Cortical responses following simultaneous and sequential retinal neurostimulation with different return configurations

Annu Int Conf IEEE Eng Med Biol Soc. 2016 Aug:2016:5435-5438. doi: 10.1109/EMBC.2016.7591956.

Abstract

Researchers continue to develop visual prostheses towards safer and more efficacious systems. However limitations still exist in the number of stimulating channels that can be integrated. Therefore there is a need for spatial and time multiplexing techniques to provide improved performance of the current technology. In particular, bright and high-contrast visual scenes may require simultaneous activation of several electrodes. In this research, a 24-electrode array was suprachoroidally implanted in three normally-sighted cats. Multi-unit activity was recorded from the primary visual cortex. Four stimulation strategies were contrasted to provide activation of seven electrodes arranged hexagonally: simultaneous monopolar, sequential monopolar, sequential bipolar and hexapolar. Both monopolar configurations showed similar cortical activation maps. Hexapolar and sequential bipolar configurations activated a lower number of cortical channels. Overall, the return configuration played a more relevant role in cortical activation than time multiplexing and thus, rapid sequential stimulation may assist in reducing the number of channels required to activate large retinal areas.

MeSH terms

  • Animals
  • Cats
  • Electric Stimulation*
  • Retina / physiology*
  • Visual Cortex / physiology*
  • Visual Prosthesis*