| 00:01 | this is lecture 21 off neuroscience and are reviewing some of the material we |
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| 00:13 | in the last lecture on the central system pathways. And then we will |
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| 00:20 | discussing the auditory system. So if recall we covered the anatomy of the |
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| 00:28 | . We covered the projections, the MP and intermediary projections that come out |
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| 00:35 | the retina and innovate the lateral Janica nucleus of the colonists. And from |
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| 00:41 | from these six layers of the the information goes into the cortex and |
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| 00:48 | , as is illustrated with this experiment labeled pro Lien was injected in long |
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| 00:58 | and it shows that despite the fact you have information at the level of |
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| 01:04 | optic tract that will contain fibers from eyes, if you inject information in |
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| 01:11 | eye, you're going to notice that Manaka lor information from a single I |
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| 01:18 | segregated at the level of the lateral Hewlett nucleus were each one of these |
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| 01:24 | G M layers, the two magna and the four power layers. They |
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| 01:29 | information from just one I and that information from the retina to the thalamus |
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| 01:38 | to the primary visual cortex is 1 1 representation point by point representation off |
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| 01:46 | visual world that is out there, a point individual point. It has |
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| 01:50 | point in direction of the process is it has a point in the |
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| 01:54 | O. J. Nicholas layer the that, as well as in the |
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| 01:58 | visual cortex and the primary visual cortex information of layer four. That's where |
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| 02:03 | major inputs from the L. G innovate into the neocortex, therefore, |
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| 02:10 | a stripe like a heralds and the where each of these lines, the |
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| 02:16 | lines represent ocular dominance from one I are interspersed with darker stain lines. |
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| 02:25 | these represent the dominance innovated by and coming from another I. So we |
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| 02:34 | these ocular dominance columns of the layer the primary visual cortex. Once |
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| 02:42 | that information remains segregated and remains hman . It innovates into the stride |
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| 02:51 | Onda therefore Isman ocular, but then from layer four into upper layers to |
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| 03:00 | in the New York cortex is where see the blending off this information, |
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| 03:05 | it's no longer separated. Segregated ocular information from one eye to the |
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| 03:11 | but rather binocular early blended information. if you recall, this is the |
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| 03:20 | flow. Some critically M and P will generate layer for an intermediary. |
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| 03:30 | or non MP pathways will bypass and layer 23 and we believe these air |
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| 03:36 | concerned with the color information processing. these Salama cortical inputs, then from |
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| 03:42 | four intra cortical of information, gets into layers to three. This is |
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| 03:48 | you have the lateral spread of the and communication between adjacent columns of the |
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| 03:54 | York cortex and between adjacent areas. projecting all the way to other areas |
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| 04:00 | extra stride or outside of the primary cortex to secondary tertiary coordinator for, |
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| 04:06 | , Centenary. And so on. Larry in 23 is this information is |
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| 04:12 | shared within the cortex that also informs deeper layers of the cortex. And |
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| 04:17 | people are the cortex will put their backs of cortical e and also in |
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| 04:23 | for inputs off the outgoing activity that coming out of the cortex into the |
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| 04:30 | cortical tissues. So now you have Salama cortical projections. Inside the |
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| 04:35 | you have the loop 4 to 3 suppressant laterally informs 56 six and forms |
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| 04:43 | four, and you have this loop . It's called Intra Cortical Loop signaling |
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| 04:49 | . And then the last connections go from the cortex into the columns. |
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| 04:54 | you remember we discussed that columnist receives of its inputs from the cortex. |
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| 05:00 | of the outputs from the retina going the columns. But what's in the |
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| 05:04 | ? Most Most of the inputs and columns air coming from these Salama cortical |
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| 05:10 | , uh, inputs that are coming from visual cortex back into the |
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| 05:14 | G. M. Onda from other cortical areas into their respective Islamic |
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| 05:22 | Blobs are associated with a side of Marx today, stain, which |
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| 05:28 | ah, increased energy metabolism. it is associated with color processing, |
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| 05:37 | it isn't a non MP inputs the or the con, your cellular inputs |
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| 05:44 | are responsible for this recall that at level of the retina, the level |
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| 05:50 | L. G. M. If were to record activity from the retinal |
