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Objective The abnormality of intrinsic brain activity in autism spectrum disorders (ASDs) is still inconclusive. Contradictory results have been found pointing towards hyper-activity or hypo-activity in various brain regions. The present research aims to investigate the spatial and spectral signatures of aberrant brain activity in an unprecedented frequency range of 1–2884 Hz at source levels in ASD using newly developed methods. Materials and methods Seven ASD subjects and age- and gender-matched controls were studied using a high-sampling rate magnetoencephalography (MEG) system. Brain activity in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), low gamma (30–55 Hz), high gamma (65–90 Hz), ripples (90–200 Hz), high-frequency oscillations (HFOs, 200–1000 Hz), and very high-frequency oscillations (VHFOs, 1000–2884 Hz) was volumetrically localized and measured using wavelet and beamforming. Results In comparison to controls, ASD subjects had significantly higher odds of alpha activity (8–12 Hz) in the sensorimotor cortex (mu rhythm), and generally high-frequency activity (90–2884 Hz) in the frontal cortex. The source power of HFOs (200–1000 Hz) in the frontal cortex in ASD was significantly elevated as compared with controls. Conclusion The results suggest that ASD has significantly altered intrinsic brain activity in both low- and high-frequency ranges. Increased intrinsic high-frequency activity in the frontal cortex may play a key role in ASD. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Our study is to investigate somatosensory dysfunction in children with spastic cerebral palsy (CP) using magnetoencephalography (MEG) and synthetic aperture magnetometry (SAM). Methods: Six children with spastic CP and six age- and gender-matched typically developing children were studied using a 275-channel MEG system while their left and right index fingers were stimulated in random order. The latency and amplitude of somatosensory evoked magnetic fields were analyzed at sensor level. The patterns of high-gamma oscillations were investigated with SAM at source level. Results: In comparison to the children with typical development, the latency of the first response of somatosensory evoked magnetic fields (SEFs) in the children with spastic CP was significantly delayed (p <0.05). High-gamma oscillations were identified in the somatosensory cortex in both children with CP and typical developing children. Interestingly, children with spastic CP had significantly higher incidence of ipsilateral activation in the somatosensory cortex following right and left finger stimulation, compared to typically developing children (p =0.05). Conclusion: The results suggest that children with spastic CP have a measurable delay of SEFs and high-gamma oscillations. The high rates of ipsilateral cortical activation imply the impairments of functional lateralization in the developing brain. This is the first MEG study to demonstrate abnormal high-gamma oscillations of somatosensory cortices representing the finger in children with spastic CP. [Copyright &y& Elsevier]

Abstract: In recent years, there has been a growing interest on the role of gamma band (>30Hz) neural oscillations in motor control, although the function of this activity in motor control is unknown clearly. With the goal of discussing the high frequency sources non-invasively and precisely during unilateral index finger movement, we investigated gamma band oscillations in 20 right-handed normal adults with magnetoencephalography (MEG). The results showed that gamma band activity appeared only during finger movement. Nineteen subjects displayed consistently contralateral event-related synchronization (C-ERS) within high gamma band (70–150Hz) in primary motor cortex (M1) of both hemispheres. Interestingly, 15 subjects displayed ipsilateral event-related desynchronization (I-ERD) and C-ERS within broad gamma band (30–150Hz). The locations of the broad gamma band I-ERD and C-ERS revealed hemispherical symmetry in M1. These findings demonstrate that there are consistent high gamma C-ERS and inconsistent low gamma I-ERD during a simple finger movement in the motor cortex. This study provides new evidence for the use of high gamma frequency oscillations as biomarkers in the analyses of functional brain activity and the localization of the motor cortex. [ABSTRACT FROM AUTHOR]