title: Electrically Evoked Responses in the Rabbit Cortex Induced by Current Steering With Penetrating Optic Nerve Electrodes.
abstract: Current steering is a neural stimulation strategy that uses simultaneous stimulation of adjacent electrodes to produce additional intermediate stimulation sites and thus improves spatial resolution. We investigated the feasibility of current steering using electrophysiological and computational methods after implanting paired penetrating electrodes into the rabbit's optic nerve (ON).
  
  
  
  Penetrating electrodes at different interelectrode distances were implanted into the ON and electrically evoked cortical potentials (EEPs) in V1 recorded with a 6 × 8 array. The current thresholds, EEP amplitudes, and spatial distributions were analyzed during current steering. Computational simulation studies were performed based on finite element models to calculate the area and spatial distribution of recruited ON fibers using a current steering stimulation strategy.
  
  
  
  Threshold reduction and EEP amplitude enhancement were found with simultaneous stimulation of closely spaced electrode pairs. Spatially shifted cortical responses were achieved using current steering, whereas the amplitudes and spatial spreads of the responses were similar to that elicited by a single electrode. Computational simulations suggested that the centroid of the ON recruitment area could be modulated by current steering while the total recruitment area did not show any appreciable variability at a fixed current intensity.
  
  
  
  Current steering is a useful strategy to enhance the spatial resolution of an ON prosthesis without increasing the number of physical electrodes. This study provides useful information for optimizing the design of stimulation strategies with a penetrating ON prosthesis.
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yiliang
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.
authors.forename: Menghui
authors.initials: M
authors.lastname: Li
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zengguang
authors.initials: Z
authors.lastname: Ma
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Pengjia
authors.initials: P
authors.lastname: Cao
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology, Shanghai First People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Sun
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Chai
authors.affiliation: Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Ren
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004558:Electric Stimulation / Q000379:methods; D004567:Electrodes, Implanted; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005240:Feasibility Studies; D009900:Optic Nerve / Q000502:physiology*; D010775:Photic Stimulation; D011817:Rabbits; D014793:Visual Cortex / Q000502:physiology*