[Music] so here we have the lateral view of the brain and dr chittani showed an image similar to this earlier so we have our primary motor cortex and primary sensory cortex for central lobule for orientation we have our wernicke's area in green between that parietal temporal occipital junction and broca's area for speech production in the left inferior frontal lobule region up in here and if you want to hear speech hearing me talk for instance the information is coming through these auditory cortex working its way back to this vertices area which is more of a conceptual space than any anything physically real and then this information goes along the arctic fasciculus to broca's area and if i wanted to repeat what is being said broca's area can send this information to motor cortex motor cortex then sends it to all the 100 or so muscles involved speech production so i can then convey words and phrases to you now if i am reading words the information goes through visual cortex also works this way to verniki's area so i can read information and if i can read braille tactile information you can take braille and that also works this way through wernicke's area for language reception and then broca's for the production and as mentioned in most right-handers 95 to 98 percent of the time these broca's and wernicke's is going to be in the left hemisphere occasionally flips over and for left-handed handers out there uh it's usually about 75 percent show strong left lateralization and then different percentages it can be either completely flipped to the other hemisphere or more bilaterally represented and that's when you want to have fmri and other tasks to try to map that out more specifically for for your patient here's an image showing the arcuate fasciculus in the left hemisphere this is most strongly developed in us uh humans relative to apes and to monkeys and here is a lesion for instance back in wernicke's here we can see here there's our thumb from the temporal lobe here's our sylvian fissure and our middle temporal jars superior temple drops middle temporal gyrus and so forth just refreshing our anatomy here we had a uh from dr broca back in 1800's a patient who had broca's area uh damaged and in that inferior frontal lobule and here are areas that are involved with language production in another individual you can see mostly in that left inferior frontal gyrus region but you also have with language production some areas of the brain light up with a functional image such as this so it's more complicated than just these areas but thinking about broca's and wernicke's is a good starting point for thinking about language systems with aphasias if you wipe out back in this temporal product occipital junction you're going to be affiliated with the vertices aphasia again up in fear of frontal lobule broca's if you cut between the two super marginal gyrus and that fascicular arcuate fasciculus you can have what's called a conduction aphasia so what you're hearing doesn't get conveyed over to what you're speaking and then all of this will be a global aphasia here in the lower left is a high-yield aphasia square make sure you guys memorize that and basically if you have good comprehension or poor comprehension fluent speech or non-fluent speech or the major two by two and then whether you can repeat or not is going to be important so if you can say argue it fasciculus and then divine says arcuate fasciculus then i will know that he had good comprehension and good fluency and the information could go from the posterior sensory side of things to the motor anterior motor side of things and so these are the four basic elements for classifying different forms of aphasia or an ability to use language and that tends to be lateralized to the left hemisphere but not always here's a cool syndrome to help think about this alexia without a graffia so if you have a lesion to the posterior cerebral artery taking out say the left pca if you are um the information that visual cortex so if you were to write down your name so if your name was divine before you write down d-i-v-i-n-e great and now if you wanted to read that you would have visual cortex back in here and here would see the words and send the information to wernicke's area to see what you're reading but with this particular stroke the visual input with the pca lesion here there's no visual processing so this area the brain is not talking to wernicke's area and if you took out the splenium of the corpus callosum the right hemisphere cannot it can read but it can't send the information to wernicke's area so with this person with this lesion they can write down their name but if you ask them to read what they wrote they wouldn't would not be able to read it what alexia without a graphic so syndromes like these this is called the disconnection syndrome also gave us some clues about the nature of how the human mind works hey everyone ryan rad here from neurosurgery 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