Neuro 11:1 Transcript PDF

Created with Coconote - https://coconote.app Neuro 11: 1 Is that on? That's loud. Is that better? Good morning. How are you? Good. Good. That was our reluctant good. It's a busy time. The whole term is busy, but I'm I am imagining that this is an extra busy time. So just to bring them all up to...

Created with Coconote - https://coconote.app Neuro 11: 1 Is that on? That's loud. Is that better? Good morning. How are you? Good. Good. That was our reluctant good. It's a busy time. The whole term is busy, but I'm I am imagining that this is an extra busy time. So just to bring them all up to date on where we are at in this class, what we're going to do today is start talking about cognitive and behavioral disorders, that result from brain damage and how different functions like language and memory and perception and spatial skills and so forth are organized by different brain circuitry. The way I do this, because I think it's the most interesting way and it's also one of the methods that has, probably yielded the greatest insights into how the brain works for these different functions, is through talking about the brain systems and then talking about how these systems break down. So for example, in the case of of language, we'll talk about aphasia in brief. In the case of memory, we'll talk about different types of amnesia and so forth. And for each of these categories, I have 1 or more videos to show you, which I think are really interesting and highlight in a really striking way, how you can have language, for example, breakdown into all these different sociable components. Don't be overwhelmed by this reading list. The textbook organizes this content differently than the way I teach it in class. I find it most helpful to have this content at the end, as opposed to your textbook, which pretty much is organized by lobe. So for example, in the chapter on frontal lobe function, it would cover everything from motor functions through to executive system functions. To me, it makes more sense to do sensory and motor functions, which are kind of core processes near the beginning and then move to these higher level processes. So I had attempted to find where the different disorders and the systems are talked about in the textbook in the 2 different editions. I'm not sure which one you're using. I may have missed a few. And, again, for chapters 18 and 19, one's on asymmetry and one's on plasticity. I have, next week, maybe 3 slides on each of those topics. So I'm not expecting you to read the 100 pages that are dedicated to those topics, but you might find it helpful to flip through and see, some of the issues that have come up that we'll briefly talk about in class. And if we're talking about different, functions, if you're using the online well, actually, even if you're using a paper version of the the book, and I've left one at the front desk. If you don't have one, it might just be easiest to look up in the back, index, aphasia, and go to the 4 pages that talk about aphasia or whatnot. Anyways, this is not meant to overwhelm you at this point in the course. It's just the way it's organized. So that's what we're doing this Monday and then next Monday. I, unfortunately, was given Monday classes this year, which I've never had before. We have no we have no say over what day we get, which means that actually next week, we were scheduled to have the makeup Monday classes because of Thanksgiving and the what's the other holiday? Because Remembrance Day, we were scheduled to have Monday, Tuesday, and Wednesday, Monday classes, which to me is crazy because that's a quarter of the course in the last week. So that's why you're doing your presentations on Tuesday and then Wednesday. Although, it will say in your schedule that there is a class, there is no class because what I did to make up for the class time was to do your test outside of class time. So that's those 3 hours. So we have today and the next Monday Tuesday. This Wednesday is your test, and the test covers not this content. It covers neuroimaging and the different etiologies, stroke, traumatic brain injury, and so forth. If you have any questions about that, please reach out in person, email, whatever as you're studying for that material. Do you need to provide us a certification? I will send out an email. I think it's in the dentistry building. Maybe the 4th floor. I'll have to check. Crystal will book the rooms. It I I think the room was booked from 8:30 to 10:15 or something like that. But what we'll do is we'll start approximately at at 8:30 5 at the normal class time, and the test will be identical. Fifty questions, multiple choice, not identical question, but identical format. Fifty questions, multiple choice. I know of an hour and it's self paced and so forth. And then, next week, we'll try to have time either on the Monday or the Tuesday for you to look at the results of that. I can't one of those 2 days. So it'll probably be some time after your presentations, because we won't those won't take the full class. With respect to your presentations, I know you all have topics. I'm not sure if you all signed up on the, topic list. If you haven't, put your topic in. They're great topics. I'm excited to hear what you're gonna