 I'm Andrew Parker, I'm a professor of physiology in the University of Oxford and my research is mainly concerned with binocular vision, how the two eyes work together in coordination. Now if you've been to the 3D movies and put the glasses on in the 3D movies or used one of these 3D televisions, you've had this experience. What's actually happening there when you put those glasses on is that your left and your right eyes are actually receiving slightly different images and the slight differences between the images arriving at the left eye and the right eye are equivalent to a sense of depth because as we walk around in the natural world our eyes are also getting a slightly different view of the world. So in the cinema what they're doing is reconstructing that by creating artificially different images of the left and the right eyes. But using the two eyes in coordination seems to be special in a couple of ways. First, it's very much linked with the fact that when we look at something we train both eyes on the target in coordination and it allows us to do one thing which few other animals can do which is that we can actually see in full 3D without actually moving from where we are and that's very important. You find that predator animals particularly and large animals have binocular vision because they don't mind sacrificing the fact that they're blind to what's coming behind them because they're large big powerful animals but the ability to stand still and just look and see things in depth is obviously very powerful. The binocular vision that we're studying is actually particularly effective in what we refer to as the near workspace. Basically this means the space around you that you can reach out and touch with your arms without getting up and moving around. It's very important for us it's actually also very important for monkeys. They do a lot of foraging like that they do a lot of grooming like that and we know that the cerebral cortex that big folded sheet of a brain matter that's you see in pictures of the brain we know that that's divided up into many different cortical areas but some of them are primarily concerned with processing visual information and it's those areas that we're investigating. We look at those areas in humans in brain scanners and we've got very lucky to have access to a high resolution seven tesla brain imaging system here in Oxford and that gets us to a certain level of resolution both in space and time so the spatial resolution is about just less than a millimeter. Time resolution is really pretty poor about four seconds. If we want to go to a final level of detail we have to record from individual nerve cells and we can do that by introducing an electrode into the brain of an experimental animal and we use macaque monkeys for this because their eyes like ours are pointing forwards. These animals are being trained to perform visual tasks and specifically to perform a task that involves identifying which of four targets is the odd one out so the animal can reach out and touch one of four different locations. We're training them to discriminate depth so the difference between the four targets one of them will be at a slightly different depth than the other three. Each time they do that they get a small reward a little drop of juice and they it's usually ribena or something they like and they're typically happy to perform maybe five hundred maybe a thousand of these trials each day actually they seem to like coming out and doing this they get quite excited and they're happy to see the people that they're working with and in a later phase of the study it will be exactly the same except that while the animal is performing that task we will also be recording from the electrical activity of nerve cells in the brain. Our research is primarily concerned with working out the different stages of processing that this binocular information goes through and for many years it was thought that the fundamental stage is in the primary visual cortex which in us is right at the back of our heads and it's indeed in pretty much the same place in macaque monkeys. Our work has shown that there's a transformation of signals from the primary visual cortex into these other areas and there's increasing evidence internationally from other labs that those signals the transformation of those signals is also very important in the development of disorders of binocular vision a significant number of the population have problems with binocular vision it's actually three or four percent people typically have one eye which they use to fixate one eye which tends to wander off the so-called sometimes the lazy eye the squinting eye the wandering off is not the only problem that that eye has it turns out that they generally also have a loss of pattern vision in that eye in a condition that's referred to as amblyopia there's nothing wrong with your amblyopic eye in terms of its in terms of the eyeball but it is actually not connecting properly into the rest of the brain and it can't deliver even monocular one-eyed pattern vision properly because it's never grown up in coordination with its partner in the clinic for example there's a good deal of surgical intervention in order to get the two eyes to work in coordination that's only partly successful because the neural connections don't get rebuilt when you do the external surgery to correct the positions of the eyes so we're very concerned with understanding what that internal neural circuitry is both from a pure science point of view it's an interesting question scientifically how do we see in depth but also it should have in the longer term implications for how we treat vision disorders particularly in childhood we're increasingly looking at switching people over to if you like orthoptic exercises of various kinds the most modern of which are getting people to play video games in order to train their eye hand coordination in specific ways we had a very interesting paper on squashing bugs in a virtual reality environment so this requires in a stereo viewing environment people to actually take an object a virtual object and squash it on to a bug which will be at a particular depth or distance or separated by depth or distance from the background they're hoping that they will be able to assist people in recovering at least stereo vision and even a partial recovery would be quite helpful in a number of ways not just in terms of recovery of a sense of depth but also in terms of the coordination between the two eyes and indeed the general improvement in the quality of vision in what up until now has been the weaker eye in the life history of those patients the evidence that they have improved at this stage is fundamentally confined to behavioral evidence that is do we say their performance is better when we measure them and actually to be honest is when we measure them on the same task in the lab we don't know two important things we don't know whether that translates out into general performance like driving a car or or working at a tool bench or something like that and second we don't know which brain areas are involved I would rather suspect on the basis of our knowledge of how the stereo vision system is organized that is actually some of those later visual areas that are picking up this information compensating for it and that's where the residual plasticity will lie because these are people quite well on in years at least well on compared with infants and so on that we normally think of as being in the critical period for the development of stereoscopic vision