Conformal Pediatric MEG
Three decades of magnetoencephalography (MEG) research have demonstrated its superior spatial resolution and equivalent temporal resolution compared to the scalp electroencephalography (EEG) for non-invasively imaging normal and abnormal brain function, yet, progress in scientific and clinical imaging with existing cryogenic MEG systems has been slowed by technological, not theoretical, limitations. Our objective is to remove this constraint by developing a 128-channel, room temperature, optically-pumped magnetometer system that will provide higher signal strength and spatial resolution compared to conventional MEG systems, greatly improving the feasibility of neuroimaging studies in adults and additionally in infants and children with large variations of head sizes. Our long-term goal is to move past the technical limitations of present SQUID technology and realize the potential of MEG as a highly sensitive yet practical imaging modality with far more widespread use than is presently realized.
Magnetrode system for non-invasive epilepsy mapping
Magnetoencephalography (MEG) has long held the promise of providing a non-invasive tool for localizing epileptic seizures in humans due to its high spatial resolution compared to the scalp electroencephalogram (EEG). Yet, this promise has been elusive, not due to a lack of sensitivity or spatial resolution, but due to the fact that the large size and immobility of present cryogenic (superconducting) technology prevents long-term telemetry often required to capture these very infrequent epileptiform events. To circumvent this limitation, this project is devoted to the development of a practical non-cryogenic (room temperature) microfabricated atomic magnetometer (鈥渕agnetrode鈥�) based on laser spectroscopy of rubidium vapor and similar in size and flexibility to scalp EEG electrodes. The project is based on our published preliminary results in which we used Micro-Electro-Mechanical Systems (MEMS) technology to construct a working miniature magnetrode and tested it in an animal model to measure neuronal currents of single epileptic discharges and more subtle spontaneous brain activity with a high signal-to- noise ratio approaching that of present superconducting sensors. These measurements are a promising step toward the goal of high-resolution noninvasive telemetry of epileptic events in humans with seizure disorders.
Multichannel TMS-MEG system
Understanding the electrophysiology of neural circuits in the human brain is critical for advancing our knowledge of human nature since fast neural communication underlies our remarkable perceptual, motor, and cognitive abilities. Studying such networks requires a method to stimulate one or more nodes of any network with precise timing and a method to accurately measure electrophysiological activity with millisecond time resolution. At present, single-channel transcranial magnetic stimulation (TMS) devices are used to stimulate one focal region of the cortex and an array of EEG electrodes to measure the consequences of such stimulations on network functions. This type of device can stimulate only one region at a time with a rather diffuse area of stimulation and record brain activity smeared by the intervening scalp, skull and cerebral spinal fluid (CSF). We are developing and testing a novel noninvasive system with the stimulation and recording capabilities required for understanding functional roles of neural circuits in the human brain with high time resolution. It consists of a 16-channel cryogenically cooled high-density TMS coil array integrated with a 25-channel TMS-compatible microfabricated optically-pumped gradiometer array.
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