Functional localization of SMA through fMRI and OPM-MEG
Poster No:
1362
Submission Type:
Abstract Submission
Authors:
Jeff Soldate1, Lester Sands1, Michelle Hampson2, Pendleton Montague1, Stephen LaConte1
Institutions:
1Virginia Tech, Roanoke, VA, 2Yale University School of Medicine, New Haven, CT
First Author:
Co-Author(s):
Introduction:
Neurofeedback tracking supplementary motor area (SMA) is a promising intervention for Tourette Syndrome, reducing symptom severity [1]. Localization of tic neural correlates to the functionally heterogeneous SMA is an important step in personalizing neurofeedback. Ideally tic production during neuroimaging could be used to set the target of interest, but sensitivity to motion in MRI makes this strategy difficult. OPM-MEG, offering similar spatial resolution to MRI at higher temporal resolution and with motion resistant, wearable sensor arrays, is an ideal imaging modality for such localization. As a nascent technology, it remain to be seen how similar functional localization results are between fMRI and OPM-MEG. This work examines localization of SMA in both modalities in four healthy participants, using a bi-manual tapping task.
Methods:
Participants performed synchronized and poly-rhythmic bi-manual tapping. This task has been shown to differentially activate SMA between the two task conditions (synchronized and poly-rhythmic tapping) [2]. Tapping was visually paced by matching rotation speed of two wedges in either side of a central point (adapted from [3]). Synchronized trials demanded 2 Hz tapping from both hands while poly-rhythmic trials demanded 3 Hz tapping from the right hand and 2 Hz tapping from the left. In fMRI, we used 16, 30 second blocks divided evenly between both conditions. In MEG, we used 80, 8 second long trials divided evenly between conditions. MRI images were obtained at 3T using a single band EPI sequence (TR=2000ms, TE=30ms). MEG recordings were taken using a 22 channel array of 11 dual axis, zero field magnetometers at 1200 Hz [4] in a custom built magnetically shielded room [5]. Recordings were filtered for gamma band neural oscillation (14-30Hz), corrected for the influence of homogeneous fields, and source localized using a linearly constrained minimum variance beamformer implemented in MNE [6].
Results:
Both tasks elicited difference in signal between poly-rhythmic and even tapping over SMA, as defined by the Eichoff-Zilles macro labels atlas [6]. Virtual electrodes from these clusters show a characteristic decrease in beta power during finger tapping and a rebound after cessation. Both methods showed significant clusters of active voxels overlapping with SMA, though the size and location of each cluster differed between neuroimaging method. Average deviation between active clusters (based on thresholds of q≤0.0001 and z≥2.5) was 23±9mm with the majority of disagreement in the Y (A-P) dimension. Both tasks saw increased activity during poly-rhythmic tapping over even tapping.
Conclusions:
We were able to show localization of SMA within participant with a contrasting tapping task in both fMRI and OPM-MEG. OPM-MEG source localization remains a difficult problem, leading to varied and spatially dispersed regions of activity. This should decrease as the number of channels and density of sensor arrays increases. Overall, these results indicate OPM is able to identify spatial signal changes related to differing levels of SMA engagement in bi-manual finger tapping.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI) 1
EEG/MEG Modeling and Analysis
Motor Behavior:
Motor Planning and Execution
Novel Imaging Acquisition Methods:
MEG 2
Keywords:
FUNCTIONAL MRI
MEG
Motor
Source Localization
Tourette's Syndrome
1|2Indicates the priority used for review
Provide references using author date format
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