The human eye has roughly three channels of color information (RGB), while the human nose has over 300 different olfactory receptor types, making smell a far higher-dimensional sensory channel than vision, even though it's still unclear exactly what each receptor codes for.

3:51school. It all came back in. Exactly. You know, and like there's filter sets, there's Gabbor [clears throat] filter sets, there's, you know, all kind there's huff trans like there's all kinds of ways of representing images and I'm super simplifying it, right? But like maps, they for certainly they're there and and we know them. We've known them for a while and the notion that like we can map color has been

4:11instrumental in building like CCDs and CMOS and therefore like digital imaging. Exactly. And then also the printers, right? So like the ink in the inkjet cartridges, we know we can combine them to make, you know, millions of of colors. There's three channels of color information roughly roughly RGB uh in the eye, but there's over 300 channels of alactory information in the nose. And it's still a mystery exactly what they

4:35code for, but it's certainly much higher dimensional, at least in terms of channel count. So when you say channel count in the nose, is that mapping to physical structures? I'm going to butcher this, but for the eye, I'm like, is it like rods and cones and stuff like that? >> Exactly. Yeah. So, there's rods and cones and together there's like four channels there, like roughly RGB grayscale. Again, there's a lot of

4:59details there. Um, those are specific receptors that are encoded in your genes, right? Expressed in in eye cells in your eye that are sensitive to light. So, the equivalent for smell are those cells are called olfactory uh sensory neurons. And those cells actually start in the brain and they poke through your skull and they actually touch the world. It's one of the two parts of your brain

5:22that actually leaves the skull. Um, and so when you smell something, your brain is physically touching another living thing that's like let off a little bit of of of some of itself for you to smell. Um, so there are millions and millions of olfactory sensory neurons in the part of your nose, the inside that actually does the smelling, that's sensitive to smell called the olfactory epithelium. Does the the the

5:46nomenclature here that these are sensory neurons imply that they're more fundamental than a rod or a cone, which I'm imagining are more like super structures, like you bigger things. >> I'm probably going to mess this up, but rods and cones are cell types. And so those are names for types of cells. And there's many other types of cells in the retina that'll help kind of compute the

6:07raw information that these cells get. So the equivalent of those like primary sensory cells like without these cells light doesn't turn into awareness right so it's it's the front line right so the frontline cells for smell are called OSN oral factory sensory neurons and these cells at the tip they basically shove part of their cell membranes into a little mucous membrane that then touches the world and those little tips are just