teach the class in 8 minutes about these really neat ideas. I have talked to a couple of you about strategies to take because they're really big topics, some of them. And the general sort of piece of advice that I've been giving is if you can find a current review article, a current book chapter, something that's really high quality that gives you a starting point to give you a bit of, a a bit of an overview of it of whatever area you've chosen. And then pick something that is more specific that you want to talk about for the rest of the time. But make sure at the start of the presentation that you provide the class and me with a bit of context. So don't delve, like, right into your specific topic. You need to have, like, a slide or 2 or 3, depending on what your topic is. It provides a bit of a framework. And as much as you can, although I know we haven't talked about these, this topic yet, try to situate it within what we've talked about in class. So, what we've talked about in class. So, for example, I know there's one group that's gonna be looking at a kind of a new technological method for treating Broca's aphasia. You can look ahead in the slides. Actually, we'll talk about today to see what I'm gonna say about Broca's aphasia. So you don't need to reiterate what Broca's aphasia is, but pick up at the point that I leave off if that is it it must be you too because you're nodding. And similarly with the other topics. And if you have any questions, like, please, I'm here to help. So just email me. I can I'm happy to meet with 1 or more of the group members to try to, guide you. So 8 minutes of what interested you about the topic. How recent do you want our sources to be? Like, we were potentially looking at one source by. That's What's your topic again? It's right. Oh, right. Yeah. Stroke, how it affects language. So there we potentially had a source by that's a little bit older. Mhmm. Well, I can talk to you specifically about that after class. In terms of how recent something should be, it's really gonna depend on what the topic is. Some of that work, I know well, and some of the really high quality work is not super recent. So it might be very appropriate to use sort of a more classic reading that's from a decade ago. Mhmm. But for some other topics, particularly the ones that are more perhaps technologically driven or really, like, new things. You wanna make sure it's recent and make sure it's something that's high quality, like, in a, like, a well regarded, like, peer reviewed journal. As far as you can tell, it looks like something that, Shelley McGibbon, who gave a librarian talk at the start several months ago, something that she would regard as being, like, a high quality source. If you have any questions about whether you think something's high quality or not, just ask. I don't know all your areas really well, but I know enough to probably guide you a little bit. But, yes, let's talk at the break or after class. Okay. And, any questions about that? Okay. So What we're going to do, is we're gonna start talking about some of the, to me, the most interesting parts of, neuroscience. And I will I know I'm not even gonna, like, ask you to read anything or even suggest that you read anything extra at this point in time. But I have posted in this, section of the course on Brightspace a number of readings by a neurologist, a neurologist, who was an American neurologist who has now, passed away, who became very well known in this area, Oliver Sacks. I know some of you, put up your hand if you've read anything by Oliver Sacks. Okay. A few of you. Oliver Sacks is how I ended up in this field. I took, like, a 2nd year brain and behavior course at Queen's University in Ontario, and, our my professor, made us read a couple of his, chapters, and I thought, what could be more interesting than this? They're really interesting case reports about patients that have different disorders. They're interesting. They're inspiring. They're, I don't know, life affirming. They're just really wonderful. I mean, he's a wonderful writer. And he wrote a column in the New Yorker magazine, for years about his cases. So they're really accessible. You don't need to be, like, a neuroscience expert to read them. My one of my daughters who did her degree in sociology read a whole bunch of his stuff and was just fascinated and had nothing to do with her academic background. Anyway, so when you have time, I highly recommend you read some of these things. And those of you who are in the speech program, next term, I'm going to make you read a couple of his, chapters that were on aphasia because they're really fascinating. So that's they're in. Download them if you, think of it, but I'm certainly not expecting you to read them right now, because I know you're all very busy. So this should look somewhat familiar, and I'm not gonna talk about all these different, core processes. But just a reminder, that, the cortex and what we're talking about here for the most part are cortical functions. The cortex is organized into primary, secondary, and tertiary areas. Primary areas, we directly receive, the sensory input, used both for most senses through the thalamus. And in the motor, cortex, it's the last step before descending signals get