NIMH Instrumentation Core Facility

Dold, George

Abstract

This past year, our Section had the unique opportunity to support the research from more than 60 different Labs &Sections within NIMH, NINDS and NICHD. During the past twelve months, investigators from these labs and branches requested 462 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. Improvements continue for the goal of stabilizing the microelectrode manipulators to enhance precision and repeatability of electrode placement. We have continued to improve the engineering and fabrication of multiple-hole grid arrays that allow precise, repeatable placement of a single electrode over a wide area. Surgically implanted recording chambers with removable grids are routinely used for studying patterns of neuronal activities in primate brains. By using the three-dimensional modeling software, we designed a novel removable grid that permitted microinjections to reach the targeted sites far beyond the standard reach of the recording chamber. The grid was fabricated using a combination of conventional machining techniques and three-dimensional printing. Recently we have been asked to design high intensity LED control boxes for important studies involving tissue response to certain wavelengths and intensity of light. The new design allows the user to accurately control the LED intensity in a linear mode using pulse width modulation. A computer program generates a parallel digital signal that is converted to an analog signal by a microprocessor. A second design was also constructed that allows manual, pulsed control of the light intensity. 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 pin-diode control systems, as well as support for the human, primate and rodent magnet imaging facilities. Non-Human Primate 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. A considerable effort is currently underway to install a state-of-the-art 3D projection system that will allow separate images to be independently viewed by each eye of a monkey in the vertical MRI. In addition, a new response lever system was developed for use in the MRI which allows optical recording of responses made by the primates, and we also developed an improved monkey lick detector that allows the investigator to record the monkeys liquid reward response to various behavioral tasks. 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. To coordinate data collection taken during scanning for a particular fMRI-based behavioral task, it is critical to sync the data collection with the initial pulse generated by the scanner. Our interface takes the sub-microsecond pulse from the scanner, lengthens and buffers it to be used by the investigators with their computer data collection software. For some experiments, it is necessary to count each of the scanner pulses that are needed for a selected volume and generate a single pulse when the scan volume is completed. An embedded microcontroller allows the user to set the number of counts proportional to the selected volume before the single pulse is generated. Tactile stimulation studies include stimulating both the hands and the feet of human subjects. The natural reaction to the stimulation is for the subject to retract their foot or hand at the onset of the stimulation. We have devised several techniques with concomitant hardware to restrain the affected appendages during the stimulation thus assuring consistent stimulation throughout the course of the study. Behavioral Direct social approach in mice has strong face validity to simple social approach behaviors in humans, which are frequently impaired in autism. During the previous year we continued development and production of our automated three chambered social approach system, which quantifies direct social approach behaviors when a subject mouse is presented with the choice of spending time with either a novel mouse or a novel object. The system tracks and records the mouse movement through three separate chambers. In addition, the system was then used as a model to quickly fabricate light-dark anxiety testing boxes. 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 have been collaboratively designed and fabricated to attenuate the RF noise. 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 the hardware and software for studies involving motor learning under feedback uncertainty using a pinch-force device, both in a normal and an MRI environment. We also developed a joystick system to study visuomotor pointing movements in healthy subjects and the cortical dynamics associated with it recorded by magnetoencephalography (MEG). Technology The Section on Instrumentation (SI) machine shop produces many mechanical assemblies and components to assist in the research goals of the NIH. 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. Our 3D printers enable us to manufacture quality parts that sometimes would be impossible to fabricate with conventional manufacturing techniques.