Artikel
Determination of excitation thresholds for retina ganglion cells using biphasic and monophasic stimulation pulses to be designed for high resolution epiretinal prosthesis
Suche in Medline nach
Autoren
-
Mahmut Emin Celik
- Gazi University, Ankara, Turkey
-
I. Karagöz
- Gazi University, Ankara, Turkey
-
M. Ozden
- Kirikkale University Electrical and Electronics Engineering Department, Kirikkale, Turkey
-
G. Sobaci
- Hacettepe University, Ankara, Turkey
| Veröffentlicht: | 7. März 2016 |
|---|
Gliederung
Text
Objectives: It is aimed that the effects of electrical stimulation parameters on retina ganglion cell excitation to be used for high resolution epiretinal prosthesis are comparatively investigated via in vitro experiments with rabbits.
Materials and Methods: Retina preparation includes anesthesia, enucleation, removing of eyeball and retinal dissection in accordance with institutional guidelines for the care and use of animals. Isolated retina tissue 8-10 mm in diameter is placed to microelectrode array (60HexaMEA-Ti, Multi Channel Systems MCS GmbH), which faces ganglion cell layer. Stimulation trains that have different amplitudes and pulse widths are formed for biphasic and monophasic stimulations separately. Stimulation trains consisted of biphasic and monophasic pulses, produced by stimulus generator are applied in dark with 2 s intervals to selected electrodes of the hexagonal microelectrode array while others are used as recording electrodes.
Results: Following the electrical stimulation, neural activity appeared is transferred to MATLAB environment and analyzed with custom-written codes to determine thresholds for different stimulation pulses in terms of elicited spike numbers and spikes per stimulation pulse. The neural activity which is relevant to applied biphasic stimulation is analyzed, stimulation threshold is determined as 10 µA, pulse width of 100 µs, while it is determined as 50 µA, pulse width of 200 µs for monophasic stimulation pulses.
Discussion: This work shows that biphasic stimulation method is resulted lower threshold levels by using shorter stimulation pulses and it is more convenient when retina ganglion cells is to be stimulated. Using the lower stimulation current in safe limits allows to run more electrodes and to design high resolution systems, which only be obtained with determination of optimal stimulation patterns.
Acknowledgement: This work was supported by The Scientific and Technological Research Council Of Turkey, TUBITAK, Grant Number 113E181.
