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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]

Summary: Purpose: Magnetoencephalography (MEG) has been shown a useful diagnostic tool for presurgical evaluation of pediatric medically intractable partial epilepsy as MEG source localization has been shown to improve the likelihood of seizure onset zone (SOZ) sampling during subsequent evaluation with intracranial EEG (ICEEG). We investigated whether ictal MEG onset source localization further improves results of interictal MEG in defining the SOZ. Methods: We identified 20 pediatric patients with one habitual seizure during MEG recordings between October 2007 and April 2011. MEG was recorded with sampling rates of 600Hz and 4000Hz for 10 and 2min respectively. Continuous head localization (CHL) was applied. Source localization analyses were applied using multiple algorithms, both at the beginning of ictal onset and for interictal MEG discharges. Ictal MEG onsets were identified by visual inspection and power spectrum using short-time Fourier transform (STFT). Source localizations were compared with ICEEG, surgical procedure and outcome. Key findings: Eight patients met all inclusion criteria. Five of the 8 patients (63%) had concordant ictal MEG onset source localization and interictal MEG discharge source localizations in the same lobe, but the source of ictal MEG onset was closer to the SOZ defined by ICEEG. Significance: Although the capture of seizures during MEG recording is challenging, the source localization for ictal MEG onset proved to be a useful tool for presurgical evaluation in our pediatric population with medically intractable epilepsy. [Copyright &y& Elsevier]

Abstract: Objective: This study aimed to use magnetoencephalography (MEG) to examine the question of whether Mandarin-English bilingual speakers recruit the same cortical areas or develop distinct language-specific networks without overlaps for word processing. Methods: Eight healthy Mandarin-English bilingual adults and eight healthy English monolingual adults were scanned while single-word paradigms were audio-visually presented. Results: Our results showed significantly stronger beta-band power suppression in the right inferior parietal lobe (IPL) covering the supramarginal gyrus (BA 40) and angular gyrus (BA 39) for bilinguals when processing Mandarin versus English. Moreover, there were no significant differences between bilinguals and monolinguals in the left inferior frontal cortex (LIFC, BA 44/45) when both were processing their first language. Conclusions: These results support the view that Mandarin-English bilinguals have a shared neural system for word processing in both the first and second language, which is highly similar to monolinguals’, but with stronger right hemisphere involvement. Significance: To our knowledge, this is the first MEG study to investigate the spatio-temporal and frequency characteristics between bilinguals and monolinguals, which provides us a new angle to better understand the language system in bilinguals’ and monolingual’s brain. [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]