1.1.9 Single-photon detection

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Del curso dictado por Peking University

Advanced Neurobiology II

51 calificaciones

Peking University

Advanced Neurobiology II

51 calificaciones

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!

De la lección

Perception: Vision

1.1.1 Ways to sense the environment-I10:18

1.1.2 Ways to sense the environment-II11:57

1.1.3 Ways to sense the environment-III8:24

1.1.4 Sensory transduction-I9:04

1.1.5 Sensory transduction-II9:12

1.1.6 Sensory processing9:12

1.1.7 Sensory representation in the brain4:57

1.1.8 Vision15:58

1.1.9 Single-photon detection16:44

1.1.10 Second messengers8:35

Conoce a los instructores

Chenjian Li
Professor
School of Life Sciences
Donggen Luo
Research Fellow
School of Life Sciences
Yan Zhang
Professor
School of Life Sciences, Peking University

Let's take a look, this is the eye.

The eye ball, if we look of course,

these structures we know this is a lens cornea.

[FOREIGN] The most important

thing actually here is

the yellow tissue here.

[FOREIGN] tissue.

[FOREIGN]

The neuron

responsible for

the detectance

of a photon.

[FOREIGN] Actually other neuron types other than.

This neuron is a output neuron and

this sends its axon to the brain.

Well [FOREIGN] let take a look here.

[FOREIGN] Make it a section.

[FOREIGN] You can see this deep

in the layers [FOREIGN] is a structure.

[FOREIGN] Okay,

this side is this side okay?

Is close to this black one, you see this is a black tissue here.

[FOREIGN] This photoreceptor and then here.

[FOREIGN] This one,

this is a,

In the nuclear

layer [FOREIGN]

mainly bipolar cell.

[FOREIGN] Horizontal cell and endocrine cell.

[FOREIGN] Output a neuron,

send to the brain to have it's axon go to the brain.

Okay, this is the another

cartoon to show this neurons, this is actually the photoreceptor, okay?

There are two types of photoreceptors you can see,

one is actually very long and very thin.

This one is called a rod photoreceptor [FOREIGN]

now this one is a different one, okay?

[FOREIGN] photoreceptor

[FOREIGN] okay?

These two type of cells should be responsible for

transduce the light into the electric signal, okay?

Detector and then you have bipolar cell,

this vertical pathway.

[FOREIGN] Your bipolar cell to ganglion cell.

[FOREIGN] In this outer flexible layer.

[FOREIGN]

You get kind of

horizontal

cell.

[FOREIGN] very special,

they don't have the axle

send the information to

downstream neuron.

And what they do is actually

make the [FOREIGN] formation

modulation [FOREIGN] okay?

[FOREIGN] Okay, so

let's take a look

actually how this guy,

this photoreceptor

detects the light.

[FOREIGN] This is a cartoon

of the photoreceptor.

Of course you know its easy to [INAUDIBLE] photoreceptor, right?

[FOREIGN] This is a cone for the receptor,

and the light detection region

only happened at this region.

[FOREIGN] Outer

segment [FOREIGN]

this we call [FOREIGN].

We call segment here [FOREIGN] this is outer segment.

[FOREIGN]

Terminal

[FOREIGN]

[FOREIGN]

Okay.

Why you need to make such a system with too many discs there?

[FOREIGN] With the tender,

harder surface area [FOREIGN]

detector, right?

[FOREIGN] Design using

a principle [FOREIGN] in

the olfactory system [FOREIGN]

[FOREIGN]

Region

here, there

is a pocket

[FOREIGN]

is this

chemical

able to

absorb

the photon,

okay?

This is important, it's not the protein, this is an 11 Cs.

11 Cs is actually

between the [FOREIGN]

okay, cyst.

[FOREIGN] If we have a photon, here this molecule,

this chemical where as absorbed with the photon energy.

The energy

will be used

to break

the bond

[FOREIGN]

what will

happen to

the protein?

[FOREIGN] The whole [INAUDIBLE]

protein act,

this confirmation [INAUDIBLE].

Now protein,

[FOREIGN] activate

the protein,

time to bind it

to the protein

[FOREIGN] okay.

[FOREIGN]

Professor

[FOREIGN]

okay,

the

photoisomerization,

[FOREIGN]

okay?

[FOREIGN]

Okay?

Yeah, the

same thing,

[FOREIGN]

okay?

This actually, the lighting effect, so

let's further take a look at this structure.

This is the ROD photoreceptor out the second one, in the second one, right?

So, [FOREIGN] increases

the surface area to,

[FOREIGN] this direction or

this direction or that direction.

[FOREIGN]

Now let's take

a look actually

about the disk

membrane [FOREIGN]

this is the real

disk inside.

This is actually

the [FOREIGN]

It's not

connected to

the disc [FOREIGN]

electric

activity of

the neuron,

coming from

where?

[FOREIGN]

Here is coming

from a very

important concept

[FOREIGN]

so, you have

a photon.

[FOREIGN] How do you have electric

signal on this [FOREIGN] so

you need something to connect theses two processes.

So why is happening here, why is happening here?

That means that you have

to have a second messenger [FOREIGN]

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