Waching daily Aug 28 2018

Where does our mind come from?

The neuroscientist Eric Kandel says

"today, most philosophers of mind agree that

what we call consciousness derives from the physical brain"

Apart from consciousness, neuroscientists also claim that

other mental activities, such as thinking

reasoning, perception, judgement, memory and emotion

also derive from the physical brain

If there is no brain

none of these mental activities will occur

Then what evidence do neuroscientists have

to support this claim?

Let's start with

a classic medical case of brain damage

It happened in 1848 in the U.S.

Phineas Gage, a foreman on the railroad

had been described as "a great favorite"

until he had a terrible industrial accident-

an iron rod passed through his head

He miraculously survived

but his personality had been radically changed

He became capricious

rude, irreverent

manifesting but little deference for his fellows

According to his friends, he was "no longer Phineas Gage"

Since then

many medical cases of brain damage have been reported

The lesson from all these cases is the same:

the condition of your brain is central to who you are

Damage to even small parts of the brain

can lead to the loss of specific abilities

There are cases in which brain-damaged patients were

unable to distinguish faces

Some of them could not even recognize their own faces in the mirror

One patient

even mistook his wife's head for a hat

He tried to lift it off and to put it on his head!

Brain damage

may also alter one's perception of reality

One stroke patient

had hemorrhage in her left hemisphere

She felt the boundaries between her body

and the external world disappeared-

two became one

All stresses were gone

Only peace and euphoria remain

In addition to brain damage

other factors can also affect the brain

like narcotics

The small molecules we call narcotics

can alter consciousness

affect cognition

and navigate behavior

We are slave to these molecules

Take cocaine as an example

A cocaine molecule consists of 43 atoms:

carbon, hydrogen, nitrogen, and oxygen

However, this molecule can plug into

the dopamine system in the brain

The dopamine system is the reward system in the brain

If it is commandeered by cocaine

the user feels invincible

and euphoric

even believing that

taking cocaine is the best possible thing that could be happening

and keeps on trying to obtain cocaine at all costs

Even though these small molecules are

1000 times smaller than the width of a human hair

they can impose tight control of their users

Beside narcotics

some viruses and bacteria

can also greatly affect how the human brain works

rabies virus is an example

When a person is bitten by a rabid dog

this tiny bullet-shaped rabies virus

climbs its way up the nerves and into the brain

Then the virus changes the patterns of neuronal activities

it induces the infected host to have confusion

hallucinations

rage

and even aggressive behavior

Many patients develop a fear for water:

drinking it

seeing it

hearing watery sounds

or even hearing the word

may frighten the patients

and trigger the spasms of the inspiratory muscles

Consequently, though suffering from raging thirst

they can hardly swallow drops of water

The rabies virus, a measly 75 billionths of a meter in diameter

can commandeer the massive body of an animal

25 million times larger than it

Both rabies virus and cocaine

can induce invisibly small changes inside the brain

that cause massive changes to behavior

Rabies virus

cocaine

cases of brain damage

all serve to show that mental activities come from our brain

And this list of examples is not exhaustive

Various evidence points to the same conclusion:

mental activities are the products of

the physical processes and the chemical reactions in the brain

Explaining mental activities with

non-physical concepts like "soul" is unnecessary

Do you agree?

For more infomation >> 3. Where does our mind come from? - Duration: 5:26.

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2. Does DNA Determine You? - Duration: 5:51.

What do you think about the saying 'DNA determines you'?

DNA is regarded as the code of life

The biological information is hidden in the DNA sequence

Does it mean that DNA sequence determines you?

Let's look at the following cases

First, we are all developed from fertilised eggs

The cells divided thereafter

have the same DNA sequence

If the hidden biological information is the same

how can these cells develop into different cell types?

The DNA sequence in different tissues is the same

why do cells in different tissues have different functions?

The DNA sequence in eye cells and stomach cells is the same

why don't the eye cells produce gastric acids as the stomach cells do?

Another case is identical twins

A fertilised egg replicates itself

The divided cells develop into two individuals

and their DNA sequence is identical

Does it mean that these twins are identical in all aspects?

Identical twins are very similar to each other

but there are still some differences

What actually causes these differences?

The above cases show us that

even with the same DNA sequence

the characteristics expressed are different

But why?

