Brain Basics

Your brain makes you who you are.

Rene Descartes: 'I think therefore I am'

It controls all we think, say and do.

• 3 pounds of mushy stuff

• 100 billion nerve cells (neurons) and cells that support them (glial cells)

• As many cells as stars in the Milky Way

Some say humans have not one brain but three…

What this means is that there are three different parts to the human brain…not three different brains!

Brainstem

• Our first most primitive brain is the brainstem.

• You can think of this as the “Reptilian Brain.”

• Similar to the brain of hardy reptiles, roughly 200 million years ago.

The Brainstem Controls

• The body’s basic functions such as breathing and heartbeat.

• Lacking language, its impulses are instinctive and ritualistic.

Next to the brainstem…

CerebellumIt is at the rear of the

brainstem.

It controls posture, movement and physical skills.

Limbic System

• This is our 2nd Brain

• It can be thought of as our “old mammalian brain.”

• The brain common to all mammals.

The Limbic System Controls

• Our body temperature, blood pressure, heart rate, and blood sugar.

• It also governs our emotions and behavior, from love to violence and aggression.

The Limbic System also…

• Is related to forming memory

• The hippocampus and the amygdala, parts of the limbic system, are especially important for forming memory.

The Man that Memory Forgot

A man known only by his initials H.M. shows us the importance of the hippocampus and amygdala.

H.M. fell from a bicycle as a child and started to have severe seizures.

By the time he was 27, these seizures were so severe that doctors offered him only one hope…to remove the site of the seizures.

What happens if you remove the hippocampus and amygdala?

H.M. soon recovered from the operation. He could carry on a conversation and he had no more seizures.

However, while his memories of the past still remained, he could not remember much of the past few years and he could not form new memories.

Inability to form new memories

H.M. couldn’t remember his uncle died the year before. Each time he heard he cried.

He could read he same magazine over and over. Each time he read it the stories were fresh.

Over 3 days H.M. did a picture maze 215 times. He never remembered doing the maze before and did not improve.

H.M.’s surgery has never been tried again!

• H.M.’s life, deprived of the ability to form new memories, was a tragic one.

• Adam Sandler, in his often awkward movie, makes fun of this type of brain damage.

“Thinking” Brain

• The 3rd Brain or “New Mammalian” Brain.

• Includes Cerebrum with its thin covering, the Cortex.

• The Cerebrum is just Latin for “Brain”

• It is the newest part to evolve.

The Cerebrum and Cortex do it all!

She is cheering for all our brain can do!!!

• Sensory perception• Voluntary Movement• Conscious Thought• Purpose• Personality

Cerebrum…it’s cerebral!

• The largest outermost part is the cerebrum.

• It has a left and right hemisphere.

• Each hemisphere controls the opposite part of the body.

What does the cerebrum do?

• Makes up 85% of the brain's weight. Thinking part of the brain.

• It lets you solve math problems, play video games, feed your fish, do a dance, remember

your sister's birthday, and draw pictures. • It's the cerebrum that makes human beings

more intelligent than animals because it's the part that lets us reason.

The Right Hemisphere

• Some scientists think that the right half helps you think about abstract things, like music, colors, or shapes.

• It helps you identify patterns and deal with three dimensional space.

The Left Hemisphere

• It is usually dominant.• It is more analytical,

helping you with math, logic, and speech.

By the way…

Can my Brain Hurt?

• NO!!! The brain itself has no feeling.

• A headache is actually muscle pain in the face, neck or head.

• Migraines are when blood vessels in the head constrict and expand, sending pain messages from all parts of the head to the brain.

And that’s a really good thing because…

• Two Prussian doctors in 1870 studied the exposed brains of wounded soldiers.

• They used electrodes to stimulate the left and right hemisphere of the cerebrum.

They found out it’s true…

• When they put the electrode on the exposed left hemisphere, the right side of the body moved.

• When they put the electrode on the exposed right hemisphere…you guessed it…the left side of the body moved.

• By the way, these kinds of experiments on humans are illegal today!!!

