A watertight acrylic-free titanium recording chamber for electrophysiology in behaving monkeys

Program in Neuroscience, University of California, San Francisco, California 94143-0730, USA.
Journal of Neurophysiology (Impact Factor: 2.89). 06/2011; 106(3):1581-90. DOI: 10.1152/jn.00405.2011
Source: PubMed


Neurophysiological recording in alert monkeys requires the creation of a permanent aperture in the skull for repeated insertion of microelectrodes. Most laboratories use polymethyl methacrylate to attach a recording chamber over the skull opening. Here, we describe a titanium chamber that fastens to the skull with screws, using no polymethyl methacrylate. The gap between the base of the chamber and the skull is filled with hydroxyapatite, forming a watertight gasket. As the chamber base osseointegates with the skull, the hydroxyapatite is replaced with bone. Rather than having a finite lifetime, the recording chamber becomes more firmly anchored the longer it is in place. It has a small footprint, low profile, and needs little maintenance to control infection. Toilette consists of occasional application of betadine to clean the scalp margin, followed by application of neomycin, polymyxin, and bacitracin ointment. Antibiotic is also placed inside the chamber to suppress bacterial proliferation. Thickening of the dura within the chamber can be prevented by regular application of mitocycin C and/or bevacizumab, an antibody against vascular endothelial growth factor. By conducting an e-mail survey, this protocol for chamber maintenance was compared with procedures used in 37 other vision research laboratories. Refinement of appliances and techniques used for recordings in awake monkeys promises to increase the pace of scientific discovery and to benefit animal welfare.

Download full-text


Available from: Daniel L Adams, Oct 01, 2015
27 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: While neural recording chambers for non-human primates can be purchased commercially, these generic chambers do not contour to the animal's skull. In order to seal gaps, a cap of dental acrylic (methyl methacrylate) is often applied around the chamber. There are multiple disadvantages associated with this method. Applying acrylic delays and further complicates surgical procedure, and overheating during the curing process can cause damage to the bone. Post-surgery, acrylic margins can give rise to bacterial growth and infection. Here we describe a method to develop custom implants which conform to the individual's skull, thereby eliminating the need for acrylic. This method shortens surgery time and significantly improves the hygiene of chamber margins.
    Journal of Neuroscience Methods 04/2012; 207(1):86-90. DOI:10.1016/j.jneumeth.2012.03.014 · 2.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: It is well recognized that micrometer and nanometer sized surface features enhance the skeletal attachment of implants within bone. However, little is known regarding the integration of implants placed outside the bone but in contact with the surface. Loosening of chronic skull anchored headposts in non-human primate based experiments can be a factor. The purpose of this study was to evaluate the effect of a simple and easily applied surface texture on bone apposition to titanium implants fixed to the periosteal surface of the skull. Implants possessed either a polished surface or a textured surface created by grit-basting followed by acid etching. The percent of bone in contact with the implant surface (bone apposition) to three polished and three textured implants was evaluated in one adult female monkey after 14 weeks. Upon harvest, implants were processed for undecalcified histology and regions of bone apposition were quantified using backscatter electron microscopy and digital image analysis. The bone apposition to textured implants was 62±20% and to polished implants was 42±21%. The application of a peak-and-pit like texture to the surface of titanium implants significantly increased bone apposition to titanium implants placed on the periosteal surface of the skull. This study demonstrates that titanium headposts can easily be modified to improve osseointegration using equipment and supplies available to most neurophysiological laboratories. In addition, implant texturing may have utility in areas including skeletal trauma and reconstruction where devices are placed in contact with the bone surface.
    Journal of Neuroscience Methods 09/2012; 211(2):237-244. DOI:10.1016/j.jneumeth.2012.09.002 · 2.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Maintaining a clean, quiescent tissue surface free of granulation and infection in the floor of a head-mounted chamber used for intracranial single-unit recording studies typically requires frequent cleaning. Considering favorable outcomes of otologic surgical techniques that have long been used to create a dry, skin-lined mastoid cavity in patients with chronic otitis media, skin should be an ideal biologic dressing to cover otherwise exposed dura mater in recording chambers. In two Rhesus monkeys with chambers that required frequent cleaning, we harvested a thin layer of skin without hair follicles from medial surface of the upper arm and grafted the skin on the exposed dura surface. Each case resulted in a clean, dry, insensate, self-healing, easily maintained tissue surface that remained healthy despite reduced frequency of chamber maintenance. We recommend this technique to reduce the potential for infection, to prevent cerebral spinal fluid leak or bleeding in experiment, and to minimize animal anxiety that might otherwise result from frequent chamber cleanings.
    Journal of Neuroscience Methods 02/2013; 215(2). DOI:10.1016/j.jneumeth.2013.02.002 · 2.05 Impact Factor
Show more