of TDCS, which is increasingly being explored as a treatment for various neuropsychiatric diseases.

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High-sensitivity TMS/fMRI of the Human Motor Cortex Using a Dedicated Multichannel MR Coil

Cited by 46 publications

References 36 publications

EPI distortion correction for simultaneous human brain stimulation and imaging at 3T

EPI distortion correction for simultaneous human brain stimulation and imaging at 3T

TMS alters multivoxel patterns in the absence of overall activity changes

Electric field dependent effects of motor cortical TDCS

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