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NESC 3237 Lecture Notes - Morphine, Neurochemistry, Psychopharmacology

Course Code
NESC 3237
Sean Barrett

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January 17th, 2013
2:33 PM
The effects of a drug increase when administered repeatedly
Psychostimulants seem to be very prone to this effect
Self-administered drugs seem to often have this effect
o Cocaine, amphetamine, nicotine, heroin and morphine
o So if you have drugs that work on the same neural systems
o For example, stress acts on the neural circuitry involved in the reinforcing properties of
many drugs
Can be conditioned to environments
o Like when an animal is in a place where it is expecting the drug, the environment will prime
that neural circuitry
Sensitization: animals
The sensitization processes can be quite long lasting
o Also in part quite context dependent
o Suggesting some LTP occurring with structural changes over time
Your brain essentially learns how to respond to the drug with repeated administrations
Sensitization: humans
Participants given a dose of amphetamine for the first time, and then given two additional doses
over the next 4 days
o Measured dopaminergic response to the amphetamine
o Response when they gave the amphetamine two weeks later was much greater, and this
response increase persisted when tested a year later
The magnitude of this sensitization is related to the extent of the person's novelty seeking
personality traits
o People that are more novelty seeking will see more sensitization in response to
Expectancy and context
You can have some sensitization or anticipatory expectancy effect when you're expecting to be
receiving a drug
o Effects the mesolimbic dopaminergic pathway
This pathway is the common pathway for many different drugs of abuse
Most of these drugs are known to increase the dopamine levels in the nucleus
o So there is an "expectation pathway" in the brain
Be able to explain in essay form the contrast between the processes that occur when
undergoing sensitization and tolerance
**Start of Lecture 3**
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