sent down, to the lower level, motor processes. Secondary areas start to interpret, the inputs. So for example, in the auditory sense, the primary map is for frequency. The secondary processing levels would start to do things like recognize a frequency as being, or a set of frequencies as being a whistle or a telephone or a word, not necessarily applying meaning to what that word is, but recognizing, like, external environmental noise from speech. The tertiary areas basically are the rest of the cortex. So if it's not primary and it's not secondary, then it would be tertiary. Another word for tertiary that your textbook uses and other sources use as well is association cortex. And why do you think the rest of the cortex might be called association cortex? It came about for a that term came about for a logical reason. What did the the tertiary areas do? Like, applies meaning to the word, so that could be including, like, retrieving memories from it or, like, kind of taking info from different senses and putting it all together for Absolutely. So the the tertiary association areas are not sensory specific. They're not process specific. So in the area of language, for example, you would have a word and associated with that word would be sounds, phonology. It would be visual, like you can read the same word. You could if you know braille, you could enter the word meaning through the sense of touch. You would have memories associated with it. You would have perhaps specific people if it's, like, the name of your dog. You have a visual image of what your dog looks like. So we're looking at a whole bunch of different processes when you look at association cortex. Cortex. And what association cortex does is bring all these processes together into some higher level, concept or or function. And that would be things like language, executive functioning. Executive function involves a bunch of different processes, but for something like planning or decision making, that doesn't rely on one sense. That's relies on a whole bunch of different things and past experiences and, sensory processes and so forth. So I have to memorize this, but this is from when I took neuroscience years ago. Maybe some of you have used this book because there have been many editions over the years, but Kendall and Schwartz, Principles of Neuroscience. It's this big it actually served as my monitor stand for many years. It's I didn't look at it after I took neuroscience in my undergrad and masters. But it's this big, big book, electronic now, that talks about neuroscience. And I just scanned this, from the section on, visual object processing. And this is showing different parts, visual object processing. And this is showing different parts of the brain, starting down here. V1 would be primary visual cortex. And then some of these other areas are in the occipital lobe, some are in the temporal and parietal lobes, but it's showing all the known pathways and connections between these different areas. And so I just put this here to highlight the fact that these are really, really complicated processes. And what we are doing in this class is just, like, the tiniest, tiniest bit. So just keep in mind, these are highly complex processes. And what I'm presenting here is really, really just a few examples, that I thought were relevant and interesting. Okay. So these are the functions we're gonna be talking about today and next time. And for most of them, I have, a sample, or more than one sample of a video that shows how these processes break down. Today, we'll talk about language and memory, and we may or may not get 2 executive functions. And the others we'll do next time. So in terms of language, in most people, and we'll talk a little bit towards the end of next class, how there are some variations in how the cortex is organized across people. But in most people, language is in the left hemisphere. And we have talked about these different areas before, but there are two main areas that play really important roles. 1 is Broca's area, and Broca's area is marked in green. And where it is anatomically, it's in the frontal lobe. It's anterior to the primary motor cortex, which is in the precentral gyrus here. And then if you go down, these different divisions of the frontal lobe, we have the superior frontal area, the medial frontal area, and then down here, we have the inferior frontal area. The inferior frontal area is divided into 3 different regions, the percular, the triangular, and the orbital. And Broca's area, because this is something that you will see in textbooks and in neuroimaging reports and so forth, Broca's area is in the posterior part of the, it's known as the frontal operculum because it's in the opercular cortex. So that's where Broca's area is. Inferior frontal gyrus, opercular area, also termed as the frontal operculum, like l u m at the end. It plays a really important role in language production. Do you want me to write some of those words on the board? Okay. I think all of those terms except for frontal over curriculum are right in the textbook. So, So that's this region here. And you can see why it it probably ended up being located in the frontal lobe because what else is in the frontal lobe that's really important? What's