These materials are produced by the National Institute on Drug Abuse, National Institutes of Health. They are in the public domain and may be reproduced without permission. Citation of the source is appreciated. Instructions: After reviewing Facts on Drugs: Brain and Addiction on the NIDA for Teens Web site (http://teens.drugabuse.gov/), take this short quiz to test your knowledge.
The human brain weighs about as much as a __________.
12-pack of soda
Neurons in the brain communicate with each other by ______________.
C: The human brain weighs about 3 pounds, about the size of a Chihuahua. A doughnut only weighs a few ounces, and a 12-pack of soda weighs 9 pounds.
B: The transfer of a message from one neuron to another occurs by releasing chemicals called neurotransmitters into the spaces called synapses between the neurons. The axon is the long threadlike fiber that transmits the message.
A: The “reward” system is part of the limbic system, which gets activated when you do something you like. Dopamine is a brain chemical that is released, producing feelings of pleasure and letting you know that something important is happening.
A: The brain is wired to remember feelings of pleasure, including those produced by drugs unnaturally. The brain then strives to repeat those feelings, which the drug user experiences as a craving for the drug.
B: At first, drug use may cause floods of dopamine. But prolonged drug abuse causes the brain’s dopamine levels to decrease. That means the brain might need more of the drug just to get the dopamine levels back to normal and even more to produce the high that it craves.
B: The limbic system is involved in emotions, learning and memory, and other functions necessary for survival. The reward circuit is part of the limbic system and is activated by pleasurable activities, such as hanging out with friends and by drugs of abuse.
A: A message travels down a neuron as an electrical impulse. To pass the message to another neuron, the electrical impulse triggers the chemical signals called neurotransmitters, which flow into the synapse (the gap between the two neurons) and trigger an electrical impulse in the next neuron. Axons are the branches of a neuron that release the neurotransmitter.
B: Drugs “fool” the brain because they are similar in size and shape as the natural brain chemicals called neurotransmitters.
C: Drugs of abuse cause the brain’s limbic system to release dopamine, the neurotransmitter that produces feelings of pleasure.
A: Drug tolerance results in people needing more and more of the same drug to get the same effect because, over time, drugs can cause the brain to produce less dopamine, the neurotransmitter that produces feelings of pleasure. Drug abusers may need more of the drug than before to reach the same level of dopamine to get the same “high.”
National Institutes of Health • U.S. Department of Health and Human Services