Neurotransmitters: Acetylcholine and Dopamine - PowerPoint Presentation

Slide1

Neurotransmitters: Acetylcholine and Dopamine

Ms.

CarmelitanoSlide2

AcetylcholineFirst Neurotransmitter to be identified and most common in the human body

Function:

Helps control muscle contraction

Plays a role in the development of memory of the hippocampus

Hippocampus: Part of the brain responsible for converting short-term memory into long-term memorySlide3

AcetylcholineAcetylcholine and memory formation

It is still not fully understood how memory formation occurs

However, research has shown that when a short-term memory is converted into long-term storage in the hippocampus, neurons in the brain help to synthesize protein molecules and new connections between neurons are formedSlide4

AcetylcholineSo, what does this have to do with psychology you ask??

Over or underproduction can cause us to act in certain ways!Slide5

Malfunction of AcetylcholineUnderproduction on Memory

Because acetylcholine plays a huge role in memory, an underproduction can cause memory loss or inhibit the formation of new memories

It has been discovered that people who suffer Alzheimer's have a deterioration in the dendrites in neurons that play a role in memory, and therefore a deterioration in the amount of acetylcholineSlide6

Martinez and Kesner (1991)

Aim: To investigate the role of Acetylcholine on memory

Procedure:

1. Rats

were trained to go through a maze and get to the end, where they received food.

Can you solve the maze?Slide7

Martinez and Kesner (1991)

Procedure:

2. Once the rats were able to do this, the researchers injected one group of rats with scopolamine, which

blocks acetylcholine receptor sites

decreasing available acetylcholine.

3. Then the second group of rats was injected with

physostigmine

, which

blocks the production of cholinesterase which does the “clean-up” of acetylcholine

from the synapse and returns the neuron to its “resting state”

4.The third group, control group, were not given any injections.Slide8

WINNER!

Second PlaceSlide9

Martinez and Kesner (1991)

Findings:

The

rats that were injected with scopolamine were slower at finding their way round the maze and made

the most errors

The

physostigmine

group ran through the maze and found the food more quickly

and

took fewer wrong turns.

The

researchers concluded that acetylcholine played an important role in creating a memory of the maze.Slide10

Nicotine and AcetylcholineWhen a person smokes a cigarette, they will put nicotine into their system

Nicotine will stimulate neurons to release more acetylcholine

The overproduction of Acetylcholine will give a person an “energized” feeling, muscles react faster and the brain functions faster

Smokers become addicted, and need a cigarette in the morning to “wake-up”Slide11

DopamineFunction:voluntary muscle movement

Learning

Feelings of emotion: pleasureSlide12

DopamineDopamine and voluntary muscle movement

When the body reacts to a stimuli that calls for muscle

movement

(example:

I hear a noise and turn my head to see what it was) Dopamine will

be released over the synapses of nerve cells.

The

Dopamine

will bind with receptors that cause a

chemical reaction to move smooth muscles in the basil ganglia – the portion of the brain that coordinates smooth muscle movementSlide13

DopamineDopamine and learning and emotion

Dopamine controls the transfer of messages in the frontal cortex of the brain which controls memory, attention, and problem solving ability

When dopamine is released, it creates a “feel-good” feeling within the individual

The individual learns what behaviors will create this feel good feeling

They will learn that if they continue this behavior, the feeling will continueSlide14

Malfunction of DopamineMalfunction of Dopamine and muscle movement

When dopamine receptors are blocked, or not enough dopamine is produced, a person will find muscle coordination difficult

People who do not produce enough dopamine develop Parkinson

Parkinson is degenerative – this means that it progressively gets worse. A person with Parkinson's Disease will gradually produce less and less dopamine over timeSlide15

Malfunction of Dopamine

Malfunction of Dopamine in learning and emotion

Because Dopamine regulates connections between neurons responsible for concentration in the frontal lobe, a person without enough dopamine may develop ADD

Low dopamine may also cause dementia because the neurotransmitter helps make connection with learning and memory. This usually occurs with age as the neurons that produce dopamine begin to degrade

Low dopamine may also be a reason for depression, low dopamine will decrease the pleasure feelingSlide16

Malfunction of Dopamine and SchizophreniaSchizophrenia is a mental illness

People suffering from Schizophrenia report feeling paranoid, having hallucinations, and even hearing voices that are not there

An

overproduction of Dopamine in one area of the brain has been linked to Schizophrenia. This overproduction of Dopamine can cause the hallucinations linked to SchizophreniaSlide17

Drugs and DopamineDrugs prescribed to help people with ADD concentrate increase the amount of dopamine that is released in the brain

People with Schizophrenia will be given drugs to inhibit dopamine production, however, as a side effect, this makes it hard for the person to concentrate, reduce feelings of pleasure, and reduce motor function Slide18

Drugs and DopamineMost drugs, such as alcohol, cocaine, and amphetamines increase the production of dopamine in the brain

This is why people get addicted to drugs

They feel good when they take them

They become used to the over production of dopamine in their brain, and find it hard

to concentrate

or feel pleasure without the drug as they become dependent on it Slide19

Cardinal et al (2001)Procedure:

Researchers gave a set of rats choices between bowls of food containing large and small portions

Rats chose the larger consistently

The researchers split the rats into two groups

L

esioned

their nucleus

accumbens

(Where Dopamine and Serotonin is produced) This caused excess Dopamine to be

produced

One group received an anti-psychotic

on did not

When presented a choice between large and small portions of food, the rats were more impulsive and simply chose the bowl closer to them. They appeared hyper-activeSlide20

Findings:Excess Dopamine in the brain lead the rats to be more impulsive

This could be why drug addicts are impulsiveSlide21

Laurelle et al (1996)Procedure:

Researchers gathered participants who were and were not diagnosed with Schizophrenia

Researchers gave participants an amphetamine, a drug, that increased levels of dopamine in the

brain

Researchers observed patients and interviewed them about how they were feelingSlide22

Findings:Observations and interviews confirmed that the “healthy” patients began to experience symptoms of

Schizophrenia

when their

Dopamine

levels were forced to

rise

Patients

tested who were diagnosed with

Schizophrenia

had their symptoms worsen