Today we're going to discuss, another animal model, that

we call Conditioned Place Preference, or CPP for short.

This model does not require a surgical procedure for the animals.

Therefore preparation and maintenance of the animals

are easier, and carry fewer health risks.

CPP does require that the investigator injects the animals, and then

uses a simple piece of equipment, which is a two or sometimes three chambered

box, with two very dissimilar chambers on each end.

CPP is generally agreed to

be less complicated, than drug self-administration.

There are photocells in the boxes, to measure

how much time the animal spends in either chamber.

This image shows a Conditioned Place Preference

apparatus, made up of two very dissimilar chambers.

One chamber might have a grid floor, and

a checkered wall, while the other might be smooth.

In CPP, there's a training phase followed by a testing phase.

In the training phase, the animal is injected with a

drug, or saline, and then placed into a specific chamber.

Always the same chamber.

This is done several times.

For example, if the animal were injected with the

drug, you might choose to place it in the chamber

with the grid floor, and if treated with saline,

it might go into the chamber with the smooth floor.

In this training period, the animal learns to associate

the feeling caused by the drug, with a specific chamber.

If the drug was rewarding and positive, on a test day, where no drug is given,

the animal will spend more time in the chamber, where it experienced the drug.

It's as though the animal is trying to find the drug experience.

This test associates environment with drug experience.

Among human drug users, environment can be

a very significant factor, in the drug experience.

We know several things about condition place preference.

When saline is given during the training period, the animal

spends about equal time, in both chambers, during the test period.

Saline is not rewarding, and does not provide

a positive or even negative experience for the animal.

When a rewarding drug like cocaine is given, the animal will

spend more time in the chamber it associates with the cocaine experience.

Also, there is an interesting advantage with this procedure.

If an aversive drug, which is unpleasant or painful

is given to the animal, it will avoid that chamber.

So the test is useful for both preferred and aversive drugs.

This is restated in this table.

Please study it and decide, what you would predict if the

smooth floor were used with the drug, instead of the grid floor.

In summary, CPP is a simpler procedure than drug self-adminstration.

Because animal surgery is not required, and the testing apparatus is simpler.

Also, CPP can identify, either rewarding or aversive substances.

There is yet another important

animal model, Electrical Brain Stimulation Reward.

This procedure is based under the discovery,

that animals will press levers, to self

stimulate electrically, certain brain regions that are

sometimes called pleasure centers, or reward sites.

It shows that there are feeling good centers in our brain as expected.

It is similar to drug self-administration, in that

the animal controls giving the stimulus to itself.

Drugs can interact with electric

self-stimulation, according to the following idea.

Like the electrical stimulation, addicting drugs produce pleasure.

Therefore, when drugs are present in the brain, and the reward centers,

the amount of electrical stimulation needed to satisfy the animal is less.

Because some pleasure is already there from

the drug, less electrical stimulation is needed.

This is another way of showing that drugs interact

with naturally occurring brain centers, that provide positive feelings feelings.

[BLANK_AUDIO]

>> The preceding program, is copyrighted by Emory University.

Conditioned Place Preference

The Addicted Brain

Meet the Instructors