So I want to go to the next frontier. The fourth frontier, which is optogenetics. It's a recent one. And the idea here, the general idea here is to develop again molecular genetic tools, to be able to stain the cells. But in this case, not anatomically necessarily, but to stain the cell or to, to implant probes into neurons, into nerve cells that are sensitive to light. So that when I would shine light in a particular wavelength onto this particular cell that we're manipulated to become sensitive to light, then the cell will respond electrically. We actually know of only one type of cells, nerve cells, in the brain that are sensitive to light and this is our, our retina. So when I see light, when I see a face, it means that the photons from the world hit particular cell type, the receptors, the photoreceptors in the retina, and these photoreceptors swallow, so to speak, the photons and generate electrical activity in response. But this is only there. But this means that there are molecules in our genes. There are genes that can generate specific molecules that are sensitive to light, and can transform, transform light into electrical activity. So this is the magic. A group of scientists found the gene or the molecule, the protein that you can embed into the cells that usually are not sensitive to light in the brain. And then, when you shine light on this brain, this group of cells respond electrically, although, usually they don't, but now you made them sensitive to light. So this is what is called optogenetics. You use genetic tools to make the cells sensitive to [INAUDIBLE], to light. And we know today of two general types of light activated cells. You can embed particular ion channel. But, we'll talk a lot about ion channels later. That when you shine blue light onto the cell, this ion channel opens and there is current flow and the cell starts to fire. So this is one example here. So, you record now from this cell, you don't stimulate the cell, you just record, just to see what the cell responds to and you flash blue light, blue light, blue light, blue light, onto the cell, onto this particular cell. And you suddenly see the cell following the light start to fire. So blue lights spike, blue lights spike. Okay? So this is activating the cell, making it fire, spikes, we spoke about spike, just using light. Okay, channelrhodopsins, that's a fantastic way to selectively and particularly, when there is a light, there will be a spike. You don't need to go into the cell anymore. This is just to show you that there are spikes. But we know today, that if this cell contains this channel, this channel that you genetically manipulated it to be there, this cell will fire with blue light. The opposite thing happened when you put another type of, of protein there. And in this case, you restrain, you block the activity of the cell. In this case, with yellow light. So you shine a yellow light, this cell usually fires. Let's say fire, fire, fire. Then yellow light, yellow light, no firing. You stop your light, fire, fire, fire. So in this case, the yellow light stops the cell from firing and this what makes me, what, what I can do with it is now to manipulate, as I want from the outside. If I have this genetic manipulation, I can activate a group of cells, make them fire or I can stop a group of cells, stop them from firing. And why this is so important? Because, this means that I will be able to detect the group of cells that may be responsible for a given, let's say, behavior or instead of stimulating them with all these electrodes that I mentioned before, I will be able hopefully to stimulate from the outside and maybe repair the network. Or maybe activate the network to make the, the, the animal move or maybe there is other activity in a particular region. I can calm down this activity using the yellow light. So I can now start to control in a very particular region, not in general brain. Just particular region or particular cell type. I can manipulate it very, very, very specifically. I want to show you a movie using this technology of manipulating, so to speak, the behavior of a mouse. So whenever there would be blue light, blue light, a group of cells will be activated and this group of cells will, so to speak, force the mouse to drink. And when this group of cells are not being activated, the mouse will be free to do whatever he wants. So, here is the movie. This is from Janelia Farm from Karel Svoboda. So here is the mouse, running freely, but this is the optical probe that inject this light. Notice that whenever there is blue light, it doesn't see the blue light. Whenever there is a blue light, is going to drink or eat from the left dish, and when there is no stimulus, he can do whatever he want. But whenever there is blue light, whenever there is blue light, he goes there. He has been trained to go there, he must go there, because a stimulated group of cells and he now really is controlled, so to speak, by this group of cells. So whenever there is blue light into his brain, not, not what you see. This is, by the way, done in dark or so, so so, he doesn't see the light. It's only for you. So this is optogenetics. It's a very, very new technique. Very, very powerful. We really put a lot of hope into this technology, because it, it may, for the first time ever, in the living behaving animal, we maybe able to induce a given behavior or control compulsive behavior or maybe control Parkinson or other diseases. Of course, the issue is whether we can use it in humans, and this is ethical issues with society will have to decide, but the technology is there. The decision whether to go into humans with it is a decision that the society should do. So we are developing methods that are very useful for research. Whether they will be useful for clinical aspect, that's a decision of society not of scientists. But I wanted to show you the technology.
