Skip links and keyboard navigation

The Brain

The My Amazing Body logo with an image of a brain
Find out what we know, and what don't we know, about the brain.

My Amazing Body is a podcast where we explore interesting, unknown and misunderstood parts of your body with help from medical experts and stories from real Queenslanders.

This episode is all about the brain – one of the most important, and most mysterious, organs in your body. Consultant epileptologist from Princess Alexandra Hospital, Dr Sasha Dionisio describes the different parts of the brain, how they work together and how the brain works with the rest of your body. He also answers curly questions like ‘What is your mind?’, speaks about how disease and injury can affect the brain, explains how he and his team diagnose and treat epilepsy, and let’s us know what it’s like to watch brain surgery.

Meet our guests

A photo of Dr Sasha Dionisio

Episode materials

Audio is great, but some things are best seen as well as heard, or might tempt you to do further reading. These materials provide more information about topics we touch on in the show.

A diagram of the brain

Follow along on the diagram as Sasha talks about the different parts of the brain.

A diagram showing the parts of the brain.

Tips for keeping your brain healthy

In this episode, Dr Dionisio gives some tips for keeping your brain healthy. Below are links for further information about mediation, drinking less alcohol and improving your diet.

Health Direct - Meditation

Quit HQ

Healthier. Happier.

More information about epilepsy

For more information about epilepsy, head to the links below.

Epilepsy Queensland

What it’s like to live with epilepsy

Episode transcript

Dr Dionisio: What's spectacular about this organ is that it functions really via electricity and also chemical interactions, and all these complex processes taking place. And yet when you look at it, it's just this really bright, white pulsating organ. I personally think it's beautiful, but probably I'm a bit weird.

Host: Hi, I'm Elise. Welcome to the latest episode of My Amazing Body, where we explore interesting, unknown and misunderstood parts of your body. In this episode, we're learning about your brain.

The brain is a mysterious organ. Even though we know a bit about how it works and connects to the rest of our body, there's still a lot to discover. We spoke to consultant epileptologist, Dr Sasha Dionisio about what the brain actually is, how it works, conditions that can affect the brain and what you can do to keep your brain healthy.

Dr Dionisio: My name is Dr. Sasha Dionisio. I'm a consultant epileptologist. That's an epilepsy specialist.

Well, the brain is an organ, first and foremost. It is probably the most complex organ in the body. It controls virtually, or it has control over every single organ in the body, and the function is everything from movement to basically all function that's compatible with life, is controlled by the brain. There are over a hundred billion cells in the brain, making it far more extraordinary than any other organ, and that's really a testament to its function and to its specialization.

Host: Dr Dionisio explains that different sections of the brain control different functions and parts of the body. As he talks through the different parts, you might want to have a look at a diagram of the brain. We've included one in the episode shownotes on our website.

Dr Dionisio: The brain has five major lobes. Starting from the front and moving backwards, so the first lobe is the frontal lobe, so the area of the brain that's located at the front of the head, above the eyes. That part of the lobe is really interesting. So, the frontal lobe from the most anterior, so from the most frontal part, where we have things like executive function and personality. And then as you start to go back in the frontal lobe, it becomes more associated with movements. At the very end of the frontal lobe, where the frontal lobe meets the next lobe, is where you have the primary movement area of the brain.

Host: In just one section of your brain, that's your thinking and logic skills, personality and ability to move. So, what do the other four sections of the brain do?

Dr Dionisio: The frontal lobe then meets the parietal lobe. So, there's a very important structure called central sulcus, which divides the frontal lobe from the parietal lobe.

And the start of the parietal lobe, which is kind of halfway on the top of your head and going backwards, there starts the sensory cortex. So, the primary sensory cortex is located in the anterior part of the parietal lobe, and that's very important for the sensation of the body. And then as you start to move back in the parietal lobe, it starts to join the occipital cortex. That's the primary visual centre. The occipital cortex is right at the back of the head. The parietal lobe, going back to the parietal lobe, it's like a highway. That's the best way to describe it.

It uses messages from the frontal lobe, from the occipital lobe, from the temporal lobes, and it integrates things like vision with memory and action. A simple example is if a tiger entered this room, your memory would recognize that that's something dangerous and it will signal to your frontal lobe to get out of here as quickly as you can. That's just a simple, bit of a silly example, but it illustrates the point.

Host: The third and fourth lobes of the brain are responsible for creating those visions and memories.