And our final part of the brain…

• Let’s have a big shout out for the Cortex

The Cortex helps us

• Organize• Remember• Communicate• Understand• Appreciate• Create

• In preserved brains the cortex has a grey color…hence the saying about “grey matter”

The Cortex has 4 Lobes

• Frontal: (largest part) planning, decision-making, connected to emotion

• Parietal: sensory information; speech

• Occipital: visual information

• Temporal: music and language

The Sad Story of Phineas Gage

Here’s a story that shows the different parts of our brain truly control separate aspects of how we function.

In 1848, Phineas Gage was a foreman of a railway crew. He was a friendly, well-liked individual who could be trusted to treat the people in his life well and be a responsible employee.

But then came a tragic accident

A miscalculation with dynamite sent a 13 pound rod through Phineas’s brain. Everyone thought he would die, but he survived!

The rod destroyed the frontal lobe of Phineas’s cortex

• He now cursed unceasingly, lied to friends, broke promises and burst into rages.

• He was still intelligent with a good memory, but he lost all respect for people.

• He couldn’t keep a job; ended up exhibiting himself as a carnival freak.

From this we learn that…

• Brain damage can change personality.

• Our frontal lobe controls moral reasoning and social behavior.

• The autopsy of Phineas Gage confirmed that his front lobe was destroyed which caused the changes to his personality.

Okay, so now that I’ve learned the different parts of the brain…

HOW DO THEY COMMUNICATE?!!!

Neuron…a messenger cell

• A Neuron is a specialized nerve cell that receives, processes, and transmits information to other cells in the body. We have a fixed number of neurons, which means they do not regenerate. About 10,000 neurons die everyday, but since we start out with between ten and 100 billion we only lose about 2% over our lifetime.

Here’s what a neuron looks like

Look at the Dendrites, Cell Body, and Axons. How do you think these might be used to send messages?

It’s kind of like playing telephone…

• The Dendrites receive information from other neurons.

• The Dendrites pass the information to the Cell Body which processes information.

• The Cell Body passes it along the Axon.

• The Axon passes the information on to glands, muscles, or other neurons.

Neurotransmitter

One problem: we saw how once the Dendrite of the neuron receives information, it transmits information throughout the neuron.

BUT: neurons do not physically touch other neurons.

How do you think neurons can send messages to other neurons?

Eureka!

If you said, through neurotransmitters, you’re right!!!

Here’s how it works…

• The gap between the end of one Axon and

the Dendrite of another is called a Synapse.

• Axons release Neurotransmitters to cover the gap.

Chemicals Carry the Message

• Neurotransmitters are chemicals

• The brains may make as many as 150 different kinds, although only a few are known.

• Axons release neurotransmitters at the space between the Axon and the Dendrite.

Which key will open the lock?

• Think of a key into a lock. That’s kind of how it works.

• Each Neurotrans-mitter molecule has a particular shape that just fits a particular Receptor.

Yes/No or Stop/Start

• There are two kinds of keys for receptors.

• Excitatory: it excites or starts an impulse (makes the body do something)

• Inhibitory: it inhibits or stops an impulse (makes the body stop something)

Dopamine: One kind of neurotransmitter

• Correlated with movement, attention, and learning

• Too little is associated with the muscular rigidity and tremors found in Parkinson’s disease.

In Awakenings, dopa-mine is given to wake up the patients.

Serotonin

• Plays a role in mood, sleep, appetite, and impulsive and aggressive behavior

• Too little serotonin is associated with depression. Some antidepressant medications increase the availability of serotonin at the receptor sites.

Endorphins

Involved in pain relief and feelings of pleasure and contentedness.

These are the body’s own painkillers.

They create feelings of happiness and well being.

They can be important to survival, like in childbirth.

Drugs mimic these natural mood changers.

Brainy Quotes

“Here is more matter for a hot brain”

--William Shakespeare

Ralph Waldo Emerson

“A man is what he thinks about all day.”

Norman Cousins

“The growth of the human mind is still high adventure, in many ways the highest

adventure on earth.”