Seminar

November 14, 2018 / 16:00 ~ 17:15
 
Speaker : Dr. Maesoon Im
 
Abstract
 
In this talk, the current status of visual prosthetic research will be introduced. In particular, retinal prosthetic research will be presented in both aspects of engineering and neuroscience. Microelectronic retinal prostheses have restored sight in individuals blinded by outer retinal degenerative diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Despite impressive clinical outcomes, the restored vision is still far away from the normal vision. To improve the quality of artificial vision that arises from retinal prostheses, it is important to bring electrically-elicited neural activity more in line with the physiological signaling patterns that arise normally in the healthy retina. The biggest challenge arises from the remarkably complex structure of the retina. For example, the retina has more than a dozen different types of retinal ganglion cells (RGCs) including ON and OFF types detecting brightness increment and decrement, respectively. Our previous study reported that electric stimulation produces a closer match to physiological responses in ON cells than in OFF cells. This finding suggests that a preferential activation of ON RGCs would shape the overall retinal response closer to natural signaling. Recently, we found that changes to the rate at which stimulation is delivered can bias responses towards stronger ON responses. Interestingly, the stimulation rate maximizing ON/OFF response ratio in in-vitro testing is similar to the rates preferred by subjects during clinical trials, suggesting the importance of optimal stimulus parameters for enhanced clinical effectiveness. This presentation will demonstrate how varying parameters of electric stimulus (e.g. stimulation rate, stimulus duration, and stimulus waveform) modulate responses differently for ON versus OFF cells. Those results will offer insights for novel designs of implantable microelectronic devices.
 
Short Bio
 
Maesoon Im is a Senior Research Scientist at KIST (Korea Institute of Science and Technology), Seoul, South Korea. Before joining KIST, he was running his own lab from 2015 to 2018 as an Assistant Scientist in the Department of Ophthalmology at Henry Ford Health System, and an Adjunct Assistant Professor in the Department of Anatomy and Cell Biology and the Department of Electrical and Computer Engineering at Wayne State University, Detroit, Michigan. As an electrical engineer by training with strong interest on neuroscience applications, he studied retinal prosthetics and visual neuroscience as a Research Fellow in the Department of Neurosurgery at the Massachusetts General Hospital, Harvard Medical School from 2011 to 2015. Prior to that, he was a postdoctoral research fellow in the Department of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor from 2010 to 2011. He received his B.S. and Ph.D. degrees in Electrical Engineering from KAIST (Korea Advanced Institute of Science and Technology), Daejeon, South Korea. At the University of Michigan as well as KAIST, he fabricated various micro-/nano-devices for neuroscientific and biological applications. With the unique combination of expertise in both retinal physiology and microfabrication, his lab at the Brain Science Institute of KIST aims to develop innovative retinal implants to restore vision to blind individuals suffering from retinal degenerative diseases.
Venue: 104 E204