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Center on Human Development and Disability
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CHDD is located on the Lake Washington Ship Canal

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Human Electrophysiology

    Brain Imaging pictures
Neva Corrigan
Neva Corrigan, Ph.D.
Director, Human Electrophysiology Component
Mark Pettet
Mark Pettet, Ph.D.
Research Scientist

A central resource of the Human Electrophysiology Component (HEC) is the Electrophysiology Laboratory, also housed in core space providing tight integration of HEC imaging services with MR image acquisition. This facilitates easy collaboration between these two brain imaging modalities and is especially important in support of the laboratory’s in-magnet EEG system. This system, consisting of a BrainAmp MRplus MRI-compatible 64-channel digital system (Brain Products, Inc.), permits simultaneous EEG and fMRI data acquisition. Use of this system in the magnet is complex and requires specialized support from HEC staff to help prepare the subject as well as to monitor acquisition to ensure a good EEG data set during the imaging experiment. IDDRC affiliates also have access to an EEG/event-related potentials (ERP) apparatus (Electrical Geodesics Inc., Eugene, OR) that utilizes the dense array electrode system that records brain activity from a 128 scalp electrode array. The lab currently has ten 128 channel nets of various adult, child, and infant sizes. The laboratory can also record a wide range of autonomic measures in conjunction with EEG for use in studies of attention, stress, and emotion.

Investigators also have access to a high-performance computing (HPC) server with 24 processors and 20 terabytes of on-board storage. These are equipped with a variety of software development tools and applications needed to build large-scale, automated EEG/ERP analysis pipelines. CHDD's HPC server is part of IBIC's Sun Grid Engine computing cluster. The cluster is engineered so that a user of one of the HPC servers can submit computing tasks utilizing that server's 24 cores, as well as any of the 200 cores currently unused by other HPC servers in the cluster. This allows for the development of scalable, parallel computing solutions.

The HEC also provides a portable EEG system that allows IDDRC investigators to acquire EEG data from subjects who are not able to come to the laboratory, providing the ability to acquire of data from individuals with limited mobility or accessibility to transportation, as well as from people who live outside the Puget Sound region. The electronics and software for this system are nearly identical to the Electrical Geodesics 400 EEG systems housed at CHDD, resulting in complete compatibility with data acquired within the laboratory. This Geodesic System 400 includes a state-of-the art amplifier that uses fiber optic signaling, hospital grade isolation transformer, high density 128 electrode sensor nets, and a laptop computer equipped with Netstation software for both acquisition and analysis of EEG data off-site. An additional laptop computer that interfaces with the EEG system is equipped with EPRIME software for presentation of visual and auditory stimuli. A custom-built Pelican case that can be checked as baggage at the airport is used for protection and transportation of the portable EEG system.

The BIOPAC system consists of several compact hardware modules that acquire and digitize electrical signals from sensors attached to a research study participant. Each module is specialized for a particular modality including electrocardiogram (ECG), electrodermal responses (EDR), impedance cardiography (ICG), and respiratory pneumography (RPG). A specialized module receives digital trigger signals generated by experimental control systems, such as stimulus delivery software, or video recorders. A central acquisition unit gathers outputs from these various modules and delivers them to a software application, AcqKnowledge, that generates a coordinated real-time display of incoming data, and saves these data for subsequent post-acquisition signal processing and analysis.

The MEG Center, located in the Institute for Learning and Brain Sciences (I-LABS) in the Portage Bay building, is focused on collecting data from infants and young children and was incorporated as part of the IDDRC Brain Imaging Core during the past grant cycle. It houses an Elekta-Neuromag VectorviewTM whole-head MEG system (Helsinki, Finland), with 306 superconducting SQUIDS sensors that allow for simultaneous measurement of magnetic activity across the cortex. The MEG system is located in a two layer magnetically shielded room (MSR), and employs Active Shielding technology. The system has specific adaptations that facilitate acquisition of data from infants and children, and can also be used to collect data from adolescents and adults.

A Fastrak 3D stylus digitizer (Polhemus, Colchester, VT) is available to model participant head shape, and to locate five continuous head position coils (cHPI) prior to MEG data acquisition. The cHPI coils produce magnetic fields that enable estimation and tracking of head position and orientation with respect to the sensor array coordinate system during data acquisition. This tracking data is then used for motion compensation in post-processing, which is especially necessary for infant and child subjects.

The MEG Center has a variety of commercially available neurological stimulus software packages including Eprime (Psychology Software Tools, Sharpsburg, PA), Stim2 (Compumedics NeuroScan, Charlotte, NC) and Presentation (NeuroBehavioral Systems, Berkely, CA) as well as I-LABS developed Python based routines using an auditory multiprocessor (RZ6,Tucker Davis Technologies, Alachua, FL) and an eye tracking system (Eyelink, SR Research, Ottawa, Canada). It is additionally fully outfitted with state-of-the-art workstations for signal processing and MEG analyses. A Linux data acquisition workstation is used to collect and store raw data. During recording, this workstation can also be used for monitoring the raw MEG signals and viewing an on-line representation of the evoked brain responses. Another workstation is available for advanced signal processing and analysis of the acquired MEG data by Elekta’s commercial software modules. Several other powerful workstations are used for new signal processing and analysis methods, developed and optimized for infant MEG data.

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University of Washington • Center on Human Development and Disability Box 357920 • Seattle WA 98195-7920 USA • 206-543-7701 • chdd@uw.edu