To think about these questions

we have to understand the mechanism of gene expression

as well as the regulation of gene expression

In gene expression

the biological information

is transcribed into RNA sequence

and then translated into amino acids which form the proteins

responsible for different cell functions

metabolism, and the characteristics of the organisms

However, all the twenty thousand genes in our cells

are not expressed at the same time

Every step of gene expression

has precise and complicated mechanism

like switches, to control

the degree of expression of these genes

The genes can be non-expressed

slightly expressed or over expressed

For example

a process called 'DNA-methylation'

is important for the regulation of gene expression

When genes are combined with methyl groups

the structure of DNA molecules are altered

Then, the genes cannot be transcribed

and thus cannot be expressed

When a fertilised egg divides and differentiates

throughout the entire process of embryonic development

the genes in every cell

at different stages and time

are controlled by various mechanisms

which causes differential expression of the genes in different cells

The cells can thus undergo differentiation and develop

into different cells, tissues and organs

As a matter of fact

gene regulation is influenced by environmental factors

For example, if a pregnant woman consumes alcoholic drinks

alcohol will affect the development of the embryo

Scientific research using human embryonic stem cells showed that

alcohol increases DNA-methylation of many genes

The expression of genes controlling cell differentiation is altered

which may result in abnormal embryo development

Scientific studies also showed that

when comparing the heavy drinkers with those who do not drink

there is a 20% difference in DNA-methylation in their brain cells

The gene expression patterns between them are also different

which may account for their weak memory and addiction

If two identical twins living in the same family

enter two different hostels in university

One of them enters a hostel which has a long tradition of drinking alcohol

the students there drink a lot of alcohol during night talks

The other one enters a hostel without such tradition,

the students there drink only water during night talks.

Do you think the identical twins having the same DNA sequence

will gradually developed different characteristics?

We know that a change in DNA sequence

may cause a change in the expressed characteristics

However, when the DNA sequence remains unchanged

there are still many precise and complicated mechanisms

to control the expression of every gene

which also causes a change in the expressed characteristics

Gene expression is affected by different factors

either directly or indirectly

These factors include the bio-molecules produced by cells

the nutrients in diets

chemicals and radiations in the environment

stress and habits, etc.

In fact, it is impossible that two people

are affected by the same factors

Therefore, even if their DNA sequence is identical

the results from their gene expressions are different

These differences may be very small at the beginning

but they will become more obvious with time

As a matter of fact, from the time of pre-natal stage to death

we are all affected by the biological information hidden in DNA

and its interaction with various environmental factors

If this is true

when someone argues 'DNA determines you'

What would you say?

For more infomation >> 2. Does DNA Determine You? - Duration: 5:51.

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1. What is Life? - Duration: 4:37.

Have you ever thought about what life is?

Is it like one of the discoverers of the structure of DNA

James Watson said

it's just a matter of exquisitely organized physics and chemistry?

Watson also believes that DNA is the code of life

What does he really mean?

To understand Watson's idea

we have to know the structure of DNA and the decoding mechanism

Then, we can understand how DNA affects the functions of cells

the communication among cells

and the formation of biological structures and characteristics

Thereby, we can have a deeper understanding on

the interaction between organisms and the environment

Let's use eukaryotic cells

which are cells with true nuclei, for explanation

Chromosomes in the nucleus consist of DNA molecules and proteins

The DNA molecules are made of two DNA strands

which form the double-helix structure

There are four nucleotide bases on each DNA strand

which are represented by the four letters A, T, C and G

The sequence of these four bases are called DNA sequence

The DNA sequences on the two DNA strands are complementary

Base A pairs with base T

while base C pairs with base G

One DNA molecule can have as many as 200,000,000 base pairs

forming a very long DNA sequence

in which the biological information is hidden

So, how could these biological information is expressed?

