Functional MRI based simulations of ECoG grid configurations for optimal measurement of spatially distributed hand-gesture information

Max A. Van Den Boom, Kai J. Miller, Nick F. Ramsey, Dora Hermes

Research output: Contribution to journalArticlepeer-review

Abstract

Objective. In electrocorticography (ECoG), the physical characteristics of the electrode grid determine which aspect of the neurophysiology is measured. For particular cases, the ECoG grid may be tailored to capture specific features, such as in the development and use of brain-computer interfaces (BCI). Neural representations of hand movement are increasingly used to control ECoG based BCIs. However, it remains unclear which grid configurations are the most optimal to capture the dynamics of hand gesture information. Here, we investigate how the design and surgical placement of grids would affect the usability of ECoG measurements. Approach. High resolution 7T functional MRI was used as a proxy for neural activity in ten healthy participants to simulate various grid configurations, and evaluated the performance of each configuration for decoding hand gestures. The grid configurations varied in number of electrodes, electrode distance and electrode size. Main results. Optimal decoding of hand gestures occurred in grid configurations with a higher number of densely-packed, large-size, electrodes up to a grid of ∼5 5 electrodes. When restricting the grid placement to a highly informative region of primary sensorimotor cortex, optimal parameters converged to about 3 3 electrodes, an inter-electrode distance of 8 mm, and an electrode size of 3 mm radius (performing at ∼70% three-class classification accuracy). Significance. Our approach might be used to identify the most informative region, find the optimal grid configuration and assist in positioning of the grid to achieve high BCI performance for the decoding of hand-gestures prior to surgical implantation.

Original languageEnglish (US)
Article number026013
JournalJournal of neural engineering
Volume18
Issue number2
DOIs
StatePublished - Apr 2021

Keywords

  • brain computer interface
  • decoding
  • electrocorticography
  • electrode configurations
  • fMRI
  • hand gestures
  • sensorimotor cortex

ASJC Scopus subject areas

  • Biomedical Engineering
  • Cellular and Molecular Neuroscience

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