tailieunhanh - Biomimetics - Biologically Inspired Technologies - Yoseph Bar Cohen Episode 2 Part 6

Tham khảo tài liệu 'biomimetics - biologically inspired technologies - yoseph bar cohen episode 2 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 432 Biomimetics Biologically Inspired Technologies interface between the electronics and neurons and the matrix to enable survival of the cellular components while being housed in microelectronics. Simulations of Prosthetic Vision One of the major arguments supporting the concept of a retinal prosthesis is the fact that cochlear implant patients can understand speech with only six input channels. Simulations of cochlear implant audition have shown that speech reduced to as few as four frequencies provides enough information for the human brain to understand language. Similarly it is hoped that visual prostheses will be able to transmit useful information without replacing the input from all 100 million photoreceptors. Several experiments were done to define the minimum acceptable resolution for useful vision. Early studies in this area focused on simulating prosthetic vision from a cortical implant. The points of stimulation pixels required for specific activities varied from 80 to more than 600 depending on the activity being performed Brindley 1965 . Most recent studies show that 625 pixels is a better estimate for certain tasks. It was concluded that 625 electrodes implanted in a 1 cm2 area near the foveal representative of the visual cortex could produce a phosphene image with a visual acuity of approximately 20 30. Such acuity could provide useful restoration of functional vision for the profoundly blind Cha et al. 1992a-c . Although these studies began to delineate the number of electrodes needed the fact that all the pixels were projected on a very small area of the retina made it impractical to translate to the design of a retinal prosthesis in which the electrodes would be spread over the entire macular region. Thus a low vision enhancement system LVES has been modified to filter images on a head mounted display in order to simulate pixelized prosthetic vision and to produce an array of dots. The results suggested that a fair level of visual .