NIMH Instrumentation Core Facility

Dold, George

Abstract

This past year, our Section had the unique opportunity to support the research from various Labs & Sections within NIMH, NINDS, NICHD, and NCCIH. During the past twelve months, investigators from these labs and branches requested 499 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. We have also continued to develop small microdrives that allow for accurate placement of electrodes that integrate with the multiple-hole arrays. Noise is a major concern when recording with electrodes. Shielding and grounding are used to minimize noise, but this can be a black art where different techniques are empirically tried. Many labs have racks of amplifier-electronics which are used to measure voltage signals on a cellular level. They have excessive noise, particularly but not at all exclusively AC line harmonics. For one particular lab, we developed measurement techniques and a topological map of the system, especially the grounds, which led us to make numerous targeted circuit changes and to recommend some specific changes in their practices. As a result, the line harmonic noise was essentially eliminated and the broadband noise was essentially reduced to fundamental electrode thermal-noise levels, taking them from nearly-unusable to high-performance signal integrity. These methods are expected to be used for other labs that have the same noise issues. fMRI 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. This past year we continued development of a novel MRI-based gustatory apparatus to investigate the areas of the brain using fMRI that respond to gustatory stimuli. Our 3D printing capabilities allow for more efficient design of the MRI-compatible fluid manifolds. We continue to provide a variety of custom head coils, cradles, and phantom holders for various fMRI applications. These cradles allow for precise placement of imaging coils in the scanner, enabling higher-resolution scanning. 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. We have become experts in many different types of force and load cells and the integration of these into working research tools. Our group continues to develop novel MRI-compatible head post systems to allow for more robust and rigid positioning and securing of the NHP head, which is difficult in the MRI-environment. We currently are testing a new smaller-footprint but yet stronger version, which allows more freedom in placing electrode chambers on the surface of the skull. Human Human research requires the creation of many novel devices that are compatible with the high-magnetic field environment. When a new magnet is installed, we are consulted with and provide the necessary components for presenting visual stimuli in the bore of the magnet, including image periscopes, screens, and mirrors. These devices are designed and manufactured with specific space and material constraints. One interesting project was the fabrication of a floating doorframe for Parkinsons studies. The door frame was constructed so that cameras could record the gait movements of patients with minimal visual interference to the cameras. 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 what effect different treatments affect learning and memory in mice. We continue to produce a variety of custom T and Y mazes for behavioral testing, and are currently fabricating a large eight-arm automated radial maze. We also designed and fabricated a novel reconfigurable mouse maze that allows the investigator to quickly make different paths for the mouse to navigate. In addition, we continue to fabricate numerous testing boxes for social interaction studies, including acoustically isolated boxes that allow for testing of multiple animals in the same testing room. Imaging The addition of small secondary coils at specific regional sites enhances the resolution of MRI images at those sites. By exploiting the capabilities of our 3D rapid prototyping systems, we are able to fabricate custom coil holders for these specific sites. In collaboration with NINDS physicists, a plethora of such devices have been designed and implemented. Also, various means to minimize radio frequency noise introduced by the associated cabling for the coils have been collaboratively designed and fabricated. Currently, NIMH produces virtually all of its short-lived radiotracers for research studies in human subjects with positron emission tomography (PET) from its own laboratory suite. A new laboratory has been created in the Clinical PET Center to produce all radiotracers for PET studies in human subjects on the NIH campus according to a high common standard in compliance with regulatory needs. The Section on Instrumentation continues to provide a substantial amount of engineering support to the Section on PET Radiopharmaceutical Sciences in the Molecular Imaging Branch (MIB) to implement the new facility. Clinical Our Section also supports a number of clinical based research requests under the broad areas of surgical, therapeutic and basic research. This FY we developed a custom novel wrist isometric sensor to test the behavioral phenomenon known as the sequence effect in Parkinsons disease. It is the gradual decrement in speed and/or amplitude of movement. This was tested using a static wrist flexion force and it measured the gradual decline in force over 20 sec blocks. Visual feedback is known to reverse the sequence effect; therefore, subjects were tested without and with visual feedback on their performance. These applications are programmed with Labview, a high-level software package. Millisecond timing of visual stimulation and recording of operator feedback are critical for these applications. Technology By using the latest technology in advanced fabrication machinery, SI is able to increase productivity and effectiveness while at the same time decreasing the amount of time needed to engineer and machine the components. Our new waterjet cutter has greatly increased our cutting and fabricating capabilities, especially with the multiple fiberglass parts we produce.