To answer this question

we have to know the decoding mechanism of the DNA sequence

that means the mechanism of gene expression

Gene is a segment of DNA sequence carrying genetic information

Through the processes of transcription and translation

the hidden genetic information is expressed

First, in transcription

the two DNA strands are unzipped

One of the DNA strands serves as the template

for the synthesis of a complementary mRNA strand

Please note that

mRNA has the base U instead of the base T

The mRNA is processed and cut to become a mature mRNA

and then leave the nucleus

The biological information in the DNA sequence

has been transcribed accurately into the mRNA sequence

At the second step of gene expression

translation

The mRNA binds with ribosomes in the cell

A step-by-step translation begins to reveal

the genetic information hidden in the mRNA strands

Three RNA bases are read as one coding unit

Two coding units are paired with two complementary tRNA molecules

which carry two specific amino acids to the ribosome

The two adjacent amino acids are then bound

and the first tRNA molecules is discharged

Then, the ribosome starts to decode the next coding unit

until the entire translation process is completed

In this way, the information in the mRNA sequence

is translated into amino acid chains

which are fold into 3D-structured proteins

with specific biological functions

Let's look at this example

In the haemoglobin gene

The biological information in the DNA sequence

is transcribed into the mRNA sequence

and then translated into haemoglobin proteins

which are responsible for carrying oxygen in red blood cells

When a person carries an abnormal haemoglobin gene

such as having a mutation in the DNA sequence

the hidden biological information is different

After transcription and translation

the amino acid chains may be different

Thus, abnormal haemoglobin proteins are formed

which cause the formation of sickle-shaped red blood cells

and hence reduce their oxygen-carrying capacity

and may result in shorten one's life span

Up to here

do you agree that DNA is the code of life?

DNA decoding is an exquisitely organized process

involving only physical processes and chemical reactions.

So, do you agree with Watson that

life is just a matter of exquisitely organized physics and chemistry?

For more infomation >> 1. What is Life? - Duration: 4:37.

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4. Do we have free will? - Duration: 6:39.

Do we have free will?

How should we define free will?

Generally speaking, free will refers to

our ability to make choices

For instance, let's say we have two choices: A and B

I could have chosen B even if I have chosen A in reality

Take a look at another example. Let's say it's the first time I take a GEF course

I've chosen UGFN this semester

but I could've chosen UGFH instead

So do we really have free will?

To answer this question

we need to clarify three important concepts:

determinism, libertarianism and compatibilism

Determinism claims that our world is deterministic

What is a deterministic system?

A deterministic system is a system

whose future state is uniquely determined by its past state

In other words, once the past state is specified

the future state cannot be any other state

For instance, let's say we toss an apple up into the air

According to Newton's laws of physics

the trajectory will be a parabola

The position and velocity of the apple at any time

are determined when it was tossed

In other words, if we know the position and velocity

of the apple when it was tossed

we will know the position and velocity

of the apple at any other time

The initial state of a system is given by the initial conditions

In other words, a deterministic system is a system

whose state is uniquely determined by its initial conditions

Note that we should not confuse determinism with fatalism

Fatalism claims that

the final state is the same regardless of the initial conditions

A classic example is the story of the tragic hero

Oedipus in Greek mythology

A prophecy revealed that Oedipus would

kill his father and marry his mother

Hence Oedipus's father freaked out

and abondoned Oedipus as a baby in the woods

Nevertheless, despite his best efforts, it was inevitable that

Oedipus killed his father and married his mother in the end

Let's look at another example

Let's say no matter whether I'm determined to study really hard

or simply to be lazy all day long

I will fail the quiz at the end of the day

That is fatalism, my friend

In fact, not only a tossed apple is a deterministic system

the whole Newtonian physics is deterministic

In other words

systems such as a tossed apple, running water, the Moon orbiting the Earth

and the Earth orbiting the Sun

are deterministic systems

If this is so

shouldn't our world be pre-determined

like a machine?

Once started, all future states are fixed?

If that's true

we can't change the future

and hence we will not have free will

Back to the question of whether we have free will or not

hard determinism, libertarianism and compatibilism

can be described in relation to the following statement:

"If determinism is true, then we don't have free will."

Hard determinists believe that the statement is true

and our world is deterministic

Hence we don't have free will

Libertarians also accept the statement

but they don't think our world is deterministic

and we do have free will

Compatibilists claim that

determinism and the existence of free will are compatible

They reject the statement altogether

They accept that our world can be deterministic

and they also believe that we do have free will

To this end, it is still a controversial question

whether we have free will or not

and there is no standard answer to it

Interestingly, although many people

believe that our world is deterministic

This belief is not strictly correct according to modern physics

The truth is, Newtonian physics isn't valid all the time

In microscopic systems

such as an atom or a molecule

there are phenomena that cannot be explained by Newtonian physics

They can only be explained by a theory called quantum mechanics

Quantum mechanics claims that

the behaviour of a subatomic particle is probabilistic

For instance, when an electron passes through a plate with double-slits

the landing position on the screen is not predictable

As a matter of fact, physicists claim that

quantum mechanics is not only applicable to microscopic systems

but also macroscopic ones as well

Our entire world is composed of probabilistic, random events

The problem is, if events in our world are random instead of deterministic

does it mean that we may have free will?

Can a die possess free will?

Or should we re-examine the definition of free will?

So do you think we have free will?