The Brain

The brain is the single most important structure in our bodies.  As far as we can tell, the brain controls most of human thought and emotion.  When you sit and think about it, the brain is also the coolest thing about you.  Every time you think about anything- it is your brain.  When you feel pain of pleasure- it comes from your brain.  Its all about the brain!!!

The brain is made up of neurons and glial cells.  I call my wife my glial cell.  Glial cells support nerve cells in the brain by providing food and support.  Although the brain is made up of millions of densely packed neurons, it actually feels no pain.  If I stuck a knife into your head, you would feel pain from the skin, scalp and skull being pierced, but once the knife reached the brain, pain stops (but the other stuff still hurts).   It was commonly believed that once you damage brain cells (through drinking, smoking, hitting your head or just holding your breath for a REALLY long time) they would never grow back.  There is some research now that points to the contrary. 

If you happen to suffer from some brain damage, do not despair.  Some of our brain functions are flexible and if one part goes out, others will try to compensate and continue to function.  The concept that some of our brain will attempt to reroute itself if damaged is called Brain Plasticity.  It does this by rerouting connections to avoid damaged dendrites.  Picture Brad Pitt or Angelina Jolie (take your pick or fill in your own fantasy) invites you over for nookie.  If the highway you were going to take to their house flooded, would you give up?  No way, you would use Mapquest to get directions using local streets.  That is essentially what our brains try to do when damaged.  Unfortunately, as we age the ability of brain plasticity working decreases.  The lesson here, if you are going to damage your brain, do it at a very young age.

Before we talk about brain structures, lets quickly go over some of the ways scientists learn about the brain.

Ways to study the Brain

Accidents

Every so often someone gets smacked in the head REALLY hard and from their injury we learn about the brain.  The most famous case occurred in 1848 to a fellow named Phineas Gage.  Phineas was working on the railroad when a iron pole shot through his head. 

Unbelievably, he survived the accident.  But his personality and behavior changed drastically after the catastrophe.  He became violent, angry and unpredictable (not just because a four foot pole shot through his head).  Phineas's accident first led scientists to believe that various parts of the brain control different parts of who we are.

Lesions

A lesion is the removal or destruction of part of the brain.  Doctors will lesion a patients brain during brain surgery (usually to remove some type of tumor).  By removing parts of the brain we were able to learn what different parts of the brain do. 

Below is a  lesion of a rat's brain

For example, if a doctor removed a tumor in your left temporal lobe of the brain and you were then unable to speak, we could assume that speech comes from that area of the brain.  Brain lesions were commonly used in the mid 1900s to control mentally unstable patients.  Part of the frontal lobe was removed (frontal lobotomy) and drastic behavioral changes occurred after surgery (we learned that our personalities are strongly centered in the front of our brains).

EEG (Electroencephalogram)

The brain is just like an electrical battery (remember the Matrix).  An EEG machine measures brain waves.  If you are awake it measures what we call alpha waves (short active waves) and when you are asleep it measures other waves like delta waves (long inactive waves).  If the EEG measures no activity then you are either brain dead or watching Jerry Springer.  It is used commonly in sleep research.

 

CAT Scan (Computerized Axial Tomography)

A CAT scan is just a really sophisticated x-ray of the brain.  It gives us a 3D picture of the brain which is great for locating tumors, but it does NOT show brain activity or function.

 

MRI (Magnetic Resonance Imaging)

An MRI gives us the most detailed picture of the brain.  It uses magnetic fields to knock electrons of their orbit and takes a picture by seeing them run back to their orbits (kind of).  There is no radiation so the procedure is safe, but once again it only gives us an idea of structure and not function.

 

PET Scan (Positron Emission Tomography)

A PET scan is the best way for us to see activity in the brain.  The patient will usually swallow a substance (like glucose) and the PET scan will see what parts of the brain are using the substance.  If a patient seems to be using alot of the substance in a certain part of the brain, we can tell what part of the brain is working.

 

Functional MRI

This is essentially a combination of the PET scan and the MRI.  The fMRI can give us the best picture of the brain while showing use blood flow information.  The Yankees of brain technology.

 

Piece of cake, now on to the heart of this unit: Brain Anatomy and Function.