| 00:02 | So this is lecture two of neuroscience as I mentioned all of your lectures |
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| 00:11 | being recorded and post recording there being on your video points dot org. |
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| 00:19 | known as U. H. Video as video points dot org. Or |
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| 00:23 | log in using your cougar nut D. And your password and you |
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| 00:27 | access to these videos that are So last time when we met on |
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| 00:33 | we had our first lecture and we an introduction on the whole course where |
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| 00:39 | explained to you different components of the everything about the testing and the |
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| 00:44 | If you missed that lecture please view and also view the syllabus which contains |
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| 00:51 | of that information. And just please that your casa tests are not at |
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| 00:58 | casa facility. It is online to you prefer to take that test. |
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| 01:04 | that's the most important thing not to the casa tests with. Taking them |
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| 01:09 | a certain location. After we talked the class, I reminded everyone that |
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| 01:16 | is uh this covid 19 virus and explained to different ways by which this |
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| 01:24 | gets inside the brains from the blood breaching blood brain barrier or by infecting |
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| 01:32 | south that comprise the blood brain barrier as in the ethereal cells and astrocytes |
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| 01:38 | cells. And uh we talked about infection of the olfactory epithelium can lead |
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| 01:48 | loss of smell which is anosmia and loss of oxygen or hypoxia which could |
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| 01:55 | due to infection of the lungs. make the brain really susceptible to further |
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| 02:01 | by breaching the blood brain barrier and by causing inflammation and causing lack of |
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| 02:09 | , which will essentially suffocate neurons to in simple terms, and we discussed |
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| 02:17 | authors of this book that the class material follows fairly closely and uh now |
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| 02:29 | will continue with the history of So we talked about the fact that |
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| 02:34 | the prehistoric times this brain entrepreneur nations thought to be the first neurosurgical procedures |
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| 02:41 | by the shamans and medicine men at time. And Imhotep is a very |
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| 02:50 | person who has documented medical injury, in and Edwin and Edwin smith surgical |
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| 02:59 | papyrus is named after the person that the excavation in Egypt and Imhotep was |
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| 03:08 | court position, later became a deity had access to a lot of injuries |
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| 03:15 | that he could start explaining the anatomy the body and potentially off the brain |
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| 03:22 | . Because in the ancient times it not allowed to take a person and |
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| 03:29 | them to look what's inside their body what's inside their hands or what's inside |
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| 03:35 | brains especially. So this is something is not allowed to be practiced |
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| 03:42 | So you cannot reveal the precise anatomy the nerves of the muscles and other |
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| 03:48 | in the body. You are resulted what is available and what is available |
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| 03:55 | the injury that might be a reveal the hand because the hand gets torn |
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| 04:01 | half and you see the anatomy of hand the same with the head as |
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| 04:06 | . And so he documents 48 injury . 27 of them had trauma |
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| 04:13 | Although head itself is not and the is not considered important. It's referred |
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| 04:18 | marrow off the skull just like you marrow bone. The brain is referred |
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| 04:23 | as marrow the skull by the Egyptians that time. However he also recognizes |
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| 04:30 | effects from the injury of the N. S. Or somebody gets |
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| 04:36 | blow on the right side of their and all of a sudden they cannot |
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| 04:40 | their left hand. The left hand completely fine the muscles and everything in |
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| 04:46 | left hand remains uninjured. The injury occurred into the brain traumatic brain injury |
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| 04:52 | so he documents cases like that where injuries into the head or the |
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| 04:58 | N. S. That affect movement affect the peripheral. He also comes |
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| 05:04 | with the triage system or treatment of ailment to be treated may be treated |
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| 05:10 | to be treated. We also have modern day triage system that if you |
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| 05:14 | into the emergency room you will probably treated much faster. If you have |
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| 05:19 | life threatening urgent situation you're bleeding to , you'll get treated much faster than |
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| 05:25 | you're coughing and suspecting a flu. there's still prioritization based on on who |
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| 05:34 | help The most Uh this kind of system was tested in 2020 and 2021 |
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| 05:41 | the hospital systems around the country around world were completely filled with people with |
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| 05:47 | infections and that was really tested because you know, a lot of people |
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| 05:51 | had surgeries for their knees or they couldn't they couldn't get them |
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| 05:57 | We were prioritizing the patients that needed attention to save their lives. So |
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| 06:04 | , they don't consider the brain very organ, but the heart is the |
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| 06:08 | organ, the brain at the time they're preserving important people's bodies, there's |
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| 06:14 | them. They're actually not preserving the . They use the stool that they |
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| 06:19 | through the nose and they scoop out brain tissue. So the brain is |
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| 06:24 | considered important and not important for even of of the mummies? So he |
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| 06:31 | has these hieroglyphic descriptions of the He starts basically writing about the |
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| 06:37 | implying something about what is found inside skull, that there are convolutions that |
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| 06:43 | know is gira and south side in modern nurse signs that there is a |
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| 06:48 | that this membrane is potentially the membrane covers underneath the skull. The brain |
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| 06:55 | we know as meninges. And we'll them in injuries such as durum |
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| 06:59 | But wouldn't it be interesting if they that there were some membranes inside, |
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| 07:03 | maybe around the neurons. That's what be able to have thought, I |
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| 07:07 | it. And then of course there's here. So there's some kind of |
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| 07:11 | flow of fluid surrounding some kind of to write like a spoon or something |
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| 07:18 | that. And that is cerebral spinal . So, their initial glimpses of |
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| 07:23 | anatomy of the brain that has some that has some fluid that has in |
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| 07:29 | parents that has convolutions are not very at interpreting ancient Egyptian art lifts. |
