Left-lateralization of resting state functional connectivity between the presupplementary motor area and primary language areas

Abstract

An abundance of evidence points to a pre-supplementary motor area (pre-SMA) role in human language. This study explores the pre-SMA resting state connectivity network and the nature of its connections to known language areas. We tested the hypothesis that by seeding the pre-SMA, one would be able to establish language laterality to known cortical and sub-cortical language areas. We analyzed data from 30 right-handed healthy controls and performed the resting state functional MRI (rfMRI). A seed based analysis using a manually drawn pre-SMA region of interest (ROI) template was applied. Time course signals in the pre-SMA ROI were averaged and cross-correlated to every voxel in the brain. Results show that the pre-SMA has significant left-lateralized functional connectivity to the pars opercularis within Broca's area. Among cortical regions, pre-SMA functional connectivity is strongest to the pars opercularis Additionally, pre-SMA connectivity was shown to exist to other cortical language-association regions, including Wernicke's Area, supramarginal gyri, angular gyri(, and middle frontal gyri. Among sub-cortical areas, considerable left-lateralized functional connectivity occurs to the caudate and thalamus while cerebellar sub-regions show right-lateralization. The current study reveals that the pre-SMA most strongly connects to the pars opercularis within Broca's area and that cortical connections to language areas are left-lateralizedamong a sample of right-handed patients. We provide rfMRI evidence that the functional connectivity of the pre-SMA is involved in semantic language processing and that this identification may be useful for establishing language laterality in pre-operative neurosurgical planning.

Static magnetic field stimulation of the supplementary motor area modulates resting-state activity and motor behavior

“…Intriguingly, the overall higher local activity we observed in the left compared to the right SMA—both in our dataset and in an independent sample from the HCP—implies that even though the placement of the magnet was symmetric, the baseline functional state of the SMA below the magnet was not. This baseline functional asymmetry is not totally unexpected, since stronger resting-state functional connectivity was previously observed with left compared to right seeds in both pre-SMA 101 and SMA proper 102 (but see ref. 103 ).…”

Language lateralization from task‐based and resting state functional MRI in patients with epilepsy

“…Recent studies show seed‐based resting state fMRI lateralizes language function in healthy controls with moderate success (Joliot & Tzourio‐Mazoyer, 2016; Liu, Stufflebeam, Sepulcre, Hedden, & Buckner, 2009; Lou, Peck, Brennan, Mallela, & Holodny, 2017; Wang, Buckner, & Liu, 2014). Results in temporal lobe epilepsy have been inconsistent (Doucet, Pustina, et al, 2015; Teghipco, Hussain, & Tivarus, 2016).…”

The role of resting-state functional MRI for clinical preoperative language mapping

“…Therefore, at this time, we cannot determine hemispheric dominance with our current SBC rs-fMRI technique. We found a study by Lou et al [ 21 ] which demonstrated that seed placement over the bilateral pre-supplementary motor area (pre-SMA) allowed identification of left language lateralization in 30 right-handed healthy patients. We did not use the bilateral pre-SMA as a seed and may utilize this area for future seed placement.…”