• Progress in Medical Physics
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• v.19 no.3
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• pp.157-163
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa or age-related macular degeneration. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we investigated differences of the retinal waveforms in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: 50 $k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. In normal mice (C57BL/6J strain) of postnatal day 28, only short duration (<2 ms) retinal spikes were recorded. In rd/rd mice (C3H/HeJ strain), besides normal spikes, waveform with longer duration (~100 ms), the slow wave component was recorded. We attempted to understand the mechanism of this slow wave component in degenerate retina using various synaptic blockers. We suggest that stronger glutamatergic input from bipolar cell to the ganglion cell in rd/rd mouse than normal mouse contributes the most to this slow wave component. Out of many degenerative changes, we favor elimination of the inhibitory horizontal input to bipolar cells as a main contributor for a relatively stronger input from bipolar cell to ganglion cell in rd/rd mouse.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.271-277
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• 2014

Purpose: The purpose of this study was to investigate the immunoreactivity of calretinin in Brazilian opossum (Monodelphis domestica) retina. Calcium-binding protein calretinin is known to play a key role in calcium-mediated signal transduction. Methods: Experiments have been performed by standard immunocytochemical techniques on retina of the Brazilian opossum. Results: Calretinin-immunoreactivity was exhibited within the horizontal subpopulations, AII amacrine and ganglion cell subpopulations in the Brazilian opossum retina. Especially, all calretinin-immunoreactive AII amacrine cells also expressed parvalbumin. Conclusions: Similar to other mammalian retinas, calretinin-immunoreactivity was also observed within the AII amacrine cells in the Brazilian opossum retina. Thus, calretinin can be a marker of AII amacrine cells in the Brazilian opossum retina.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.533-540
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• 2013

Purpose: To investigate the synaptic pattern of NMDA glutamate receptor subtype NMDA R1 on the dendritic arbors of ON-OFF direction-selective retinal ganglion cells (DS-RGSs) in developing [(5,10) days postnatal (PN)] mouse retina. Methods: ON-OFF DS-RGCs were injected with Lucifer yellow and the cells were identified by their characteristic morphology. To identify glutamatergic excitatory input from bipolar cell, we used a marker for the membrane traffic motor protein kinesin. Results: We identified DS-RGCs in P5, and P10 mouse retina. The immunofluorescence labeling of NMDA R1 was most prominent in the IPL. Our results showed that their presence upon the entire dendritic arbor of ON-OFF DS-RGCs is without any evidence of asymmetry, which would predict direction selectivity. Conclusions: The glutamatergic input from bipolar cell reveals symmetry pattern in all periods of P5, and P10. The results may suggest that direction selectivity not lies in the specific pattern of NMDA R1 receptors.

• Journal of Life Science
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• v.23 no.6
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• pp.804-811
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• 2013

Melanopsin is an opsin-like photopigment found in the small proportion of photosensitive ganglion cells of the retina. It is involved in the regulation of the synchronization of the circadian cycle as well as in the control of pupillary light reflex. The purpose of the present study is to investigate whether melanopsin is also expressed in the other areas of the central visual system outside the retina. We have studied the distribution and morphology of neurons containing melanopsin in the mouse visual cortex with antibody immunocytochemistry. Melanopsin immunoreactivity was mostly present in neuronal soma, but not in nuclei. We found that melanopsin was present in a large subset of neurons within the adult mouse visual cortex with the highest density in layer II/III. In layer I of the visual cortex, melanopsin-immunoreactive (IR) neurons were rarely encountered. In the mouse visual cortex, the majority of the melanopsin-IR neurons consisted of round/oval cells, but was varied in morphology. Vertical fusiform and pyramidal cells were also rarely labeled with the anti-melanopsin antibody. The labeled cells did not show any distinctive distributional pattern. Some melanopsin-IR neurons in mouse visual cortex co-localized with nitricoxide synthase, calbindin and parvalbumin. Our data indicate that melanopsin is located in specific neurons and surprisingly widespread in visual cortex. This finding raises the need of the functional study of melanopsin in central visual areas outside the retina.

• Progress in Medical Physics
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• v.18 no.1
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• pp.20-26
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• 2007

It is expected that synaptic construction and electrical characteristics In degenerate retina might be different from those In normal retina. Therefore, we analyzed the retinal waveform recorded with multielectrode array in normal and degenerate retina using principal component analysis (PCA) and Independent component analysis (ICA) and compared the results. PCA Is a well established method for retinal waveform while ICA has not tried for retinal waveform analysis. We programmed ICA toolbox for spatiotemporal analysis of retinal waveform. In normal mouse, the MEA spatial map shows a single hot spot perfectly matched with PCA-derived ON or OFF ganglion cell response. However In rd/rd mouse, the MEA spatial map shows numerous hot and cold spots whose underlying interactions and mechanisms need further Investigation for better understanding.