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| 05:55 | cells or from the relay south and G M, you would record receptive |
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| 06:01 | properties that are center surround on and or off and on concentric luminescence like |
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| 06:11 | of the outside world. And when start recording what the primary visual cortex |
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| 06:18 | are responsive when you capture. So is looking at this window in the |
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| 06:23 | field, you realize that the south the primary visual cortex are not responsive |
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| 06:29 | the receptive fields air no longer. consented on and off except the fields |
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| 06:34 | the south, or most responsive, bars of life, individual field, |
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| 06:39 | not only bars of light. But the bar is in this orientation is |
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| 06:44 | in this diagram, you will neuron respond with the maximal amount of the |
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| 06:49 | potentials. That means that this sell recording from in the primary visual cortex |
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| 06:55 | most responsive. Teoh a bar in certain orientation, a bar of light |
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| 07:01 | this visual field of view in the orientation. And if you shift that |
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| 07:06 | off, this bar of light into horizontal issues is shown here below. |
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| 07:10 | can see that the number of action and the coding of that information is |
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| 07:16 | a strong in this particular cell. it tells you that this particular cell |
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| 07:20 | you're recording from prefers this specific orientation the bars of life and this |
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| 07:29 | Selectivity is also in layer for cells also coupled with directions of activity. |
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| 07:36 | means that the neuron zehr not only of the bars of life, but |
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| 07:41 | also arm or responsive. If that of light is being passed through the |
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| 07:46 | field onto which that cell is receiving from in one direction over that. |
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| 07:52 | so if you pass the bar of here from left to right, you |
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| 07:56 | a lot of action potentials and layer cells. But if you pass that |
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| 08:01 | bar and you're recording from the same from right to left through its receptive |
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| 08:07 | , you generate just a number of potentials here as it crosses into the |
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| 08:11 | of the receptive fields. But for rest of the time, as this |
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| 08:16 | crossing across the receptive field, you now actual potential being produced So there |
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| 08:23 | direction Selectivity. Now, if you these, uh, concentric on and |
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| 08:30 | receptive fields or center surround receptive fields retina are similar to the ones that |
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| 08:39 | would see in the L G M the L G M neurons converge onto |
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| 08:46 | for neuron. So the L. M inputs have come into the cortex |
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| 08:50 | converge onto the south, from which recording in the primary visual cortex. |
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| 08:55 | if you can now imagine taking these centers around cells with on Senator receptive |
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| 09:04 | properties and blending them together, converging information together you would get again a |
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| 09:09 | of life, the bar of life a certain direction. A certain |
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| 09:16 | um so complex cells again are And the point off discussing the simple |
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| 09:27 | complex cells really is the fact that the level of the retina at the |
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| 09:33 | of L. G m the visual representation would be luminescence off these on |
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| 09:41 | off center surround concentric, receptive And once you get to the primary |
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| 09:48 | cortex simple cells, they have varieties different, receptive field properties. The |
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| 09:55 | of these receptive fields are very They can be semi circle, so |
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| 10:00 | bars of live in certain orientation. the convergence of these concentric cells on |
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| 10:07 | simple cells and the convergence of simple further onto the complex cells from the |
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| 10:13 | cortex that now give us a variety shapes that we're perceiving there in the |
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| 10:20 | visual world in this variety of shapes the primary visual cortex creates what we |
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| 10:26 | a primal sketch. Primal Sketch is contours and lines the sir primal or |
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| 10:35 | off the receptive field properties off the visual cortex cells capable of putting the |
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| 10:43 | rudimentary image off the outside world that the contoured lines, the shapes, |
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| 10:49 | has emotion, and it also has color and then subsequently, ah lot |
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| 10:56 | complex Hierarchically Mawr complex processing Visual information in V two V three, and |
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| 11:03 | , once it reaches the association is where information from these multiple sensory |
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| 11:13 | and these multiple sensory cortical areas will blended together on will be also blended |
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| 11:22 | with the state off. Being oven on the emotional state of being on |
