 I'm Matthew Rosworth, I'm a research scientist, and my particular interest is trying to understand the prefrontal cortex, a part of the brain. So the prefrontal cortex, like many areas in the brain, is actually a mosaic of different areas. Each little tile in this mosaic of areas has a different job to do, and one of the things that we're interested in is understanding what all of the different parts of the prefrontal cortex are doing, what contribution they're making to our mental life. So to give you an example, recently we've been looking at a particular part of the prefrontal cortex, we call it the lateral-old frontal cortex, and we think this brain region has a very special role to play in discerning what events in the environment cause each other. So how does one thing cause another thing? What events lead to which consequences? So in order to try and study this, one of the first things that we were doing was looking at macaque monkeys, and we were looking at activity in the orbital-frontal cortex of these macaque monkeys, while they were performing very simple tasks. The tasks that we give them are a little bit like a computer game for a monkey. What they're doing is they're looking at a computer monitor, and they see several different visual patterns that we call stimuli that are presented on their computer monitor, and their job is a very simple one to work out which is the best pattern to pick, to reach out and choose with their hand, and if they pick a good pattern, then they get a small juice reward. What we were interested in is how the animal links together the pattern that they choose, and the good consequence, the juice reward that they get afterwards. And it turns out this ability to make those links, to make those associations, is reflected in activity that we can measure in the orbital-frontal cortex. One of the things that we have also been doing is looking at what happens when the orbital cortex isn't working properly. What are the consequences for behaviour? And we can try and investigate that by making a very precise disruption to the orbital-frontal cortex. We can do this by using a special surgery that stops the specific brain region from working in the normal way, while leaving the rest of the brain working just as it would do in every natural situation. And there's a consequence of this type of manipulation. We can see that animals are no longer so good at linking one event to another. They're no longer so good at working out which of these patterns that we're showing them is the one that leads to the juice reward. So this is telling us that this particular brain area is doing a very basic, but also a very important job in our mental life, enabling us to see what events cause which other events in the environment around us. Since we made this discovery, we've gone on to see if it has any relevance for understanding how the human brain works because a large part of our work in the lab is actually working with human volunteers. And there have been a couple of different ways in which we've taken the work forward with human subjects. One of them has been to put ordinary healthy humans into MRI scanners and to try and record activity in the human brain. But we're able to get a rough sense of where activity changes in our human volunteers, and we've been able to discern a similar pattern of activity in the orbital frontal cortex of our human volunteers, while they're performing similar types of computer games. Only now, instead of winning small amounts of juice, they're winning points that are going to be translated into money at the end of the game. A second way that we've tried to take the research forward is to collaborate with other researchers working with human patients who've suffered strokes. Sometimes when people suffer a stroke, they lose the ability to use their arm or their leg and to move around in the normal way. But sometimes a stroke can affect the prefrontal cortex, the areas that we're interested in. And in such situations, people suffer a different type of disability. They might be able to move normally, they might be able to see and to hear normally, but they don't seem to be capable of independent living in the same way. And it's difficult for us sometimes to understand what it is that's gone wrong. And some of our recent research suggests that this process of working out what causes what is one of the things that's compromised in these patients if the stroke affects this particular region that we've been investigating. But this is something that we hadn't realised before. And then another way in which we're trying to take the work forward is looking at how people with various different psychological illnesses such as depression make sense of cause and effect in the world around them. One of the things that we know sometimes happens in depression is that people assume too much responsibility for an undesirable outcome, some event that perhaps they haven't really been causally responsible for. And so what we're interested in doing now is seeing if our understanding of how the orbital frontal cortex works and how we work out cause and effect in the normal healthy brain, if that has any relevance for understanding how this ability may sometimes go wrong in psychological illnesses.