sitting here and anterior to it? Motor cortex. And so the last stage of language production, of course, is is a motor act. It's, articulation. And as we'll see, Broca's aphasia is not a disorder of articulation. It's actually a higher level language problem. But, of course, it needs to be closely connected to the motor function, and in particular, it's very closely connected to the facial region of the primary motor cortex. Wernicke's area is here in the superior temporal gyrus. So the temporal lobe is divided again into superior, medial, and inferior, and it's sitting up in this area here. So what and Verdecay's area, as you know, and as I'll mention in a minute, is really important in understanding of language. Why do you think this is a really basic question. Why do you think this ended up being here? What's sitting right here? Auditory. Auditory cortex. And, of course, a big part of language comprehension, it needs to be intimately connected to hearing. So Boerneke's area plays an important role, not just in understanding spoken language through the through hearing. It would also play a role in reading or if you were using braille. It's a it's a multimodal area. But it makes sense that it's very closely, connected to auditory cortex. These areas also get known as being perisylvian areas. And the reason for that is this is the lateral fissure. And another term I think I've used it and it's in the text. Another term for the lateral fissure is, the Sylvian fissure. Those terms are interchangeable. Peri means next to. So if it's next to the Sylvian fissure, it would be a perisylvian area. So if you were reading a patient's MRI report and it said they've had a a left hemisphere stroke encompassing much of the perisylvian cortex or the perisylvian areas, what should immediately, like, be front and foremost in your mind is aphasia and language because the perisylvian areas are so intimately and inter intimately and, highly specialized language. All of these regions in here. Okay. Any questions? Alright. A few other terms that are associated with these areas. This numerical scheme that was based on what the anatomist, Broadman saw when he looked under his microscope, and he saw that different areas of the brain actually looked different in terms of the cells that were there. And so he suggested that if they look different, they must be doing different things. And he came up with this numbering system, not even knowing what the areas were doing. But Broca's area is in areas 4445, and those numbers are still used in clinical practice as well. And Wernicke's area is in area 22, and primary auditory cortex is here in 41. I think it doesn't extend a bit into 42 as well. So it's right next to, the auditory cortex, as I said. Okay. So language is complicated, but the most basic model of which the the general principles, for the most part, still apply today was actually developed a long time ago. So Verdecay was a neurologist in the 1800, who studied a number of different patients with aphasia, and wrote the first reports about Wernicke's aphasia. And Geschwind was, a neurologist in Boston in the 19 sixties and 19 seventies who refined Wernicke's earlier models. And the basic model is what I've told you already. Wernicke's area is important in multimodal language comprehension. Broca's area is involved in language production at the level of at the the cognitive level as opposed to the articulation level, and we'll talk about it more about what that means. Like, actually coming up with a word that has meaning and knowing what that word would be in terms of its phonology, but not the actual motor act of of moving your mouth and tongue and lips and so forth to make the appropriate sounds. But what the third part of this model so we have comprehension, we have production, but then there's this band of fibers that I think I've mentioned before. It's known as the arcuate the systinilis, and you can actually see it if you slice into the brain this way. There's a big band of fibers that connects the comprehension areas to the production areas. So a big white matter band known as the arcuate fasciculus. And it's really important because comprehension and production don't act in isolation. To have normal language, to have a conversation with somebody, you have to be able to link these 2 areas. And so what function do you think the arcuate fasciculus plays a really important role in especially? Like relaying it in nature? Or or repetition. Yeah. Exactly. So if I were to say to you, it's raining out today, what happens? Well, there's a whole bunch of processes that happen in the, hearing, realm, but eventually, that sentence end up ends up being processed by Wernicke's area. For you then to repeat it, if I were to ask you to repeat his raining up today, like, immediately after May, you would then have to send that content forward to the production area for you to then repeat it. So what this model basically proposed is that there are 3 core language functions. There's comprehension, there's production, and there's repetition. And although language is way more complicated than that, the the bay that basic model still pretty much holds. And so when we're in the speech program, next term, when we actually look at how do