A MEG Study Of Gamma Oscillations During Unilateral Movement

Recent studies have found the consistent contralateral high gamma activities in sensorimotor cortex in adults during a unilateral finger movement. However, no study has ever reported the same phenomenon in children. We hypothesized that the contralateral high gamma activities also exist in children during a unilateral finger movement. Sixty normal children (6-17 years old) were studied with a 275-channel MEG system combined with synthetic aperture magnetometry (SAM). Sixty participants displayed consistently contralateral event-related synchronization (C-ERS) within high gamma band (65-150Hz) in primary motor cortex (M1) of both hemispheres. Interestingly, nineteen younger children displayed ipsilateral event-related synchronization (I-ERS) within the high gamma band (65-150Hz) just during their left finger movement. Both I-ERS and C-ERS were localized in M1. The incidence of I-ERS showed a significant decrease with age. Males had significantly higher odds of having ipsilateral activity compared to females. Noteworthy, high gamma C-ERS appeared consistently, while high gamma I-ERS changed with age. The asymmetrical patterns of neuromagnetic activities in the children´s brain might represent the maturational lateralization and/or specialization of motor function. In conclusion, the present results have demonstrated that contralateral high-gamma neuromagnetic activities are the potential biomarkers for the accurate localization of the primary motor cortex in children. In addition, the interesting finding of the ipsilateral high-gamma neuromagnetic activities open a new window for us to understand the development changes of the hemispherical functional lateralization in the motor system.