A Virtual Electrode through Summation of Time Offset Pulses
Retinal prostheses have been successful in eliciting
visual responses in implanted subjects. As these prostheses progress,
one of their major limitations is the need for increased resolution. As
an alternative to increasing the number of electrodes, virtual
electrodes may be used to increase the effective resolution of current
electrode arrays. This paper presents a virtual electrode technique
based upon time-offsets between stimuli. Two adjacent electrodes are
stimulated with identical pulses with too short of pulse widths to
activate a neuron, but one has a time offset of one pulse width. A
virtual electrode of twice the pulse width was then shown to appear in
the center, with a total width capable of activating a neuron. This can
be used in retinal implants by stimulating electrodes with pulse
widths short enough to not elicit responses in neurons, but with their
combined pulse width adequate to activate a neuron in between them.
[1] Stone J L, Barlow W E, Humayun M S, Dejuan E and Milam A H.
Morphometric analysis of macular photoreceptors and ganglion-cells in
retinas with retinitis-pigmentosa Arch. Ophthalmol. Vol. 110 pp. 1634–
9, 1992.
[2] Sekirnjak C, Hulse C, Jepson L H, Hottowy P, Sher A, Dabrowski W,
Litke A M and Chichilnisky E J. Loss of responses to visual but not
electrical stimulation in ganglion cells of rats with severe photoreceptor
degeneration J. Neurophysiol. Vol. 102 pp. 3260–9, 2009.
[3] Humayun M S, Weiland J D, Fujii G Y, Greenberg R, Williamson R,
Little J, et al. Visual perception in a blind subject with a chronic
microelectronic retinal prosthesis Vis. Res. Vol. 43 pp. 2573–81, 2003.
[4] Yanai D, Weiland J D, Mahadevappa M, Greenberg R J, Fine I and
Humayun M S. Visual performance using a retinal prosthesis in three
subjects with retinitis pigmentosa Am. J. Ophthalmol. Vol. 143 pp. 820–
7, 2007.
[5] Ahuja A K, Dorn J D, Caspi A, McMahon M J, Dagnelie G, Dacruz L,
Stanga P, Humayun M S and Greenberg R J Blind subjects implanted
with the Argus II retinal prosthesis are able to improve performance in a
spatial-motor task Br. J. Ophthalmol. Vol. 95 pp. 539–43, 2011.
[6] Hecht, Eugene. Optics, 2nd Ed, Addison Wesley, 1987.
[7] McCreery D B, Agnew W F, Yuen T G H and Bullara L Charge density
and charge per phase as cofactors in neural injury induced by electrical
stimulation IEEE T. Bio-Med. Eng. Vol. 37 pp. 996–1001, 1990.
[8] Weiland JD, Liu W, Humayun MS Retinal Prosthesis. Annu Rev Biomed
Eng Vol. 7 pp. 361-401, 2005.
[9] Khalili M G, Lovell N H, Wilke R G, Suaning G J, Dokos S.
Performance optimization of current focusing and virtual electrode
strategies in retinal implants Comput. Meth. Prog. Biomed. To be
published.
[10] Charles T, Choi M, Hsu C H. Conditions for generating virtual channels
in cochlear prosthesis systems. Ann. of Biomed. Eng. Vol. 37 pp. 614-24,
2009.
[11] Suzuki S, Humayun M S, Weiland J D, Chen S J, Margalit E,
Piyathaisere D V, et al. Comparison of electrical stimulation thresholds
in normal and retinal degenerated mouse retina, Jpn J Ophthalmol, Vol.
48 pp. 345–9, 2004.
[12] Lo Y, Chen K, Gad P, Liu W A fully integrated high compliance voltage
soc for epi-retinal and neural prostheses IEEE Trans. Biomed. Circuits
Sys. Vol. 7 pp. 761–72, 2013
[13] Jensen R J, Rizzo J F, Grumet A E, Edell D J, Wyatt J L Single unit
recording following extracellular electrical stimulation of rabbit retinal
ganglion bodies. Technical Report 600, MIT Research Laboratory of
Electronics, 1996
[14] Rattay F, Aberham M. Modeling axon membranes for functional
electrical stimulation IEEE T. Bio-Med. Eng. 40 pp. 1201-1209, 1993.
[15] Coburn B. Neural modeling in electrical stimulation Critic. Rev. Biomed.
Eng. Vol. 17 pp. 133-78, 1989
[1] Stone J L, Barlow W E, Humayun M S, Dejuan E and Milam A H.
