So again, there are different ways to teach the newer techniques.

But I think SS set, the broad spec would be most

to establish both correlation and

causality at different levels.

But specifically,

we have already touched upon some aspects of the techniques in neuroscience.

For example, how different model organisms can contribute

to our understanding of neural systems like action potential.

How does it generate by the interplay of what is grade a sodium and

potassium channels, right?

But in addition, different animal models can provide

different aspects of knowledge or information.

For example, the vertebrates that are closer to human okay.

So one will expect that the information for

them is partially the non human primate can provide

information of a higher cognitive processing like emotion.

We'll study worms for emotion.

Might be a little bit more difficult because it's difficult to find, okay.

But there are some simple model organisms that can provide

to the simplicity to understand a complex development

of neuro-circuitry that can control behavior.

For example, we have already talked about a screen but

other invertebrates, butterflies that today have very sophisticated behavior and

some of their cells are huge and beautiful, right?

And this can provide the information to study how the invertebrate

nerve cells development, recognize each other and organize to process information.

Okay, if those information that obtained are conserved,

then because of their simplicity they can provide a testable principle for

people to study in a more complicated animal

models like a mouse or even some human cells.

If those principal or if those molecules

are structured and no conserved, but

I think is still useful because it provides

a vivid example that how nature evolve to use

different strategies to solve the same problem.

For example, human can smell something.

Well, butterfly can also chase some flowers.

Even if it turns out that the principles in butterfly, or

the receptors that the butterfly used to sense those odors

are completely different than humans, it provides a very

unique perspective to understand the diversity of evolution.

How different strategies, like how we evolve, so

different species in different geography conditions to deal with the same problem.

For example, how to distinguish different odors.

How to achieve the sensitivity,

how to dynamically change the sensitivity and different conditions.

And I think those are still very useful for people to understand nature.

So then a lot of times people think to understand nature that some people

they very dear to their heart

trying to understand the disease mechanism because that is related to human health.

But, a lot of study, especially research are curiosity driven, and

I think one of the curiosity is just to appreciate how nature evolves for

those different strategies.

It will be some sort of feelings

that you figure out how nature works.

And this is the amplification, zoom in.

This is a very complicated neuron

with this diversified dendrites.

And the simplicity of the invertebrates for

example, the model organism of flies and

sciaticas allows much simple genetic manipulation.

And indeed, people have already found out

the conserve principal the conserver molecules or

sometimes the almost identical for

those molecules control the nerve assembly that control human's neuronal assembly.

For example, the natural molecule

seems to be used the same way in worms and

in humans to induce axonal guidance.

And people also use special vertebrae

model organism taking advantage,

again, of their unique property.

For example, zebrafish because of these transparency that

allows much easier imaging in the live animal.

So it's very useful for the neuroscience research.

And because it is a water prey and a zebrafish is relatively small so

one can also take advantage of the genetic and

the relative cheaper to grow to culture to use that to searching for

important molecules that are important for.

Because there’s still a big difference between invertibrates and vertebrates.

And especially for zebrafish

actually lady.

She actually is a fly geneticist and after doing

her nobel prize work in flies to identify a lot of

[INAUDIBLE] important molecule for fly segmentation.

She spear head, she's becoming a pioneer in

the zebrafish field by using zebrafish along

with the community to develop into a vertebrate model

system to study or to model the human disease.

And you can see the transparency, especially people can,

in this zebrafish to make additional mutation to make a really transparent,

to eliminate the pigments.

So indeed some of my friends in Harvard was complain

to me they were using some albino mutant fish that without pigment.

And frequently what happened was that the rotation student in his lab

sink those there's no fish in that water, just dump the fish, okay.

So, they had huge trouble to maintain those fish,

because some careless rotations student couldn't see the fish inside the water,

because they are so transparent.

Okay, so, now they have to use huge labels.

There is a fish inside.

Please take care of it, okay?

And you can see in the live fish different part of

the brain, resemble eyes, heart brain okay.

And as I said, mice, rats, and nonhuman

primates are closer comparing with fish.

