Magnetoencephalography (MEG) and electroencephalography (EEG) are the only non-invasive human brain imaging methods measuring neural currents directly thus providing exquisite temporal resolution and allowing detection and precise timing of transient changes in brain activity as well as studies of dynamic interactions between brain regions. With multichannel MEG and EEG recordings it is possible to locate the sources underlying the measurements in best cases with an accuracy of less than 1 cm. Recently, there has been increasing interest in studying weak high-frequency oscillations associated with normal brain function as well as fast signals related to abnormal epileptic events, observed in invasive recordings. Furthermore, it has been demonstrated that under suitable conditions it is feasible to detect activity from deep brain areas on and outside the cortex. For all these studies a fine amplitude resolution and fast sampling rates are a prerequisite. Due to their very real-time nature, MEG and EEG signals are very suitable for applications involving real-time processing of signatures of brain activity such as brain-machine interfaces (BMI) and experiments in which the stimuli presented are controlled by the """"""""brain state"""""""". To enable detection of low-amplitude and/or high- frequency signals and real-time data processing, we propose an upgrade to the electronics of the whole-head MEG/EEG at the Martinos Center of Massachusetts General Hospital (MGH), the only state-of-the-art MEG installation in New England area. The new electronics will provide higher sampling rates (up to 8 ksamples/s instead of present 3 ksamples/s), higher amplitude resolution (24 bits instead of 16 bits) than the present electronics, developed in the late 90s and installed with the system in 2001. In addition, the new modern MEG/EEG electronics will allow direct access to the data during recordings for BMI and other real-time applications. The MGH MEG/EEG system is used by a multitude of research groups in the Boston area, all of which will directly benefit from the proposed upgrade. In addition, our clinical MEG service provides multimodal imaging of epileptic activity and presurgical functional mapping for patients from local and regional hospitals.
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