Download Neurobiology of learning

Biology of Learning
Anatomy of a Thought
Memory is a funny thing. We all experience it, but it’s hard to describe,
unless… you’re a neuroscientist.
With decades of hard work we’ve learned a lot about what happens when you
learn and form a new memory, and how we use our memories to solve new
problems.
Let’s start with some basics:
Do this 
1) Write down the name of the object to the right:
To name the object signals from your optic nerve (coming from the eyes) were
relayed to a bundle of a few hundred thousand nerves about 4 inches behind
your right ear (put your hand there a moment). That bundle of nerves has
become associated with apples over the course of your life, and so the nerves
“fired” together, sending a signal to the language area of your brain, just
above your left ear (put your hand there a moment), where another bundle of
nerves has become associated with letter and word patterns. After that bundle
of nerves “fires” you are ready to write the word “a-p-p-l-e.”
Now lets reverse the process.
Do this 
2) Draw a picture of a Banana:
To remember, or “picture” a banana in your mind, signals from your optic nerve
first relayed to a bundle of nerves 3 inches behind your left ear that “fire” when
letter sequences like “b-a-n-a-n-a” are read. A second signal is then relayed to
an area on the opposite side of your head (4 inches behind your right ear) where
bundles of nerve networks are associated with different images. Here the bundle
of nerves that have become associated with bananas “fires” repeatedly and you
are able to “picture” a banana in your mind.
The whole process occurs in a fraction of a second. More sophisticated ideas, or
more sophisticated learning, involves many more bundles of nerve networks, but
essentially it’s the same process.
Now here’s the cool part…when you learn anything, nerve networks
begin to grow. Because of what you just read above, nerve branches called
dendrites are growing out of nerve cells in several different parts of your brain.
Biology of Learning
Anatomy of a Thought
A Closer Look:
Brain cells (called neurons or nerves) are similar to all other cells in many ways.
They use the sugar glucose for energy, they custom make proteins needed for
themselves or other cells in your body, and they grow.
White blood cell
Amoeba
Red blood cell
Muscle cell
Cheek cells
Sperm
Nerve cell
Paramecium
Unlike other cells in your body, neurons don’t regularly divide to make new
neurons (a process called mitosis). When neurons die, they DIE.
But most neurons can last your whole life (if you take care of yourself), and they
can GROW. Specifically they grow branches or “arms” called dendrites and
axon terminals.
Where the branches of two nerves almost touch is called a synapse, and at the
synapse nerves can “communicate” with each other.
Finally Nerves can generate an electric current!!!
Biology of Learning
Anatomy of a Thought
Use your notes from the learning PowerPoint to label the following nerve parts:
Dendrites, Nucleus, Cell body, Axon, Myelin, Nodes, Axon Terminals
Nerves don’t touch. Between the Axon Terminal of one nerve, and the
dendrite of the next nerve, there’s a space called a Synapse. Because of all
the dendrite and axon branches, any one nerve may have thousands of synaptic
connections to other nerves. It’s like each nerve is a cell phone with 7000
different numbers programmed into it’s address book.
Axon Terminal with
electric signal
Neurotransmitters
Synapse
Dendrite
Biology of Learning
Anatomy of a Thought
Nerves use about 500 of the calories you eat in a day to generate electric
current and make new neurotransmitters.
The electric current always moves one direction; from the tip of a
dendrite, through the cell body, down the axon, and ends at an axon
terminal.
Myelin on the axon is made of fat and works like insulation on a wire. It lets
the electric current skip from node to node over huge distances, allowing the
electric signal to move very fast!
How nerve cells generate the electric current is something we’ll study when
we look more closely at cells.
The neurotransmitters nerves use to communicate across the synapse are
little protein molecules made in the nerve. Some neurotransmitters excite
other nerves (make them fire an electric signal) while other neurotransmitters
inhibit nerves (stop them from firing).
Drugs, both legal and illegal, work by manipulating levels of these
neurotransmitters in the brain. Below is a summary of the common
neurotransmitters you’ll learn about (don’t let the big names scare you)
Noradrenaline
Dopamine
Acetylcholine
Serotonin
GABA
Excites nerves, sometimes called adrenaline or
norepinehprine
Excites nerves, especially in the pleasure center of the
brain
Excites nerves
Can excite or inhibit nerves, regulates mood
Inhibits nerves, has a calming effect
How nerves make these proteins is something we’ll explore when we study
genetics.