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| 07:36 | there it is, we're kind we're gonna jump through the history until |
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| 07:41 | come all the way to this century and we're gonna make a few |
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| 07:47 | important stops. Uh, they've contributed our modern day neuroscience. And mind |
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| 07:54 | that these stops here highlighted a certain . It doesn't mean that a lot |
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| 07:59 | these things were not happening concurrently in parts of the world, that we |
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| 08:04 | don't have time to talk about this more detail from the historical perspective. |
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| 08:10 | father of medicine, Hippocrates. So you finish the medical school, you |
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| 08:16 | the oath of Hippocrates, which is help people to heal people. That |
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| 08:23 | is your dedication. This is what there for. And he's considered the |
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| 08:30 | father, the father of modern medicine the same time, medicine and his |
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| 08:38 | ages 4 62 3 79 before Before christ medicine is still a craft |
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| 08:45 | the time. So what do you by craft? Well, it probably |
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| 08:51 | can still be considered it was a 200 years ago because you didn't have |
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| 08:57 | rays and you didn't have Mri's and didn't have the biomarkers and things like |
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| 09:02 | . So you know, it remains craft for a long time. But |
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| 09:07 | were again at the time the men the women that would help you and |
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| 09:12 | to heal you and solve your medical . So he considers the brain as |
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| 09:18 | major control of organ of the which is a shift from the Egyptians |
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| 09:26 | brain is a seat of intelligence. , Aristotle, which you can |
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| 09:32 | Aristotle comes after 3 84 3 22 . C. He still believes that |
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| 09:40 | is the center of intellect. He to the brain as the air conditioner |
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| 09:46 | the blood and body. That same that we discussed when we talked about |
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| 09:52 | trapper nations and we said that interpretation the spirits obsessed people, spirits containing |
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| 10:00 | would rise and lead to the The same notion here is it's at |
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| 10:04 | top of your body. So all the heat in the body and the |
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| 10:08 | and the blood would rise and would out through the ears probably. So |
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| 10:15 | a little bit disappointing. So there's debate how important the brain is and |
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| 10:20 | goes on for essentially centuries. But is the shift that is noticeable already |
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| 10:27 | the fourth century Bc. There are dark times that the humanity goes through |
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| 10:36 | during those dark times, the religious and empires around the world are the |
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| 10:49 | , the law of the lands whether roman empire, Byzantine empire. Ottoman |
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| 10:57 | , Mongolian empire, other places in America that existed also. There are |
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| 11:06 | times and there isn't much done and far as development of sciences and in |
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| 11:11 | in the development of our understanding of anatomy of the human body and the |
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| 11:18 | . So there is suppression until the of the renaissance which is the rebirth |
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| 11:25 | was the rebirth period in the arts cultures and music in sciences and during |
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| 11:35 | times, things that were very tightly by the kings and cons and Popes |
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| 11:46 | uh other religious rulers basically there's an now where there's an allowed mode to |
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| 11:57 | exploring to start doing dissections and so vesalius starts really dissecting the human body |
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| 12:05 | the brain drawing it trying to describe in greater detail. It says he |
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| 12:12 | gallons anatomical description. So galan was scientist before him who did a lot |
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| 12:19 | dissections and pigs. And he also an opportunity in on top of looking |
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| 12:26 | dissecting pigs to look at the injuries the gladiators at the time that he |
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| 12:32 | exposed to in Rome and so gallons descriptions. Risotto was a fusion of |
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| 12:40 | he saw in pigs and what he an injured torn apart gladiators in some |
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| 12:47 | and that's not exactly human, that's blend of of of a swine and |
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| 12:52 | . Uh so at the time he that and he does his own |
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| 12:58 | his own dissections of the brain. he describes a couple of very interesting |
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| 13:05 | . First of all he describes by through the brain that they're these very |
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| 13:11 | ventricles and these ventricles are filled with and they're localized centrally. And so |
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| 13:18 | decides that potentially brain functions are localized somehow distributed the commands through the fluid |
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| 13:29 | is found in the ventricles. He cuts cross sectional e through the brain |
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| 13:36 | exposes the white matter and the gray gray matter as we know now are |
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| 13:44 | of stillness of neuron cell bodies and white matter are the external projections and |
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| 13:51 | axons that are myelin ated and therefore appear white. That interconnect different regions |
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| 13:57 | the brain from the thalamus to the and between the cortex and so |
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| 14:02 | So he pushes onto this gray matter the finger and says you know it's |
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| 14:07 | of soft like a sponge. And pushes his finger onto the white matter |
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| 14:12 | says you know it's a little bit . So he decides that this gray |
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| 14:17 | because it's sort of a sponge like this must be where we store all |
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| 14:22 | the information. This is how where learn where things get basically absorbed intellectually |
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| 14:28 | the sponge like matter. That was interpretation of of what you saw and |
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| 14:34 | ventricular localization of the brain function persists that time and persist for quite a |
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| 14:42 | period of time uh where we come now about 50 to 80 years later |
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| 14:54 | there is a renada cart because he's french mathematician, philosopher physiologist, he |
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| 15:00 | the first one in the Western world systematically account for the mind body |
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| 15:07 | And this is what concerns Western origins this mind body distinction. And at |
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| 15:15 | same time it's happening in africa, happening in Mesopotamia is happening in Southern |
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| 15:23 | , It's happening everywhere. This these is happening, happening with native populations |
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| 15:29 | with with pagans that are trying to really the connection to the spirits of |
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| 15:35 | mind and the body and all of things. So all of the humanity |
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| 15:38 | trying to really figure this out how works in the way. Renee the |
