High gamma oscillations of sensorimotor cortex during unilateral movement in the developing brain: a MEG study.
ABSTRACT Recent studies in adults have found consistent contralateral high gamma activities in the sensorimotor cortex during unilateral finger movement. However, no study has reported on this same phenomenon in children. We hypothesized that contralateral high gamma activities also exist in children during 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 (65-150 Hz) in the primary motor cortices (M1) of both hemispheres. Interestingly, nineteen younger children displayed ipsilateral event-related synchronization (I-ERS) within the high gamma band (65-150 Hz) 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 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 opens a new window for us to understand the developmental changes of the hemispherical functional lateralization in the motor system.
- SourceAvailable from: Tatsuya Asai[show abstract] [hide abstract]
ABSTRACT: Electrophysiological studies have suggested that the activity of the primary motor cortex (M1) during ipsilateral hand movement reflects both the ipsilateral innervation and the transcallosal inhibitory control from its counterpart in the opposite hemisphere, and that their asymmetry might cause hand dominancy. To examine the asymmetry of the involvement of the ipsilateral motor cortex during a unimanual motor task under frequency stress, we conducted block-design functional magnetic resonance imaging with 22 normal right-handed subjects. The task involved visually cued unimanual opponent finger movement at various rates. The contralateral M1 showed symmetric frequency-dependent activation. The ipsilateral M1 showed task-related deactivation at low frequencies without laterality. As the frequency of the left-hand movement increased, the left M1 showed a gradual decrease in the deactivation. This data suggests a frequency-dependent increased involvement of the left M1 in ipsilateral hand control. By contrast, the right M1 showed more prominent deactivation as the frequency of the right-hand movement increased. This suggests that there is an increased transcallosal inhibition from the left M1 to the right M1, which overwhelms the right M1 activation during ipsilateral hand movement. These results demonstrate the dominance of the left M1 in both ipsilateral innervation and transcallosal inhibition in right-handed individuals.Cerebral Cortex 05/2008; 18(12):2932-40. · 6.83 Impact Factor
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ABSTRACT: There has been increasing interest in the functional role of high-frequency (>30 Hz) cortical oscillations accompanying various sensorimotor and cognitive tasks in humans. Similar "high gamma" activity has been observed in the motor cortex, although the role of this activity in motor control is unknown. Using whole-head MEG recordings combined with advanced source localization methods, we identified high-frequency (65 to 80 Hz) gamma oscillations in the primary motor cortex during self-paced movements of the upper and lower limbs. Brief bursts of gamma activity were localized to the contralateral precentral gyrus (MI) during self-paced index finger abductions, elbow flexions and foot dorsiflexions. In comparison to lower frequency (10-30 Hz) sensorimotor rhythms that are bilaterally suppressed prior to and during movement (Jurkiewicz et al., 2006), high gamma activity increased only during movement, reaching maximal increase 100 to 250 ms following EMG onset, and was lateralized to contralateral MI, similar to findings from intracranial EEG studies. Peak frequency of gamma activity was significantly lower during foot dorsiflexion (67.4+/-5.2 Hz) than during finger abduction (75.3+/-4.4 Hz) and elbow flexion (73.9+/-3.7 Hz) although markedly similar for left and right movements of the same body part within subjects, suggesting activation of a common underlying network for gamma oscillations in the left and right motor cortex. These findings demonstrate that voluntary movements elicit high-frequency gamma oscillations in the primary motor cortex that are effector specific, and possibly reflect the activation of cortico-subcortical networks involved in the feedback control of discrete movements.NeuroImage 09/2008; 42(1):332-42. · 6.25 Impact Factor
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ABSTRACT: We investigated gender differences in motor performance in 9-, 12-, and 17-year-olds. The tasks included simple thumb tapping (sTT), handwriting (HW) and finger-to-thumb opposition sequence (FOS) learning. In sTT there was a significant advantage for the 17-year-old males. In HW, 12-year-old females were faster, initially, than the males, but this gap was closed by a single training session; in the 17-year-olds although no significant difference was found initially, the males became faster than the age-matched females post-training. In the FOS, there were no initial gender differences (speed or accuracy). However, males benefited more from training, with the 17-year-old males attaining a significant post-training speed advantage. Moreover, males, of all three age-groups, evolved significantly larger delayed ("off-line") performance gains in the FOS task compared to females; gains which were retained 6-weeks post-training. There may be a male advantage in motor learning rather than in motor performance per-se; this advantage is enhanced during adolescence.Behavioural brain research 12/2008; 198(1):165-71. · 3.22 Impact Factor