Dr Dionisio: Then you have the visual cortex, the occipital lobe right at the back of the head. That's obviously as the name will suggest, taking information from the eyes and processing that to other regions of the brain. And then just on the sides of the ear, on both sides obviously, because a brain is symmetrical, you have the temporal lobes. The temporal lobes are most known for memory. Within the temporal lobes is a very old structure called a hippocampus, which is Latin for seahorse, and this region there contains memory. Memory itself is a fascinating subject to talk about.

Host: Lastly, there's the mysterious fifth lobe of the brain.

Dr Dionisio: And then you have the fifth region of the brain, the fifth lobe of the brain, which is a structure nestled deep inside the frontal lobe and deep inside the temporal lobe. There is a groove that separates the two, called a Sylvian fissure, and between that groove lies a structure called the insula. The insula is a very enigmatic region, because for a long time we didn't really understand its function or how it behaved.

But it's really a major area, has major function from everything from processing of our internal emotions, how we feel, to things like heart rate control, to things like movement of the gut. So gut control, that's all dominated by the insula. It's involved in many other functions, such as sensation, even visual processing. It's a very rich structure. In fact, all the different lobes have really quite unique function, and also they work together to produce certain functions as well.

Host: Have you ever heard of the brain having a 'dominant hemisphere'? Even though everyone's brain has basically the same structure and shape, Dr Dionisio says that different people use different parts of their brain for some functions.

Dr Dionisio: The brain is also interesting, because we talk about a dominant and a non-dominant hemisphere. The dominant hemisphere is the part that has language. Most right-handed people, that's on the left side of our brain. In most left-handed people, it's still on the left-hand side, but there are certainly a bigger proportions of left-handers who have language on the right side of their brain. And so, the language system is in fact extremely complex as well. It spans across the frontal lobe, the lateral parts of the frontal lobe. It spans across the lateral parts of the temporal lobe, and also the lateral parts of the parietal lobe too.

Host: Conditions and diseases that can affect the brain, like dementia, often affect memory. We asked Dr Dionisio - how does memory actually work? Like most brain functions, it turns out the answer is pretty complicated.

Dr Dionisio: Memory is like most of the function in the brain, it's a network, meaning it's not ... ascribed to any one particular place. Within this network, there are major players. With the memory system we have identified some of those major players, however, what we've identified is no means the whole story, I think.

The circuit of memory really comprises certain structures in the temporal lobe, the hippocampus, the entorhinal cortex, which is the base of the temporal lobe, the amygdala, and then travels back to the posterior cingulate, which is an area within deep inside the parietal lobe. This projects to the orbitofrontal cortex, which is deep inside the frontal lobe, down to the mammillary bodies, which are going down towards the brainstem structures. But even now we're beginning to find that there are other centres that have major memory function. In the occipital lobes, and deep inside the frontal lobes in the singular systems.

Host: Once you've made memories, how do you access them? And why do you sometimes forget really obvious things, like where you put your keys a minute ago?

Dr Dionisio: How does memory function? A very difficult question. At the most basic, we understand that memories are basically introduced into the hippocampus or the hippocampal system, and then within that network it's transferred to the high senses of brain, to the other cortical regions through different signal interactions, as I explained earlier. But specifically, why we forget certain things and why we may have short-term memory loss, or not know our memories from a certain age, that's really an area that I don't think is answerable at this stage.

Host: Like memory, consciousness is another possible brain function that we don't truly understand. What really is your mind, where is it and how does it work? While we can guess that consciousness has something to do with our brain, Dr Dionisio says that these are questions that branch out beyond the field of neuroscience.

Dr Dionisio: Consciousness is very difficult, because I don't think we truly understand how consciousness works. Certainly, as human beings we are dominated by our senses, so light, smell, touch, vision, but how that transforms into consciousness is a very difficult field that borders everything from neurology, to philosophy, to spirituality.

We know that there are certain areas of the brain, for example in the brainstem, there's a region called a reticular activating system which promotes sleep, and so therefore definitely changes consciousness. There's an area of the brain in the parietal cortex called the default mode network, which is an area where at rest the brain will basically reset itself to a certain level of functioning.

But these are things that are only newly discovered, and whether or not they are consciousness, I think is impossible to answer. As I say, I do not think that we'll be able to solve this in our lifetime. I think we're barely scratching the surface of what the organ can do and these very high-level questions will probably remain for the next hundreds or probably thousands of years, within the realms of neurosciences, philosophy, spirituality.

Host: Are you ready for this episode's Mystery Body Part? See if you can guess the body part from the clues given. We'll give the answer at the end of the episode.

