By Topic

Visual neuroprosthesis: a non invasive system for stimulating the cortex

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

5 Author(s)
Piedade, M. ; Electr. & Comput. Eng. Dept., Tech. Univ. of Lisbon, Portugal ; Gerald, J. ; Sousa, L.A. ; Tavares, G.
more authors

This paper describes a complete visual neuroprosthesis wireless system designed to restore useful visual sense to profoundly blind people. This visual neuroprosthesis performs intracortical microstimulation through one or more arrays of microelectrodes implanted into the primary visual cortex. The whole system is composed by a primary unit located outside the body and a secondary unit, implanted inside the body. The primary unit comprises a neuromorphic encoder, a forward transmitter, and a backward receiver. The developed neuromorphic encoder generates the spikes to stimulate the cortex by approximating the spatio-temporal receptive fields characteristic response of ganglion cells. Power and stimuli information are carried to inside the cranium by means of a low-coupling transformer, which establishes a wireless inductive link between the two units. The secondary unit comprises a forward receiver, microelectrode stimulation circuitry and a backward transmitter that is used to monitor the implant. Address event representation is used for communicating spike events. Data is modulated with binary frequency-shift keying and differential binary phase-shift keying in the forward and in the backward directions, respectively. A prototype of the proposed system was developed and tested. Experimental results show that the spikes to stimulate the visual cortex are accurately generated and that the efficiency of the inductive link is relatively high, about 28% in average for 1 cm intercoil distance providing a power of about 50 milliwatts to the secondary implanted unit. Application specific integrated circuits were designed for this secondary unit, showing that, with current technology, it is possible to implement such a unit, respecting the power constraints.

Published in:

Circuits and Systems I: Regular Papers, IEEE Transactions on  (Volume:52 ,  Issue: 12 )