Morphometric analysis of macular photoreceptors and ganglion-cells in
retinas with retinitis-pigmentosa Arch. Ophthalmol. Vol. 110 pp. 1634–
9, 1992.
[2] Sekirnjak C, Hulse C, Jepson L H, Hottowy P, Sher A, Dabrowski W,
Litke A M and Chichilnisky E J. Loss of responses to visual but not
electrical stimulation in ganglion cells of rats with severe photoreceptor
degeneration J. Neurophysiol. Vol. 102 pp. 3260–9, 2009.
[3] Humayun M S, Weiland J D, Fujii G Y, Greenberg R, Williamson R,
Little J, et al. Visual perception in a blind subject with a chronic
microelectronic retinal prosthesis Vis. Res. Vol. 43 pp. 2573–81, 2003.
[4] Yanai D, Weiland J D, Mahadevappa M, Greenberg R J, Fine I and
Humayun M S. Visual performance using a retinal prosthesis in three
subjects with retinitis pigmentosa Am. J. Ophthalmol. Vol. 143 pp. 820–
7, 2007.
[5] Ahuja A K, Dorn J D, Caspi A, McMahon M J, Dagnelie G, Dacruz L,
Stanga P, Humayun M S and Greenberg R J Blind subjects implanted
with the Argus II retinal prosthesis are able to improve performance in a
spatial-motor task Br. J. Ophthalmol. Vol. 95 pp. 539–43, 2011.
[6] Hecht, Eugene. Optics, 2nd Ed, Addison Wesley, 1987.
[7] McCreery D B, Agnew W F, Yuen T G H and Bullara L Charge density
and charge per phase as cofactors in neural injury induced by electrical
stimulation IEEE T. Bio-Med. Eng. Vol. 37 pp. 996–1001, 1990.
[8] Weiland JD, Liu W, Humayun MS Retinal Prosthesis. Annu Rev Biomed
Eng Vol. 7 pp. 361-401, 2005.
[9] Khalili M G, Lovell N H, Wilke R G, Suaning G J, Dokos S.
Performance optimization of current focusing and virtual electrode
strategies in retinal implants Comput. Meth. Prog. Biomed. To be
published.
[10] Charles T, Choi M, Hsu C H. Conditions for generating virtual channels
in cochlear prosthesis systems. Ann. of Biomed. Eng. Vol. 37 pp. 614-24,
2009.
[11] Suzuki S, Humayun M S, Weiland J D, Chen S J, Margalit E,
Piyathaisere D V, et al. Comparison of electrical stimulation thresholds
in normal and retinal degenerated mouse retina, Jpn J Ophthalmol, Vol.
48 pp. 345–9, 2004.
[12] Lo Y, Chen K, Gad P, Liu W A fully integrated high compliance voltage
soc for epi-retinal and neural prostheses IEEE Trans. Biomed. Circuits
Sys. Vol. 7 pp. 761–72, 2013
[13] Jensen R J, Rizzo J F, Grumet A E, Edell D J, Wyatt J L Single unit
recording following extracellular electrical stimulation of rabbit retinal
ganglion bodies. Technical Report 600, MIT Research Laboratory of
Electronics, 1996
[14] Rattay F, Aberham M. Modeling axon membranes for functional
electrical stimulation IEEE T. Bio-Med. Eng. 40 pp. 1201-1209, 1993.
[15] Coburn B. Neural modeling in electrical stimulation Critic. Rev. Biomed.
Eng. Vol. 17 pp. 133-78, 1989
@article{"International Journal of Medical, Medicine and Health Sciences:64742", author = "Isaac Cassar and Trevor Davis and Yi-Kai Lo and Wentai Liu", title = "A Virtual Electrode through Summation of Time Offset Pulses", abstract = "Retinal prostheses have been successful in eliciting
visual responses in implanted subjects. As these prostheses progress,
one of their major limitations is the need for increased resolution. As
an alternative to increasing the number of electrodes, virtual
electrodes may be used to increase the effective resolution of current
electrode arrays. This paper presents a virtual electrode technique
based upon time-offsets between stimuli. Two adjacent electrodes are
stimulated with identical pulses with too short of pulse widths to
activate a neuron, but one has a time offset of one pulse width. A
virtual electrode of twice the pulse width was then shown to appear in
the center, with a total width capable of activating a neuron. This can
be used in retinal implants by stimulating electrodes with pulse
widths short enough to not elicit responses in neurons, but with their
combined pulse width adequate to activate a neuron in between them.
", keywords = "Electrical stimulation, Neuroprosthesis, Retinal
implant, Retinal Prosthesis, Virtual electrode.", volume = "8", number = "9", pages = "595-6", }
