Creating virtual electrodes with two-dimensional current steering
| dc.contributor.author | Spencer, Thomas | |
| dc.contributor.author | Fallon, James | |
| dc.contributor.author | Shivdasani, Mohit | |
| dc.date.accessioned | 2019-02-11T05:48:12Z | |
| dc.date.available | 2019-02-11T05:48:12Z | |
| dc.date.issued | 2018-02 | |
| dc.description.abstract | OBJECTIVE: Current steering techniques have shown promise in retinal prostheses as a way to increase the number of distinct percepts elicitable without increasing the number of implanted electrodes. Previously, it has been shown that 'virtual' electrodes can be created between simultaneously stimulated electrode pairs, producing unique cortical response patterns. This study investigated whether virtual electrodes could be created using two-dimensional current steering, and whether these virtual electrodes can produce cortical responses with predictable spatial characteristics. Approach: Normally-sighted eyes of seven adult anaesthetised cats were implanted with a 42-channel electrode array in the suprachoroidal space and multi-unit neural activity was recorded from the visual cortex. Stimuli were delivered to individual physical electrodes, or electrodes grouped into triangular, rectangular, and hexagonal arrangements. Varying proportions of charge were applied to each electrode in a group to "steer" current and create virtual electrodes. The centroids of cortical responses to stimulation of virtual electrodes were compared to those evoked by stimulation of single physical electrodes. Results: Responses to stimulation of groups of up to six electrodes with equal ratios of charge on each electrode resulted in cortical activation patterns that were similar to those elicited by the central physical electrode (Centroid's: RM ANOVA on Ranks, p>0.05; Neural Spread: Stats Test; p>0.05). We were also able to steer the centroid of activation towards the direction of any of the electrodes of the group by applying a greater charge to that electrode, but the movement in the centroid was not found to be significant. Significance: The results suggest that current steering is possible in two dimensions between up to at least six electrodes, indicating it may be possible to increase the number of percepts in patients without increasing the number of physical electrodes. Being able to reproduce spatial characteristics of responses to individual physical electrodes suggests that this technique could also be used to compensate for faulty electrodes. | en_US |
| dc.description.sponsorship | Funding for this research was provided by the National Health and Medical Research Council (NHMRC) Project Grant #1063093 and the Bart Reardon PhD Scholarship. The Bionics Institute acknowledges the support it receives from the Victorian Government through its Operational Infrastructure Support Program. | en_US |
| dc.identifier.citation | Spencer, T. C., J. B. Fallon, and M. N. Shivdasani. 2018. Creating virtual electrodes with two-dimensional current steering. Journal of Neural Engineering. 15(3): 035002. | en_US |
| dc.identifier.issn | 1741-2552 | |
| dc.identifier.uri | http://repository.bionicsinstitute.org:8080/handle/123456789/331 | |
| dc.language.iso | en | en_US |
| dc.publisher | IOP Publishing Ltd | en_US |
| dc.subject | Current steering | en_US |
| dc.subject | Electrical stimulation | en_US |
| dc.subject | Retina | en_US |
| dc.subject | Retinal prosthesis | en_US |
| dc.subject | Retinitis pigmentosa | en_US |
| dc.subject | Visual electrodes | en_US |
| dc.subject | Visual cortext | en_US |
| dc.title | Creating virtual electrodes with two-dimensional current steering | en_US |
| dc.type | Article | en_US |