What am I? I am one of the most sensitive parts of your body, with over 1million nerve endings. Just like your fingers, I leave a unique print. I don't have sweat glands of my own, which means I can dry out very quickly. Do you know what I am?

The brain is possibly the most important part of your body in terms of keeping you alive and functioning. The tissue of the brain is very soft, which is why it's encased in the protective hard shell of the skull. But still, it's possible to injure the brain, either from a blow to the head or from diseases or conditions that affect brain tissue. Dr Dionisio explains what happens when the brain is injured.

Dr Dionisio: When the brain has trauma, neurons will die, and not only will neurons die at the site, but you may also get atrophy, which is a more widespread neuronal death. So, it depends where you are. Let's say you've got an injury on your occipital cortex, you may lose your vision. If it's in the frontal regions, there may be major personality problems. Epilepsy is definitely something that can arise from a traumatic brain injury. Those are the more obvious features, but then you can have the subtle features.

Host: In the case of a large blow to the head, some neurologists describe the resulting brain trauma as like shaking jelly on a plate and watching the soft tissues twist and tear.

Dr Dionisio: So, with that analogy, the jelly, and shaking the jelly, and tearing the brain, that's the situation when you get high velocity impact. That's the kind of stuff you see from, for example, a car accident or a bike accident where somebody's been traveling at a huge amount of speed, and there's sheer forces, and there's really destruction of the brain, and people are either locked in, comatose, or there's brain death.

Host: Not all brain injuries come from such catastrophic trauma, but this doesn't mean they shouldn't be treated seriously. Even mild concussions might have long-lasting effects on the brain.

Dr Dionisio: For example, there's now research into this whole idea of chronic traumatic encephalopathy, whereby you've got sports people who have head injuries, boxers, even soccer players heading the ball, MMA fighters, who after many, many years of repeated concussions, knocks to the head ... rugby players ... may not present outwardly any different, but they have serious problems with executive function. So, doing tasks that are paying the bills, figuring out their tax forms, doing multiple tasks, going to the supermarket, picking up this person. They can't do it.

Host: An injury to the brain can affect the function of that part of the brain. For example, if a person has a stroke in the part of their brain controlling language, they might have slurred speech or difficulty remembering the right words to say. Amazingly, the brain can 'rewire', shifting function from the damaged part of the brain to a working part.

Dr Dionisio: The best example of that is in children. In children, where their brain's still developing, if there is early insult you will actually see re-connections of the brain. The best example of that is language. In kids who suffer with neonatal strokes, where they're born and they have an early stroke, if they stroke out the left side of the brain, their language function will transfer to the right side. The same is true in epilepsy. So, in early childhood epilepsy's, as they grow into adults, they will actually transfer function to the contralateral side. It's not only language, it also happens in memory.

When our patients, when we operate on patients with epilepsy, if they have scar tissue in the memory centres, often when we do memory tests, that part of the brain will not be working, so it's almost exclusively transferred to the other side. So, this idea of transfer of function is definitely real and I think it actually goes on throughout life. The most dramatic is obviously early on, if there is an injury, but even as a full-grown adult that still can happen. Maybe the recovery is not as full as with a child, but it certainly is there.

Host: If you've known someone who's had a stroke, you might have watched them do rehab activities to help them learn to speak again or move their limbs properly. Dr Dionisio says that these activities aren't necessarily healing the injured part of the brain but instead teaching the brain to control these functions from a different place.

Dr Dionisio: And we see that with stroke, in elderly people who've got a stroke. When they have the initial stroke, they may be really hemiparetic and weak, but with physio and rehabilitation some of them may get substantial return to power.

Host: There are a lot of different conditions that can affect the brain and how it functions. Dr Dionisio's work focuses on epilepsy, a condition that causes abnormal electrical activity in the brain.

Dr Dionisio: Epilepsy is a very common medical condition, it affects 1% of any population on earth. It doesn't discriminate between rich, poor, race, et cetera. It has no discrimination. What is epilepsy? So broadly speaking there are two types. There's a focal epilepsy, where there's one area of the brain which fires off, results in symptoms. Or the second type, this is very broad, the second type is a genetic epilepsy, which is an epilepsy that has more involvement of the subcortical and cortical systems.

Host: You might be familiar with the idea of epilepsy causing tonic-clonic seizures, where a person loses consciousness and experiences muscle contractions. But this isn't the only way that epilepsy can manifest.

