This lesson is called Damage and disease in the human brain, including CT and PET scanning, and is from the unit Coordination and control: the human nervous system.

Hi there.

My name's Mrs. McCready and I'm here to guide you through today's lesson, so thank you very much for joining me today.

In our lesson today, we're going to describe some of the difficulties in studying and treating damage in the nervous system and the brain, and we're gonna have a look at some specific techniques used to help to understand what is going on.

Now, we're gonna come across a good number of keywords in our lesson today, and they're listed up here on the screen for you now.

You may wish to pause the video and make a note of them, but I will introduce them to you as we come across them.

So in our lesson today, we're going to first of all look at investigating brain function and damage and some of the problems that are associated with this, before we zoom in on two specific techniques, CT and PET scanning.

Once we've considered them, we're then going to have a look at how we might treat the brain and the nervous system and some of the problems and some of the developing technologies for that.

So, are you ready to go? I certainly am.

Let's get started.

So we know that the brain is a hugely complicated organ, and it's also incredibly fascinating, because after all, it controls everything about our body and our personality.

But when we look at the brain, say perhaps removing one from a recently dead animal, we can't really tell very much about how it works just by its appearance.

So by looking at it, we can see that it has two halves to it, two hemispheres.

We can see that it is highly folded.

You can see all of those folds within those red streaks on the diagram there.

And we can see that it's got a really good blood supply, so it needs a lot of oxygen, it needs a lot of nutrients.

But other than that, that's about all that we can tell.

And even if we zoom in using a microscope, we can't really tell much more detail about how the brain actually functions, in other words, what parts of the brain are controlling what parts of our body, just by looking at it.

So this makes understanding how the brain works really, really difficult to do, but it's really important that we understand how the brain functions because if someone develops brain damage of some form, we need to be able to understand how the brain works in order to be able to predict the kind of damage that is likely to have been incurred by that damage.

So if a certain part of the brain gets damaged, say within a stroke, then if we understand how the brain works, we can then predict what damage that patient is likely to have upon recovery.

But if we don't understand what the various different parts of the brain do in the first place, then we couldn't possibly make those predictions secondarily.

It's also really important to be able to understand how the brain works if we want to develop treatments for damage and disease that might be incurred to the brain.

So diseases might include dementia and Parkinson's disease, epilepsy and depression, and maybe brain damages from injuries, such as sustained through an accident, a car crash, for instance.

These are all instances where damage can be caused to the brain.

And not only do we want to know what damage has been inflicted, but we also want to treat it and improve the condition for the patient.

So understanding how the brain functions is really important to both understanding what part does what and how we might then go and improve that function should it be damaged.

However, there are lots of different problems associated with doing this kind of research.

Firstly, we're dealing with patients who are living, and when we're dealing with any living organism, be that human, lab mouse, a plant, we have to do so ethically.

Now, doing so ethically means that we consider the impact of all of the actions that we are going to be taking on the patient.

So that means that the actions that we're taking, the consequences that those actions will have, are they right? Are they fair? Are they moral? Will they cause harm? And if they're going to cause harm, then we shouldn't do them.

So trying to be ethical in our approach means that we are trying to be considerate of the actions that we're taking and the consequences that those actions will have, and we're trying to make sure that those consequences are right, they are fair, they are moral, and that they don't cause harm.

So if the actions that we are taking have damaging consequences, then they are not ethical, and we need to be ethical in all of the approaches that we take when we're dealing with any living organism, be that human, lab rat, or plant, for instance.

Now, with humans, ethical practises also involve seeking informed consent.

Now, informed consent means that the patient fully understands what they are agreeing to before they give their consent.

So we haven't just asked them to sign on a dotted line without explaining what they are agreeing to, and we aren't just carrying on without asking for their permission in the first place.

Now, there's a real difference here to be very clear about.

Getting someone to sign on a dotted line does not equal informed consent, and in fact, informed consent does not require a signature.

It requires the patient to be of understanding of what is going to happen.

Now, they might not be able to sign on the dotted line, but if they understand what is going to happen to them, then they can give consent.

Conversely, you could ask somebody sign on a dotted line and then not understand what on earth they're signing up to.

