https://stream.echo6.co/videos/watch/50e11025-f91e-4210-9549-91ee8d8a39e3 Official Ninja Nerd Website: https://ninjanerd.org Ninja Nerds! In this lecture, Professor Zach Murphy will take you step-by-step through the phototransduction cascade, the process by which light is converted into an electrical signal in the retina. We begin by reviewing the resting state of a photoreceptor in darkness, where high intracellular cGMP levels keep cGMP-gated sodium channels open, allowing a steady influx of Na⁺ (the “dark current”) and continuous release of glutamate onto bipolar cells. Next, we follow what happens when light strikes the photopigment. Rhodopsin in rods (or photopsins in cones) undergoes a conformational change, activating the G-protein transducin. This activation stimulates cGMP phosphodiesterase (PDE), which breaks down cGMP into GMP, lowering intracellular cGMP concentration. As cGMP levels fall, sodium channels close, causing hyperpolarization of the photoreceptor membrane and a decrease in glutamate release. We then connect these changes to visual signaling pathways, explaining how reduced glutamate release differentially affects ON-center and OFF-center bipolar cells, ultimately altering ganglion cell firing patterns that travel via the optic nerve to the brain. The lecture also emphasizes the rapid and continuous nature of this process, adaptation to different light levels, and recovery mechanisms—such as rhodopsin kinase activity and the restoration of cGMP levels by guanylyl cyclase—that reset the photoreceptor for future light detection. Enjoy the lecture and support us below! 🌐 Official Links Website: https://www.ninjanerd.org Podcast: https://podcast.ninjanerd.org Store: https://merch.ninjanerd.org 📱 Social Media https://www.tiktok.com/@ninjanerdlectures https://www.instagram.com/ninjanerdlectures https://www.facebook.com/ninjanerdlectures https://x.com/ninjanerdsci/ https://www.linkedin.com/company/ninja-nerd/ 💬 Join Our Community Discord: https://discord.gg/3srTG4dngW #ninjanerd #Phototransduction #EENT Mon, 13 Apr 2026 22:55:36 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://stream.echo6.co https://stream.echo6.co/client/assets/images/icons/icon-512x512.png https://stream.echo6.co/videos/watch/50e11025-f91e-4210-9549-91ee8d8a39e3 All rights reserved, unless otherwise specified in the terms specified at https://stream.echo6.co/about and potential licenses granted by each content's rightholder.