字幕列表 影片播放 列印英文字幕 [MUSIC PLAYING] YAEL HANEIN: So I want to describe to you research activity that is taking place in my lab over the past several years, including some extensive collaboration that we do with several colleagues. And I want to get started with describing just a little bit the visual system. The visual system basically looking across different creatures, different animals, is fundamentally the same. And at the very core, it's the capacity of the brain to reach out and to look into the environment. And one of the fascinating things about the visual system is that it's really adapted to accommodate the different needs of different creatures. So humans in particular have very strong needs, one of which is actually to recognize facial expression. And clearly, as humans we have developed technology that goes hand in hand with our visual capacity. So overall, put together, about 80% of what we perceive and comprehend, but also remember and plan, is based on visual information. So we're really technological creatures, I mean, and this is probably one of the best places to highlight this point. But it's really not just about survival. It's survival, but also expanding our capacity in terms of our ability to read, to learn, to plan the future, which really goes hand in hand with our technological capacity and our visual capacity. Now the important thing to realize is that technology and modern science actually have some additional link with visual information. And this is a little bit tricky to comprehend. So if we look overall at longevity, we all know that people live longer. The numbers are quite amazing when we look at them. And so if you just look at what was the reality just about 100 years ago, people didn't live very long. So modern medicine had immense capacity at prolonging life and making all of us live much longer. So clearly there are some differences between developing and developed countries. But generally in the developed world, people live very long. And this has to do with the ability to eradicate a lot of diseases that typically cause early death. Now how does that relate to vision? So one of the consequences of living longer is the fact that certain diseases, as I mentioned, have disappeared. But on the other hand, several other diseases that were unknown before are becoming very prevalent. And one of them is AMD, or age-related macular degeneration, which is the situation where the central part of our macula, or central part of our visual system, which is the macula, it's the center of the retina, becomes degenerate. And that means that when we age, there's an onset of the disease. And when we look at the population of 80-year-olds and above, there's a staggering number of people that will suffer from this disease. So if you go ahead and extrapolate what would be the situation in 20 years, in 50 years, the numbers are going to be very high. So the current estimates is by the year 2050, among the American population, there would be over 5 million people suffering from AMD. Now AMD doesn't mean total blindness, but what AMD means is that our capacity to read, to write, to recognize faces is severely damaged to the point that in many patients it's damaged completely. And the consequences are loss of independence, depression, and a major financial burden on the patients themselves, but also on additional circles of family and friends. So by this point you're all spooked. And this is probably the time to start talking about the future and the technological solutions. And so this is where we introduced the issue of artificial vision. Now artificial vision sounds like complete science fiction. But in fact, over the last several decades, there is a whole range of related technologies that have been developed and have been proven to do just what we're aiming to do in artificial vision. So cochlear implants are devices that are implanted in the cochlea in the ear and have been used already with just over 200,000 people. And what these devices do, they can take auditory information, transfer that into electrical stimulation, and stimulate nerve cells, and basically address the nerve track in order to stimulate information that ultimately is conceived as auditory information. And so this technology has been really the trigger and the motivation to develop additional technologies such as the artificial vision. And so artificial vision are devices that you see on the right-hand side. These are actually devices, actual prototypes, two of which have already passed even regulatory cycles and are approved for use not for AMD patients, but for RP patients. And such devices utilize microfabrication technology and allows people to see. Now what does it mean, it allows people to see? It allows them to have the sensation of visual information. So what these pioneering studies have demonstrated is several very fundamental issues. First, it has demonstrated the fact that you can build a device. You can implant it for a long term. And you can transfer electrical signals that are perceived by the brain as visual information. The second point is that you can also demonstrate using cochlear implants and these implants, that the brain plasticity have the capacity to, over time, to understand better and better this visual information that is being transferred. So basically the science fiction part of it has been taking a little bit out of it in the sense that we know that these things are