title: Low profile halo head fixation in non-human primates.
abstract: We present a new halo technique for head fixation of non-human primates during electrophysiological recording experiments. Our aim was to build on previous halo designs in order to create a simple low profile system that provided long-term stability.
  
  
  
  Our design incorporates sharp skull pins that are directly threaded through a low set halo frame and are seated into implanted titanium foot plates on the skull. The inwardly directed skull pins provide an easily calibrated force against the skull.
  
  
  
  This device allowed for head fixation within 1 week after implantation surgery. The low-profile design maximized the area of the skull available and potential implant orientations for electrophysiological experiments. It was easily maintained and was stable in 2 animals for the 6-8 months of testing. The quality of single unit neural recordings collected while using this device to head fix was indistinguishable from traditional head-post fixation. The foot plates used in this system did not result in significant MRI distortion in the location of deep brain targets (∼0.5mm) of a 3D printed phantom skull.
  
  
  
  The low profile design of this halo design allows greater access to the majority of the frontal, parietal, and occipital skull. It has fewer parts and can hold larger animals than previous halo designs.
  
  
  
  Given the stability, simplicity, immediate usability, and low profile of our head fixation device, we propose that it is a practical and useful means for performing electrophysiological recording experiments on non-human primates.
authors.affiliation: School of Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: kazimi@qmed.ca.
authors.forename: Kousha
authors.initials: K
authors.lastname: Azimi
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Surgery, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada. Electronic address: ianprescott@gmail.com.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Prescott
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Surgery, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada. Electronic address: marinor@queensu.ca.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Marino
authors.affiliation: Animal Care Services, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: andrew.winterborn@queensu.ca.
authors.forename: Andrew
authors.initials: A
authors.lastname: Winterborn
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Surgery, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada. Electronic address: ron.levy@queensu.ca.
authors.forename: Ron
authors.initials: R
authors.lastname: Levy
mesh_terms: D000200:Action Potentials; D000818:Animals; D001132:Arm / Q000502:physiology; D016477:Artifacts; D001858:Bone Nails; D004594:Electrophysiology / Q000295:instrumentation; D004867:Equipment Design; D005917:Globus Pallidus / Q000000981:diagnostic imaging / Q000502:physiology; D006257:Head; D019416:Head Movements; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D008839:Microelectrodes; D023421:Models, Animal; D009043:Motor Activity / Q000502:physiology; D009474:Neurons / Q000502:physiology; D019736:Prostheses and Implants / Q000009:adverse effects; D012886:Skull / Q000000981:diagnostic imaging / Q000601:surgery; D013997:Time Factors; D014025:Titanium
chemical_list: D014025:Titanium
keywords: Halo; Head fixation; Non-human primates; Skull pins