• Applied Microscopy
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• v.30 no.2
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• pp.121-139
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• 2000

The morphogenesis of neuroblasts and plexiform layers, and establishment of its synapses were studied by electron microscopy in human embryos and fetuses ranging from 10 mm to 260 mm crown-rump length ($5\sim30$ weeks of gestational age). At 30 mm fetus the developing retina was composed of outer and inner neuroblastic layers . Cell division of outer neuroblast was occurred until 90 mm fetus. The transient layer of Chievitz was formed by 30 mm fetus, inner plexiform layer by 50 mm fetus, and outer plexiform layer by 150 mm fetus. The cytoplasm of differentiating ganglion cells contained ribosomes, rough endoplasmic reticula, Golgi complexes, microtubules and dense bodies. The processes of $M\ddot{u}ller$ cell penetrated between groups of ganglion cell axons, and formed the cellular component of the inner limiting membrane at 30 mm fetus. At 90 mm fetus radial fibers of M ller cells contained extensive smooth endoplasmic reticula and microtubules. In each specimen , apposing paired membrane specializations were classified as junctions without synaptic vesicles, conventional synapses and ribbon synapses. At 50 mm fetus the processes of neuroblasts in inner plexiform layer were interconnected by junctions without synaptic vesicles. Conventional synapses developed by addition of synaptic vesicles to initially vesicle-free junctions at 90 mm fetus. At 150 mm fetus ribbon synapses were first recognized by the inclusion of a prominent electron-dense material associated with synaptic vesicles. By 260 mm fetus conventional and ribbon synapses and junctions without synaptic vesicles formed similar to those found in the adult.

• Development and Reproduction
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• v.16 no.2
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• pp.101-106
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• 2012

Importance of behavior factors or environmental factors in visual organization and visual function of fish is treated with great care in visual ecology, and there is no study about initial ocular growth and development on the dark banded rockfish, Sebastes inermis. Thus, this study was performed. The total length, head length, head depth, eye diameter and lens diameter of the dark banded rockfish showed positive allometric relationship between parturition stage and 60 days post-parturition (dpp). The increase in total length relative to head length and head depth, head length growth relative to eye diameter and lens diameter, and head depth growth relative to eye and lens diameter were nearly isometric. The eyes were formed completely at parturtion stage. At this age, the eye has an optic nerve fiber layer, a ganglion cell layer, an inner plexiform layer, an inner nuclear layer, an outer plexiform layer, an outer nuclear layer, an outer limiting membrane, a rod and cone layer and an epithelial layer. Thickness of retina at 60 dpp was higher than that of at parturition stage. During this experiment, the proportion of the rod and cone layer, outer nuclear layer, and optic nerve fiber layer of retina were significantly increased, while the proportion of the outer plexiform layer, inner nuclear layer and ganglion cell layer of retina were significantly decreased (P<0.05). The essential demands that must be met by the retina in this species pertain to light sensitivity and spatial resolution.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.349-355
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• 2014

In this paper, we propose the artificial vision system using human visual information processing and wavelet. Artificial vision system may be used for the visually impaired person and the machine recognition system. In this paper, we have constructed the information compression process to ganglion cells from the human retina. And we have reconstructed the primary visual information using recovery process to primary visual cortex from ganglion. Primary visual information is constructed by wavelet transformation using a high frequency and low frequency response. In the experiment, we used the faces database of AT&T. And the proposed method was able to improve the accuracy of face recognition considerably. And it was verified through experiments.

• Progress in Medical Physics
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• v.16 no.4
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• pp.214-219
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• 2005

As part of Korean retinal prosthesis project, we have provided preliminary experimental results regarding voltage parameters for the stimulation of chemically degenerated rabbit retina. Since our APB-treated chemically degenerated retina is only ON-pathway blocked, now we switch our experiments to more appropriate retinal degeneration model, genetically degenerated retina model (RD mouse: rd/rd (C3H/HeJ)). Before studying with RD mouse, we started control experiments with normal SD rat to understand characteristics of retinal ganglion ceil activity with postnatal maturation in rodents. Ganglion cell activities were recorded with 8${\times}$8 multi-electrode array. Moving spontaneous bursts appeared until postnatal day of 15. During pre-eye opening period, no light evoked response appeared. After postnatal day of 2 weeks (post-eye opening period), ON-, OFF- and ON/OFF response appeared. The fractional distributions of ON, OFF, and ON/OFF ganglion cell is about $40\%,\;50\%$, and $5\%$. The percentage ($\%$) of light evoked response in each dorso-temporal, ventral, and dorso-nasal area of eye is about $50\%,\;37.5\%$ and $12.5\%$, respectively. We concluded that the optimal period for experiment in rodent is about postnatal day of 2${\~}$3 weeks.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.161-168
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• 2017

In this study, we examined the effect of Perilla frutescens extract (PFE) on oxidative stress-induced cell death in RGC-5 cell lines. Staurosporine-differentiated RGC-5 (ssdRGC-5) cells obtained by treating RGC-5 cells with $1{\mu}M$ staurosporine were incubated with PFE for 30 min and then exposed to buthionine sulfoximine plus glutamate (B/G) for 20 h. Cell death was detected using lactate dehydrogenase release assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. To investigate the mechanism underlying cell death, we determined caspase-3 activity, level of reactive oxygen species (ROS) formation, and expression levels of cytoplasmic cytochrome c and mitochondrial Bax. Treatment of ssdRGC-5 cells with B/G increased intracellular ROS and induced apoptosis with increasing caspase-3 activity. PFE rescued ssdRGC-5 cells from oxidative stress-induced cell death by inhibiting intracellular ROS production and caspase-3 activation and regulating apoptosis-related proteins such as cytochrome c and Bax. These findings suggest that PFE may have a beneficial neuroprotective effect against oxidative stress-induced apoptotic death in ssdRGC-5 cells.