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| Activity Number | Web Version |
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Activity 1 |
No |
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Activity 2 |
No |
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Activity 3 |
No |
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Activity 4 |
No |
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Activity 5 |
Yes |
| For the class | For each student |
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1 transparency of Master 4.4, Playing the Game 1 transparency of Master 4.5, Who Is Addicted? |
1 copy of Master 4.1, Data for Rat Self-administration Experiment 1 copy of Master 4.2, Worksheet for Rat Experiment Data 1 copy of Master 4.3, Evaluating the Experiment 1 copy of Master 4.6, Long-term Effects of Drugs on the Brain (only if using the non–Web site activity) |
| Activity Number | Material |
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Activity 1 |
none |
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Activity 2 |
colored pencils |
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Activity 3 |
playing cards (one deck for each group of 3 students; see Preparation section) overhead projector |
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Activity 4 |
overhead projector |
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Activity 5 |
computers |
Gather decks of playing cards for use in Activity 3. Each group of three students can share one deck of cards. Separate the face cards (jacks, queens, and kings) and place them in one pile. Place the aces and number cards in another pile.
Arrange for students to have access to computers for viewing the Web site mini-documentary in Activity 5.
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1. Begin the activity by holding a class discussion. Ask students, "What is a drug?" Write their answers on the chalkboard or on an overhead transparency. Give students the opportunity to present differing views.
Students will respond with a variety of answers. Some will give examples of illegal drugs, such as marijuana or cocaine, others may give the names of prescription medications. If so, prompt students to think about a definition for the word drug. Some students will describe a drug either as an illegal substance that harms a person's health or as a chemical that a person takes to treat a disease or illness. At this point, based on students' knowledge, both definitions are correct.
Several terms will be introduced in this lesson. It is very important to use these terms according to the definitions provided.
2. Write the following definitions for drug and medication on the board or transparency and inform students that, for this discussion, you will use the terms according to the following definitions.
3. If the students didn't do this in the previous question, ask them to consider examples for both medications and drugs. List each response in the proper category as a medication or a drug.
According to these definitions, all medications are drugs, but not all drugs are medications. This unit uses the word "drug" to refer to psychoactive drugs, or drugs of abuse. Drug abuse refers to the use of illicit drugs or to the inappropriate use of a legal drug, such as alcohol or nicotine.
Societal and political factors sometimes influence into which category a substance falls. Alcohol and nicotine (tobacco) are drugs that are illegal to use and possess if the individual is below legal age, but not for adults to possess and use responsibly. Also, inhalants (paints, glues, and sprays, for example) are not illegal to possess when they are used for their intended purposes. However, they are drugs when used improperly to alter brain function.
Some students will raise the idea that medications can also be drugs if they are used inappropriately. For example, overuse of a prescription medication, such as a sedative, is inappropriate and could be considered a drug in that case. Alternatively, students may indicate that morphine is an illegal drug when used without medical supervision, but is a valuable medicine when used appropriately in a hospital, or at home, to relieve pain associated with various diseases. Students may also propose that marijuana can be a medication to relieve the pain that accompanies various diseases. (In some states, marijuana is legal as a medication, but is illegal according to federal law.) If students bring this up, point out to them that scientists need to continue studying marijuana to determine whether it may be effective as a medicine. Marijuana contains hundreds of chemical compounds; the effects of most of these compounds in the body are unknown. Marijuana also poses many problems outside of the brain, such as cancer. Use this as an opportunity to inform students that scientific research is being done to determine if marijuana is more effective than other medicines (see the Background Information section).
4. Ask students to respond to the question, Why do people start abusing drugs?
Students may provide a wide range of answers to this question including peer pressure, experimentation, boredom, or fun. Some students may also respond that people take drugs to escape from life's pressures.
 Content
Standard A:Mathematics is essential in scientific inquiry. Content Standard A: Scientists rely on technology to enhance the gathering and manipulation of data. Content Standard C: Organisms have behavioral responses to internal changes and to external stimuli. Content Standard F: An individual's mood and behavior may be modified by substances. |
1. For this activity, students will work in groups of four. Prior to having students divide into their small groups, set the stage for the activity. Tell students they will be analyzing data from experiments using rats. For the experiments, rats were placed in individual cages with two levers that the rat could press. If the rat pressed the food lever, a pellet of food was released. If the stimulus lever was pressed, the rat received an injection or an electrical stimulus.