Biology of Learning
Anatomy of a Thought
Learning
In response to new experience or repeated experience neurons change and
reorganize. New synapses may form, existing synapses may strengthen, some
synapses may be eliminated, or more dendrites and axon terminals may grow.
The brain’s ability to change and reorganize is called Plasticity. Although the
brain maintains it’s Plasticity throughout life, it is strongest during early
childhood and the teen years.
In general learning occurs like this:
Step 1
New experience and practice causes the release of nerve growth factor. This
causes dendrites to grow and new synapses to form. It can also increase stress
hormones, which leads to feelings of frustration.
Biology of Learning
Anatomy of a Thought
Step2
The front of your brain (the frontal lobe) is the area where you
make decisions, plan, and set goals. When you are paying attention
while trying to learn, the frontal lobe communicates with the new
synapses formed in step one. It’s also sending signals to the reward
center of your brain, getting it ready. When the new dendrites and
synapses fire correctly, and you achieve a goal, the chemical
dopamine is released in your pleasure center and you feel happy.
Your brain rewards itself for avoiding mistakes and reaching the
goal. Your stress level drops, you crave more dopamine, and you try it again.
Focus, anticipation, and goal setting drive learning. If you are not focused
on the task, and not setting an expectation for yourself, learning cannot
physically occur.
Step 3
Over time you practice and keep adding to your skill or knowledge base, which
now physically resides in a large network of connected neurons. Neurons that
are stimulated to form additional synaptic connections grow and strengthen.
However, neurons or synapses that are neglected weaken over time (which
helps you avoid mistakes, but also causes you to ”forget” how to do
something).
The brain is wired to learn through trial and error. Getting it right the first
time does not lead to intelligence. Making mistakes and learning from them
leads to intelligence.
Continued Practice improves the brains efficiency (how quickly it can do
something). For instance, when a person first learns to play the piano, he or
she uses a large amount of the motor section of their brain (which controls
movement). However, professional piano players who have been playing for
many years devote a much smaller region of their motor cortex to finger
dexterity. How is this possible? By repeatedly stimulating the same region of
their body (fingers) for the same action (piano playing), their brains have
strengthened the related synapses. Thus, fewer neurons are needed to perform
the same task.
Factors that effect Learning
Exercise, environment, stress, and emotion
Studies have revealed that physical, social, and mental activity enhances
memory and alertness. For example, mice raised in an “enriched”
environment, which contains other mice and a variety of stimulating toys,
Biology of Learning
Anatomy of a Thought
displayed dendrite growth and performed better on learning tasks than
inactive, isolated mice did. These results were observed in mice of all ages.
Mice raised with toys but no social interaction, as well as mice raised with
other mice but no toys, performed less well on learning tasks and showed less
neural growth than those raised with both toys and social interaction did. In
addition, mice that were made to do learning tasks tend to retain more of
the dendrite growth they experience during enrichment than do mice that are
left alone after enrichment.
Recent studies with show that the same is true for humans of all ages. Thus,
mental, social, and physical stimulation are all positive regulators of
neural growth and seem to have an additive effect on learning and memory.
Lack of social contact, and absence of mental stimulation, and constant
stress have a negative effect on neural growth.
The human brain is designed to focus attention on social interactions happening
around it. The next time you are in a store, or restaurant, or
classroom, try to note how often you eavesdrop on other
conversations, and how eavesdropping derails your train of thought.
Studies show that if two or more people are being social about a
learning task, dendrite growth increases dramatically. But if social
interaction is not on task, not only is learning severely compromised,
but dendrite growth is compromised for anyone else in the room.
Biology of Learning
Anatomy of a Thought
Realistic Goals- Avoiding internal stress
Focusing on small incremental goals allows for dopamine to be released in the
reward pathway, which alleviates stress and frustration. Setting unrealistic
goals leads to building frustration and fear of failure. The defense mechanism
for fear is anger, and the frustrated learner often gets turned off.
“Why do I have to learn this?”
“I’m never going to use this!”
“This is stupid!”