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| 11:32 | physical state of being and other aspect aspects and in the end, well |
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| 11:40 | us to form a complete picture of outside world and make certain cognitive tasks |
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| 11:49 | well as motor outputs accordingly. So and weasel, where the really famous |
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| 11:57 | describe these what we call orientation and they were describing these orientation columns |
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| 12:05 | micro electrodes so they would essentially stick electrodes. This column will contain tens |
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| 12:13 | thousands off neurons within this column so would stick different electorates is in the |
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| 12:19 | , and they would realize that Wait second. If we go to the |
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| 12:22 | center of the area, we get that are responsive to different orientations of |
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| 12:27 | . But if we go on to edge of the column, the cells |
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| 12:31 | responsible to the vertical orientation of But if we go on to the |
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| 12:36 | outside of this micro column, the , they're mostly responsive to the same |
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| 12:42 | but to a bar of life that is in the horizontal orientation. And |
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| 12:50 | what these colors represent here is that color stands for a group of cells |
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| 12:58 | is most responsive to a certain orientation that bar off white, which is |
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| 13:06 | for that style. And it's receptive properties and coded as well. And |
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| 13:11 | as you move around these micro which are essentially 30 to 100 micrometers |
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| 13:18 | , the cortex is about two millimeters , three millimeters deep and you have |
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| 13:25 | , uh, basically can well like and these orientation columns. These dots |
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| 13:35 | individual cells. Blue dots, green , yellow dots. Red dots represent |
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| 13:41 | cells that are most responsive. Thio orientation of life. So these air |
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| 13:47 | heat maps that represent the levels of . In this case, the color |
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| 13:53 | this map corresponds to a certain Certain angle off the orientation off this |
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| 14:02 | off light, as indicated below blue all of the vertical bars of light |
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| 14:09 | red eyes, all of the horizontal off life. So the same image |
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| 14:18 | can be done with both of sensitive image ing. And we will discuss |
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| 14:23 | when we talk about some matter sensory and talk about brain maps that will |
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| 14:28 | some videos that show some voltage sensitive image ing movies and what it means |
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| 14:33 | the general. We'll discuss some very , uh, image ing techniques, |
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| 14:39 | , later in the course. But we have to also talk about high |
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| 14:44 | column. So you have these orientation Collins and these micro columns. So |
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| 14:50 | joined into hyper columns, hyper for example. You can see this |
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| 14:55 | patch of the cortex that will contain lateral off on contra lateral ocular dominance |
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| 15:03 | . Within these ocular dominance columns, will have multiple orientation columns processing information |
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| 15:10 | visual field from different orientation and bars life. In the middle of these |
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| 15:16 | dominance columns, you will see darker for cytochrome oxidase days, indicating blobs |
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| 15:22 | higher increases in metabolic energy specialist too, but also as five and |
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| 15:28 | . And if you look in this here, you see this. If |
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| 15:32 | look longer, you see this light shaped fork in light color. |
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| 15:37 | this is, Ah, optical imaging that we call intrinsic optical signal that |
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| 15:42 | not require any stain or any And if you stimulate one, I |
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| 15:49 | you can. On the surface of cortex is you have access to the |
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| 15:53 | of the cortex can actually see changes the reflective properties of the neurons, |
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| 15:59 | more active neurons will be consuming more and showing certain swelling of the cells |
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| 16:07 | thereby changing the reflective properties off off tissue off the brain tissue without any |
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| 16:17 | . And so this is a very imaging technique. It's more, of |
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| 16:21 | , of the experimental image ing But in general, as we, |
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| 16:28 | , come back to the brain maps we'll talk about all of the functional |
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| 16:32 | techniques will review the things that we've covered, such as calcium imaging. |
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| 16:38 | talk about both its sensitive damaging to techniques that help you understand the signaling |
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| 16:43 | the synapses and also the signaling in own networks. And then we'll move |
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| 16:48 | into mawr of clinical application and remind was the two types of the functional |
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| 16:54 | ing that we've already discussed. And a functional magnetic resonance imaging and positive |
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| 17:04 | emission tomography on. Of course, , when we talk about neuronal circuits |
