 Hi everyone, my name is George Opie and I'm a researcher from the University of Adelaide. As a part of Brain Awareness Week, I'm just going to be talking a little bit about how concussion affects the brain. Just before I start though, I'd like to thank the Brain Foundation for their invitation to be involved. So concussions are something that we're all aware of, but what are they? So broadly speaking, they're a form of mild traumatic brain injury and they occur when a hit to the head or body causes the brain to collide with the skull. This happens because the brain is floating in a fluid and doesn't have anything to stop it moving around. They can have a really wide variety of symptoms. They often include headache, deficits in motor function, difficulties with thinking and attention and changes in mood. So concussions are often thought of as relatively minor injuries, mostly because the majority of patients recover pretty quickly. But there's actually a substantial proportion of patients that go on to experience significant symptoms for months, 10 years after injury. We're also coming to realize that they might be associated with long-term disease. So we're quickly coming to that to actually think of concussions as pretty serious injuries. The impact of concussion on the brain is something we still don't understand very well, but we have learnt a lot, particularly in recent years. So at the cellular level, we know that these injuries are associated with damage to brain cells and disruptions to brain chemicals. But these issues are thought to resolve after a few days. So the question then becomes what causes the side effects that we see after this early point, particularly for those patients that go on to suffer really prolonged symptoms? We don't know all the details, but one important factor is that after resolution of the early changes, we also see more global and long-term changes in brain function and structure. And our understanding of these has been driven a lot by the development of brain imaging techniques. In particular, magnetic resonance imaging or MRI has been really informative. The outcomes of MRI studies of concussion can be broadly classified into three domains. The first of which is changes in how the brain is activated. So different brain regions are involved with different tasks. And when a region is activated, there's an increase in blood flow to that area. So we can assess brain activity by looking at changes in blood flow as individuals complete a simple task or just lay quietly in the scanner. So a lot of studies have used this approach to show that the way we activate our brain is different after concussion. Unfortunately, though, it's not as simple as it's always increased or always decreased. So both have been reported. And this could be for a lot of reasons, but some of the important ones include the types of tasks that are used or maybe the specific nature of an individual's injuries. So these figures are showing some examples of these effects, the colors showing areas of the brain that are active. So concuss patients are on the left and controls on the right. And as you can see in the top panel, there's a lot less color, so a lot less brain activation in the control group, sorry, the concuss group relative to the controls. Whereas in the bottom panel, we see a lot more color in the concuss group. So just giving us an example of the fact that we see both increases and decreases in brain activation. So the functional relevance of these sorts of changes is often unclear. But an increase is often suggested to reflect greater allocation of resources to compensate for loss function, whereas a decrease might reflect dysfunction. So the second domain of MRI studies is changes in brain communication. As I mentioned in the previous slide, different brain areas are involved in different tasks. However, brain function depends on these different areas being able to communicate with each other. And this is referred to as functional connectivity. And similar to brain activation, a lot of studies have shown that functional connectivity is altered after concussion. The specifics of this are again varied, but concussions often associated with an increase in connectivity at the front of the brain, but a decrease in connectivity at the back of the brain. So these figures are showing an example of this. The red dots are showing all the areas that are communicating with the area shown by the green dot. In the figure to the left, you can see that the green dot is at the front of the brain. And the congust scan has a lot more red dots attached to it. In the figure on the right, though, we can see that the green dots at the back of the brain, and the congust scan has a lot less red dots on it. So the third domain of MRI studies is changes in brain structure. So broadly speaking, the brain is composed of gray matter and white matter. The gray matter contains the bodies of brain cells, whereas the white matter contains the wiring that allows brain cells to communicate with each other and to send messages to the rest of the body. White matter in particular is thought to be damaged by concussion. This is because white matter forms long tracks, and these are twisted and pulled and torn when the brain bounces around the skull during a concussion. So the figure shown here is from a recent study that investigated changes in white matter after concussion. So the gray sections are showing the white matter tracks, whereas the colored sections are showing sections that are thought to be damaged by the concussion. Given what white matter does, it's possible that this sort of damage contributes to the changes in brain activation and communication that we saw in the previous slides. So MRI is an amazing tool that's been incredibly important for understanding of how concussion affects the brain. The problem is that it can't really be used in managing patients clinically. This is because it's really expensive. MRI scanners can't be moved around, and MRIs are already in really high demand. We also need to use really specialized analyses to see the effects of concussion with MRI. Because of this, there's a lot of research that's investigating other more clinically relevant ways to assess the brain after concussion. One of these options is to look at the brain's electrical activity. So brain cells function by generating a tiny electrical current, which is passed to other brain cells. And this allows messages to be sent around the brain. This electrical current can be measured noninvasively by placing electrodes on the scalp. And this is a technique called EEG. So we can see an example of an EEG cap here with a number of electrodes shown across the head. And above that is an example of what the brain's electrical activity actually looks like with each line showing the response of an individual electrode on the head. So when assessed with EEG, brain activity is characterized by rhythmic voltage fluctuations called oscillations. We can see some examples of oscillations here in the EEG trace. And these are a particular type of oscillation called alpha waves. So as oscillations are a direct measure of brain cells, they can tell us a lot about brain activity and communication. Because of this, a number of studies have used them to try and understand how concussion affects the brain. And similar to work with MRI, these studies also tend to suggest that injury leads to changes in brain activity and connectivity. So using EEG to measure oscillations could be a great way to assess the concuss brain. It's an easy technique that's relatively cheap, very available, and is already used in the clinic for other conditions. The problem is that we still don't understand a lot about how concussion influences oscillations. Yes, there's been a few studies that reported changes after injury. But the nature of these varies a lot. It's also unclear how the reported changes relate to side effects and symptoms of injury. So this means that we need to look at oscillations from a slightly different perspective. And the last thing I want to talk to today about is a study that thanks to generous support from the Brain Foundation, we're just about to start and is going to allow us to do exactly that to look at oscillations from a slightly different perspective. So while most previous studies have looked at specific oscillations in isolation, we instead plan to look at interactions between different types of oscillations. So brain activities made up of several different types of oscillations that are characterized by different frequencies. As an example, this line over here is showing some raw EEG, whereas the lines below are showing four different types of oscillations that combine together to form the raw EEG. While each of these oscillations are thought to have specific jobs, the way that they interact with each other is thought to be really important, particularly for functional connectivity. Given that changes to connectivity are an important feature of concussion, these oscillatory interactions may be really sensitive to the effects of injury. And if so, they might be a really useful clinical measure. So just before I finish up, I'd like to quickly acknowledge collaborators, students and funding that have supported my work in concussion, in particular the Brain Foundation. Thanks everyone for watching.