So especially the non human primate.

The recent development of genetic manipulation tools

allowed people to do the genetic manipulation in non human primates, and

this opens up a new window to study The higher cognitive function in the primates.

And again, human itself can also provide good

experimental examples if you follow the ethical procedure.

For example the psychology test frequently use human as an example

coupled with this recent development of brain imaging.

So one can couple with the human's response with the image data in

different brain region, or using some special normal activation

method in humans to study, at a human level, the neuronal functions.

And geneticist's techniques, because of the conservation of DNA,

all living organism provides a unique,

powerful, scalable techniques.

Those two allowing, observing, or perturbing the system

to study biosciences, including neuroscience.

The reason neuroscience is more complicated actually motivate

a lot of scientists, including the book’s author, Dr. to develop them.

To develop more sophisticated techniques

to answer the neuronal questions.

For example, how to achieve a single cell labyrinth,

biogenetic technique, to label a single neuron, it’s morphology.

For example, how to just predict

one gene in one neuron in the brain

to study whether there is a cell autonomous effect.

For example, some guided molecule is serving as a receptor

to guide to the molecule to guide to the neuron to grow, or

it's working as a non cell autonomous function to secrete

from adjacent cell to attract or repel a neuron to grow.

Because of the sophistication of the complicated,

complex of neural anatomy when requires this sophisticated

technique just to manipulate a single neuron in a rare

type background to get a very specific answer.

And there's other ways, for example, how to label one single

neuron in its entire connecting neuron in the brain.

That also recently been developed by the genetic technique.

And the genetics can be separated as

the full genetics, or reverse genetics.

This sounds like we are going to have a genetics class, which can itself last for

one or two semesters.

And the full genetics is that you don't know which gene might be important for

some functions.

So you can sort of randomly mutate [INAUDIBLE] and

then identified the outcome, and

then sequencing to find out which gene responsible for that.

Whether [INAUDIBLE] genetic is you have already some idea which gene or

which pathway might be.

Then you just diverted testing by perturbing looking out mutating them and

then to look at the phenotype that's responding to those mutations.

And the phenotype could be at a cell level or

at a behavior level and then you will start a different aspect.

The mutagenesis process, the important part is that

usually to achieve the phenotype understanding,

most of the single point rotation will be recessive.

So if there are mutation alone, we will not have phenotype.

And therefore, they need to achieve the homozygous

to observe the phenotype for most of the mutations.

And reverse genetics that people will use different ways to perturb the gene and

one of the powerful way and we discuss is so

that no cut in the old days using the combination

which is increasingly being replaced.

So this is combination you can generate some reactors and

then that allow yourself to have selection marker to select for the.

Because the efficiency is relatively low, so

[INAUDIBLE] to have a selection marker select for

those [INAUDIBLE] for the recent development of the reverse

genetics is that allow more sophisticated manipulation.

There is the conditional manipulation meaning that

one can introduce specific creed dependent,

recombinant dependent allele into a gene and

using a specific, tissue specific expression of this recombinase.

One can only manipulate in a specific tissue, those genes so

they can further achieve the tissue specificity.

And this tissue specificity,

again this is showing how this technique wise is being done

in the embryonic stem cell through this modification,

and then you transplant those modified cells into the.

For example, to create those genetically

modified reverse genetics engineered mouse.

And then more recent development of genome added into a,

for example, the system because it can using this

base parent dependent of cutting to generate double string break.

So you can much highly increase the efficiency.

So this revolutionized the whole thing by allowing one

to start it those animals that you don't have the cultural ES cell.

You can still achieve this genetic modification.

So that expanded the animal models that one can have the genetic manipulation.

And previously, one has to rely on the ES cell because efficiency is so

low so you have to culture tens of thousands of ES cell the screen for

those and then allow them to survive and to enrich them.

But now the efficiency can be much higher, so one can just simply inject and

then screen with 100 cells rather than 10,000 cell okay.

So it doesn't require the culture ES cell system to have this genetic modification.

10.2 Animal models in neurological research

Advanced Neurobiology I

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