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| 17:10 | activity image and we'll also discuss voltage damaging as well. So we'll come |
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| 17:17 | to the slide and we'll elaborate quite bit on neural activity image and, |
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| 17:23 | , not quite a bit, but probably dedicate about 15 or 20 minutes |
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| 17:28 | time to this in the next couple lectures. Mhm. So this is |
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| 17:37 | starting the discussion on the hearing And as with visual system, we |
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| 17:47 | describe what life is s o. first here will describe what sound is |
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| 17:56 | what what what hearing is hearing, is neural perception off sound energy. |
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| 18:06 | it's neural perception off these particles moving the air. Sound waves move at |
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| 18:20 | m per second for 767 m Um, so if you were watching |
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| 18:34 | launch off the space six, you have seen that when the rocket was |
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| 18:40 | off the austra noughts and the I was watching the clicker that was |
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| 18:47 | the speed. And it was really , because when it went above 767 |
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| 18:55 | , they went supersonic on didn't stop . I don't know what the |
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| 19:03 | um, velocity or speed waas, I believe I know that it was |
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| 19:10 | 6000 MPH. At some point, were trekking really, really fast, |
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| 19:18 | away from the gravity to go into orbit eso 343 m per second or |
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| 19:28 | MPH. What they are is traveling of air. And of course, |
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| 19:34 | sound waves are slower than light. if you see fireworks, who will |
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| 19:40 | see a flash, and with some , you will see not only the |
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| 19:46 | but with some delay. You will the sound from those fireworks going |
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| 19:53 | Okay, so now what these waves off is ultimate regions off compression and |
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| 20:03 | faction off air molecules. So imagine you took a pitchfork, a sound |
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| 20:11 | , and you get it on a thing. What did we do is |
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| 20:16 | two sides of the fork with So this vibration then creates these waves |
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| 20:25 | compression and rare faction and send those in the form of sound radiated out |
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| 20:31 | the form of sounds. It's really vibration. It's a vibration of your |
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| 20:38 | cords and your sound box, which your mouth, and the movement of |
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| 20:46 | tongue and lips that produces difference movement these molecules air molecules that you can |
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| 20:56 | through the microphone right now where you hear it coming from the speaker. |
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| 21:02 | if you haven't analog system record label to tube amplifier. The speaker. |
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| 21:11 | the closest, um, analog But if you have digital system, |
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| 21:16 | have digital CD player or your phone connected through Bluetooth to a speaker or |
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| 21:27 | ear, but in your ear will these tiny speakers that all have |
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| 21:33 | And so when the information, the analog information this amplified and sent to |
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| 21:42 | speaker's vibrates, the membranes and the of these speakers and the vibration of |
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| 21:51 | diaphragms of the speakers produced the compression rare faction off the air molecules and |
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| 22:00 | changing the air this air pressure and your sword like fashion over distance. |
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| 22:07 | over time, human audible range is to 20,000 hertz or 20 kilohertz. |
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| 22:18 | above 20 kilohertz or 20,000 hertz is . Um ah. Lot of animals |
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| 22:28 | this world have communications that our ultrasound dolphins and herring and other fish can |
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| 22:39 | and perceived frequencies as high as 180 . Very, very, very high |
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| 22:48 | , very, very high pitch So infrasound, on the other |
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| 22:56 | is below 20 hurts and infrasound below . Hertz is car vibrations, but |
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| 23:06 | Subbu for vibrations. And if you at some of the Subbu for |
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| 23:11 | if you are into audio equipment, are looking at some specifications for sub |
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| 23:18 | for us to see that some of will be listed to go down to |
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| 23:21 | hertz. It hurts, and that not no longer perceived by our. |
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| 23:30 | the sensor organs, but it can be perceived by the mechanical movement off |
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| 23:35 | air. So if you're standing close the Subbu far, you can sense |
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| 23:39 | movements a matter sensory movement off this if it is really, really |
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| 23:47 | which is the intensity of sound. low frequency sound as you can think |
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| 23:54 | low pitch or high frequency is Pitch low intensity is high. Intensity |
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| 24:04 | the same page, but much Okay, that's that's the difference. |
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| 24:11 | , so the frequency really tells you pitch and the intensity is the amplitude |
