title: The impact of electrode characteristics on electrocorticography (ECoG).
abstract: Used clinically since Penfield and Jasper's pioneering work in the 1950's, electrocorticography (ECoG) has recently been investigated as a promising technology for brain-computer interfacing. Many researchers have attempted to analyze the properties of ECoG recordings, including prediction of optimal electrode spacing and the improved resolution expected with smaller electrodes. This work applies an analytic model of the volume conductor to investigate the sensitivity field of electrodes of various sizes. The benefit to spatial resolution was minimal for electrodes smaller than ~1mm, while smaller electrodes caused a dramatic decrease in signal-to-noise ratio. The temporal correlation between electrode pairs is predicted over a range of spacings and compared to correlation values from a series of recordings in subjects undergoing monitoring for intractable epilepsy. The observed correlations are found to be much higher than predicted by the analytic model and suggest a more detailed model of cortical activity is needed to identify appropriate ECoG grid spacing.
authors.affiliation: Human Rehabilitation and Neural Engineering Laboratory, Department of Physical Medicine and Rehabilitation, University of Pittsburgh, USA. bcw31@pitt.edu
authors.forename: Brian
authors.initials: B
authors.lastname: Wodlinger
authors.forename: Alan D
authors.initials: AD
authors.lastname: Degenhart
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Collinger
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Tyler-Kabara
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D004566:Electrodes; D004569:Electroencephalography / Q000295:instrumentation* / Q000379:methods; D006801:Humans