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Mapping of primary somatosensory cortex of the hand area using a high-density electrocorticography grid for closed-loop brain computer interface

Kramer, Daniel Richard and Lee, Morgan Brianna and Barbaro, Michael and Gogia, Angad S. and Peng, Terrance and Liu, Charles Y. and Kellis, Spencer and Lee, Brian (2021) Mapping of primary somatosensory cortex of the hand area using a high-density electrocorticography grid for closed-loop brain computer interface. Journal of Neural Engineering, 18 (3). Art. No. 036009. ISSN 1741-2560. doi:10.1088/1741-2552/ab7c8e.

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The ideal modality for generating sensation in sensorimotor brain computer interfaces (BCI) has not been determined. Here we report the feasibility of using a high-density "mini"-electrocorticography (mECoG) grid in a somatosensory BCI system. Thirteen subjects with intractable epilepsy underwent standard clinical implantation of subdural electrodes for the purpose of seizure localization. An additional high-density mECoG grid was placed (Adtech, 8 by 8, 1.2-mm exposed, 3-mm center-to-center spacing) over the hand area of primary somatosensory cortex. Following implantation, cortical mapping was performed with stimulation parameters of frequency: 50 Hz, pulse-width: 250 µs, pulse duration: 4 s, polarity: alternating, and current that ranged from 0.5 mA to 12 mA at the discretion of the epileptologist. Location of the evoked sensory percepts was recorded along with a description of the sensation. The hand was partitioned into 48 distinct boxes. A box was included if sensation was felt anywhere within the box. The percentage of the hand covered was 63.9% (± 34.4%) (mean ± s.d.). Mean redundancy, measured as electrode pairs stimulating the same box, was 1.9 (± 2.2) electrodes per box; and mean resolution, measured as boxes included per electrode pair stimulation, was 11.4 (± 13.7) boxes with 8.1 (± 10.7) boxes in the digits and 3.4 (± 6.0) boxes in the palm. Functional utility of the system was assessed by quantifying usable percepts. Under the strictest classification, "dermatomally exclusive" percepts, the mean was 2.8 usable percepts per grid. Allowing "perceptually unique" percepts at the same anatomical location, the mean was 5.5 usable percepts per grid. Compared to the small area of coverage and redundancy of a microelectrode system, or the poor resolution of a standard ECoG grid, a mECoG is likely the best modality for a somatosensory BCI system with good coverage of the hand and minimal redundancy.

Item Type:Article
Related URLs:
URLURL TypeDescription
Kramer, Daniel Richard0000-0003-4551-2977
Lee, Morgan Brianna0000-0001-6936-0109
Gogia, Angad S.0000-0001-8193-1824
Kellis, Spencer0000-0002-5158-1058
Additional Information:© 2020 IOP Publishing Ltd. Received 29 November 2019; Revised 18 February 2020; Accepted 4 March 2020; Accepted Manuscript online 4 March 2020.
Issue or Number:3
Record Number:CaltechAUTHORS:20200902-142357422
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Official Citation:Daniel R Kramer et al 2021 J. Neural Eng. 18 036009
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105225
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 23:29
Last Modified:16 Nov 2021 18:41

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