Reflexes, Phantom Limbs, and Cultural Differences – Oh my! Psychology Riverside High School Mr. Basich.

Reflexes, Phantom Limbs, and Cultural Differences –

Oh my!

Psychology

Riverside High School

Mr. Basich

Objectives:

Describe why reflexes happen. Describe the facts about phantom limbs. Describe the cultural differences in

regards to transmitters.

Reflexes

We all are equipped with natural reflexes. When the doctor hits your knee with a rubber

hammer, your leg jerks forward. When a new born feels a touch on the bottom

of it’s foot, it’s toes will flare out. (Babinski reflex)

When you touch a hot light bulb, you recoil. When a football player is about to get tackled

from the side, he will do the Heisman pose.

What is a reflex?

Reflex – An unlearned, involuntary reaction to some stimulus.

Reflexes are pre-wired – you don’t have to learn them.

Now we are going to briefly describe the steps in a reflex.

Step #1 - Sensors

The skin of your fingers have specialized sensors.

When you touch a hot light bulb, these skin sensors trigger neurons that start the withdrawal reflex.

Step #2 – Afferent Neuron

From the receptors in your skin, long dendrites carry “pain information” in the form of electrical signals to the spinal cord.

Afferent neurons – sensory neurons that carry information from the senses to the spinal cord.

Then the pain is transmitted to a second neuron.

Step #3 - Interneuron

Interneuron – Short neuron whose primary task is making connections between other neurons.

The interneuron will then send it to a third neuron.

Think about it like volleyball – your setter (interneuron) is getting the ball ready to be spiked (by your efferent neuron).

Step #4 – Efferent Neuron This is the final phase. Efferent Neuron (Also called motor neurons)–

Carry information away from the spinal cord to produce responses in various muscles and organs throughout the body.

These efferent neurons cause your hand to jump back when you touch something hot.

Other efferent (motor) neurons will send pain information to muscles in your face and throat to that you can show pain in your face and say “OUCH!!”

So…..Why do we have reflexes?

It has to do with survival. Reflexes have evolved over millions of years. They protect body parts from injury and harm. Some reflexes (such as the hair standing up

on your arms when you’re cold) are no longer needed.

The raising hair would help keep the heat “in” your body for better insulation.

Phantom Limb – A Case Study

In 1993, Donald Wyman was in the forest driving a bulldozer.

A giant oak tree suddenly fell and pinned him to the ground.

He was all alone and no one could hear his shouts for help.

Donald knew what he had to do. He took out his 3 inch pocket knife and cut

off his leg, just below the knee.

More about Donald

He was bleeding badly, but was able to drag himself to his truck and drive a mile and a half down the road to get help.

His limb was too badly damaged to be reattached. (they recovered the part of his leg he sawed off)

Donald now has an artificial limb that is fitted to the stump of his leg.

His Recovery

His recovery went well, though he does have a problem.

“The toughest part since the accident is dealing with phantom pain. It feels like somebody’s holding an electrical shock to your foot that’s not there. It makes you jump around.”

We are now going to discuss the strange phenomenon of the phantom limb.

Phantom Limbs

Doctors have been puzzled by the phantom limb since they were first reported in 1866.

Phantom limb – Feeling sensations or movements coming from a limb that has been amputated.

These sensations are felt as if the limb were still present.

Does this happen frequently? The vast majority of individuals claim to feel sensations or

intense pain coming from their removed limb. They often refer to it as “pins and needles” They insist that it is “real” pain, not memories of previous

pain. Some individuals claim that their phantom limb was still

present and that it was stuck in certain positions. (straight out from their bodies)

Some felt that they had to be very careful not to hit their phantom limb when going through doorways!

Answers: #1:

Sensations come from cut nerves in the stump.

Early research thought that when nerves were cut near the spinal cord, phantom limb should have been prevented.

The sensations still remained though. This early answer has been rejected.

Answer #2:

Sensations come from the spinal cord. If sensations from phantom limbs do not come

from the stump, perhaps they originate in the spinal cord.

Well…Even individuals whose spinal cords have been severed above the stump report phantom limb sensations.

A severed spinal cord prevents sensations. This theory doesn’t work either.

Answer #3:

Sensations come from the brain itself. Researchers have enough data now to

indicate that the origin of phantom limb sensations must be the brain itself.

They are still puzzled however, how the brain generates sensations from phantom limbs.

Answer #4:

Sensations come from a body image stored in the brain.

This theory states that we are all programmed with a system of sensations that show us where are body parts are.

