Power of ~5 Hz Spontaneous Oscillatory Rhythm in Degenerate Retina Might Modulate RGC Spikes to Electrical Stimulation
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1
Chungbuk National University, Department of Physiology, Korea
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2
Chungbuk National University, Department of Physiology, Korea
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3
Alfaisal University College of Medicine, Neuroscience, Saudi Arabia
Motivation: Emergence of aberrant spiking activity coupled with 5 ~15 Hz oscillatory rhythm has been reported in degenerate mouse retinas [1-2]. This rhythm has been regarded as noise which reduces the efficacy of prosthetic stimulation. In our previous study, ~5 Hz and ~10 Hz rhythms in rd10 mouse retina vary with postnatal ages [3]. Here, we investigated if oscillatory rhythms affect retinal ganglion cell (RGC) response to electrical stimulation in rd10 retina according to progression of degeneration.
Material and Methods: Electrically-evoked RGC spikes were recorded using 8 ¡¿ 8 multi-electrode array (MEA) in rd10 mice (B6CXB1) at postnatal week (PNW) 2 ~34. Retinal patches were placed RGC layer down on MEA. Fifty cathodic phase-1st biphasic square pulses (duration: 500 ¥ìs, pulse amplitude: 5 ~60 ¥ìA) were applied at every 1 sec. Previously, 1st peak in post-stimulus time histogram (PSTH) showed better modulation efficacy than subsequently appeared remnant peaks [4]. Therefore, 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 oscillatory rhythm was calculated.
Results: Modulation range of RGC response to electrical stimulus is narrower at PNW 6.5, 10, and 20, when power of ~ 5 Hz oscillation is much higher (PNW 6.5 and 20) or lower (PNW 10) than those in other age groups (Fig 1A,B). Remnant peaks show broader modulation range at PNW 8 and 26 than those at other ages (Fig 1C). Power of ~5 Hz oscillation has good correlation with evoked spike number in PSTH 1st peak at PNW 6.5 and 20 with high amplitude stimulation (>30 ¥ìA)(R¡Ö0.7, p<0.001), while at PNW 10, it shows no correlation (R¡Ö0.1, p>0.05)(Fig 2). Groups of PNW 6.5 and 20 show the strongest power of ~5 Hz oscillation among all age groups (p<0.001). After excluding data points which have stronger oscillatory power than 3 ¡¿ 10^5 dB, the correlation between ~5 Hz oscillation and PSTH 1st peak spike became much weaker in these age groups. This result suggests that power of ~5 Hz oscillation may increase the electrically-evoked spike number when its power is stronger than 3 ¡¿ 10^5 dB (at PNW 6.5 and 20), but not when its power is weaker than 3 ¡¿ 10^5 dB (at PNW 10).
Discussion: At PNW 6.5 and 20, evoked RGC spike number at 5 ¥ìA in PSTH 1st peak is much higher, but modulation range is much narrower than those at other ages (Fig 1B). This suggests that significant phosphenes can be induced even with low amplitude of electrical stimulation, but much difficulty with modulating evoked phosphenes. At PNW 10, evoked spike is much smaller in number and its modulation curve shows much narrower than those at other ages (Fig 1B). This result implies that many difficulties are expected to induce and modulate phosphenes for visual perception at PNW 10.
Conclusion: Power of ~5 Hz oscillation in rd 10 retinas might modulate RGC spike response to electrical stimulation in PSTH 1st peak. High modulation efficacy of PSTH remnant peaks at PNW 8 and 26 may support the possibility that remnant peaks play an important role for carrying visual information (Fig 1C).
Figure legend:
Fig 1. Response curve of electrically-evoked PSTH peaks in rd 10 mouse RGCs. Each data point represents the electrically-evoked RGC spike number with various stimulus amplitude (5 ~ 60 ¥ìA). A, B : Response curve of PSTH 1st peak spikes. All other groups which were not shown in these graphs (PNW 3, 4.5, 15, 26, 34) show similar response curve with PNW 8. C : Response curve of PSTH remnant peak spikes. Response curve at PNW 26 is similar to that at PNW 8 (Data not shown).
Fig 2. Correlation between power of ~5 Hz oscillation and PSTH 1st peak spikes at PNW 6.5 (A), PNW 10 (B), and PNW 20 (C). Amplitude of applied electric pulse is higher than 30 ¥ìA. Only the cells near to stimulus electrode (recording electrode distance: 200 ~ 400 ¥ìm) were used for correlation analysis.
Reference:
[1] Stasheff S.F. (2008) Emergence of sustained spontaneous hyperactivity and temporary preservation of OFF responses in ganglion cells of the retinal degeneration (rd1) mouse. J Neurophysiol 99, 1408-1421.
[2] Margolis D.J, Newkirk G, Euler T, Detwiler P.B. (2008) Functional stability of retinal ganglion cells after degeneration-induced changes in synaptic input. J Neurosci 28, 6526-6536.
[3] Goo Y.S, Ahn K.N, Song Y.J, Ahn S.H, Han S.K, Ryu S.B, Kim K.H. (2011) Spontaneous oscillatory rhythm in retinal activities of two retinal degeneration (rd1 and rd10) mice. Korean J Physiol Pharmacol 15, 415-422.
[4] Ryu S.B, Ye J.H, Goo Y.S, Kim C.G, Kim K.H. (2010) Temporal response properties of retinal ganglion cells in rd1 mice evoked by amplitude-modulated electrical pulse trains. Invest Ophthalmol Vis Sci 51, 6762-6769.
Acknowledgements
Supported by grants of the MEST of Korea (NRF-2010-0020852, NRF-2013R1A1A3009574) to YSG.
Keywords:
Retinal Degeneration,
Retinal prosthesis,
rd10 mouse,
Oscillatory rhythm
Conference:
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays, Reutlingen, Germany, 28 Jun - 1 Jul, 2016.
Presentation Type:
Poster Presentation
Topic:
MEA Meeting 2016
Citation:
Goo
YS,
Park
DJ,
Ahn
JR and
Senok
S
(2016). Power of ~5 Hz Spontaneous Oscillatory Rhythm in Degenerate Retina Might Modulate RGC Spikes to Electrical Stimulation.
Front. Neurosci.
Conference Abstract:
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays.
doi: 10.3389/conf.fnins.2016.93.00010
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Received:
22 Jun 2016;
Published Online:
24 Jun 2016.
*
Correspondence:
Dr. Yong S Goo, Chungbuk National University, Department of Physiology, Cheongju, Korea, ysgoo@chungbuk.ac.kr