you assess aphasia, many of the core assessment instruments that look at impairment, not how someone is functioning in the world despite their impairment, not how someone is functioning in the world despite their impairment. But if you're actually looking at how language processes are working at a very core cognitive level, they're basically broken down into production tasks, comprehension tasks, and repetition tasks. So this model, although it's old, still widely is widely applicable. Just to provide a few updates though, much and there's a video that I'll show you that discusses this a little bit. All of these functions are complex, and it's not that all of comprehension is taking place just in these cells here, and all of production is taking place just in these cells here. All processes likely work with a network. So you would have I can't even begin to show you what it would look like, but there would be all sorts of things going on throughout the brain whenever you do any task. And not just in the left hemisphere. The right hemisphere is active too during language, but the left hemisphere plays a special role. So this network approach, is is definitely the way these functions work. It doesn't go in a linear fashion from box to box to box. Functions are represented diffusely, especially something like semantics or understanding. We know if you're in a neuroimaging scanner and you're given words on the screen that you have to read, and so you're understanding the words as you look at them, the whole brain lights up. Wernicke's area lights up a lot, but many, many other areas of the brain do as well. So the brain works as a network, and the the type of network like this. So we're not going through all the different areas. We're just looking at very basic, core processes that are are especially involved. And, also in these original models, Wernicke and Geschwind thought that Broca's area was really involved in the articulation processes, and we know now that Broca's area is actually like the mental representation. It's not it's the cognitive representation. It's not just the motor representation. Okay. So maybe just to highlight some of these points, before we look at different types of aphasia. Here's an overview of language impairment. It is this is from a series that actually came with your textbook. And I've shown you a number of the videos that were associated with the text. But, this might be this illustrates some of the concepts we talked about already. A 100 years ago, scientists believed language depended on 2 key areas in the left hemisphere. A region behind the ear, identified by a German doctor, Karl Danica, seemed to be responsible for overall meaning. It handled word selection and sentence construction. An area further forward found by a French doctor, Paul Broca, was thought to control the last stage of generating speech sounds. Since then, a far more complex picture has emerged. Doctor Wilson Talley, award winning nuclear physicist, scientific adviser to the American government, will never be able to speak like this again because he suffered a stroke. Of nuclear energy. Much very nice. It's March this 1998. The stroke. You have March 6th sleep. And here about 2 PM, it got up. The bathroom found him. This is very strange. Doctor Talley has a great deal of difficulty understanding anything that's said to him or even things that he reads, and he also has a great deal of difficulty in producing language. Now what happens when he tries to talk is that the words come out very fluently, but what he says doesn't have all that content to it. He has difficulty in finding the words that he wants, and he has a great deal of difficulty also in producing sentences that are coherent, that really reflect what it is he wants to say. A brain scan revealed that a hemorrhage had destroyed large parts of Wilson's lived scans of stroke patients with language disorders. It turns out that many have indeed damaged the 2 classic language areas, but the broader picture reveals a network of many different brain areas which handle specific aspects of language. Specific aspects of language. We've seen that there are certain patients who have a great deal of trouble really just naming things. We've found patients who have difficulty understanding the grammatical rules of language. All of those different kinds of patterns tell us, first of all, that the process of language is incredibly complex and also that there must be many different brain areas that subserve each and every one of those be many different brain areas that subserve each and every one of those different functions. Charge of white circle. Patients often seem to recover some of the basic aspects of language, like the ability to recognize word sounds, which suggests that these functions don't require their own specialized brain structures. Touch the green square. Unfortunately, we rarely see complete total recovery in our aphasic patients. Thank you. The fact is that in most of them, a fairly significant amount of brain has been affected by their injuries and that it is difficult for other brain areas that have for such a long period of time been doing something else to suddenly take on this new function. And what we think happens is that the remaining