Monthly Archives: January 2004

Physics and Free will

This Veritas was written on Tuesday, January 20, 2004

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 Friends, I have been bothered by a question for some weeks now and I wish to share it with you. In my opinion this is a fundamental question and still a great mystery.

       First let me state the assumptions. But what I call assumptions are much stronger than that. These assumptions are not just assumptions. These are things we believe in. Things that we base our lives on. So I call these beliefs:

1) The Laws of Physics are the most fundamental laws of nature.  So if something exists physically then the laws of Physics  are applicable to it. The laws of Physics are valid for  electrons, atoms, cells, human flesh/skin, planets, universe…   everything.

2) Man is capable of free will. Or free thought. i.e if I decide to  look at my black phone right now then it is a matter of my choice.  I could have chosen to look at my white phone as well! So I choose  what I look at. My brain can make choices. I am capable of  free thought, free will.

       Now according to our first point of faith the laws of Physics are valid for the Brain and neurons in the brain and the cells in the neurons etc etc. This is because the Brain exists physically and that means that it cannot violate Physics.

       Now what do typical laws of Physics look like: an electron placed in a magnetic field will behave like so and so. The electron has NO choice. The magnetic field acts on the electron and the “so and so” happens. The phenomenon will NEVER change. i.e the laws of Physics are
deterministic i.e you will know what will be the situation later if you know what the situation is now.

       So everything in our brains is determined by laws of Physics. And these laws are unchangable. So that means that your brain will function in a deterministic fashion. There is no choice! If I place you in a closed room and I use laws of Physics on every electon in the brain and solve the equations then I can determine what you will be thinking a year from now!

       What is the first thing that happens when I make a choice. Does my choice tell the electron in my brain which neuron to go to?? How do I tell the electron? That has to be done using some physical phenomenon! Choices dont move electrons! Electric and magnetic fields do. And how would that be told by my choice? How would I choose the amount of electric field to create to move the electron? Choices dont create fields! And we can go deeper and deeper but we can NEVER get choice from the deterministic laws of Physics.

       So we have two possibilities here. Both are very disturbing:

1) The laws of Physics are not fundamental and there is something deeper.   ( I will hate this).

2) I am not capable of free will ( My life can be determined by a complex equation and I have no choice in any matter. My life is decided by my environment and I am a mere variable)

       Please do not say that the indeterminacy in the Quantum Level is the cause of free will. It cannot be because you can NEVER chose
the result of the collapse of the wave function and then your life will be purely random! A probability on which you have no control.
And that is even scarier.

       I have an answer to this question. But more thought is needed before I share it with the world.

       A Wallace Stevens song: “
       They said,;You have a blue guitar,
       You do not play things as they are.;
       The man replied, ;Things as they are
       Are changed upon the blue guitar.;”

constantly disturbed,
Kanwar

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 Go, wondrous creature! mount where Science guides:
 Go, measure earth, weigh air, and state the tides:
 Instruct the planets in what orbs to run,
 Correct old time and regulate the Sun;
|======================================================|

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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Mysteries of the Brain Part – 10 – BLOOD BRAIN BARRIER

This post was written on Wed, 7 Jan 2004.

Friends, this is part 10th of our series in which we explore the mysteries of the human brain. Today we will explore an area of the brain which is one of the biggest challenges for modern medicine. If we could solve this challenge we could cure the diseases of the brain as easily as we can cure the diseases of the body.

  In the late 1800s a German scientist  Paul Ehrlich made a  discovery: he injected colored dyes into the blood stream of frogs. He found that the
dye has color stained all organs of the frog showing that blood moves throughtout the body. All parts except the BRAIN!!! His student Goldman
injected a dye into the brain of another frog. And he found that no other part of the body became colored. Only the brain was coloured. So it seems that the brain and the body lie on two different sides of a wall.

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  This wall is now known as the Blood-Brain barrier. This barrier is very important because it protects the brain from all sorts of chemicals ,
bacteria and virus that may enter the blood. This barrier is very strict and careful about what passes through to the brain. And it is responsibe
for maintaining a constant environment for the brain.

