페이지 정보작성자 관리자 댓글 조회 작성일 22-07-20 23:40
2022년 06월 27일 (월) 오후 4시
연사: 가톨릭대학교 의대 해부학교실 김인범 교수님
제목: Stunning Relationship between Anatomy and Physiology in Retinal Circuit Organization: Lessons from Non-image-forming Photoreception Processing
초록: For hundred years or more It has been known that rods and cones are the only photoreceptive cells in the retina. The light signals generated in these photoreceptors, after processing by downstream retinal neurons (bipolar, horizontal, amacrine and ganglion cells), are transmitted to the brain via the axons of the ganglion cells for further analysis. Bipolar cells are the second order neurons of the retina. They relay visual signals from photoreceptors to the ganglion cells which are the projection neuron of the retina. Based on their morphology, there are ≈10 types of cone bipolar cells and one type of rod bipolar cells. These bipolar cells are divided ON and OFF cells according to the light response polarity. The OFF bipolar cell axons ramify in sublamina a (OFF sublamina) in the inner plexiform layer (IPL), where the proximal half synapses onto dendrites of ganglion and amacrine cells showing OFF response, while ON bipolar axons stratify in sublamina b (ON sublamina), where the distal half makes synapses onto dendrites of ganglion cells and amacrine cells showing ON response. This stunning relationship between anatomy and physiology is the fundamental principle of retinal circuit organization.
Recently, convincing evidence has emerged indicating that a small subset of retinal ganglion cells in mammals is also intrinsically photosensitive. Melanopsin is the signaling photopigment in these cells. The main function of the intrinsically photosensitive retinal ganglion cells (ipRGCs) is to generate and transmit non- image-forming visual information, although some role in conventional vision
(image detection) is also possible. Interestingly, ipRGCs break a beautiful relationship between anatomy and physiology in the retina, that is, their main dendrites stratify in sublamina a (OFF sublamina) of the IPL, but electrophysiologically, they show the light-driven ON responses.
In this presentation, I introduce various retinal neurons and their light-driven responses, and some retinal circuits for image forming processing. In addition, a non-image-forming retinal circuit is introduced and demonstrate the origin of paradoxical light-driven response of intrinsically photosensitive ganglion cell.
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