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| 15:43 | uh looks at the body as if was a machine mechanical, built like |
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| 15:52 | mechanism that is a fluid mechanical So he looks at the body, |
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| 15:57 | looks at the brain, he notices there's certain behaviors that are reflexive. |
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| 16:04 | he looks at the very young child that child puts his hand over the |
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| 16:11 | and the first thing the child does very quickly withdraws the fire. The |
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| 16:15 | has never seen. The fire never . The fire, therefore doesn't know |
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| 16:20 | it is, but reflexively withdraws the . And so there is reflexive behaviors |
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| 16:26 | you step on the nail, you think about it and contemplate whether you |
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| 16:29 | step off the nail. And then course everything that happens reflexively still involves |
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| 16:35 | informs our conscious perception and the higher centers in the cerebral Yeah, |
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| 16:45 | that's fine. Can you repeat the a influence? But everything that came |
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| 17:00 | him, just like we all But he's also a giant mind of |
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| 17:06 | own because obviously he's a multitalented person many different fields and is trying to |
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| 17:14 | what is a very complex problem at time. That's still to be a |
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| 17:18 | problem. How does the human body ? How does the brain work? |
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| 17:22 | does the brain connects to some spirits some thoughts? What are the entry |
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| 17:28 | ? And so he finds this pineal inside the center of the brain and |
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| 17:34 | this one structure. Most of the have the left and the right side |
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| 17:39 | pineal gland is one and it's sitting in the center. And so he |
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| 17:43 | that must be really important. And is where the connection between the spirits |
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| 17:50 | interpretation, the spiritual with the mind . Therefore, then there are these |
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| 17:57 | and these pipes are nerves and these will carry the information into the muscles |
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| 18:05 | you will move your mouth and speak response to your thinking and whatever spiritual |
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| 18:13 | you may be connecting with this was explanation. Nonetheless, we just thought |
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| 18:18 | it's some fluid or some gasses that or pipes basically, that are distributing |
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| 18:24 | these ventricular fluids or some other substances gasses throughout the body and affecting the |
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| 18:31 | . Obviously, the movements of the , the thoughts and so on. |
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| 18:36 | Renee, the card is also responsible one of the most famous phrases. |
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| 18:43 | think therefore I am cognito ergo I think therefore I am. If |
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| 18:54 | don't think you're not. So now jumping to the 18th century. So |
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| 19:06 | about this, the ventricular localization of brain function, 15th 16th century, |
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| 19:13 | fluid mechanic model of nerves as the distributing some gas sister fluids around so |
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| 19:20 | we can move and communicate also, some entry points and only in the |
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| 19:25 | century 17 80 Luigi Giovanni, the of Bologna demonstrates that nerves are like |
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| 19:36 | and he demonstrates it by using a static electricity generator or laden jar that |
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| 19:45 | small amount of electricity. And he a little froggy that he dissect in |
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| 19:50 | desk and he shocks the frog's muscle electricity and the frog's muscle contracts. |
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| 19:58 | then he sees that there's a nerve attached to the frog's muscle like a |
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| 20:04 | and he shocks this nerve and the also contracts. So he proclaims that |
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| 20:11 | are wires that they can carry electricity they can also generate electricity. And |
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| 20:19 | that point on, our view of nervous system and the nerves and how |
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| 20:25 | communication happens between the cerebrum and the areas and the periphery becomes a lot |
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| 20:34 | uh closer to what it is in modern days. So their electrical conductors |
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| 20:42 | can generate electricity. Nerves are like of the wires that you're using for |
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| 20:48 | cell phones and uh any equipment charges things like that are insulated. So |
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| 20:54 | wires are not exposed. This installation called Myelin nation. Mhm. And |
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| 21:02 | are nerves that are wires that are inside the cerebrum down through the spinal |
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| 21:08 | and into the periphery out of the cord. If we roughly look at |
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| 21:14 | is the nervous system, The central system is the brain which is cerebrum |
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| 21:21 | in the back of the brain, brain stone, the spinal cord and |
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| 21:28 | the spinal nerves that are coming out the spinal cord is now part of |
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| 21:33 | peripheral nervous system going into the Both sensory nerves that collect sensor information |
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| 21:40 | also motor neurons that command the muscle . The cerebrum is divided into two |
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| 21:49 | . So you have the right hemisphere the left hemisphere and those hemispheres are |
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| 21:54 | into lobes the frontal lobe, the lobe, the temporal lobe, the |
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| 21:58 | lobe and these lobes they have their distinct functions. So when we talked |
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| 22:05 | the language areas we'll start talking about language areas, you'll notice that some |
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| 22:11 | these functions like language is distributed in different areas is vision and processing of |
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| 22:20 | information is distributed in several different areas the lobes in the cortex though the |
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| 22:26 | lobe is dominated by visual processing visual , temporal lobe is auditory information but |
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| 22:35 | is a division of labor which parts structures in the brain in which parts |
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| 22:40 | the cortex of processing different types of . And so you learn about these |
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| 22:45 | and you learn about the anatomy and functionality of these circuits all the way |
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| 22:51 | the periphery to the six layered When we look at all of the |
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| 22:58 | from the neck below, it gets touch each mosquito bite, heat bites |
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| 23:09 | anything unpleasant clothing that you're feeling, somebody's hand. This is some matter |
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| 23:17 | sensor information. This is how we're the environment, touching something. You're |
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| 23:23 | the environment. Everything from the basically below is processed through the spinal the |
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| 23:33 | nerves will have the dorsal component that into the dorsal side of the back |
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| 23:39 | of the spinal cord and is a component. And these are these are |
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| 23:44 | dorsal root ganglion cells. So DRG so they will have the nerve ending |
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| 23:50 | in the skin and the muscles and joints. And if something touches or |
