title: Histological evaluation of a chronically-implanted electrocorticographic electrode grid in a non-human primate.
abstract: Electrocorticography (ECoG), used as a neural recording modality for brain-machine interfaces (BMIs), potentially allows for field potentials to be recorded from the surface of the cerebral cortex for long durations without suffering the host-tissue reaction to the extent that it is common with intracortical microelectrodes. Though the stability of signals obtained from chronically implanted ECoG electrodes has begun receiving attention, to date little work has characterized the effects of long-term implantation of ECoG electrodes on underlying cortical tissue.
  
  
  
  We implanted and recorded from a high-density ECoG electrode grid subdurally over cortical motor areas of a Rhesus macaque for 666 d.
  
  
  
  Histological analysis revealed minimal damage to the cortex underneath the implant, though the grid itself was encapsulated in collagenous tissue. We observed macrophages and foreign body giant cells at the tissue-array interface, indicative of a stereotypical foreign body response. Despite this encapsulation, cortical modulation during reaching movements was observed more than 18 months post-implantation.
  
  
  
  These results suggest that ECoG may provide a means by which stable chronic cortical recordings can be obtained with comparatively little tissue damage, facilitating the development of clinically viable BMI systems.
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. Center for the Neural Basis of Cognition, Pittsburgh, PA, USA. Systems Neuroscience Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Degenhart
authors.forename: James
authors.initials: J
authors.lastname: Eles
authors.forename: Richard
authors.initials: R
authors.lastname: Dum
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Mischel
authors.forename: Ivan
authors.initials: I
authors.lastname: Smalianchuk
authors.forename: Bridget
authors.initials: B
authors.lastname: Endler
authors.forename: Robin C
authors.initials: RC
authors.lastname: Ashmore
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Tyler-Kabara
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Hatsopoulos
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Batista
authors.forename: X Tracy
authors.initials: XT
authors.lastname: Cui
mesh_terms: D000818:Animals; D062207:Brain-Computer Interfaces; D024042:Collagen Type I / Q000378:metabolism; D000069280:Electrocorticography / Q000009:adverse effects* / Q000295:instrumentation*; D004567:Electrodes, Implanted / Q000009:adverse effects*; D015745:Granuloma, Foreign-Body / Q000473:pathology; D006225:Hand / Q000294:innervation / Q000502:physiology; D007150:Immunohistochemistry; D008253:Macaca mulatta; D008264:Macrophages / Q000473:pathology; D008297:Male; D008839:Microelectrodes; D018613:Microscopy, Confocal; D009044:Motor Cortex / Q000473:pathology* / Q000502:physiology
chemical_list: D024042:Collagen Type I