Students may ask what substance was injected in response to the press of the stimulus lever. Tell students that the answer to that question will be revealed during the activity.
 Figure 4.3: Diagram of a rat in a cage during a drug self-administration experiment. |
2. Give each student a copy of Masters 4.1, Data for Rat Self-administration Experiments, and 4.2, Worksheet for Rat Experiment Data. Each student will graph on Master 4.2 the data for only one of the rats. Instruct the teams to decide which member will graph the data for rat A, B, C, and D. The students will plot the total number of times that the rat presses the stimulus lever vs. time and the total number of times that the rat presses the food lever vs. time.
The graph of the data for each rat will have two lines, one for the stimulus lever and one for the food lever. Students can use a different color of pencil for plotting each set of data, or they can use a solid line and a dashed line to distinguish between the two graph lines.
3. After students have completed their graphs, give each student a copy of Master 4.3, Evaluating the Experiment. Each student should share his or her graph with the other members of the group. Group members then discuss the similarities and differences among the rats' responses and answer the questions on Master 4.3.
4. When the groups are finished answering the questions, hold a class discussion to ensure that each group has come to the appropriate conclusions.
Question 1. Why do the rats press a lever the first time?
The rats initially press a lever while they are exploring the cage. The rat may even press the lever by accident. Whether the rat presses the food lever or the stimulus lever first is usually random.
Question 2. Compare the lever-pressing behaviors of the four different rats. Which rat pressed the stimulus lever the most? Which one pressed the stimulus lever the least? Which rat pressed the food lever the most? Which one pressed the food lever the least?
Rats A and C pressed the stimulus lever about the same number of times and many more times than either Rat B or Rat D. Rats B and D did not press the stimulus lever very many times, but they pressed the food lever more times than Rats A and C did. Overall, Rats A and C behaved similarly and Rats B and D behaved similarly.
Question 3. Rat A was injected with cocaine each time it pressed the stimulus lever. Can you use this fact to explain why Rat A behaved the way it did?
The cocaine activated the reward system in the brain and caused the rat to continue its stimulus-lever-pressing behavior. If necessary, remind students that the reward system is the part of the brain stimulated by drugs to cause feelings of pleasure.
Question 4. Based on the data you analyzed, do you think Rat B was injected with cocaine when it pressed the stimulus lever? From what you have learned so far in this unit, do you think Rat B was injected with a different addictive drug when it pressed the stimulus lever? Why?
It appears that Rat B was not injected with cocaine when it pressed the stimulus lever because its behavior was very different from Rat A. If Rat B was injected with cocaine or another addictive drug, it should display behavior similar to Rat A.
(Rat B actually received a saline injection when it pressed the stimulus lever.)
Question 5. Do you think Rat C received cocaine when it pressed the stimulus lever? Why?
It is possible that Rat C received cocaine when it pressed the stimulus lever because its behavior was very similar to that of Rat A. However, you cannot be sure it was cocaine.
Question 6. Rat C did not receive an injection of cocaine when it pressed the stimulus lever. When Rat C pressed the stimulus lever, it received a mild electrical stimulation in the brain. Based on what you have learned, can you predict what part of the brain was stimulated?
The reward system (ventral tegmental area (VTA) or nucleus accumbens) is the part of the brain stimulated. Stimulation in that area of the brain caused the rat to continue pressing the stimulus lever.
Question 7. Rat D also received a mild electrical stimulation in the brain when it pressed the stimulus lever. Do you think the same part of the brain was stimulated in Rat D as was stimulated in Rat C? Why?
Rat D did not receive an electrical stimulation in the same part of the brain that was stimulated in Rat C. If the same part of the brain, the reward system, was stimulated, Rat D should behave similarly to Rat C.
(Rat D received an electrical shock in the cerebellum, which is not part of the reward pathway.)
Question 8. Why did Rats A and C press the stimulus lever more than the food lever?
Rats A and C received a greater "reward" when they pressed the stimulus lever than they did when they pressed the food lever.
Question 9. Why did Rats B and D press the food lever more than the stimulus lever?
Rats B and D received greater "reward" when they pressed the food lever than they did when they pressed the stimulus lever.
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