Article
Temporal patterns of single-unit responses from on- and off-cells in the lateral geniculate nucleus elicited by suprachoroidal-transretinal stimulation
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Published: | November 30, 2017 |
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Objective: To investigate differences in the pattern of neural responses from on- and off-cells to suprachoroidal-transretinal stimulation (STS), we recorded single-unit responses from relay cells in the lateral geniculate nucleus (LGN).
Methods: Under general anesthesia, a recording electrode was inserted into the LGN of cats (n = 5), and 18 single-units (9 on-center and 9 off-center) were recorded. Receptive fields and cell types were identified by light stimulation. For suprachoroidal stimulation, a multiple electrode array comprised of bullet-shaped platinum electrodes (diameter = 0.5 mm and height = 0.3 mm each) were used. The array was inserted into the scleral pocket at the posterior pole of the eye. Single biphasic pulses of 0.5 ms/phase were applied to the retina. Spike discharges evoked by STS at a variety of current intensities were recorded in each unit. The patterns of spike discharges were analyzed using a post-stimulus time histogram.
Results: In both on- and off-cells, repetitive bursts were obtained in response to STS. Within 10 ms after the stimulus onset, spike discharges were observed in both on- and off-units. Between 10 and 60 ms after the stimulus onset, the on-and off-units discharged alternately.
Discussion: Crapper and Noell have reported that repetitive bursts occurred in retinal ganglion cells in response to transretinal electrical stimulation in rabbits (JNP, 1965). Therefore, the characteristic patterns of responses in on- and off-cells were probably derived from the activation of retinal circuits. The results might contribute to develop optimal stimulation methods that selectively activate different cell types.