So just because they've signed doesn't mean to say they are giving informed consent.

It's really important that informed consent is obtained before procedures and research is then carried out.

There are some other ethical issues and hurdles that have to be overcome when we're studying the brain.

So firstly, when we're trying to study the brain, we've got to get access to it, and that involves removing part of the skull, and removing part of the skull instantly exposes the brain to potential damage.

It might not necessarily damage the brain, but it highly increases the risk of brain damage being incurred.

So, accessing the brain via the skull is in itself really precarious and potentially very damaging.

Furthermore, we need to make sure that they have consented with understanding in order for us to carry out brain research.

And then alternatives to that might be involving lab animals, for instance.

But damaging an animal's brain just to see the effects of that damage is in itself very difficult to justify, especially when there are other techniques available to be used.

So studying the brain, given that when we look at it it doesn't really tell us very much, is really, really challenging.

Now, some of our understanding has come from researching people who have sustained significant damage to their brains, and this has often been through investigating the damage caused by warfare to soldiers, or to people from significant injury, such as through a car crash, or from disease, like cancer.

Historically, these techniques have provided us with a lot of information about how the brain works and was a great starting point.

However, the morality and the ethics sitting behind these research methods are questionable, and we wouldn't be able to use these techniques in our modern-day society, and quite rightly so.

However, with developments in technology, there have been significant developments in the way that we can research the function of the brain, and we're gonna have a look at some of these techniques in a little bit.

These have created quite a significant improvement in how we understand what parts of the brain are controlling what parts of our body or personality.

So, let's quickly check our understanding on this term ethical practises.

What does that mean? Does it mean A, good and godly, B, moral and right, or C, no injury caused? I'll give you five seconds to think about it.

Okay, so ethical practises means moral and right.

Did you get that correct? Well done if you did.

What about this term informed consent? So what does that mean? Does it mean A, the patient can sign on the dotted line, B, the patient has been told about what is going to happen, or C, the patient understands what they are agreeing to? Again, I'll give you five seconds to think about it.

So informed consent means that the patient understands what they are agreeing to.

But remember, it doesn't require a signature on the dotted line and it doesn't just involve them being told.

What about this then? Which of these statements indicate ethical issues involved in studying patients with brain damage? So is it A, the patient may not benefit from the research, B, the patient's brain function may be severely limited from the stroke, C, the patient may not be able to consent to the research, or D, the brain is a dense mass of neurons and connective tissue? But which of these are ethical issues? Again, I'll give you five seconds to think about it.

Okay, so from this list, you should have chosen that A, the patient may not benefit from the research, and C, the patient may not be able to consent to the research, are both ethical issues.

Now, whilst B and D are true, they aren't ethical issues, which is why we haven't indicated these as correct.

If you got both of those correct, well done indeed.

So what I'd like you to do now is to consolidate our understanding about investigating brain function and damage by considering these two generalised techniques of causing deliberate damage to laboratory animal brains or using equipment to take a live brain scan of humans.

So what I'd like you to do is to describe the benefits and the problems with these two techniques, that's deliberately damaging lab animals or using equipment to scan live human brains.

So I'd like you to describe the benefits and the problems of these techniques when we are trying to learn more about brain function.

So pause the video and come back to me when you're ready.

Okay, let's see what you've included then.

So I asked you to describe the benefits and problems of using lab animals and human live brain scans when we're trying to learn more about how the brain functions.

So for lab animals, you should have included that the benefits include that damage can be caused very precisely, and that therefore can be used to identify specific areas of brain activity with their function.

However, the problems are that the ethics to do with this technique are very challenging, because what we are doing is causing deliberate harm to the animal, and that's very difficult to justify.

However, with the brain scans of humans, you should have identified that the benefits are that they are not harmful techniques; they are completely ethical and can be done with informed consent and without causing harm.

However, the problems are that interpreting the data that we get from these sorts of scans is really complex, and it's also really difficult to get people to sign up to these studies.

And sometimes this is because patients aren't actually able to do that because of the type of brain damage that they have incurred.

And also when you're that poorly, you might not want to do anything other than focus on medical treatment and getting as well as you can do.

So have you included all of those aspects within your answer? Add anything in that you have missed.