Signs of a learner
suffering from fear of
failure
Downtime
In the center of your brain is a curved bundle of neurons called the
Hippocampus, which is responsible for coordinating memory formation
in different parts of the brain (think: if I ever went camping wit a hippo… and
you’ll remember Hippocampus). People with a damaged hippocampus can’t
form new memories or learn new skills (marijuana also erodes the hippocampus
over time).
Now the hippocampus, and all the neurons in your brain need frequent down
time, about 2 to 3 minutes for every 15 minutes of focused learning. Neurons
need to replenish their store of glucose (sugar) from the blood. Mitochondria
in the nerve cells need to use the glucose to make ATP, an energy molecule
that the nerve uses to generate an electric signal. And finally, neurons need to
make more neurotransmitters
Taking breaks is not a waste of time. It allows neurons to recover, so that
future growth and performance is optimal (made the best it can be).
Sleep and Diet
Americans used to rank in the top 5 world wide for life expectancy (how long
we lived) and height. Today we rank 41st in the world for life expectancy, and
most Europeans are growing taller then us. Both changes seem to be related to
diet and sleep.
More about this in a later unit
A basketball player could never play a whole game without pausing occasionally
for a timeout to drink some Gatorade, stretch, and catch their breath.
If they didn’t take a little downtime, their performance would really
suffer in the second half of the game. It’s the same for the brain when
it’s trying to learn.
Biology of Learning
Anatomy of a Thought
Sleep
It goes without saying that sleep is awesome. Here’s the reason why:
When you sleep your brain goes through 6 to 9 very short cycles of REM sleep
(called Rapid Eye Movement sleep because your eyes move back and forth very
quickly). Each cycle lasts about 5 minutes, and during that time your brain does
the following:
1) Signal the body to make Human growth hormone which:
 Builds lean muscle and repairs skin and other tissue throughout
the day and night.
 Increases the body’s ability to metabolize fat (burn fat for energy)
2) Your brain also produces it’s dopamine (the “happy” neurotransmitter)
during REM sleep.
3) Finally, During REM sleep, your brain “relives” everything you focused on
during the day, causing neuron networks to fire. If you practiced piano for an
hour, your brain relives that experience, and those neurons fire again, growing
thicker and stronger. At the same time you also relive your driving lesson, the
conversation you had while texting in math class, the essay you wrote, the
fight you had with your mom, etc… You don’t relive the things you weren’t
really paying attention to, like the drive to school, eating cereal, what your
teacher was saying during math class, etc…
This process is called consolidation, and it’s the time when the dendrite
connections you established during the day become stronger.
Again, your sleeping brain doesn’t decide what is important or unimportant.
You decided that when you were awake, and chose to focus on or ignore
certain things.
Unfortunately half of a persons REM cycles occur during the last 90 minutes of
natural sleep…what you biologically need. For ages 12-19 it’s about 9 hours of
sleep. About 80% of teens in America are sleep anorexic, sleeping 7 hours or
less on weeknights, meaning that they are missing half of the benefits they
would get from sleep.
Extensive research demonstrates that teens who sleep 8 hours or more a night
have healthier body weights, are less depressed, and perform much more
efficiently on mental tasks, then their peers who sleep 7 hours or less a night.
Note: Research also shows that catching up on the weekend has no benefit.
Biology of Learning
Anatomy of a Thought
Diet
In the end you really are what you eat. If you feed your body the right
combination of nutrients it can make all the proteins it needs to build
dendrites, and muscle, hormones, and neurotransmitters. If you feed your body
junk, it will suffer. Consider the following snack choices:
Peanuts and an apple:
The fat in the peanuts will be used to build new dendrites and myelin to cover
axons. The protein in the peanuts will be used to build more neurotransmitters.
The carbohydrates (sugars) will be released slowly into the body because of the
fiber in the apple, providing the brain with a steady flow of fuel.
Chips and a soda:
The saturated fat in the chips is useless to the body, and will get stored for a
starvation emergency (which is unlikely). The refined sugars in the soda will
case a huge release of insulin into the blood, which will promote fat storage
and cause blood sugar levels to drop like a brick, leaving the brain with no fuel
after the initial rush.
Biology of Learning
http://members.shaw.ca/hidden-talents/brain/113-maps.html
Anatomy of a Thought
Biology of Learning
Anatomy of a Thought