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| 23:55 | they feel that information sensor information. carry that information through the bundle of |
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| 24:01 | nerves into the dorsal part of the cord. It will also connect onto |
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| 24:06 | motor neurons that are on the ventral front side of the spinal cord and |
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| 24:11 | motor neurons will put a motor that means that when they exit out |
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| 24:18 | are a parents going into the central system, into the spinal cord. |
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| 24:23 | are parents leaving the central nervous system into the periphery. And when these |
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| 24:29 | er is projected to the periphery the is gonna be somebody tapped it. |
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| 24:34 | gonna reach out and want to shake hand so they're tapping you. This |
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| 24:40 | your command. When they tapped you sense this is the sensor information through |
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| 24:45 | dorsal and your response is now to their hand. This is through the |
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| 24:50 | motor neuron command. Of course that will ascend this tap and what you |
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| 24:57 | to do will ascend. Because most somebody taps, you're gonna turn and |
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| 25:02 | other things not just wait for their or special tap. So you know |
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| 25:10 | it is. Somebody taps you Also you're gonna you're gonna turn your |
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| 25:14 | and look at them. So you're to process that information. So that |
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| 25:18 | is also gonna ascend that information. information is going to ascend into the |
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| 25:24 | centers into the brainstem and cerebellum into cerebral cortex and then you're going to |
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| 25:31 | a decision that you're gonna shake fist or whatever you're gonna do. This |
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| 25:36 | the motor command that now comes out your response but the ultimate motor action |
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| 25:41 | that shake our fist bump comes from ventral neurons that are initiating or doing |
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| 25:47 | final output for the muscle contraction. , so we can see these nerves |
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| 25:57 | um once we look at the different of the brain and we, you |
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| 26:01 | now see that there are ventricles that is white matter, gray matter, |
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| 26:09 | there are salsa and gyro, that is wires running through their insulated that |
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| 26:18 | are different lobes here. This, example, so central sulcus separates the |
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| 26:25 | lobe from the parietal lobe. This sylvian fissure which defines very clearly the |
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| 26:30 | lobe here. So, we're looking these all of these structures in the |
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| 26:35 | . We're looking at the anatomy and spinal cord and now the quest for |
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| 26:41 | 19th century, Okay, for the of the 18th century and for the |
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| 26:49 | century, the quest becomes localization of functions of the brain. Yes. |
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| 27:01 | electrical current that, Yes, Oh, we'll get to that. |
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| 27:16 | we'll get to that maybe another two . Okay, The fluid and then |
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| 27:23 | calls. It's a very good Was called cerebral spinal fluid and that |
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| 27:28 | is produced in the ventricles. It throughout the cns and the cerebral and |
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| 27:37 | the way into the spinal cord. was joking about two hours. We're |
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| 27:40 | talk about that in the in the slides but it circulates throughout and it |
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| 27:46 | the necessary nutrients to the brain tissue it gets refreshed and it gets reproduced |
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| 27:52 | day, basically. And it's almost gel ag gelatinous like it's not exactly |
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| 28:00 | fluid. It also provides a level protection to the brain because it places |
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| 28:05 | within this fluid this environment. So is a strong movement or shaping up |
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| 28:11 | head. It gets softened by the surrounding the brain. So mult multiple |
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| 28:17 | of that fluid. But it's a question. We'll get to it in |
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| 28:21 | in a few slides if not in election in the following yet you do |
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| 28:26 | action and then you talk or Are those the same nerve or it's |
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| 28:31 | different if you like. Oh So that's a good question. Alright |
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| 28:43 | I told you that everything from the down is processed by the spinal corridor |
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| 28:49 | ? You don't you don't speak with hands although you do if you do |
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| 28:53 | sign language But we typically speaking the . So there is in the brain |
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| 28:59 | there are cranial nerves and they're There's 12 cranial nerves will study them |
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| 29:05 | . And of course when we talk the c. n. s. |
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| 29:09 | parts and functions and those cranial nerves responsible for different functions such as sensation |
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| 29:15 | your face is by trigeminal nerve which one of the cranial nerves in the |
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| 29:22 | stem. So all of that information that is both sensory and motor the |
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| 29:28 | mastication or chewing will be motor nerves control the movement of the tongue movement |
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| 29:36 | the eyes. It's ocular motor is cranial nerve. Again, that is |
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| 29:41 | in the brainstem. And so we'll get into those details. But it's |
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| 29:44 | very good question. And I actually have mentioned it because if everything from |
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| 29:48 | down is processed by the spinal Well from here up, the Samata |
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| 29:54 | motor information that we do are coming the cranial owners. The motor command |
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| 29:59 | ultimately coming from the motor cortex. the cerebral and the neocortex and the |
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| 30:05 | cortex is the highest water, the processing order centers and give the commands |
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| 30:11 | give the highest level of perception of you're seeing happens at the level of |
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| 30:16 | cortex. Neocortex. All right, questions. Uh now that we know |
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| 30:24 | this brain looks like, the we want to know what part of |
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| 30:28 | brain is responsible for, what So, there is one kind of |
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| 30:35 | belief that maybe all of the brain responsible for all of the functions. |
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| 30:43 | , if you lose one piece of brain, a small piece of the |
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| 30:47 | , you're not gonna injure one but you'd rather lose a little bit |
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| 30:52 | all of the functions. But that not the case. And soon |
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| 30:58 | people start searching for an understanding that parts of the brain may be responsible |
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| 31:04 | different functions. And so there's a of phrenology that came from the theories |
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| 31:10 | this Viennese physician franz joseph gall and joseph gall decided that yes, the |
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| 31:21 | contains multiple organs. Or it contains different areas and yes, those multiple |
