• Progress in Medical Physics
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• v.21 no.2
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• pp.209-217
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• 2010

Retinal prostheses are being developed to restore vision for the blind with retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Since retinal prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. Therefore, in this paper, we focused on retinal ganglion cell (RGC) responses to different voltage stimulation parameters and compared threshold charge densities in normal and rd1 mice. For this purpose, we used in vitro preparation for the retina of normal and rd1 mice on micro-electrode arrays. When the neural network of rd1 mouse retinas is stimulated with voltage-controlled pulses, RGCs in degenerated retina also respond to voltage amplitude or voltage duration modulation as well in wild-type RGCs. But the temporal pattern of RGCs response is very different; in wild-type RGCs, single peak within 100 ms appears while in RGCs in degenerated retina multiple peaks (~4 peaks) with ~10 Hz rhythm within 400 ms appear. The thresholds for electrical activation of RGCs are overall more elevated in rd1 mouse retinas compared to wild-type mouse retinas: The thresholds for activation of RGCs in rd1 mouse retinas were on average two times higher ($70.50{\sim}99.87\;{\mu}C/cm^2$ vs. $37.23{\sim}61.65\;{\mu}C/cm^2$) in the experiment of voltage amplitude modulation and five times higher ($120.5{\sim}170.6\;{\mu}C/cm^2$ vs. $22.69{\sim}37.57\;{\mu}C/cm^2$) in the experiment of voltage duration modulation than those in wild-type mouse retinas. This is compatible with the findings from human studies that the currents required for evoking visual percepts in RP patients is much higher than those needed in healthy individuals. These results will be used as a guideline for optimal stimulation parameters for upcoming Korean-type retinal prosthesis.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.95-103
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• 2022

This study aims to understand a gamer participatory mechanism by comparing Gamer Participation 1.0(Bartz Liberation War) and Gamer Participation 2.0(Truck Demonstration). The process of gamers' political participation is analyzed by applying the communication-mediated O-S-O-R model with the case of gamers' truck protests caused by probability items' issue. This study found out that changes in the social, technological, and discursive layers that constitute the gamer's communication ecology led to diversification of communication channels and changes in the perception of games. Gamers utilized the technological layer of the media environment that presupposes immediate mutual communication, expressed opinions on issues in the mobilization process, and shared the necessity of participation to derive collective mobilization. Through communication, gamers were able to participate in socio-political issues with high participation thresholds. This study is significant in that it discussed the gamers' democratic citizenship and role as issue publics. The study suggests that the need for theoretical and methodological expansion to analyze various participatory cases.