Pons Activity Immediately Before Teeth Clenching Using MEG

Objectives: The aim of this study is to clarify using magnetoencephalography (MEG) how the pons is involved in intracerebral activity immediately before clenching.

Methods: The subjects were five right-handed males with no history of neurological disorders. MEG recordings were obtained with a whole-head 151-channel system. Visual cues (VC) for the movement paradigm were presented to the subject. A single trial consisted of maintaining clenching for 2 seconds followed by a semirandomized interval of 2-4 seconds, with 25 trials performed in a single run. Each subject performed a total of 125 trials over 5 runs. The average signal was computed from single trials aligned to VC from –600 to 300 ms with VC set at zero. We used magnetic field tomography (MFT) to obtain a tomographic reconstruction of intracerebral activity for each time slice of the average signal for each subject and run. Regions of interest (ROI) were defined for each subject in cerebellum and pons. An ROI activation curve was computed from the MFT results for each ROI. The difference of the peak amplitude of the pons area between the base line (interval) and main run was statistically analyzed using paired t-test. Additionally we used two-way analysis of variance to test for significant differences in latency (from VC) to the first peak response between pons and cerebellum areas.

Results: Pons activations were identified in five subjects. The peak amplitudes for pons in the main run were greater than those in baseline (P<0.01). There were no significant differences in the latency between from VC to the first peak response for pons areas and from VC to cerebellum area.

Conclusions: Our findings suggest that the pons activity is part of the signal pathway immediately before teeth clenching.