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Dae-jin Park, JungRyul Ahn, Seong Kwang Cha, Yong Sook Goo, Solomon Senok; Oscillatory Rhythm in Degenerate Mouse (rd10) Retina Modulates Retinal Ganglion Cell Response to Electrical Stimulus. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3730.
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© ARVO (1962-2015); The Authors (2016-present)
Appearance of aberrant spiking activity coupled with 5 ~15 Hz oscillatory local field potential (LFP) has been reported in degenerate mouse retinas. These LFPs have been regarded as noise which reduced the efficacy of prosthetic stimulation. Since LFP varies with postnatal ages in rd10 mice, here, we investigated if the LFP might affect RGC responses to electrical stimulation in rd10 retina according to degeneration process.
We recorded electrically-evoked RGC spikes using 8×8 multi-electrode array (MEA) in rd10 mice at postnatal week (PNW) 2 ~34. Retinal patches were placed RGC layer down on MEA. Fifty cathodic phase-1st biphasic square pulses (duration: 500 µs, pulse amplitude: 5 ~60 μA) were applied at every 1 sec. Previously, 1st peak in post-stimulus time histogram (PSTH) showed better modulation efficacy than subsequently appeared remnant peaks. Thus, stimulus efficacy of PSTH 1st peak and remnant peaks was compared among different age groups to clarify potential information-carrying role of multiple peaks. Also, correlation between evoked spike numbers in PSTH peaks and LFP was calculated.
Evoked spike number of PSTH 1st peak is significantly higher at PNW 6.5 (p<0.05), PNW 20 (p<0.001) and lower at PNW 10 (p<0.05) than that of all other ages except PNW 2. Modulation range of RGC response to electrical stimulus is narrower at these ages, when power of ~ 5 Hz oscillation is much higher (PNW 6.5 and 20) or lower (PNW 10) than those in other age groups. Remnant peaks show broader modulation range at PNW 8&26 than those at other ages. Power of ~5 Hz oscillation shows good correlation with evoked spike number of PSTH 1st peak in group of PNW 6.5&8 (R=0.7, p<0.001), but it has weak correlation with 1st peak in group of PNW 15 ~34 (R=0.4, p<0.05). There is no correlation between power of oscillation and evoked spike number of remnant peaks across all ages (R=0.2, p<0.05).
Power of ~5 Hz oscillation in rd 10 retinas modulates RGC response to electrical stimulus in PSTH 1st peak at PNW 6.5 ~8. At PNW 15 ~34, ~5 Hz oscillation has only a limited effect on PSTH 1st peak. These results suggest that power of oscillation may be an important factor determining the efficacy of electrical stimulus. Furthermore, high modulation efficacy of PSTH remnant peaks at PNW 8&26 may support the idea of information-carrying role of remnant peaks.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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