Dr Dionisio: Epilepsy can manifest in really any way. When we talk about epilepsy, the average person thinks that it's the convulsion, so the person who's shaking all over, frothing at the mouth, but that's not for everyone. Epilepsy can also be very experiential feelings and signs as well. For example, people can get all types of manifestations. They can get déjà vu, where they feel that they've been there before. They can feel fear, which may be misdiagnosed as a panic attack, and proceed onto a loss of awareness. There may be singing, where people just start singing out of the blue. There may be people who suddenly have a personality change and become very angry. There can be hallucinations, visual hallucinations, auditory hallucinations.

It really depends on which part of the brain is affected. Some people may even get their heart rate starting to fall down and plummet as a manifestation of their seizures. Again, epilepsy can manifest in many, many different ways.

Host: For people whose seizures affect them more subtly, getting an epilepsy diagnosis can take time.

Dr Dionisio: It's usually an astute GP who picks up the fact that these are very stereotyped. That's the key. That they're always the same. That the memory's always the same, for example. Or the feeling that they get in their stomach and then the salivating associated with it is always the same. The stereotyped presentation is usually the key, but you're quite right, that's often difficult to pick up and usually what happens in the clinic is we see somebody's who's had a convulsive seizure and then we ask them, "Have you had any seizures before?" And they say, "No, that's my first one." Then you go back in history and say, "Do you ever get feelings that, for example, you've been there before?" And they're like, "Oh, Déjà vu?" And you say, "Yup."

They say, "Yeah, I get that, and then I feel fearful." I say, "Okay, and is that always the same?" "Yeah, yeah. It's always the same. But that's not a seizure." And you start to put it together, and in fact it is. And then you go back, "And how long's this been happening for?" "Oh, it's been happening two or three years." "Well, that's epilepsy. Those are seizures."

Host: So, what causes epilepsy? Dr Dionisio says that sometimes the root cause of epilepsy can be identified, while for other patients, the cause of their epilepsy remains a mystery.

Dr Dionisio: When you have seizures coming from one area of the brain, the cause of that is potentially what's important. What is the cause, first of all? When we're in the clinic we always ask for risk factors? Has this person had a brain infection that then caused scar tissue, that then caused the epilepsy from that area of the brain? Had they had prolonged febrile convulsions? The emphasis is on prolonged, because febrile convulsions are common, but they're not common if they go on for one to two minutes. That's a prolonged febrile convulsion.

Other things, have they had head injury? But many times, there's no obviously cause, and then in a situation of focal epilepsy, we're dealing with something called a focal cortical dysplasia. It's a bit of a mouthful, so what does it mean? So, when a brain is developing you've got cells that really have to track wide regions of space in order to connect and form or be the final brain. In some situations, and we don't really know what causes this, if those cells don't get together or don't meet their counterparts they're basically just grow in and not develop further, and as the rest of the brain develops, this area may not. As a result, it'll start to fire, and in time that surrounding sparking almost starts to affect other regions and cause symptoms.

With that logic, epilepsy doesn't happen at the first seizure. It's a process that was probably happening in the background, and finally when it's effected enough regions is when it presents itself.

Host: The treatment required for epilepsy depends on a number of factors, including what kind of seizures the person is experiencing and what part of their brain is affected.

Dr Dionisio: The mainstay of treatment is with medicines, so all patients, irrespective if it's a focal epilepsy, or a generalized epilepsy, will have medication treatment. Usually with the generalized epilepsies, it's a lifelong epilepsy, and with medication though they are controlled. They're very well controlled. In fact, most people with epilepsy are very well controlled. In the focal epilepsies, about 30% will not be controlled. And a little bit less in the generalized epilepsies. But in the focal epilepsies about 30% are not controlled. In these situations, not being controlled is defined as failing two or more appropriately chosen medications.

In these patients the treatment is very different, and one of the mainstays of treatment is epilepsy surgery. So, as I said to you, epilepsy affects 1% of the population. In Queensland, roughly it's 100,000 people with epilepsy, 70,000 people will be well controlled, but there's approximately 20,000 to 30,000 people out there that will require surgery. It's huge. Now, surgery is not so straightforward. It's very complicated and it's very involved. But in the situation where medications are not working, then surgical therapy is really the choice.

Host: Dr Dionisio isn't a surgeon but is often involved in his patients' epilepsy surgery. We asked him, what's it like to watch a brain operation?