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       Briefly the rules of this barrier are these:

1) Molecules having a molecular weight of > 500 daltons( approx) are not allowed inside. Note that water has a weight of 18 daltons. The  smallest viruses have a weight of millions of Daltons.

2) Low lipid soluble molecules are not allowed.

3) Molecules with a high electric charge are not allowed.

       Lets see how this Blood-Brain Barrier works. For this we will have to look at the blood vessels that carry blood all around the body. The
blood vessels are made of flat endothelial cells joined together.  These blood vessels are impermeable enough to keep most of the stuff inside the
vessel but leaky enough to let some stuff to move through the vessels into the sorrounding organs. The joints between the cells lets stuff leak from these vessels. But the vessels that move in the brain and the spinal cord have a different arrangement of these cells. In these vessels the
endothelial cells overlap each other and have VERY little space in between. These tight junctions form the remarkable blood brain barrier.

       The blood brain barrier is so efficient that the brain is saved from all the bad stuff that keeps going inside us. But this barrier is a challenge for modern medicine as well! The problem is that if the brain does get a disease somehow then it is very dfficult to cure. VERITAS readers, most of our medicines have a moleclar weight of  much much more than 500 daltons!!!! Medicines invented for Alzheimer’s disease, Huntingston’s chorea, stroke all have molecular waights of 10,000 to 100,000. We have small molecular weight drugs for only a small set of diseases like epilepsy, depression, migrane etc. So most of our medicines cannot be delivered to the brain!

      Scientists are working hard to find a way to bypass this barrier and deliver drugs to the brain. Injecting drugs directly into the brain by drilling past the skull would be horrible. Now there are situations which “open” up the Blood brain barrier: high blood pressure, trauma to the brain. Also large amounts of sugar can open the blood brain barrier for about 20 minutes before the excess sugar gets absorbed by insulin. But these ways are not good for the body so they cannot be used to deliver drugs to the brain.

       Latest research shows that the Blood Brain barrier is not a wall but a gate. Some chemicals that are needed for the brain are allowed to pass through even if they are large. The Blood -Brain barrier has some special molecules( think of them as gatekeepers) who will escort these needed chemicals into the brain. For example iron is packed into a molecule called transferrin and the Blood Brain barrier sucks the transferrin into the Brain side. Scientists are now thinking of ways to create such gatekeepers or use the barriers gatekeepers to transfer the large molecule drugs into the brain.

       There are several parts of the body where the Blood Brain Barrier is weak. Through these parts the Brain monitor’s the makeup of the blood.
One such place is the Area Postrema or the Vomiting centre. When you eat something that the Brain detects as toxic then the Brain will order the stomach to throw up!! So the toxic food is discarded before it can do harm.

       Friends, The Human Brain is a astonishing thing. The more you study it the more mysterious it appears. In the last 10 parts of this series we have only looked at a very small part of this Grand Mystery. And this series has not over yet. I am planning the next 10 parts. I am proud to say that this VERITAS series has become hugely popular among the VERITAS readers. And we are not going to stop. Lets look back at the old parts and what we have covered:

part 1 ( 20-5-02) : Brain Hemispheres
part 2 ( 2-07-02) : Why deep emotions are always permanent
part 3 ( 21-8-02) : consciousness
part 4 ( 30-10-02): Brain and the immune system
part 5 ( 13-11-02): The brain that adapts to loss of organs
part 6 (23-01-03) : Sex differences and the brain
part 7 (01-05-03) : Dreams
part 8( 11-09-03  : Methodology of memory storage
part 9 ( 25-09-03): Cells that store memory
part 10 ( 7-01-04): The Blood Brain Barrier

 

More dope : Jill Bolte Taylor got a research opportunity few brain scientists would wish for: She had a massive stroke, and watched as her brain functions — motion, speech, self-awareness — shut down one by one. An astonishing story.

we will not stop wondering,
Kanwar

|=============================

=========================|
 Go, wondrous creature! mount where Science guides:
 Go, measure earth, weigh air, and state the tides:
 Instruct the planets in what orbs to run,
 Correct old time and regulate the Sun;
|======================================================|