Hello everyone! Welcome to advanced neurobiology! Neuroscience is a wonderful branch of science on how our brain perceives the external world, how our brain thinks, how our brain responds to the outside of the world, and how during disease or aging the neuronal connections deteriorate. We’re trying to understand the molecular, cellular nature and the circuitry arrangement of how nervous system works. Through this course, you'll have a comprehensive understanding of basic neuroanatomy, electral signal transduction, movement and several diseases in the nervous system. This advanced neurobiology course is composed of 2 parts (Advanced neurobiology I and Advanced neurobiology Il). They are related to each other on the content but not on scoring or certification, so you can choose either or both. It’s recommended that you take them sequentially and it’s great if you’ve already acquired a basic understanding of biology. Thank you for joining us!
2.2.1 Sound transduction-I
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来自 Peking University 的课程
Advanced Neurobiology II
59 个评分
从本节课中
Perception: Auditory
与讲师见面
Chenjian LiProfessor
School of Life Sciences
Donggen LuoResearch Fellow
School of Life Sciences
Yan ZhangProfessor
School of Life Sciences, Peking University
So the auditory system is the sense of hearing.
So here in the front is a picture.
You can look at this picture so you appreciate actually when
you enjoy the music, it doesn't matter what kind of music.
So all the sound should detect by the auditory system.
So we also actually showed you last time,
the hearing, also important for
the survival of the animal.
For example, for this bird to catch the food.
Here is a mouse or rat.
So this is actually in complete darkness.
And then, we talked about it last time,
how this bird can really precisely locate the target without any other cue,
only by the sound cue?
So, today we'll talk about it more,
those kind of underlying mechanism to achieve this.
So if I ask you to describe the process of
the hearing, how will you describe it?
>> So I guess even in the high school, everybody, I guess,
learned their kind of biology, so of physiology.
Apparently you know something about the hearing,
without the book knowledge actually,
I guess you also know some of the process.
How can you describe the process of hearing?
Any volunteers?
>> Well actually I [INAUDIBLE] I have a theory.
[INAUDIBLE] If I can [INAUDIBLE]
the physical sound is
mechanical oscillation.
And it will- >> It's a wave, a sound wave.
>> Yeah, it will cause oscillation of maybe a sound or something like that.
And the mechanical
oscillation will transduce
into [INAUDIBLE] and
transduce into neuron.
>> Okay.
>> [INAUDIBLE] or maybe something like that [INAUDIBLE]
>> Okay, I'm very surprised.
[FOREIGN]
>> [LAUGH]
>> [FOREIGN]
>> [FOREIGN]
>> [LAUGH]
>> Yeah, surprise, okay.
[FOREIGN] Okay, so
that process actually is quite
complicated, okay?
It's more elegant than what [FOREIGN] described.
So let's take a look, actually there
is another book actually describes the process.
It's a writer [FOREIGN].
Yeah, I guess you can read quite a signal.
And then this process.
So this is the whole process of the sound propagation
from the outside to your auditory system.
So this actually is quite elegant a description of the hearing process.
So today we'll go through each steps, talk about this issue.
So let's begin with the first, actually the sound wave propagation.
So from here this is actually,
those are particles actually will vibrate by the sound of the wave.
And then you look at here, i says
the sound of the wave somehow collected by either
on the outer ear, and then you will have the biological process here.
So let's take a look, there's the sound propagation.
So the sound wave come in, and the wave hit a membrane.
And then you see these three bones actually
will relay the sound wave to the cochlea.
This cochlea is giant snail, this actually varies.
This region is some cells within this cochlea,
we transduce sound signal into
the electric signal, happen here.
So, let's take a look,
the next step, what happened
within this cochlea.
Actually, we want to take a look at the anatomy of this structure.
So you make a section, and then you will see these kind of structures.
Right?
Then, apparently, this is a cell, transducer sound signal.
We have this some movement of this membrane across some hair bundle.
Waiting the tip of this hair cell to move.
And then somehow, this neuron then will have the electrical activity happen.
And then will transfer this electric activity to the neuron, to the brain.
This is what happens in the first step of the hearing.
So actually this is the anatomy of this structure.
So you can take a look.
This is what we call hair cell.
This is called inner hair cell.
There are two types of hair cells, one is the inner hair cell,
the other is the outer hair cell.
So for the hair cell, it's a little bit different
from the photoreceptor, the light detector.
So, this cell has a huge cell body for the inner hair cell here.
And then there is a process, actually,
for the tip there is a feel,
those kind of cilia is hair bundle.
[FOREIGN] Now, this hair bundle,
and then we'll receive the mechanical force.
And then somehow, for this hair bundle,
they have mechanosensory channel at this place.
So where you have a mechanical force move this bundle,
like deflected, and then the channel will open directly and
then produce the electric signal.
So for this one, thing is, all the hair cell looks
a little bit different, it's more kind of elongated.
[FOREIGN] But it's a process actually that's quite similar.
They also have the hair bundle to transduce the mechanical force into
electrical signal.
But this cell actually quite interesting, they don't have the axon.
So you can look at this process,
and, this process, the red one.
It should be a neuron, it sends a process called
maybe a dendrites or some other process that shoots it
into the neurons to make it's connection there.
So, this is form another cell to
relay the signal from the hair cell to the brain stem.
[FOREIGN] Why there are two types of these cells?
It's quite interesting.
Now we know, actually, this inner hair cell
carries a lot of information to the brain.
That means, this actually, take a look.
This is actually called afferent, this red one.
Afferent, this exon carries the information
found in the hair cell to the brain.
And this actually to make the sound perception is carry
the signals mainly carried by this afferent in the hair cell.