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| 31:30 | areas, Each one of them will responsible for certain characteristic trait aptitude. |
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| 31:42 | he thought that because during early development skulls are soft and the shape around |
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| 31:51 | growing brain because our brains grow and the skull was not soft and the |
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| 31:56 | wouldn't be able to grow from a into an adult brain. The skulls |
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| 32:01 | soft. In fact, in newborns can see these soft spots and feel |
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| 32:07 | here and in the back of the , where the skull plates refusing. |
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| 32:12 | that fusion takes a year, sometimes years for that soft spot to go |
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| 32:17 | with the skull plates fuse completely the , so it is soft, it |
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| 32:22 | forming around the brain. And so he said, because each faculty has |
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| 32:28 | separate cedar organ, the size of organ, the size of that organ |
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| 32:33 | the brain, other things being is a measure of its power. |
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| 32:37 | he said, because the brains are and shaping the skull is soft. |
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| 32:45 | skull will take shape around the And he decided that the shape of |
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| 32:51 | brain is determined by the development of various organs. As the skull takes |
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| 32:56 | shape from the brain, the surface the skull and the red is accurate |
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| 33:02 | , psychological aptitudes and tendencies. So he is very forward thinking is that |
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| 33:13 | trying to divide the brain into more just 1-4 or five regions. There's |
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| 33:18 | 35 areas I believe at least 35 . So he's forward thinking that there |
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| 33:24 | 35 trades characteristics, generosity, whatever that you carry that. The |
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| 33:32 | is different brain parts, that will responsible for these different character trades these |
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| 33:37 | thinking about that. What is wrong you cannot read the book by its |
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| 33:44 | And you cannot really in this these 35 areas. He outlines them |
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| 33:51 | the skull. And so he as the skull takes its shape. |
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| 34:00 | means that if you have area that is the area of generosity and |
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| 34:07 | grew up and you were actually a generous person That he believed that if |
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| 34:14 | used these sophisticated geometrical tools at the of measuring the symmetry, the |
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| 34:22 | the bumps and ridges of the he could tell that you're very generous |
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| 34:28 | because there's slightly bigger bumping on the in area 14. And so you |
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| 34:34 | go into the phone ologists office and would feel your head and they would |
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| 34:40 | the measurements, the tools, they the notes, they do their math |
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| 34:45 | they would tell you that indeed your generous person. I can tell because |
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| 34:49 | bump on the skull just shows that that is wrong. Yes. This |
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| 35:11 | just limited to the skull, which a big mistake to do that to |
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| 35:17 | bone. Um and that is antiquated outdated and this is something that nobody |
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| 35:25 | to interpret in anybody's characteristics, into abilities. Uh and if the size |
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| 35:33 | an organ, other things being equal a measure of its power and the |
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| 35:39 | that have much larger brains and size us, you know, should be |
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| 35:46 | the top of the food chain and hurting us around, but that |
|
| 35:54 | but that is again not the it is not the size and it |
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| 35:58 | not the the outside of the skull determines the aptitudes and the intellectual |
|
| 36:04 | but it is the networks and the and the connectivity that we have on |
|
| 36:08 | inside of the brain. Yeah, . So his contribution to, to |
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| 36:20 | sciences, technology, you would walk 1848 and you would read and |
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| 36:30 | you see you have all of these things, you're very industrious, you |
|
| 36:34 | , you're good, good socialize, it looks like you guys are |
|
| 36:38 | So this is this, this reaches certain level of popularity where you |
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| 36:46 | you know, subscribe or go to library and read uh you know, |
|
| 36:52 | nature, not science, but Journal phonological american phonological journal. Uh and |
|
| 37:01 | that was probably the only neuroscience publication would find in the middle of the |
|
| 37:05 | century. So, so what's your on Einstein train because founded that his |
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| 37:15 | about some percentage figures, I don't that they found that his brain was |
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| 37:22 | certain percentage bigger. I believe that found maybe a different connectivity and higher |
|
| 37:30 | of the gray matter if I'm not . So, but I have to |
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| 37:34 | exactly what they found in Weinstein's So um yeah, we all have |
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| 37:42 | sizes and I again wouldn't say that in this case size uh is not |
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| 37:49 | the most important thing. Yeah, , cortex that was like 30% bigger |
|
| 37:54 | average or 50% of some Yeah, the new cortex itself, but not |
|
| 37:59 | brain. So I think maybe the I think, yeah, okay, |
|
| 38:03 | thickness of the layers and the thickness the cortex was thicker. Yeah, |
|
| 38:08 | size does matter to a certain extent if you have this much of the |
|
| 38:15 | you have only this number of you don't have billions now, you're |
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| 38:20 | about thousands. And if billions of can have trillions of relationships and effects |
|
| 38:29 | activities and thousands can probably have millions hundreds of millions of. So it |
|
| 38:35 | is important to certain extent, but is about the internal anatomy of the |
|
| 38:39 | . And we finally get to the answers with what we call the loss |
|
| 38:45 | function studies. And it's Dr. Broca in the 19th century he has |
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| 38:52 | patient that has expressive aphasia expressive aphasia difficulty in conveying thoughts through speech or |
|
| 39:02 | . So speaking or writing output. patient that has expressive aphasia knows what |
|
| 39:08 | wants to say but cannot find the he or she needs. If they |
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| 39:16 | the words, they cannot produce a sequence of these words where they are |
|
| 39:21 | within a sentence or a phrase. he discovers postmortem that this person had |
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| 39:30 | injury here in the hole in this . So in the 19th century, |
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| 39:37 | then sent out mail to all of colleagues in Europe throughout Europe asking if |
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| 39:46 | have any of the patients that have type of condition expressive aphasia. So |
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| 39:56 | that you have to write lettuce, have to stamp them, put a |
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| 40:01 | on it with a wax and put in a buggy with the carriage |
|
| 40:07 | you know between Italy and France and of these different places. But within |
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| 40:13 | guess a few years he assembles a of brains. It was almost like |
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| 40:19 | beginning of the brain banks, brains already being stored for interesting studies of |
|
| 40:25 | anatomy. He discovers other brains and have injured in the same area and |
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| 40:30 | area that's called Broca's area and it's here in the front alone, right |
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| 40:35 | on the edge of the motor cortex the motor cortex would be initiating the |
|
| 40:41 | verbal and written expression of language. missing the Broca's area does not take |
