So as I mentioned, the break-point is a measure of
how much the animal will work to get the drug.
It's a measure of the drug's value to the animal.
We can talk about a real experiment.
A brain chemical called CART Peptide is known to reduce the behavioral
effects of cocaine when it is injected into a specific region of the brain.
The question is, is CART affecting how the animal values the
drug or is it having some other nonspecific effect on behavior?
When the drug was employed in the break-point
study, the result showed that injection of CART
peptide lowered the break-point, suggesting that CART somehow
lowered the value of the drug to the animal.