Dr Dionisio: It's fascinating. I mean, it depends on what kind of operation we're dealing with. When we deal with epilepsy surgery, there may be potentially many stages. The final outcome is actually removal of that part of the brain where the seizures are coming from, but epilepsy surgery also involves other things. For example, we may need to locate exactly where the seizures are coming from. If the patient has a "normal" MRI, and it's not seen, we then have to go hunting for this. We will place electrodes into the brain to try and pinpoint the location of where the seizures are coming from.

Sometimes if we are close to very important language areas, or movement areas, the patient may have to be awake during surgery. And at that point we put electrodes on the top of the head, when the head's been exposed and open, and we stimulate to see if we stimulate the region, is a patient going to stop talking? So, the surgeon and ourselves will carefully delineate which are the language areas, and when the surgeon cuts around that region, he'll avoid all the areas that we've identified as being language areas.

Host: If you think having brain surgery while you're awake sounds scary, Dr Dionisio says that you're right, it is!

Dr Dionisio: I think it's terrifying for the patient. I mean, if I put myself in that situation, I'll be absolutely terrified. It's not a situation that is very common. That's the first thing, so that's good. But when we do have to do it, we spend a long time with the patient, and we go through a lot of dry runs. In our experience, all our patients have been fine so far.

Host: After all you've learned about your brain and how powerful it is, you'd be right to wonder what you can do to keep yours healthy and in great condition. Dr Dionisio shared his tips.

Dr Dionisio: Look, I think that this is a really interesting question. We live in a society where we use our brain less and less. Where due to a culture of consumption, we think less, we are less critical, we read less books, we're entertained more than constantly thinking, and I think that's really important. I think that's really important that we keep reading, that we keep asking questions, and keep analysing and be critical. And simple stuff, exercising. It'd be a bit weird, but I think meditation would be wonderful, if people would really consider that.

Things like meditation are very powerful, because meditation, when a person meditates, they absolutely engage their prefrontal cortex to a level that usually is seen only with intense studying or intense problem solving. So, there's something huge in meditation as well.

Simple things, like diet and smoking. Not smoking. Please watch out for alcohol. Alcohol's extremely toxic to neurons, to the brain, and will damage the brain. I mean, I myself don't drink, and it's for this reason, because of the work I do, but I ... Yeah, I think those are simple things.

Host: Looking to making some changes for the sake of your brain health? For information about how to start meditating, quit smoking, drink less alcohol or improve your diet, visit the shownotes on our website.

Dr Dionisio clearly loves his job. We asked him why he does what he does, and what breakthroughs he hopes to see during his career.

Dr Dionisio: Best part of the job is really being able to help my patients. That may be a bit of a cliché, but it's massive. I think when the patient comes to us with epilepsy, they're hugely effected, their family's hugely effected. It's more than just the seizure, it's everything that surrounds the seizure. We spend a lot of time working with our patients. It's one-to-one. It's long days. Especially when we're doing things like epilepsy surgery, it's very involved, and we become attached to people as well. And to see them going from having seizures to being completely seizure free, to being able to function again, to see the way they develop, and flourish is just the best thing.

With that kind of work, we're very privileged, because we get to really look closely into the brain and how it functions. I'll often say to my team, we're in this amazing opportunity. It's like when I read the old books about the sailors who were traveling the world because they assumed the world was flat, even though there are people today that think the world is flat.

When you read those old stories, and you see the adventure that they're embarking on and how there are so many unknowns, and how they're discovering so many things, it's very similar to the work that we're doing. We're in this amazingly privileged position to be able to do this and to help people, most importantly.

If there's one thing with all my heart that I'd really love to solve, it'll be to understand what is epilepsy, and why it happens, and more than that how to stop it. Because, to me, it's my fight.

Host: Thank you for listening to this episode of My Amazing Body. This is the final episode for season 1 of our podcast. Have thoughts on the season or what we should do next? We invite you to fill out a quick survey to tell us what you liked about My Amazing Body, what you think could be better, and what podcast topics you'd like to hear about in the future. Head to qld.health/mabsurvey to fill out the survey. You can also find the link in our shownotes.

Before we go, did you guess this episode's Mystery Body Part? The very sensitive, uniquely printed part of your body are you lips! Congratulations if you figured it out.

My Amazing Body is brought to you by Queensland Health. With special thanks to our expert guest Dr Dionisio, the media team at Metro South Hospital and Health Service and my podcast colleagues - Lauren our researcher, writer and producer, Carol our audio technician, Dan our music guru and Helen on sound effects.

Last updated: 21 October 2019