|
| 40:51 | your language ability, you can you can read, you can |
|
| 40:58 | you're just not capable of speaking very or writing very well and understand all |
|
| 41:03 | the words. Yes, but you have something like that or like you |
|
| 41:07 | you had a hole like that in head and whenever you're like super young |
|
| 41:10 | like 23 you think like you know would be missing a chunk in areas |
|
| 41:14 | they were able to compensate or be or stronger question. Yeah. So |
|
| 41:22 | so it goes back to our concept plasticity and in young brains there is |
|
| 41:29 | potential for the recovery of this loss function and I have a personal experience |
|
| 41:38 | my family, my nephew had a , three weeks of age and this |
|
| 41:44 | here and here look pretty black on on the cat scan and the neurologist |
|
| 41:53 | predicted he's probably not gonna be able speak and if he does it's not |
|
| 41:59 | be, it's not going to be auditor, very capable language person. |
|
| 42:05 | didn't know, they did think it's affect this expression because it was covering |
|
| 42:10 | area and he is in college now trilingual and he's not an orator, |
|
| 42:21 | he has absolutely no problems in speaking languages and he's recovered and it's |
|
| 42:27 | it's a it's a remarkable recovery because it were to happen after what you |
|
| 42:33 | after a few years of life and don't know when that cut off exactly |
|
| 42:37 | in each individual. It also depends the severity of the injury. The |
|
| 42:41 | for that injury to yes, if happens later, then you end up |
|
| 42:47 | the loss of function. So just aphasia. Um, for a while |
|
| 42:57 | could have a traumatic brain injury in area. You could have an |
|
| 43:03 | uh busted blood vessel which causes the of the tissue around it. It's |
|
| 43:09 | , it's not like an infection that expresses. There is no bug or |
|
| 43:14 | that that that causes that you you , but it's who we don't know |
|
| 43:27 | we're born with. We never do scans. We we don't until there |
|
| 43:33 | a serious problem, you know, we we don't know what we may |
|
| 43:38 | . Actually have. Certain problems. like little babies. We don't even |
|
| 43:44 | of them, you know, like don't know exactly. So it's not |
|
| 43:47 | developmental problem. Nonetheless. Um, aphasia involves difficulty understanding, spoken or |
|
| 43:55 | language. So the patient hears voice sees the print. That cannot make |
|
| 44:00 | of the words and vernick Assyria was shortly after that. And this is |
|
| 44:06 | area. Now that is receptive, the information. There's another two types |
|
| 44:13 | aphasia, economic or amnesia. it's the least severe form of |
|
| 44:17 | We have difficulty in using the correct for particular topics. People, places |
|
| 44:21 | events. I can't remember hardly anybody's unless I interact with them like two |
|
| 44:30 | three times. There's a lot of that I mentioned to you. You |
|
| 44:35 | cell phones, we have like cellphone , cellphones, medicine through cortical |
|
| 44:42 | we have all of that. You the other thing is we don't remember |
|
| 44:47 | number whose whose whose telephone numbers do know how many parts like two? |
|
| 44:55 | maybe if you're lucky and that was different when the cell phones and the |
|
| 45:00 | of a button was not existent because actually had to repave, repeat the |
|
| 45:06 | digit number. Press it over and and over and over. You know |
|
| 45:10 | parents, your grandmother, girlfriend. you know your friend and you have |
|
| 45:14 | press it over and over and you these numbers you carry that memory. |
|
| 45:19 | if somebody tells you a number very actually forget. So. Yes. |
|
| 45:32 | , so no and when we talk global ev asia you have a severe |
|
| 45:39 | damage to the language areas of the . This this is objects, |
|
| 45:44 | places or events. It's it's amnesia or forgetting things. It's not very |
|
| 45:52 | and yet will involve different parts of brain because we don't store member in |
|
| 45:55 | part of the brain. But Global , if you had extensive damage in |
|
| 46:02 | language areas, you have almost all function comprehension of expression lost due to |
|
| 46:12 | . So this this points to very few things. First of all, |
|
| 46:19 | isn't one area that is responsible for , there are multiple areas, this |
|
| 46:26 | area, this expression area and there's areas even in between. And so |
|
| 46:33 | can lose and have a traumatic brain in the frontal lobe and you'll still |
|
| 46:38 | able to receive all of the information understand what's going on around but may |
|
| 46:44 | be able to express yourself express Yeah, that's broke this expression. |
|
| 46:53 | is uh this is reception. So Eastern, your nephew had a |
|
| 46:59 | scan and showed the shading in Broca's . Did later cat scan show |
|
| 47:06 | They did and then they stopped doing because that's just if the function improves |
|
| 47:15 | if something is better, you if we did scans of our brains |
|
| 47:20 | bodies, each one of us we'd be like hypochondriacs because we would think |
|
| 47:26 | there's something wrong and something here and there and here, you know to |
|
| 47:31 | look good. You know, it's , you know, we don't, |
|
| 47:34 | actually don't know. We kind of go around with this complex body and |
|
| 47:38 | system and and do pretty well most the time. You know, there's |
|
| 47:42 | and there's diseases and things, but it's a very robust system in |
|
| 47:49 | Pretty, pretty, pretty resilient. so now we understand about localization of |
|
| 47:57 | . So we say, okay, person if they have a missing part |
|
| 48:01 | broker Broca's area, they have the evasion. So now we're starting to |
|
| 48:10 | localization of brain function. Speech motor areas, things like that is |
|
| 48:17 | most famous patient in neuroscience history Phineas and then 1848 gauge with his |
|
| 48:31 | Their lane railroads in New England was railroads in New England. They're exploding |
|
| 48:38 | rocks and the mountains to go through mountain ranges in New England and this |
|
| 48:45 | the tool. He used the explosives and he uses this metal tool to |
|
| 48:53 | explosives and the crevices of the rocks set off the explosions and an accident |
|
| 49:01 | . Whereas he's packing with this metal , the explosion happens and goes off |
|
| 49:11 | he's out of there and this metal enters underneath his left cheekbone here and |
|
| 49:22 | out shoots out through the top of head here, mostly over the front |
|
| 49:32 | . So if you witnessed an accident injury like this, you would likely |
|
| 49:38 | that person is probably dead in Phineas is case he comes back I think |
|
| 49:47 | months later to ask for his job . He's missing the left eye because |
|
| 49:54 | where the injury. Physical injury actually and took his left eye out. |
|
| 50:01 | can walk, he can speak, can do a lot of other things |
|
| 50:08 | he's overly aggressive and he swears a and he cannot control his executive functions |
|
| 50:18 | being normal with other people so we that there are centers of the brain |
|
| 50:24 | are responsible for motor commands, moving . There are centers of the brain |
|
| 50:31 | for language, multiple language areas and are parts of the brain and centers |
|
| 50:36 | the brain that are responsible for emotion for memory encoding or recall of that |
|
| 50:44 | that are responsible for our normal behavior the accepted or societal norms that that |
|
| 50:52 | we have and Phineas gauge. His is very interesting. There's actually still |
|
| 51:00 | ongoing debate of how bad he was his brain injury and some scholars argue |
|
| 51:08 | it was not as bad as they to paint him. And others had |
|
| 51:11 | story that was so aggressive, didn't a job, ended up in Mexico |
|
| 51:16 | three people sailed back over to port and uh ended up back somehow in |
|
| 51:24 | area and going back to Northeast So there's different accounts, scholarly accounts |
|
| 51:30 | how severe this injury was for an , how much of an aggression it |
|
| 51:35 | caused or it was more of a of a myth that came out of |
|
| 51:39 | , you know? So at the time as we're starting to understand different |
|
| 51:45 | of the brain function, there are cortical stimulation studies that are ongoing mostly |
|
| 51:50 | the animals. And so people are the brains, they're putting little electrode |
|
| 51:57 | the right side and they're seeing the hand move and left leg move or |
|
| 52:02 | like an animal starting to to be because of the emotion. So we're |
|
| 52:08 | to now delineate different areas of the . And we will mention briefly, |
|
| 52:16 | talk about Darwin who studies animal behavior the Galapagos islands in Ecuador and he |
|
| 52:27 | animal behavior in natural surroundings and of , is a big contributor to the |
|
| 52:33 | of evolution. Evolution of behavioral Similar, similar. Others are very |
|
| 52:40 | . His observations are very interesting because on the Galapagos islands and those islands |
|
| 52:46 | located close to each other in but they have very different ecological environments |
|
| 52:52 | there's a consequence of these different ecological . He's looking at the turtles, |
|
| 52:56 | looking at the birds, he's looking the fish, he's seeing small variations |
|
| 53:02 | these different species of animals that they to that local environment, that their |
|
| 53:08 | are different, that their beaks are different depending on which island they live |
|
| 53:13 | . But they actually live in very proximity with each other. And so |
|
| 53:17 | same way as our external bodies and external bodies develop and adapt through the |
|
| 53:26 | to have longer beaks or shorter beaks um bigger dorsal fins on the |
|
| 53:34 | rather than smaller dorsal fence. This is happening and it's very much is |
|
