Magnetoencephalography

The facility houses a 306-channel whole-head MEG system, and a collection of magnetically-silent stimulus presentation equipment for cognitive neuroscience experiments. The Elekta model instrument is equipped with 102 magnetometers and 204 planar-gradiometers (306 independent magnetic sensors), and has the capability for simultaneous acquisition of 64-channel EEG. The instrument is housed within a Lindgren magnetically-shielded room (MSR) that is equipped with coils within the room walls for active shielding (i.e., the MSR responds to environmental perturbations by generating competing magnetic fields to compensate). Beyond this “smart-shield,” the Nebraska MEG facility is equipped with spatiotemporal Signal Space Separation (tSSS) software for additional noise reduction. 

The MEG system is also configured for continuous head localization and head-movement correction. The capacity to correct MEG data for head movements is relatively new, and Nebraska was amongst the first few MEG sites in the world to be equipped with the necessary hardware and software. Our magnetically-silent stimulus delivery equipment includes remote auditory transducers for pneumatic sound delivery, 3-chip DLP video projection onto a back-projection screen, electrical somatosensory stimulation, mechanical (air-puff) somatosensory stimulation, two dual-axis accelerometers, two 5-button response “gloves” made specifically for the left and right hands, an in-room high-sensitivity microphone, two fiber-optic laser pads for recording the onset of motor responses, and a force transducer system that includes both tensile- and compression-transducer options for measuring isokinetic joint extension forces.

Magnetic Resonance Imaging

UNMC recently purchased a new 3-Tesla Siemens Prisma MRI scanner. This research-dedicated scanner is equipped with 20-, 32-, and 64-channel head coils, as well as array of other coils for cardiac, spinal, and other types of imaging. This Prisma includes multiband imaging capabilities for advanced brain imaging, and all available commercial sequences offered by Siemens. These include numerous MRI sequences for advanced diffusion, spectroscopy, structural, and functional brain imaging. The system is equipped with the [204×64] XR 80/200 gradients, which are the most powerful commercially available gradients for any scanner currently on the market. 

The XR gradients combine a maximum gradient amplitude of 80 mT/m with a 200 T/m/s slew rate. Dedicated force compensation on each axis yields low vibrations and low acoustic noise, while high-performance cooling for each axis allows full duty cycle over long-term measurements with optimal stability. Finally, the Prisma MRI Suite is also equipped with all necessary peripherals to present experimental stimuli and acquire behavioral responses. This includes the BOLDScreen-32 (a 32” in-room LCD monitor for presenting stimuli), and multiple ergonomic subject response devices.

Brain Stimulation

The DICoN laboratory also utilizes state-of-the-art electrical brain stimulation equipment, including three Soterix Medical systems that are housed in a brain stimulation suite. The suite includes a general preparation and setup area, as well as two testing/stimulation areas, and can be reserved in one-hour increments using a dedicated online calendar system that is editable by each approved user. Regarding equipment, the suite includes a standard two-pad tDCS system, a two-pad transcranial electrical stimulation (tES) system, a five-lead multipolar high-definition tDCS system (HD-tDCS), and a five-lead alternating-current stimulation (tACS) system. All of the systems are equipped with settings for sham-stimulation, which allows investigators to use “placebo-controlled” experimental designs. In addition to the stimulators, there is a Polhemus digitizer for coregistering the stimulation sponges or metal electrodes to neuroanatomical images, and a PC and the necessary software for stereotactic neuro-navigation. Core users will also have access to advanced software for finite-element modeling (FEM) of current flow using the participant’s individual anatomy, and there is existing expertise within the Core to conduct such analyses.

Data Processing

The DICoN laboratory includes a high-performance computing space that was built and fully equipped in the summer of 2016. This space currently includes 26 dedicated high-performance workstations for data processing, a 36 terabyte (RAID5) storage array for MEG and MRI data, and a video conferencing system for virtual meetings. All of the computers are linked via gigabit connection to the storage array and to a backup server located offsite. Each computer has Matlab and other important software for neuroimaging and statistical analyses, including many free packages such as SPM, FSL, AFNI, FreeSurfer, CONN, R, and other leading toolboxes. 

Many of the computers are also equipped with the Brain Electrical Source Analysis (BESA) software, BrainVoyager, SPSS, and current-distribution modeling software. The open concept space is meant to encourage collaborative programming (e.g., algorithm development) and data processing efforts among students and faculty. Dr. Wilson’s office is next door to the high-performance computing area, which facilitates his involvement in day-to-day operations and data analyses.

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