technologically possible. The challenge remains though that the systems that have been developing over many, many, many years-- this is a long path it takes from the design to the actual realization of these devices-- they're still very bulky, very big, require external energy source, and requires extensive wiring. And often this wiring has to extend out of the eyeball, which makes the whole thing pretty messy when you think about it in terms of surgical procedures. So that the moon shot thought is really to take all of that and turn that into a compact device, basically something that can be inserted neatly into the eye and placed against the retina. So this is clearly what you would like to do when you talk about an artificial retina, but then the question is how do you go about doing that? So what you really need is new materials, either new polymers, new nanotechnology tools, just tools that actually did not exist when the original artificial retina devices were beginning to be developed. So now we do have new materials available. And what we've been trying to do is really to go back to the very basics and to try to imitate the system to the very, very fundamental levels. So a natural system is relied on photoreceptors. The photoreceptors are the elements that are degenerated in AMD. And what you want is actually the capacity to be able to elicit electrical information instead of those elements, instead of these photoreceptors that are gone. Now in the natural system, especially in the macula, there are a lot of these photoreceptors. There's a very high density of them. And they operate in a very efficient way. And so what we're trying to do is to use carbon nanotube as a scaffold onto which we want to introduce energy harvesting elements or photo harvesting elements, and the combination of these two, the photo conducting elements on the one hand and the carbon nanotube as a scaffold on the other hand, can simultaneously generate the needed electric field, which is needed in order to stimulate the retina. Now in terms of actually demonstrating that, so one approach that we've demonstrated very recently with colleagues from Bangalore is using conductive polymers. So you can take newly-developed conducting polymers, deposit them on the interface of electrodes. You can take a blind retina, place the blind retina on the interface, shine light in a very precise way, and demonstrate that the retina can see. So this is a blind retina that sees visual information that are mediated by the special interfaces. The actual approach, or the major effort in my lab, is actually to use the carbon nanotubes as a scaffold. And this is an ongoing work that we've been doing for the past 10 years in which we've been constantly demonstrating the great advantage of using carbon nanotubes for this application. So carbon nanotubes have several fundamental properties, which are really ideal for this application. One is that it's almost like a natural Velcro, which makes a very strong and intimate contact with biological systems. And we've been demonstrating that in vitro, ex vivo, and in vivo. So these are absolutely fantastic materials in binding to the biological system. The other thing is that they are a fantastic electrochemical system, and you can use them as electrodes both for recording and stimulation. You can really convince yourself that you obtain absolutely fantastic recording capabilities just because of their very large, three-dimensional structure. The other thing, which comes from their entangled nature, is the fact that you can make films from these surfaces. You can work out the fabrication process in such a way that you can integrate that into many different carriers, into polymeric carriers, which are biocompatible, and can automatically integrate this whole system into a standalone device. So when you take all of these together and use the carbon nanotube as a scaffold, and now bring into this party, the quantum rods, now you have a system that can do both. It can anchor or bind to the biological system, but it can also do the energy transfer of taking photons and converting them into charge separation, which ultimately stimulate the retina. Now there's a lot of science in the science fiction in the sense that you really have to work out a lot of details. There are many, many, many details, and I have exactly 32 seconds to lay them out. But you really have to work about how you couple the carbon nanotubes and the quantum dots. You really have to make sure that the system is stable and biocompatible, that the charge transfer happens in such a way that it doesn't damage the system. And all of these things have to be, of course, proven. But once you do that, you actually realize that it works. And you can demonstrate again, using blind retina, ex vivo, that using nice, sharply-defined optical pulses, that you can stimulate the retina and reconstruct visual information in essentially a blind system. So there's a long way to go in order to fill the full picture of this. But this is where we're at at the moment and really looking forward for the future. So just to conclude, the real challenge is really at the bottom, not just to extend life, but really to make sure that this prolonged life is happy, healthy, and independent. So thank you very much.
B1 中級 解決X - Yael Hanein - 人工太陽視網膜。 (Solve for X - Yael Hanein - Artificial Solar Retina) 51 4 richardwang 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字