Abstract
Purpose :
We aimed to understand the properties of neuronal responses to electrical stimuli, which is crucial for improving efficacy of prosthetic vision. In this study, we investigated the temporal pattern of lateral geniculate nucleus (LGN) relay cell responses elicited by Suprachoroidal-Transretinal Stimulation （STS）.
Methods :
Under general anesthesia, a metal microelectrode was inserted into the LGN of cats (n = 4), and single-unit activities were recorded. Receptive fields and cell types were identified using light stimulation. For STS, a multiple electrode array, which comprised bullet-shaped electrodes (0.5 mm in diameter) ,was inserted into a scleral pocket created at the posterior pole of the eye. Biphasic pulses with current intensity of either 0.5 or 1.0 mA were applied to the retina. Both single- and double-pulse stimulations were tested. The double-pulse stimulation included an inter-pulse interval, which ranged from 5 to 50 ms. The temporal pattern of responses was investigated for cells with their receptive fields located within 5-degree visual angle from the stimulating sites.
Results :
Single-stimulus pulses of STS caused repetitive bursts in both on- and off-cells. Within 10 ms after stimulus onset, the burst was obtained in both on- and off-cells, whereas between 10 and 60 ms after the onset of stimulus, the burst latencies differed between on- and off-cells, and the bursts occurred alternately. Regarding double-pulse stimulation, the second pulse failed to produce the first burst when the inter-pulse interval corresponded with the latency of the silent period (10–20 ms) by the preceding first pulse.
Conclusions :
The results of this study suggest that suppression occurs in the silent period between bursts, and that the difference in the response patterns of on- and off-cells may derive from the retinal circuits. These results may contribute to the optimization of stimulus patterns in STS.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.