NIMH Instrumentation Core Facility

Dold, George

Abstract

This past year, our Section had the unique opportunity to support the research from more than 35 different Labs &Sections within NIMH, NINDS and NICHD. During the past twelve months, investigators from these labs and branches requested 498 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. 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. We recently fabricated a unique system to shield a multiple electrode positioning system, using 3D plastic printed pars and electrically conductive paint. The noise attenuation was significant. Surgically implanted recording chambers with removable grids are routinely used for studying patterns of neuronal activities in primate brains. We continued our previous work designing a novel removable grid using the three-dimensional modeling software that permitted microinjections to reach the targeted sites far beyond the standard reach of the recording chamber. Both on-axis and angled holes are now possible. The grid was fabricated using a combination of conventional machining techniques and three-dimensional printing. 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 provided extensive engineering and fabrication of a new microcontroller and discrete amplifier-based pin-diode control systems. With this system it is possible to manually adjust which of eight capacitors on a gradient coil will be activated, in any combination. We also continued our support for the human, primate and rodent magnet imaging facilities. 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. We recently developed a new microdrive for the movement of chronic electrodes implanted in NHPs. The electrodes are bundled into a very fragile array, and must be held firmly enough to allow translation into the brain but not so hard as to crush the bundle. The electrodes must also be moved precisely along a single axis, since any bending movements will break the bundle. The need for strong reliable monkey chairs is critical to the intramural research program. The elegance of the design of the monkey chairs we manufacture is confirmed when we have to repair chairs that are broken. Since the chairs are used daily, a quick turnaround time is important. Our turnaround time is a day or less for major repairs. 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. Custom head coils are important for various fMRI applications. Using our 3D printers, we were able to design and fabricate various custom head holding (cradle) systems as requested by our investigators. These cradles allow for precise placement of imaging coils in the scanner, enabling higher-resolution scanning. 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 produce a variety of custom T and Y mazes for behavioral testing. This past year, as requested by an investigator testing mouse anxiety, we fabricated custom, adjustable LED strips for illuminating sections of the mazes in a darkened room. We were also asked to consider a project were incorporated a number of sensors to monitor the rodent housing room to check for variation in their living environment that might affect their behavior during testing. We have constructed a unit that will monitor sound levels, vibration, temperature variations, light and also ultrasound levels. The monitoring signals will be controlled by a computer that will alert the investigator to any abnormal environmental factors. 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. A continuing request is for custom helmets for securing the heads of marmosets which are undergoing MRI scans. Custom data files are sent to us that can be translated into 3-D images and fabricated on our 3-D printer. The custom helmets reduce anxiety for the marmosets that are being scanned. Clinical Our Section also supports a number of clinical based research requests under the broad areas of surgical, therapeutic and basic research. In particular, we developed several applications for studies involving motor learning under feedback uncertainty. 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. This past year we were also asked to fabricate an interface for a deep brain stimulation cable. The purpose of this cable is to allow the patient to be mobile while under stimulation testing. Technology By using the latest technology in CAD/CAM programming, Rapid Prototyping techniques, and reverse engineering, 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. We recently invested in a Labview-based embedded microprocessor development system, which allows us to quickly produce low-cost but highly-functional electronic equipment.