title: A carbon-fiber electrode array for long-term neural recording.
abstract: OBJECTIVE
  Chronic neural recording in behaving animals is an essential method for studies of neural circuit function. However, stable recordings from small, densely packed neurons remains challenging, particularly over time-scales relevant for learning.
  
  
  METHODS
  We describe an assembly method for a 16-channel electrode array consisting of carbon fibers (<5 µm diameter) individually insulated with Parylene-C and fire-sharpened. The diameter of the array is approximately 26 µm along the full extent of the implant.
  
  
  RESULTS
  Carbon fiber arrays were tested in HVC (used as a proper name), a song motor nucleus, of singing zebra finches where individual neurons discharge with temporally precise patterns. Previous reports of activity in this population of neurons have required the use of high impedance electrodes on movable microdrives. Here, the carbon fiber electrodes provided stable multi-unit recordings over time-scales of months. Spike-sorting indicated that the multi-unit signals were dominated by one, or a small number of cells. Stable firing patterns during singing confirmed the stability of these clusters over time-scales of months. In addition, from a total of 10 surgeries, 16 projection neurons were found. This cell type is characterized by sparse stereotyped firing patterns, providing unambiguous confirmation of single cell recordings.
  
  
  CONCLUSIONS
  Carbon fiber electrode bundles may provide a scalable solution for long-term neural recordings of densely packed neurons.
authors.affiliation: Department of Biology, Boston University, 24 Cummington Mall, Boston, MA 02215, USA.
authors.forename: Grigori
authors.initials: G
authors.lastname: Guitchounts
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Markowitz
authors.forename: William A
authors.initials: WA
authors.lastname: Liberti
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Gardner
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D017097:Electric Impedance; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046369:Finches / Q000502:physiology*; D046228:Microarray Analysis / Q000295:instrumentation; D009044:Motor Cortex / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014828:Vocalization, Animal / Q000502:physiology*
chemical_list: D001672:Biocompatible Materials; D000077482:Carbon Fiber; D002244:Carbon