And well done.

Even if you've come up with only a few of these suggestions, that's excellent, because trying to identify the ethics and the moralities around these techniques is really quite challenging.

So good job, well done.

So in this part of the lesson, we're going to have a look at how we can investigate brain function using CT and PET scanning techniques.

So let's start with CT scanning.

So CT stands for computed tomography, and CT is a technique that is used to build up a picture of what is going on inside the body.

Again, it's essentially taking snapshot layer photographs of the brain or whichever part of the body you're investigating and building them up into either a 3D model or a series of sliced photographs.

Now, in order to do that, it uses x-rays, and the patient's body or the part of the body which is of interest is scanned using x-rays whilst they are lying down on a bed.

So the patient lies on the bed and then they move into the circular CT scanner, and once in, the x-ray scanner and the detector orbit the body taking scans through the body.

So you've got the detector on one side and the scanner on the other, and they orbit the body.

Now, the images that are generated show slices through the patient's body, and these slices can be then analysed and interrogated separately.

Now, you can see that kind of separate slices of pictures through the brain in the picture on that slide.

And it's worth noting that CT scanning is safe for people who have metal implants, such as mechanical heart valves or pacemakers or replacement joints, for instance, whereas other scanning techniques may not be able to be used for people with these conditions with these metal implants because of the types of technology that they're using.

However, it's worth bearing in mind that CT scanners are using x-rays, and of course, x-rays emit ionising radiation.

So there is a benefit-risk analysis to be done here.

Is the benefit of having the CT scan more than the risk of being exposed to ionising radiation? Where does that risk-benefit balance lie and how therefore should the patient and the medical team respond to that? So let's quickly check our understanding about CT scans.

Which of these are true? A, that CT scans use gamma rays, B, that CT scans use ionising radiation, or C, that CT scans can be used by people with a pacemaker? Which are correct? I'll give you five seconds to think about it.

Okay, so you should have said that A is incorrect, CT scans use x-rays, not gamma rays; that CT scans do use ionising radiation nevertheless; and that they can be used by people with a pacemaker.

So B and C are correct and A is incorrect.

If you spotted all of those, well done indeed.

So let's have a look at PET scanning.

So PET stands for positron emission tomography, and PET scanning is another technique that can be used to obtain internal body scans; not just of the brain, but of the whole body.

Now, PET scanners use a radioactive substance which emits a gamma ray, and then the scanner itself detects the gamma ray and can build up a picture of the body through that.

So radioactive glucose is used which has got a radioactive fluoride ion attached to it, and as that decays, it emits a gamma ray.

So in order for this technique to function properly, the patient needs to be given a dose of radioactive glucose before they are scanned.

So they're given a glass of radioactive glucose, essentially a sweet drink, specific sweet drink, and this is called a tracer.

So the radioactive glucose is administered to the patient and then it's given time to be absorbed into their bloodstream.

So glucose is used by all cells in the process of respiration, and the more active a cell is, the more glucose it requires.

So the more active a cell is, the more radioactive glucose it will take on, and therefore the more gamma rays it will emit.

So the radioactive glucose, the radioactive fluoride ion, that decays, and a gamma ray is emitted which can be detected by the PET scanner.

And the scanner is detecting these gamma rays which are being emitted by the radioactive glucose as it decays and is able to build up a picture of activity within the body.

So areas which have higher activity are coloured in red and areas with lower activity are coloured in a darker colour, dark blue.

So in some PET scans, patients will complete a task whilst they're being scanned.

In other cases, they may lie still.

Either way, areas of the brain which are most active at the time of being scanned will show up as being more active by the scanner because of this uptake and use of glucose and the release of gamma rays from the decaying radioactive glucose.

That also means that areas where brain activity is abnormal or missing can also be identified, and this means identifying brain damage through disease or injury is relatively straightforward to identify.

So, let's quickly check our understanding who has correctly explained part of how a PET scanner works? Aisha says, "The PET scanner detects gamma rays released from decaying glucose molecules." Lucas says, "The more active a part of the brain is, the more radioactive glucose it absorbs." And Laura says, "Areas of high activity are healthy areas, and areas of low activity are not." But who has correctly explained part of how a PET scanner works? I'll give you five seconds to think about it.

