title: Custom-fit radiolucent cranial implants for neurophysiological recording and stimulation.
abstract: BACKGROUND
  Recording and manipulating neural activity in awake behaving animal models requires long-term implantation of cranial implants that must address a variety of design considerations, which include preventing infection, minimizing tissue damage, mechanical strength of the implant, and MRI compatibility.
  
  
  METHODS
  Here we address these issues by designing legless, custom-fit cranial implants using structural MRI-based reconstruction of the skull and that are made from carbon-reinforced PEEK.
  
  
  RESULTS
  We report several novel custom-fit radiolucent implant designs, which include a legless recording chamber, a legless stimulation chamber, a multi-channel microdrive and a head post. The fit to the skull was excellent in all cases, with no visible gaps between the base of the implants and the skull. The wound margin was minimal in size and showed no sign of infection or skin recession.
  
  
  METHODS
  Cranial implants used for neurophysiological investigation in awake behaving animals often employ methyl methacrylate (MMA) to serve as a bonding agent to secure the implant to the skull. Other designs rely on radially extending legs to secure the implant. Both of these methods have significant drawbacks. MMA is toxic to bone and frequently leads to infection while radially extending legs cause the skin to recede away from the implant, ultimately exposing bone and proliferating granulation tissue.
  
  
  CONCLUSIONS
  These radiolucent implants constitute a set of technologies suitable for reliable long-term recording, which minimize infection and tissue damage.
authors.affiliation: McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, United States. Electronic address: grantm@mit.edu.
authors.forename: Grant H
authors.initials: GH
authors.lastname: Mulliken
authors.affiliation: McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, United States.
authors.forename: Narcisse P
authors.initials: NP
authors.lastname: Bichot
authors.affiliation: McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, United States.
authors.forename: Azriel
authors.initials: A
authors.lastname: Ghadooshahy
authors.affiliation: Picower Center for Learning and Memory at MIT, Cambridge, MA 02139, United States; Picower Institute for Learning and Memory, MIT; Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Department of Radiology, Harvard Medical School, Boston, MA 02129, United States.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Sharma
authors.affiliation: Picower Center for Learning and Memory at MIT, Cambridge, MA 02139, United States.
authors.forename: Simon
authors.initials: S
authors.lastname: Kornblith
authors.affiliation: AnalyzeDirect Inc., Overland Park, KS 66085, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Philcock
authors.affiliation: McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Desimone
mesh_terms: D000818:Animals; D001577:Benzophenones; D001672:Biocompatible Materials / Q000737:chemistry; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D007659:Ketones / Q000737:chemistry; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers; D019736:Prostheses and Implants; D012886:Skull / Q000033:anatomy & histology
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols
keywords: Brain–machine interface; Implant; Macaque; Microdrive; Neurophysiology; Radiolucent