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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…
Cerebellum
It 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, decisionmaking, connected to emotion
• Parietal: sensory information; speech
• Occipital: visual information
• Temporal: music and language
The Cortex!
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 Neurotransmitter 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, dopamine 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.”