Okay, so let's see what you decided.

So you should have said that Aisha is correct in her explanation and so is Lucas, but Laura is not correct, because areas of high activity do not necessarily equal healthy areas.

Did you get both of those correct? Well done if you did.

So what I'd like you to do now is to consolidate your understanding about CT and PET scanning by creating a patient information leaflet of these two procedures.

And in the patient information leaflet, I would like you to include a description of each of the procedures, how they stimulate or create an image of the brain, what they might be able to treat or observe, and any restrictions or cautions that need to be heeded.

So pause the video and come back to me when you're ready.

So let's have a look and see what you've written.

So for CT scanning, you might have included that CT or computer tomography scanning uses x-rays, and the patient lies on a bed which is inserted into the scanner, and then the x-ray machine and its detector circle the patient and scan slices of their body at a time.

These images are then built up into a detailed picture and can be used to identify areas of abnormal or missing activity.

Now, the CT scanner is safe for people with a metal implant, but it does come with the risk of being exposed to low levels of ionising radiation.

So did you get all of those points? Well done if you included them all, and add to your notes if you've got any missing.

So now let's have a look at PET scanning.

So for PET scanning you might have included that PET or positron emission tomography scanning uses radioactive glucose, so the patient ingests or is injected with the glucose tracer, and this is used by cells throughout the body in the process of respiration.

Now, the more active the cell is, the more glucose it will absorb, and when the radioactive element of the glucose decays, gamma rays are emitted and these can be detected by the PET scanner.

You might also have included that the gamma rays are then picked up by the PET scanner and turned into a detailed picture of the patient's body.

And in some occasions, the patient completes tasks whilst they're in the scanner.

Now, the more active parts of the brain are identified by the PET scanner, and this can be used to research brain function and it can also be used to identify areas that are damaged due to injury or disease.

So just check over your work, make sure you've got all of those salient points as well.

Add to your notes anything that you're missing, and well done again, that was quite a detailed task to get through.

Now, in the last part of the lesson, we're going to have a look at how we might treat the brain and the nervous system.

So when we're dealing with the brain and the nervous system, we're ultimately talking about neurons.

Now, neurons are extremely complex cells, and you can see just a glimmer of that from the image there on the screen.

They have many different parts to them, each of which is highly specialised.

They are very long cells often, and they interconnect with many, many other cells in very specific ways.

So they are very complex, and that makes them incredibly difficult to treat if they become damaged through disease or injury.

Added to that is the fact that neurons cannot undergo mitosis, and mitosis is a form of cell division which creates identical copies of the original cell.

Now, neurons, because they are so complex in their structure, that is what is prohibiting them, preventing them from completing mitosis.

So neurons cannot make new copies of themselves through this process of mitosis, and this means that they cannot fix themselves, in addition to the fact that it's incredibly difficult for us to fix them too.

Put the two together and it makes treating any neuron-related damage incredibly difficult to complete.

Added to that the problem of the very important role of coordination and response that the nervous system has within our body.

If we start tinkering around with different parts of the brain or the neurons in the nervous system, we have to do so extremely carefully, because one false move, one minor mistake, could lead to irreversible loss of function for a particular part of the body, and that would be disastrous.

Because not only would it have caused more damage than we had before, it's also incredibly difficult to then undo that damage that has been caused because neurons can't fix themselves because they cannot undertake mitosis, and because they are so complex, it's very difficult for us to fix them for them too.

Now, when we're talking about certain types of brain damage or disease, there are certain techniques that we can use to help manage those conditions.

So for instance, epilepsy, Parkinson's, and depression are all diseases that can be treated or at least managed through certain types of brain stimulation, for instance.

Now, brain stimulation is about triggering certain parts of the brain into being activated, and for certain conditions and for certain patients, this might be a useful technique to use.

However, what is on the cutting edge of science is whether stem cells can be used to grow replacement neurons, because that ultimately might actually be the easier way of dealing with problems to do with nervous system if we can simply take a damaged neuron or neurons out and replace it with some new ones.

So what's a stem cell? A stem cell is an undifferentiated cell.