brain areas try to take on this task of language, but they do it in their own way. Unfortunately, they're not as good at it as those left hemisphere language mechanisms because they haven't been doing that all of those years. Okay. So what did you think? I finally when Yes. Especially when you consider, his pre morbid background, when where language was such an enormous part. Interestingly, did you notice I won't talk a lot about it in this class, but we we will next term. Did you notice anything about his sort of, like like, affect? Like, did he seem, like, distressed or frustrated or no. It's kind of interesting because we're we'll talk about, different categories of aphasia briefly. But with this type of aphasia, which is known as fluent aphasia, his speech came up what it didn't make sense, but it came up, like, fluently. There were words, and what he was primarily having difficulty with was understanding language. But it seems to go along with kind of difficulty understanding the world around themselves and also understanding the nature of their difficulty. So very commonly, when people have fluent aphasia, they don't even seem especially bothered by it because I don't think they can really appreciate that there's been a change in the way that their family and friends and clinicians that work with them and so forth have. And that is very different than nonfluent aphasias where people struggle so much to come up with words and just have, like, enormous frustration, like, would be in tears at trying to do a task like this that they couldn't manage. So it's I I wouldn't say that everybody presents like this, but you do see this sort of failure to understand the difficulty that goes along with a fluid aphasia, which shows that these functions really are like, they're multimodal. It's not just difficulty understanding language. It's difficulty understanding yourself and understanding your chain, What's happened at it? Who you were before and how you're different now, which I I think well, as a clinician, it's really important to understand that. There was another hand up here. I was just thinking because I find it really interesting to use kind of the real world examples because I know in, like, my, like, neuroscience books and, like, undergrad and stuff, you know, when you talk about, like, corpus aphasia. I mean, no, sorry. Like, they sort of say that it's, like, your speech is almost, like, incomprehensible. Like like, the words you're saying are just, like, completely irrelevant. Where with this patient, like, I even those kind of a mix of both areas and so, like, that's a lot of damage. I guess when he's talking about what happened, I could still, like, understand kind of roughly what he was trying to say even though, like, it's very good. It's, like, a large degree of impairment. It wasn't just complete, you know, like, it was, like, you could tell his brain was still trying to, like, explain to somebody. Sense, like, it's not just, like, word salad. And with all of these disorders, there's a continuum. It could be something that's very mild. Maybe somebody only has difficulty understanding language when there's really complicated syntax, like, grammar. Maybe it's when there are only, like like, highly, abstracts, like, high level vocabulary that's used. So these really specialized problems versus somebody that absolutely is not able to understand anything or say any words. So there's a wide range of, ability that goes along. And so though and so I think, like, one of the reasons I think this is important to talk about now before we talk about the different specific disorders is classical aphasia theory has always lumped aphasia into different, like, discrete categories, but it doesn't work that way. And like Nina Dronker, she's a really well known, aphasia aphasia researcher, also known as an aphasiologist. Like she said, you can look at like, everybody's different, and there are so many sub processes. So to say that someone has Wernicke's aphasia or to say that someone has broke his aphasia or transcortical aphasia or conduction aphasia, that's a really simplistic way of looking at it. It it doesn't work that way, but it's a good starting point. So any other thoughts? Let's just do a couple more introductory slides, and then we'll take a break. So in terms of looking at disorders of language, the the core term that's used is aphasia, and this refers to an acquired disorder of language. And acquired means that the person had pretty much normally functioning language processes and then something happened. If somebody has difficulty learning language through a developmental, process, it wouldn't be considered aphasia. So if somebody has So somebody has normal language and then they have a stroke. Someone has normal language like, Gabby Giffords, the American senator who had the the gunshot wound to her head through her frontal lobe. I think we looked didn't we look at that video? And she had, like, she recovered remarkably well, but she had a Broca's aphasia. Or somebody has, you can have, there's different degenerative diseases that lead to aphasia symptoms. There's a class of disorders known as frontotemporal dementia that, where language really predominates. But language is normally