NIMH Instrumentation Core Facility

National Institute Of Mental Health

Investigators

Linked publications, trials & patents

Abstract

This past year, our Section had the unique opportunity to support the research of various Labs & Sections within NIMH, NINDS, NICHD, and NCCIH. During the past twelve months, investigators from these labs and branches requested 332 formal projects from our staff. Each of these requests was documented and the time recorded to complete the job. In addition to the formal requests, we are available daily for numerous walk-in, phone call or e-mail requests for assistance. In general, our technical support this past year can be divided into the following research areas: Electrophysiology: The Section on Instrumentation staff continuously strives to improve the utility of various components that comprise electrophysiology. We have continued to improve the engineering and fabrication of multiple-hole grid arrays that allow precise, repeatable placement of a single or multiple electrodes over a wide area. fMRI/MRI: The Section on Instrumentation provides a wide range of support for fMRI-related research. Fabrication of devices for use in MRI environments is a specialized area of expertise, with great attention given to design without ferrous metals and minimization of all metal components. In addition, commercial industrial fiber optic components and systems are evaluated and integrated into many designs and devices we fabricate. SI continues to provide considerable effort in the design and fabrication of primate chair systems to incorporate new features as requested by researchers. Non-Human Primate (NHP): Our group is responsible for providing a wide range of engineering and fabrication services to support non-human primate research. Many of the mechanical assemblies that are necessary for this type of research are engineered and fabricated in-house. Our group provides a diverse array of custom systems and components to many different investigators, such as custom primate chairs, high-strength restraints, MRI positioning systems, custom head coils, reward systems, data acquisition, analysis and optical response systems, plus a wide range of small mechanical components. Human and Clinical: Optically pumped magnetometer sensor array system. During the last four years, the SI assisted the NIMH Magnetoencephalography (MEG) Core facility with a project central to their research program. In 2019, Dr. Allison Nugent was awarded a Brain Initiative grant to develop an array of optically pumped magnetometer sensors designed to image the brain with unprecedented spatial resolution. The project required the design and fabrication of a fixture to hold the sensors, as well as a calibration jig and electronics. This involved close collaboration between the SI and the MEG Core Facility. The design of the sensor array fixture required several considerations. First, it had to be extremely accurate so that the location of the sensors was known precisely. Second, the goal was to place the rectangular sensors as close together as possible. Third, the sensors needed to be on a curve so that the sensors would be as close as possible to the head, while allowing for different head shapes. Finally, the sensors produced heat, so that thermal dissipation was a consideration. The final array we developed in collaboration with the MEG Core Facility addressed all of these needs. The other major element of this project was the design of a calibration jig and associated electronics. Because the sensors were assembled into the array, deviations of the sensors from their exact locations in the array were possible. In addition, there could be manufacturing inconsistencies that resulted in small differences in the orientation or gains of each sensor. In order to calibrate the precise locations and orientations of each sensor, as well as their gains, known magnetic sensor sources were required. In collaboration with the MEG core facility, we designed two iterations of this project. The final iteration consisted of a five-sided prism, with each face having four magnetic dipole coils. The calibration electronics were designed to take a signal from a function generator to produce a current in each coil individually. In addition, to obtain the most precise measurements, the current in each coil needed to be measured and returned, so that the fields produced by each coil are known precisely. SI continues the development of a novel ECT system (MIST). In collaboration with the Experimental Therapeutics & Pathophysiology Branch, the Section on Instrumentation is developing a multi-channel ECT system (iLAST). While modifications of ECT have improved its safety and tolerability, none of the currently used procedures individualize the current amplitude for each patient despite knowledge that anatomical variation significantly impacts the strength of the current delivered to the brain. iLAST introduces three areas of improvement over conventional ECT. 1) Conventional ECT uses two large disc electrodes that are spaced widely apart, which leads to a non-focal electric field distribution in the brain. In iLAST, we use a multi-electrode array to selectively target regions of the brain similar to one employed in high-definition tDCS studies. 2) Conventional ECT uses a high and fixed current amplitude (800 mA). The fixed current amplitude is much higher than necessary to elicit an adequate seizure, and also results in individual differences in the amount of current entering the brain, possibly leading to variability in clinical outcome. In iLAST, we titrate the amplitude of the current for each patient. 3) Conventional ECT monitors seizure induction with two-channel EEG recording in the prefrontal cortex, which does not characterize seizure topography. In iLAST, we will use high-density EEG electrodes that are weaved into the multi-stimulation electrode array so that topographical ictal EEG is recorded. The ECT system is a multi-year collaboration, incorporating the development of a considerable amount of custom electronics and custom software development. SI has completed the design of the individual channel boards and the main motherboard. Considerable effort remains on software development and testing the system with high voltages and currents. This past FY, SI used some of the software concepts and hardware from the Cinnamon ECT system to quickly design and fabricate a single channel version with an enhanced user interface for testing ECT on NHPs. This system is currently being used successfully for ECS titration studies. Behavioral: Several different types of mazes are used to study spatial learning and memory in rats. These studies have been used to help understand general principles about learning that can be applied to humans, and to determine how different treatments affect learning and memory in mice. We continue to produce a variety of custom T and Y mazes for behavioral testing. Imaging: The Section on Instrumentation continues to produce a variety of equipment that supports two-photon microscopy, such as novel titanium headposts and stereotaxic frames, faraday cages for electronic and light shielding and custom mirror mounts. In addition, behavioral testing equipment such as low-inertia mouse wheels are fabricated for use with two-photon microscopy. SI is redesigning and fabricated several behavioral testing systems that will be used to provide a platform for studies using a technique known as total internal reflection fluorescence microscopy. Key events in cellular trafficking occur at the cell surface, and it is desirable to visualize these events without interference from other regions deeper within. The technique has many other applications as well, most notably for studying biochemical kinetics and single biomolecule dynamics at surfaces.