That means it has no particular function at present; it has yet to differentiate into its specific role.

And stem cells come from a number of different places, including embryos, and in adults in bone marrow, and stem cells can then differentiate into a specialised cell, one of many, and a neuron is one of those.

So we could possibly take a stem cell, an undifferentiated cell, and differentiate it into a neuron.

Now, that process of differentiating a stem cell into a specific cell can happen in a lab, and by happening in the lab it can be used to create tissue.

Now, this is a potential technique for replacing large sections of damaged tissue, such as large sections of pancreas in patients with type I diabetes.

Alternatively, stem cells could be injected into the damaged area and then triggered to differentiate and grow in situ.

That means in the location required.

Now, this would be more suitable for replacing neurons because they're not large organs like the pancreas, but instead a few very fine strands bundled together, such as in the spine.

And if someone has, for instance, damaged their spine and become paralysed, from say the waist down, if stem cells can be inserted into where the damaged part of the spine is and then triggered to differentiate into neurons, it's possible that those stem cells can turn into neurons and essentially bridge the gap between the top half of the body which is working and the paralysed lower half which has been severed from the top half, bridge that gap and restore function.

And in fact, that's actually been done in the UK, and whilst it's still a work in progress, it is leading to some remarkable improvements in patients' quality of life, where people who have been paralysed and are unable to walk are suddenly able to start to learn to walk again.

It's really quite remarkable.

So we've got these two uses for stem cells, one, either growing them in a lab and then inserting whole pieces of tissue into the patient, or inserting the stem cells directly into the patient and then triggering them to differentiate into the specific type of cell that is required, such as a neuron.

So, let's check our understanding.

What is a stem cell? Is it A, a specialised cell, B, a differentiated cell, or C, an undifferentiated cell? I'll give you five seconds to think about it.

So a stem cell is an undifferentiated cell.

Well done if you got that right.

What about this then? Damage to neurons is difficult to repair because the cell cannot undergo meiosis.

Is this true or false? I'll give you five seconds to think about it.

Okay, you should have said that that is false, but why? Okay, so you should have said that that is false because neurons are very complex cells and cannot undergo mitosis to create new copies of themselves, not meiosis.

Be careful of those two forms of cell replication, because they are different, and well done if you got both of those right.

So what I'd like you to do now to conclude our lesson is to firstly define the term stem cell and then describe how, theoretically, patients who have suffered extensive injury to the nerves in the spinal cord, leaving them paralysed, may be able to walk again with stem cell treatment.

So, pause the video and come back to me when you're ready.

Okay, let's see how you got on.

So firstly, I asked you to define the term stem cell.

So you should have said that a stem cell is an undifferentiated cell which can differentiate into any specialised cell.

Then I asked you to describe how people who have been paralysed may be able to use stem cell treatment to learn to walk again.

And you should have said that stem cells are able to differentiate into neurons, and if they are injected into the body where the new neurons are required, such as in the spinal cord where the damage is, then they may be able to differentiate into neurons and repair the damage.

And as I said, this is actually happening.

This research has been proven, in its infancy, to work.

So check over your work and well done if you got those right.

Okay, so we've come to the end of our lesson, and gosh, that was quite a long complex lesson as well, so well done for getting through it.

So in our lesson today, we've seen that it's really difficult to study the brain and learn how it functions and how it's affected by disease and injury because of the very complex nature of the brain and also how little we can tell by just looking at it.

We've also seen that in addition to the complexities of the anatomy of the brain, the extra complexities of having to conduct research that is safe and ethical and with the informed consent of patients adds to the complexity of analysing and assessing the brain itself.

Now, we've seen that there are many techniques available for studying live brain function, including CT and PET scanning, but these are quite complex techniques in themselves, but they are able to give us a good idea of what's going on inside the brain.

We've also seen that treating brain damage through disease and injury is really difficult, in part because of the complex nature of the structure of neurons and the fact that they cannot repair themselves because they can't enter mitosis.

We've also seen, however, that the use of stem cells is offering some really promising opportunities for treating diseases of the nervous system.

It's complex, but it's been proven to be possible, and so it's still work in progress.

So I hope you found that an interesting lesson and I hope to see you again soon.

Bye!.