| 53:42 | our brains throughout the evolution and it's reflected in different animals. So, |
|
| 53:49 | for example, rats that spend a of their time and life and their |
|
| 53:56 | and their food supply depends on sniffing around. You don't see rats coming |
|
| 54:04 | and touching things that sniffing things around the whisking around. Okay, so |
|
| 54:11 | portions of this animal's brain will be to all factions in the sense of |
|
| 54:18 | into whisking or to the whisker And if we look at the anatomy |
|
| 54:23 | these animals, this is the olfactory And compared relatively to the size of |
|
| 54:30 | whole brain, it's huge. It's one eight, maybe 1/9 of the |
|
| 54:36 | brave. And also we'll look at amount of sensory cortex of somatic |
|
| 54:45 | In this case, amount of sensory that processes information from the whisker pad |
|
| 54:51 | the face. We have what is the barrel cortex and then this barrel |
|
| 54:58 | and the parietal lobe and some other cortex, Each one of these |
|
| 55:04 | This darker areas represents a single whisker the whisker path. So these animals |
|
| 55:12 | have huge olfactory evolves and the whole in the brain, they have five |
|
| 55:20 | of whiskers and seven whiskers, there be five rows of barrels and seven |
|
| 55:26 | in that given road that you're looking these animals have this map. Do |
|
| 55:32 | think we have a whisker pads map our brands? We don't, we |
|
| 55:39 | a lot of facial hair, especially , you know, but it doesn't |
|
| 55:45 | that this is a significant way of for us. That depends that we |
|
| 55:51 | find food or whether we will basically information through our facial hair. That |
|
| 56:01 | happen. So it's the environment and animals adapt to that environment and their |
|
| 56:09 | adapted an environment on the outside of animal? You have a whisker pad |
|
| 56:13 | the inside of the brain? You a whisker pad map. It's a |
|
| 56:18 | map that's also functional map huge barrel information from a single whisker. You |
|
| 56:27 | at the high water species, non primates, monkey brains, this is |
|
| 56:33 | own factory ball compared relatively to the size of the brain. Is it |
|
| 56:41 | ? No. Is the sense that's important for for monkeys and for humans |
|
| 56:45 | is of course. But again we a lot more on other senses. |
|
| 56:51 | very visual and if we have this is occupying a lot of our |
|
| 56:57 | space. It's a very sophisticated visual that we have. So if you |
|
| 57:03 | in the occipital lobe and will study anatomy and the exhibit alone in the |
|
| 57:08 | visual cortex, it's a very sophisticated there that I'm not revealing the details |
|
| 57:14 | it right now in the primary visual . So again it depends on what |
|
| 57:22 | environment animal lives in and when animals to their environments, the shape of |
|
| 57:29 | beak changes the processing of the information that beak, the structure and the |
|
| 57:37 | for processing that information in the brain changes and adapt with evolution. So |
|
| 57:44 | changing our amount of sensory maps into digits. Cellphone maps. Um At |
|
| 57:51 | moment somebody had a question. And , so with a very large object |
|
| 58:06 | um an individual that do survive that do like one after that. Is |
|
| 58:13 | any chance of like um like neural and brain matter afterwards or any type |
|
| 58:19 | like lifespan? Or is it Oh, it can be a lot |
|
| 58:24 | . So, first of all, can happen following a dramatic brain injury |
|
| 58:28 | this is that it can be a period where you're having emotional aggression problems |
|
| 58:34 | then later you develop a glioblastoma, growth or later you develop epilepsy and |
|
| 58:42 | that are coming from that area of brain. And those would be called |
|
| 58:47 | morbidity. These or other things that over time that can also kill you |
|
| 58:54 | , they're related but they are not from the injury. It may take |
|
| 58:58 | for these things to develop. Um cases, everything that we're talking about |
|
| 59:05 | because other cases have shown that It's just that these were the most |
|
| 59:11 | cases in particular gauge. Um There other than many cases and again, |
|
| 59:22 | just depends on the side of the in the middle of the brain. |
|
| 59:29 | the brain. We have one of favorite, if not the most favorite |
|
| 59:34 | structure. It's a collection of blood called the circle of Willis and circle |
|
| 59:40 | Willis basically distributes different blood vessels to different parts of the brain. You |
|
| 59:47 | vessels coming from here, arteries, coming back and circulates it. |
|
| 59:54 | you know, if somebody gets an here in the artery there. |
|
| 59:59 | you know, there's no way to unless it somehow suture that quickly. |
|
| 60:05 | There are many different cases of recovery traumatic brain injuries. There was a |
|
| 60:09 | case of congresswoman who got shot in parking lot while she was doing her |
|
| 60:15 | speech and I believe she got shot . One bullet penetrated through the |
|
| 60:24 | She recovered here in Houston texas from medical center, but she went back |
|
| 60:30 | congress after a while and now her is a congressman who is, he |
|
| 60:38 | astronomical actually. So Clifford. Uh there are many different cases where you |
|
| 60:45 | have a severe traumatic brain injury and you can be shot to the head |
|
| 60:50 | still recover just certain functions will be . But you can still potentially function |
|
| 60:56 | the society and go back to your too. Uh so now as we |
|
| 61:01 | understanding sort of the macro view of brain, we see the ventricles, |
|
| 61:08 | see the spinal nerves, we see lobes, we see Broca's area. |
|
| 61:13 | injuries, we want to understand what comprising this tissue. And Up until |
|
| 61:22 | century microscopes were of poor optical And the first microscopes capable of resolving |
|
| 61:29 | cells which are 10 micrometers in They came about in 1820s, Which |
|
| 61:38 | that we could not visualize and see until 1820s and the brain presented another |
|
| 61:48 | because if you just took the brain you made a thin slice to the |
|
| 61:54 | to see at a microscopic level. , what you can see, the |
|
| 62:00 | tissue is translucent and it wouldn't really you neurons and glia, it would |
|
| 62:07 | you a little kind of a darker spots, but you won't be |
|
| 62:11 | to really distinguish anything in greater And so in order to reveal the |
|
| 62:18 | anatomy of the brain, we have develop stains or discover stains that will |
|
| 62:25 | neurons that will stain glia. And talk about several stains throughout this court |
|
| 62:31 | the same time, when you have discovery of the microscopes In the 19th |
|
| 62:40 | , when you took the brain it's all sort of one, it's |
|
| 62:45 | interconnected the appeared like a capillary vascular for nerve fibers. And then there |
|
| 62:54 | this theory ridiculous theory that said you know, because it's all in |
|
| 62:59 | , it's kind of difficult to tell one thing starts. Another thing |
|
| 63:07 | All of the particular theory, proponents that the brain is a sensation. |
|
| 63:14 | a collection of nuclei, we now as billions of nuclei that are surrounded |
|
| 63:21 | one continuous cytoplasm and therefore somehow present one continuous environment. Uh chemical environment |
|
| 63:34 | fluid environment. The opposing theory at time was the neuron doctrine also known |
|
| 63:41 | the self theory and other biological sciences the neuron doctrine argued that each neuron |
|
| 63:49 | a discrete unit, individual unit that's by its own membrane independent of another |
|
| 63:57 | . That's also surrounded by its own . And this is the neuron |
|
| 64:05 | Amelia Golgi in 1873 publishes a method based on silver re agents at the |
|
| 64:14 | that we use them photographic development. the time, you would have no |
|
| 64:23 | phones, so no camera, you have to go to a photographer. |
|
| 64:29 | photographer would expose you onto film. that film would be developed using the |
|
| 64:37 | agents in the dark room and exposed the red light and and to reveal |
|
| 64:44 | images. So this is the beauty science. You go to a photographer |
|
| 64:49 | photographers putting some silver nitrate staying into dish chemical and giving you a photograph |
|
| 64:57 | you're a scientist. A professor at university said, Aha, I'm gonna |
|
| 65:01 | that in the brain. And he . And when he puts that silver |
|
| 65:08 | agent into the brain Selectively a small , about 1-3% of neurons pick up |
|
| 65:17 | silvery agents, saying, and as get stained with that silvery agent, |
|
| 65:22 | reveal the precise anatomy of all of processes, all of the Democrats, |
|
| 65:27 | of the branches, all of the , all of the exonerees branches, |
|
| 65:32 | only a fraction of them. So is the this is a thing you |
|
| 65:38 | do as a basic scientist. You do that as a clinician, |
|
| 65:45 | Where you have some substance. And says it's useful photography. Okay, |
|
| 65:49 | , I'm gonna give it to you know, to consume as an |
|
| 65:53 | . You cannot do that. But basic science you can you can take |
|
| 65:57 | brain, expose it to some chemical win a nobel prize. And uh |
|
| 66:05 | Golgi was the most famous spanish uh Ramon Icka Hall, who is familiar |
|
| 66:15 | is student and ra Monica. How the most famous spanish neuroscientist instituto terra |
|
| 66:22 | . Hall in spain Ramon alcohol is ra Monica. Hall has these brain |
|
| 66:32 | that have self stained the note. staring at them with a microscope just |
|
| 66:36 | in this picture. But it's a microscope. This microscope is called camera |
|
| 66:43 | . It's actually not a camera but called camera lucida because as he's looking |
|
| 66:50 | the tissue here seen the cells. microscope has built in system of mirrors |
|
| 66:57 | an arm that allows one to precisely they're looking at the cell under the |
|
