Title
Cortico-muscular synchronization by proprioceptive afferents from the tongue muscles during isometric tongue protrusion.
Abstract
Tongue movements contribute to oral functions including swallowing, vocalizing, and breathing. Fine tongue movements are regulated through efferent and afferent connections between the cortex and tongue. It has been demonstrated that cortico-muscular coherence (CMC) is reflected at two frequency bands during isometric tongue protrusions: the beta (β) band at 15–35Hz and the low-frequency band at 2–10Hz. The CMC at the β band (β-CMC) reflects motor commands from the primary motor cortex (M1) to the tongue muscles through hypoglossal motoneuron pools. However, the generator mechanism of the CMC at the low-frequency band (low-CMC) remains unknown. Here, we evaluated the mechanism of low-CMC during isometric tongue protrusion using magnetoencephalography (MEG). Somatosensory evoked fields (SEFs) were also recorded following electrical tongue stimulation. Significant low-CMC and β-CMC were observed over both hemispheres for each side of the tongue. Time-domain analysis showed that the MEG signal followed the electromyography signal for low-CMC, which was contrary to the finding that the MEG signal preceded the electromyography signal for β-CMC. The mean conduction time from the tongue to the cortex was not significantly different between the low-CMC (mean, 80.9ms) and SEFs (mean, 71.1ms). The cortical sources of low-CMC were located significantly posterior (mean, 10.1mm) to the sources of β-CMC in M1, but were in the same area as tongue SEFs in the primary somatosensory cortex (S1). These results reveal that the low-CMC may be driven by proprioceptive afferents from the tongue muscles to S1, and that the oscillatory interaction was derived from each side of the tongue to both hemispheres. Oscillatory proprioceptive feedback from the tongue muscles may aid in the coordination of sophisticated tongue movements in humans.
Year
DOI
Venue
2016
10.1016/j.neuroimage.2015.12.058
NeuroImage
Keywords
Field
DocType
Magnetoencephalography,Cortico-muscular coherence,Neural oscillation,Muscle spindle,Trigeminal nucleus,Hypoglossal motor nucleus
Anatomy,Psychology,Electromyography,Somatosensory system,Motor cortex,Muscle spindle,Proprioception,Primary motor cortex,Neural oscillation,Tongue
Journal
Volume
ISSN
Citations 
128
1053-8119
0
PageRank 
References 
Authors
0.34
6
6
Name
Order
Citations
PageRank
Hitoshi Maezawa111.06
T Mima2186.26
Shogo Yazawa341.14
Masao Matsuhashi421.76
Hideaki Shiraishi511.40
Makoto Funahashi610.72