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| 24:19 | these waves. Now this information enters the outer ear and then into the |
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| 24:26 | air and finally in the inner where these sound waves and mechanical vibrations |
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| 24:34 | translated into an electrochemical signal. In outer air. You have the |
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| 24:41 | which is the outside of the air have specific shape that drives the signals |
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| 24:47 | the auditory canal. It's also refer as external auditory mediators. Auditory |
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| 24:55 | That sound vibration reaches the 10 panic or the ear drum, and the |
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| 25:01 | groom is connected to three very small called the also calls. And when |
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| 25:06 | is vibration and the auditory canal vibration the air drown, the to panic |
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| 25:12 | is in amplified vibration of the obstacles the middle Aaron movement of the oval |
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| 25:20 | , which is connected to the cochlear off the vestibular cochlea. Perata's. |
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| 25:28 | if you recall, this is cranial eight, which is auditory, vestibular |
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| 25:34 | or the stimulus cochlear nerve, if may. The top portion of this |
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| 25:39 | the vestibular Peratis, and we're not going to discuss the stimulus varieties or |
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| 25:45 | stimulus A portion of the stimulus but rather the cochlear portion in the |
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| 25:52 | hearing system hearing apparatus that is located in the inner ear in the cochlea |
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| 25:59 | the outputs of it comprised auditory or cochlear component of cranial nerve. |
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| 26:05 | Which is this tubular cochlear nerve. is another representation of the anatomy off |
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| 26:12 | here, from outer to inner Pinar external here, external auditory mediators or |
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| 26:19 | Ear Canal or the auditory canal. is if you have obstruction of |
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| 26:25 | This is where you have poor Thio here. If you have obstruction |
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| 26:31 | wax, of course, you have clean it very carefully. Um, |
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| 26:36 | middle here you have the Tim panic and then you have the auditory obstacles |
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| 26:44 | you also have for middle ear from region right here, an extension from |
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| 26:51 | from the hearing of Peratis, almost this region here into the fairing What |
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| 26:57 | call the use station to it's illustrated well here, and you station tube |
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| 27:03 | used to balance out the pressure in pharynx on dwa. Once you have |
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| 27:11 | the pressure, you can hear things well. So a lot of times |
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| 27:15 | doing the pressure changes, you may obstruction of hearing a little bit, |
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| 27:21 | if you're on the plane you're or going downhill with a car, your |
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| 27:28 | . People say my ears are and that's because the pressure is |
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| 27:33 | And if it is not equalizing, can help yourself popular here. So |
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| 27:38 | will see people looking like this on . That's what I did, kind |
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| 27:43 | gasping for here, trying to move this area here that is connected to |
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| 27:48 | station tube to equalize the pressure so my hearing is not dampened. You |
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| 27:55 | also see people on a lot of grabbing their noses and Canada trying to |
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| 28:01 | their ears open. And that's again trying to equalize the pressure through the |
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| 28:07 | station tomb is also a place that quite often a very nice, moist |
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| 28:17 | between the firings, the throat and air that is conducive to bacterial environment |
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| 28:26 | . And so, if you hear saying, Oh, my child or |
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| 28:31 | child, it's often and Children had tubes replaced. What does that |
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| 28:36 | That means that they had a plastic here inserted replacing the station tube. |
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| 28:44 | reason why, uh, it is often and young Children is if young |
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| 28:51 | during the auditory system development. If Children during this auditory system development |
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| 28:58 | um cannot hear very well because they infections, they can lose the sense |
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| 29:07 | hearing Okay, so if you don't well and you have chronic ear |
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| 29:15 | then you have an insertion of these tubes. Replacement of the station tubes |
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| 29:21 | then plastic is not a very good for bacteria to grow, so you're |
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| 29:26 | doing that in case of chronic ear to prevent any loss to hearing development |
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| 29:33 | loss of hearing during the early Now, during the early development, |
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| 29:38 | is very important that we understand the information incoming sensor information If we deprive |
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| 29:48 | developing brain from sensor incoming information if hearing is dampened because the here's a |
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| 29:55 | If the hearing is dampened because of chronic, uh, ear infections, |
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| 30:03 | will be in effect not only on the language but also including the synaptic |