| 67:06 | , to precisely through the mirror draw and reconstruct the morphology and anatomy |
|
| 67:15 | that self precisely as it is seen the real slides. So these are |
|
| 67:22 | with their reconstructions. He's looking at stained and he has a mirror system |
|
| 67:30 | camera lucida where he can reconstruct and still exists. The modern day software |
|
| 67:37 | called neural neural lucidity trademark. So this same technique still exists the |
|
| 67:46 | Golgi stain is still one of the stains to reveal selective anatomy of a |
|
| 67:52 | of neurons, especially if you're studying networks. And ramon alcohol is a |
|
| 67:59 | of conducting gold G. Is a of the particular theory. Although he |
|
| 68:08 | the distain himself, Charles. Carrington wins the Nobel prize because he starts |
|
| 68:17 | the connections between these neurons and coins term synapse and starts really trying to |
|
| 68:24 | what happens at the synapse and so . Let me see what the next |
|
| 68:28 | is. So in 1906, Amelia and Monica Hall except Nobel prize |
|
| 68:40 | but they remain rivals and they don't on the particular theory versus neuron |
|
| 68:47 | And Darien isn't that interesting how you have a mentor discovered a stain. |
|
| 68:55 | his student, you're using the You accept Nobel prize together. But |
|
| 69:02 | fundamental thing, whether these are individual or not is a disagreement about |
|
| 69:09 | but you can still accept the normal together with your mentor. Even if |
|
| 69:13 | don't agree in his theories, and proposing trying to prove a new theory |
|
| 69:19 | , apart from making these drawings and recreating the morphology and anatomy of these |
|
| 69:26 | . Ra Monica Hall decides that some these processes that we know is |
|
| 69:34 | They're sort of like antennas. he proposed that they will be receiving |
|
| 69:40 | information through the sometimes that information will travel into the Selma's of these |
|
| 69:49 | And then in black, he showed and he said there's gonna be a |
|
| 69:56 | principle of dynamic polarization that comes from top. It's polarized those here and |
|
| 70:03 | is connections and information travels and connects the adjacent neurons and travels even further |
|
| 70:10 | connect to other adjacent neurons. And proposes that these connections are plastic. |
|
| 70:20 | over 100 years ago, this is insightful ramon into ha was to go |
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| 70:27 | the theory of his mentor, to the principle of dynamic polarization, |
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| 70:37 | processing and outputs which are the access to start contemplating synaptic plasticity that these |
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| 70:46 | are not set in stone that they change. And maybe these neurons can |
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| 70:52 | to other neurons in the living And at the time we don't know |
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| 71:01 | neurons can generate action potentials. We that they can produce electricity. We |
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| 71:06 | that neurons can produce electricity. But haven't discovered an action potential until 1940s |
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| 71:12 | we needed quite sophisticated time equipment in to pick up these very fast |
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| 71:20 | I think I have maybe. a more slides so let me try to |
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| 71:25 | through this material. Another stain that's is initial stain. It's different from |
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| 71:34 | stain. Missile stain will stay in of the nerves and all of the |
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| 71:39 | all of the neurons will pick it . So what is nestle stain good |
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| 71:43 | nestle stain is not good for really the precise morphology or anatomy of these |
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| 71:49 | . Nestle stain is great for revealing architecture with dancing is of the cells |
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| 71:55 | large the cells are, how they're . 123456. You will know the |
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| 72:02 | is the lateral nucleus of the columns for visual information processing. You will |
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| 72:09 | this structure is the hippocampus responsible for memory and emotional information encoding and |
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| 72:16 | Okay, so this was a very thing to discover that was used by |
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| 72:22 | Corbin ian broad MMA. It's called architect tonic methods where he precisely basically |
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| 72:31 | slices and slices of human brains and the layering the densities the parents is |
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| 72:38 | these salads and basically different functional areas said are determined by observing variations in |
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| 72:45 | structure of these cells. Finally what ologists wanted to do and we're doing |
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| 72:53 | the level of the skull surface. man now using the stance and the |
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| 72:59 | is being capable of doing inside the , creating different broad man areas, |
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| 73:06 | them precisely and you'll know area 17 V. One or primary visual |
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| 73:13 | And if anybody in nurse I install area 17. I know it's broad |
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| 73:17 | . Area 17 and it's also area . One or primary visual cortex and |
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| 73:22 | on. These areas here like 44 be broke this area that we talked |
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| 73:28 | had a specific pattern of of cellular . Site architecture. Now standard light |
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| 73:38 | that we have in the labs are powerful. They can resolve up to |
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| 73:42 | μm but still not powerful enough to inside the synapses and to look inside |
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| 73:48 | synapses. We need resolution of less 20 nanometers. The space between two |
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| 73:54 | . The physical space between two discrete doctrine neurons is 20 nanometers. And |
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| 74:01 | we have to have a resolution to that and to do that we have |
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| 74:05 | go to electron microscopes which have 0.1 resolution nano is 10 to the minus |
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| 74:14 | m. This is micro 10 to minus six m and 10 to the |
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| 74:21 | nine. You can see this is synaptic terminal, these round red uh |
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| 74:30 | al's or vesicles that are filled with . You have a dendrite. That's |
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| 74:36 | . You have post synaptic density on post synaptic cell and you have dendritic |
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| 74:43 | . And so now we know that contain these dendritic spines. These dendritic |
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| 74:48 | come in different shapes and their densities distribution of their densities depends on different |
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| 74:57 | subtypes. But these synapses is where of the connections into the neurons take |
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| 75:03 | and they're also the most plastic elements the neurons. That means that they |
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| 75:08 | change their shape. Their number. can strengthen communication between pre synaptic and |
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| 75:15 | synaptic or you can weaken the communication pre synaptic Pazin optic and depressed activity |
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| 75:23 | this particular connection. And so we that neurons receive up 250,000 inputs in |
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| 75:30 | instances and a lot of these inputs be coming from pre synaptic neurons and |
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| 75:35 | terminals. Contacting these dendritic spines on dendrite uh in modern day uh neuroscience |
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| 75:45 | gonna probably stop here not to go time too much. And modern day |
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| 75:50 | we don't have to use stains to cells. And when we come back |
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| 75:54 | gonna tell you about the techniques by we can do so experimentally looking at |
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| 75:59 | molecules and single cells and experimental neuroscience in clinical neuroscience. Looking at the |
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| 76:06 | invasively at the activity in the brain as using pet scans or positron emission |
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| 76:12 | market. We have a good weekend I will see you on Tuesday. |
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| 76:17 | you. |
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