Based on sensations from body parts, the brain pieces together a complete body image.

Having this “body image”, the brain can generate sensations coming from any body part, even if that part is a phantom limb.

So, What does this information tell us?

That the brain sometimes functions in mysterious ways.

Think about dreams – What’s that all about?

Next, we are going to be talking about how certain drugs affect the functioning of the brain and the body.

Cultural Diversity and Drugs:

The very first drugs that affected the brain came from various plants.

People used these drugs long before researchers knew what those plants contained.

We are going to discuss three drugs: cocaine, curare, and mescaline – which come from plants.

We will also see how each of these drugs affects the nervous system.

Cocaine:

For almost 3,500 years, South American Indians have chewed leaves of the coca plant.

Some of today’s Indians (not the baseball team) still carry toasted coca leaves, which contain cocaine.

Throughout the day, these Indians would chew small amounts of coca leaves to relieve fatigue and hunger.

Now we will see how cocaine affects neurotransmitters.

Cocaine:

Cocaine blocks a process called Reuptake. Reuptake – A process through which some

neurotransmitters (such as dopamine) are removed from the synapse by being transported back into the end bulbs.

If the dopamine was not removed, the neuron would be continually activated and cause extreme over arousal.

More about Cocaine:

Cocaine cause the dopamine to remain longer in the synapse.

Neurons are stimulated longer feelings of arousal and euphoria.

Cocaine also relieves fatigue and hunger because it blocks the reuptake of dopamine.

Mescaline:

Mescaline – A golf ball sized grayish- green plant called peyote cactus that grows in Mexico and in the Southwestern USA.

Peyote contain Mescaline which mimics a neurotransmitter.

Mescaline causes physiological arousal as well as visual hallucinations.

Mescaline is very similar to the neurotransmitters norepinephrine.

More about Mescaline:

Check this out! In 1965, an estimated 250,000 members of the

Native American Church in the USA and Canada won a Supreme Court case that permits them to be the only group legally authorized to use peyote in their religious services.

To enhance mediation, members eat peyote plants which result in visual sensations, euphoria, and sometime nausea or vomiting.

Curare:

When hunting animals, the Indians of Peru and Ecuador coat the ends of blow darts with the juice of a tropical vine that contains the paralyzing drug curare.

Curare – A drug that enters the blood stream, reaches the muscles, and blocks receptors on the muscles.

As a result, the neurotransmitter that usually activates muscles, (Acetylcholine) is blocked, and the muscles are paralyzed.

More about Curare:

Once hit by a Curare-tipped blow dart, an animal’s limb muscles become paralyzed, followed by paralysis of chest muscles used to breathe.

Today the purified active ingredient in curare is used by doctors to induce muscle paralysis.

Curare does not easily enter the brain because the body’s blood must go through a filtering system before it can enter the brain.

Let’s Review! – Cultural Diversity and Drugs. Question 1 - Which group has used coca leaves throughout the

last 3,500 years? Answer - South American Indians. Question 2 - Which neurotransmitter is blocked by cocaine? Answer - Dopamine Question 3 - What is another name for Mescaline? Answer - Peyote. Question 4 - What do South American Indians use to aid in

their hunt of animals? Answer - Curare tipped darts. Question 5 – South American Indians found that coca leaves

relieved these two things:Answer - Fatigue and Hunger.

Review – Phantom Limbs Question 6 – Why did Donald have to cut his leg off? Answer – Trapped under a tree. Question 7 – What sensations do people with phantom limbs often

complain about? Answer – Pins and needles. Question 8 – Which one of these is probably most correct: Sensations

come from cut nerves in the stump, sensations come from the spinal cord, sensations come from a body image stored in the brain.

Answer – sensations come from a body image stored in the brain. Question 9 – In what year were phantom limbs first studied? Answer – 1866. Question 10 – What was Aron Ralston doing when his arm became

trapped under a boulder? Answer – Hiking.

Last Review - Reflexes Question 11 – The skin in your fingers has these that are sensitive to

all kinds of things: Answer – Sensors. Question 12 – The other name for an effect neuron is a __________

neuron. Answer – motor. Question 13 – The type of neuron that “sets the ball up for the spike” is

called the ___________ neuron. Answer – Interneuron. Question 14 – This term describes an unlearned, involuntary reaction

to some stimulus. Answer – Reflex. Question 15 – Which reflex do we still have but is not needed as much

as it used to be (a long time ago). Answer – Hair standing up on our body – to keep warm.