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| 30:10 | connections. And for us to understand I mean by that, I'm actually |
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| 30:16 | paddle back into the visual system. going to remind you something about the |
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| 30:22 | system that I forgot to do, ? And I will talk about a |
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| 30:32 | important concept off plasticity. We just about basically how important it is to |
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| 30:38 | the sensor information in the developing and I wanted to come back to |
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| 30:43 | visual system and highlight this example. know, for example, that laterals |
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| 30:49 | Nicollet nucleus inputs innovate layer for in New York or types, and we |
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| 30:56 | have this concept off critical period of This is one very important take home |
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| 31:03 | and this take home message refers Any system need visual system. Auditory |
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| 31:09 | amount of sensory any sensory systems where have external stimulation. There's critical period |
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| 31:15 | development, and not only in sensory in general, in brain system and |
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| 31:20 | body system in the brain circuitry, in particular, and humans. This |
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| 31:27 | period of development is varied, but have a lot of brain development. |
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| 31:34 | Natalie. That is happening within the few years of life and mawr. |
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| 31:41 | animal species such as rodents such as or rats. If you're looking at |
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| 31:47 | development of the visual system, when critical period of development, when there |
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| 31:52 | the most plasticity in the visual system retina, L, G N and |
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| 31:58 | cortex, this is happening over the month of life, sometimes into the |
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| 32:05 | month of life. But critical period development and rodents for the visual system |
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| 32:11 | about the first 3 to 4 post weeks of life. And so what |
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| 32:20 | if you interfere with a sensory What happens if you have a partial |
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| 32:28 | short term deprivation of the sensor input sensory stimulation. So this is an |
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| 32:35 | where you have deprivation off the visual , you Soochow one eyelid or these |
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| 32:44 | rodents and you do this. Damon ocular deprivation. Three days. |
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| 32:51 | animal is deprived from vision from one , and what you do later is |
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| 32:57 | look at the ocular dominance. We that there is equal ocular dominance of |
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| 33:02 | dominance that's represented by these ocular dominance . We have the ocular dominance |
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| 33:09 | Okay, this ocular dominance So left and right eye. And as you |
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| 33:15 | see normal, you have the same dedicated toe left, eyes you have |
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| 33:20 | to write. I left, I , I left my right eye. |
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| 33:24 | the cells in the cortex are in brains are equally responsive from the inputs |
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| 33:30 | the left to the right. I have their ocular dominance, but they |
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| 33:36 | equally a strong response of right. sells this area to the image inputs |
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| 33:41 | right. I left I from Now what happens if you deprive this |
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| 33:48 | during early development? It's in that . You Souter the island for three |
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| 33:57 | and then two months of age. one month after this short term, |
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| 34:03 | day deprivation. Does a mouse a not seeing the outside visual input. |
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| 34:12 | happens when you stimulate about ice and record the cells that are responsive to |
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| 34:19 | input from the left or the right ? You can see that even after |
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| 34:25 | days, there is, ah, in the cortex and in the cells |
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| 34:31 | responsibility to the eye that remained open this three day period. Mhm. |
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| 34:40 | what happens if you extend this three ocular deprivation in the six days off |
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| 34:48 | and operation. What happens then, that one month later. So remember |
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| 34:55 | just closing the island here instead of days for six days during this critical |
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| 35:02 | of development, this critical period of ? Uh huh. Then you come |
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| 35:08 | a month later, you stimulate both , and now you know, they |
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| 35:13 | one eye in the cortical cells when I stimulated are no longer responsive to |
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| 35:20 | and the ocular dominance That means that entire cortex has now shifted. It's |
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| 35:27 | connections and shifted Is responsiveness toe on ? The I that remained open and |
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| 35:34 | tells you that this is a very change and sometimes can be a permanent |
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| 35:40 | . That's why any sensor information be it visual information deprivation or auditory |
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| 35:46 | deprivation will restructure neuronal circuits and even short term deprivations. But if they |
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| 35:54 | during the critical period of development, also can have long term of |
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| 36:01 | Now, during the critical period of tells you that if you reverse this |
