Abstract
Retinal prostheses can restore the basic visual function of patients with retinal degeneration, which relies on effective electrical stimulation to evoke the physiological activities of retinal ganglion cells (RGCs). Current electrical stimulation strategies have defects such as unstable effects and insufficient stimulation positions, therefore, it is crucial to determine the optimal pulse parameters for precise and safe electrical stimulation. Biphasic voltages (cathode-first) with a pulse width of 25 ms and different amplitudes were used to ex vivo stimulate RGCs of three wild-type (WT) mice using a commercial microelectrode array (MEA) recording system. An algorithm is developed to automatically realize both spike-sorting and electrical response identification for the spike signals recorded. Measured from three WT mouse retinas, the total numbers of RGC units and responsive RGC units were 1193 and 151, respectively. In addition, the optimal pulse amplitude range for electrical stimulation was determined to be 0.43 V-1.3 V. The processing results of the automatic algorithm we proposed shows high consistency with those using traditional manual processing. We anticipate the new algorithm can not only speed up the elaborate electrophysiological data processing, but also optimize pulse parameters for the electrical stimulation strategy of neural prostheses.
Highlights
Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are retinal degeneration (RD) diseases with a prevalence of about 1 in 4000 [1,2,3]
It can be seen that the sums of retinal ganglion cells (RGCs) units for the 17 stimulation trials are both 1193, while the total numbers of responsive RGC units in two results are 151 and 149, respectively
The number of responsive RGC units gradually decreases with the increasing distance, which agrees with previous studies [26, 27]
Summary
Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are retinal degeneration (RD) diseases with a prevalence of about 1 in 4000 [1,2,3]. The photoreceptor cells of RP and AMD patients degenerate irreversibly and cannot convert optical inputs into neural spikes, resulting in the loss of part or even all visual functions. Even for profound RD patients, some physiological structures and functions of the retinal ganglion cells (RGC) are usually still preserved [4, 5]. The RGC can be stimulated to evoke the neural activity of the remaining retinal neurons [6,7,8], thereby providing a straightforward method for the blind to restore visual function.
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