functioning for the most part, and then something happens. And the language problems can present in in speech production or comprehension, reading. Dyslexia refers to a reading disorder. Another term that's sometimes used interchangeably is atlexia. A means absence of, so absence of. Interchangeably is atlexia. A means absence of, so absence of reading, and or in writing. And the term that's used is dysgraphia or agraphia, if you have a writing problem. So it can be at any level of input or output and it's multimodality, and everybody's different. You can have some people that have enormous difficulty understanding spoken language, but you show them the word on a piece of paper, and they can read it. Or people will go I don't know. I know some of you have done volunteer work with people who have aphasia. And one thing that sometimes happens when people have Broca's aphasia is they have difficulty coming up with the word, but it's easier for them to write it. So let's say they're trying to come up with the word, garbage can. They can't come up with the word at that point in time. They take out a pen. They write down garbage can, and they read it back. So they found a way to work around that problem, because they can't spontaneously generate the word. That's not everybody, but you do see that from time to time. So wait. How the difficulty manifests? It varies from person to person. The most common cause of aphasia is stroke. More than 80% of cases, result from a stroke. And what what vessel did the stroke be in? We've talked about this when we talked about, Savannah? Yeah. Yeah. Yep. Middle cerebral 3. Yeah. The middle cerebral artery of the left hemisphere, and you can see why here is because the vessel starts out quite, wide, and then there are all these little narrow branches that basically supply blood to the entire, lateral surface of the hemisphere. And so what type of stroke would be, be would lead to this? Yeah. Enembolus? Enembolus. So although embolic strokes are not as common overall as thromboitic strokes, they more commonly result in, aphasia because of the way the anatomy of the vessel is organized, because these emboli can pass fine through the wider part, and then they get lodged in one of these little parts that's supplying language to Broca's area or Wernicke's area. So stroke makes up the biggest, subset of this population, but you can have a brain injury. More commonly an open head injury, like, Gabby Giffords had with the the gunshot wound. Or I think I mentioned the patient that I saw once that had a, like, a a knife put through his language areas, you know, an awful event. Term closed headed traumatic brain injury is less likely to lead to aphasia, but it can happen. You can have a brain tumor in a language zone. You can have a brain infection. There's a type of infection, that is herpes simplex encephalitis. It's actually don't panic. Students always panic when they hear this, but it actually arises from, like, a cold sore, but it's extremely rare. So don't don't think I have a cold sore. I'm gonna have aphasia. But what happens is the virus travels along the trigeminal nerve into the temporal and frontal lobes, and it can lead to just devastating cases of aphasia. You can have dementia, like I mentioned, like frontotemporal dementia that can lead to aphasia as well, but stroke in the middle cerebral dementia that's related to aphasia as well, but stroke in the middle cerebral artery, the embolic type is the most common. Okay. Aphasia one last slide, but I'm gonna break. Aphasia is broadly classified into disorders of comprehension where people have difficulties with understanding, but their speech comes out fairly fluently. Meaning that they're not struggling to find words, but the words don't necessarily make sense. So the video that we just saw would have been an example of that. He didn't struggle to find words, but what he said didn't make sense. So you can think of this as being like a disorder of semantics in many ways. Understanding what they hear, understanding what they read, but also under the level of of production, the semantics behind it, what they say doesn't make sense either. And so I think, Kristen, did you use the word word salad? Yeah. That's kind of a derogatory term. I don't really like it, but it really does characterize what many of fluent, aphasia patterns of of language sound like. It's like you took all these words and you put them in a salad bowl and you toss them together. They don't have trouble coming up with the word, but how they use the word does not make sense. But there's varying degrees of semantic impairment because when he was asked, what happened to him, you could get some of the gist, but it didn't make sense in the way that someone who had, a nonfluent aphasia. They would be although they may have difficulty coming up with the words, how they put the words together would be more, sensical, and we'll look at some examples of that in a minute. So there's disorders of comprehension, which are fluent aphasias, and then there's disorders of production, which are known as non fluent aphasias. So disorders like Broca's aphasia. Okay. So why don't we it's 9, 22 now. Why don't we take a 10 minute break? And then we'll talk not about all of the. Okay?