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| 36:06 | early on and it happens during the period of development, you still can |
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| 36:12 | a lot of the activity a lot the responsibility for the high. But |
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| 36:16 | this damage becomes longer for this, becomes longer than you may have a |
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| 36:22 | shift and ocular dominance to the eye remained open. If you look on |
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| 36:28 | diagram, you're on the left. term binocular deprivation shows that you still |
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| 36:33 | really strong bushy projections that air coming the columnists, and there's aware for |
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| 36:40 | the neocortex at the same time. you look at the this is the |
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| 36:46 | I and if you look at the I This is short term binocular deprivation |
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| 36:50 | the deprived. I just short term deprivation of 3 to 6 days. |
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| 36:57 | happens in the is the ax. the deprived. I show massive |
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| 37:04 | So you don't have as much of innovation coming from the columnist into the |
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| 37:09 | anymore because that I was irrelevant. it happened during the critical period of |
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| 37:16 | , this critical period of plasticity in you can like in this critical period |
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| 37:22 | plasticity quite easily Thio languages on toe foreign languages. If, for |
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| 37:31 | you came Teoh a country where it's your native language at a very early |
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| 37:38 | , like four or 56 and you studying English language, let's say, |
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| 37:43 | United States from very early age and came to this country when you were |
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| 37:48 | or a child, then you possibly Ah, no accent. Um, |
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| 37:57 | false. Cannot say if you have foreign background by listening to you speak |
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| 38:06 | . If you come to this country or if you start learning another language |
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| 38:11 | 18 years old and you put the amount of time, you may not |
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| 38:17 | able, Thio develop the same So this plasticity. And if you |
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| 38:25 | start learning the language in the twenties thirties and you're putting a lot of |
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| 38:29 | in tow learning these languages. You not be able Thio perfect this language |
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| 38:34 | skills. And so, um, some of us are immigrants that came |
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| 38:40 | this country and if you came here you came with older parents, for |
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| 38:45 | , then there's a stark difference and your parents were perfectly understand English and |
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| 38:52 | speak English. But they have very accent, and maybe it's difficult to |
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| 38:57 | sort of things in Grandma because they that language of a much later |
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| 39:02 | And you are somebody younger may have another. Foreign language is a much |
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| 39:08 | age when you have a lot of , when you have this critical period |
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| 39:12 | development where you can not only cause deprivation, restructuring and you know these |
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| 39:22 | damage. But also during this critical of development, you can cause a |
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| 39:26 | of synaptic plasticity and development of the . And that's why any type of |
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| 39:33 | information input is very, very important the visual and if you have the |
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| 39:40 | , it tells you just 3 to days of visual inputs, you restructure |
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| 39:45 | cortex permanent and you may regain some that function, but depending on the |
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| 39:52 | period and the duration off this, , this case deprivation, let's go |
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| 40:00 | to the auditory system again that if were to deprive an auditory signal and |
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| 40:06 | fact, there are studies that show students that sit in the back of |
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| 40:11 | classrooms and if there is not a good audio projection in the classroom not |
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| 40:18 | good sound that they don't perform a , just not by hearing. So |
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| 40:22 | you can understand that during the critical of development, if you have obstruction |
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| 40:28 | hearing, uh, either physical or have obstruction and hearing because of the |
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| 40:36 | , then you could be changing the of the circuitry and the Coakley and |
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| 40:42 | on up into the central auditory processing . So again, let's look in |
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| 40:49 | closer into this anatomy. In the of the ear drum on the movement |
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| 40:55 | the ear and the were faction and of the air molecules would then essentially |
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| 41:02 | into the auditory canal, remove the and the movement off this drum |
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| 41:08 | This Tim panic membrane would start moving nah Lius, which is connected to |
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| 41:14 | interests and they're connected to the Um, increases connected to the stay |
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| 41:20 | and stay peace. It was like arm that is now going to very |
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| 41:25 | , depending on the frequency of the . Vibrations is going to translate this |
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| 41:31 | , uh, frequencies in and the air molecules into mechanical vibration of the |
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| 41:39 | drum into a mechanical vibration. Off , uh, stay peas, obstacle |
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| 41:48 | . Uh, that is now going vibrate the over window off the |
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| 41:54 | And so the obstacles will amplify the of the air drum because you have |
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| 42:02 | connections and you have angles and you torque so you can amplify the mechanical |
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| 42:09 | of the air drum even further. then once you stimulate the oval |
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| 42:17 | then you're stimulating the window that is to the fluid filled chambers off the |
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| 42:24 | . It Coakley in general, is up sort of like a snail. |
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| 42:30 | if you were thio, unwrap the , and the size of that coakley |
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| 42:35 | humans is about this size of a pea on. If you were |
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| 42:41 | unwrap on fold this cochlear. This uncoiled cochlea, which you would see |
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| 42:47 | you were cutting through the cochlear. a three chambers, the scholar, |
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| 42:50 | stipulated scholar media and Scalia timpani. three of them are fluid filled |
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| 42:56 | and the scaly media will contain the of Corti that is responsible for trans |
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| 43:03 | the movement the fluid through the hair , which is McCann, a |
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| 43:09 | So individual system. We had photo , and in the next lecture, |
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| 43:14 | will talk about mechanical receptors. How mechanical movement of the dictatorial membrane following |
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| 43:21 | movement of the fluid is encoded as electrochemical signals by the hair sauce that |
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| 43:28 | then projected out of the KO A cochlear component of the studio. |
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| 43:34 | . A cranial nerve. Eight. also a certain structure in anatomy to |
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| 43:41 | cochlear. This is that the You have the open window, and |
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| 43:45 | the apex you have structure called Hillary . Here, this is the apex |
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| 43:50 | the cochlea. On the top, have this count of the stimulate. |
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| 43:53 | is callin media, the bottom of heart, the scholar timpani, which |
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| 43:57 | has the round when we'll come back more of the scenario and the following |
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| 44:03 | , the last thing I would like discuss today. ISS the attenuation |
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| 44:08 | And as you can see, there these stupid IUs muscle and tends to |
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| 44:14 | . Muscle these air the muscles that can control, how much the obstacles |
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| 44:24 | moving and attenuation reflexes a reflex of you're hearing a loud sound. Imagine |
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| 44:32 | . What do you do when you a loud sound coming from someplace and |
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| 44:37 | repetitive, All the first answers. cover your ears, you put the |
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| 44:44 | plugs on. Why do you want do that? Well, excessive movement |
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| 44:49 | the air, drunken rupture, the drum, intense sound waves, intense |
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| 44:55 | waves can rupture the air drums. sound, intense airwaves that it doesn't |
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| 45:02 | to the air drum. It can vibrate the obstacles to such an extent |
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| 45:09 | costs such a mechanical movement, massive of pressure and mechanical movement across the |
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| 45:15 | of Corti that can actually kill the assaults and result in the hearing |
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| 45:22 | Who will discuss that as we talked the inner and outer hair cells and |
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| 45:27 | irreversible hearing loss that can happen when go and listen to a very loud |
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| 45:33 | on DSO What do you do if have loud noise coming and you don't |
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| 45:39 | cover your ears? Let's say you're two bags off fish Eso You're too |
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| 45:47 | your hands and this loud noises So what do you dio? I |
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| 45:51 | kind of illustrated kind of like squint like docking squint Or what it does |
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| 45:59 | that does attenuation reflex Try doing it you will see if that you do |
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| 46:03 | . As I'm talking, you'll hear less so we have the ability it |
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| 46:08 | thio attenuate the sound by stiffening the . So not allowing the movement of |
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| 46:14 | articles to be exaggerated to such an that it becomes damaging to our |
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| 46:19 | Try incidents reflexive because again, you cover over the years. So you |
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| 46:24 | of do this funny squinting movement and like trying toe stepping up the articles |
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| 46:32 | stiffening about the muscles that are working obstacles and preventing the potential damage thio |
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| 46:39 | cochlear cells to the hair cells. , so we'll stop here today and |
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| 46:44 | pick up and talk about the auditory from or on the following lecture and |
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| 46:49 | into the somatic sensory system. So thank you very much and I will |
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| 46:55 | you the next lecture. Take |
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