Heads Up Heads Down?

Grades: 9-12

By Jack Elwell

Principal Investigator: Dr. Sara Arnaud

Overview

What do lying in bed and living in space have in common? That's what researchers for NASA's Life and Microgravity Sciences Spacelab Mission are trying to find out. By studying the performance of test subjects who must lie in bed for 17 days, the NASA researchers hope to better understand how astronauts will perform while in microgravity.

In this activity, students conduct a similar study, but without the 17 days of bed rest. Students first test their cognitive abilities while in a normal seated position. Then they do the same test while lying down with their feet up, and compare the results with those from test taken in seated position. By restricting their test subjects to head down tilted bed rest, NASA scientists hope to simulate the fluid shift that occurs in the body of astronauts in microgravity. In the students' tests, subjects lying with their feet up likewise cause the blood pressure in their head to increase, also simulating the condition of microgravity.

Student and NASA scientists alike will have to wait for the results of the experiments conducted during space flight to decide whether head down tilted bed rest can act as an accurate model for microgravity simulation.

Key Questions

• Does lying down with your feet up affect your normal cognitive abilities?
  
• How do NASA scientists design Earth-based experiments to simulate the conditions of space flight?
  
• How do the results of the head down bed rest experiments compare with test results from astronauts in space flight?
  

Time frame

Preparation: about 15 minutes

Conducting the bed rest experiments: 45 minutes

Compiling and analyzing data from the experiment: 30 minutes

Materials

For the whole class:

• timer with a second hand

For each group of 3­5 students:

• chair and pillow
  
• Heads Up/Heads Down Data Sheet Page 1
  
• Heads Up/Heads Down Data Sheet Pages 2 &3
  
• set of Flash Cards

Getting Ready

1. Assemble the materials before beginning the activity.

2. Warn the students ahead of time so they can dress appropriately for the activity.

Classroom Activity

1. Explain the purpose of the study. NASA researchers are trying to simulate the conditions that astronauts experience in microgravity. By having their test subjects lie with their heads tilted down, the researchers expect the blood pressure in their test subjects' heads to rise above normal levels. This raising of blood pressure is expected to simulate the raising of pressure in astronauts' heads while in microgravity. By comparing the results of the heads down tilted bed rest experiment with the data collected from astronauts during actual space flight, the researchers expect to learn more about how to accurately simulate the conditions of microgravity.

The results of the Earth-based part of this study which you do in your classroom will help you understand the effect increasing the blood pressure in your brain has on your cognitive abilities.

2. Organize the class. Divide the class into teams of four. Each team has a time keeper, score keeper, data recorder, and test subject. The test subject will be lying on their back with their feet up during part of the experiment.

3. Explain the tests. Explain each of the two cognition tests to the class. In the first, called the "E" search test, the test subject looks at each card that is shown and responds, "Yes," if there is a letter "E" on the card and "No," if there is not. In the second test, called the "MC" test, the test subject looks at each card and responds, "True," if the letters "M" and "C" appear next to each other on the card.

4. Explain the difference between the NASA tests and the classroom tests:

In the research experiments conducted at NASA, the test subjects were tested during three 17 day periods. During the first, control period, the subjects were tested in a normal seated position. During the second, bed rest period, the tests were conducted while the subjects were lying with their head tilted downward slightly. During the third, or recovery period, the tests were conducted with subjects again in the normal seated position. Each period lasted 17 days because the mission during which astronauts will be taking the tests is expected to last approximately 17 days.

In the classroom you will not be restricted to bed rest for 17 days. But , like the NASA scientists, you must conduct the experiment before, during, and after a period of head down tilted bed rest. In each test the subject will be handed a stack of 20 flash cards. The timer records how long it takes the test subject to go through the stack of cards and give the appropriate responses. The score keeper will tally the number of correct responses given during the test period.

5. Set up the experiments. Distribute data sheets and flash cards to each group. Arrange chairs and pillow for each group to use. During the control period, the test subject examines cards while holding them in front of their face as they sit comfortably in the chair. For the heads down test period, the cards should be shuffled and the subject should again examine the cards while holding them in front of their face. This test is conducted as the test subject lies on his or her back with their feet elevated on the chair after ten minutes of lying in this manner. In conducting the heads down portion of the examination, the cards should be held directly in front of the subject's face, to eliminate card position as a variable. Finally, the recovery period tests will immediately follow the bed rest period tests and be conducted in the same manner as the control tests, while the subject is seated comfortably in the chair. The cards should be shuffled before each test.

6. Do the experiments. Allow time for teams to complete the experiments at their own pace. Each team should use the data sheet to record three sets of data, one before bed rest, one while still lying after ten minutes of bed rest, and one while seated following the bed rest period.

7. Share the data. Ask each team to enter the data collected during each test period into a table on the board for a class summary of all the data.

8. Analyze the data. Use the cognitive index to analyze the data. The cognitive index is used by researchers to combine the variables of speed and accuracy with which test subjects respond to the flash cards. The formula for calculating the cognitive index is:

Cognitive index (CI) = (1 + % wrong) x ( time (sec))

Ask students to calculate the cognitive index for each test subject for each trial of each test and enter the scores into the table on page two of their data sheets. Provide time for each student to find the average of the cognitive index scores for all the subjects tested in the class. Enter the class average scores into the last row of Table #3 on page two of the data sheet.

Wrap-up Session

1. Ask each group of students to graph the data collected by their group and to present their findings to the rest of the class. In their presentation, students should explain how the cognitive index score changed, if at all from the control, bed rest, and recovery periods. They should also report on any problems they had that they feel may have influenced their results.

2. As a class, discuss the results. Were most group's results similar to the class average? Can you guess why the groups got the variety of results they did? Were there any variables affecting the results that were not accounted for?

3. Discuss results presented in the six month report on the Life and Microgravity Sciences Spacelab Mission from NASA:

Overall, there was no apparent cumulative effect of bed rest on cognitive performance. Generally, for each task, response time decreased while accuracy increased. The effect of bed rest on motor control tasks was more substantial, but much of this effect could be caused by differences in testing positions.

Following a short period of performance stabilization at the beginning of the bed rest period, slight but steady performance improvement continued. For most tasks, this performance improvement was enhanced during the recovery period.

It is important to remember that this summary is based on group averages. Assessment of the individual effect of bed rest on each subject remains to be completed.

Ask, "How do the results of the bed rest study conducted in your class compare to the results from the NASA study described above?" Discuss similarities and differences between the your study and NASA's.

More Activity Ideas:

1. Create posters to present the findings of the research. Poster should include a title and summary for the experiment. as well as the question being studied, a hypothesis, a table and graph of all test results, and an explanation of these results. The posters might also include a discussion of the validity of the experiment, and what changes might be made to the experiment to improve its effectiveness.

2. Students design their own cognitive ability tests. The performance tests conducted at NASA included the 'E' and 'MC' search tests described above as well as the following other cognitive performance tests:

Mood Survey - Subjects respond with answers ranging from, "very much," to, "very little," to questions about how they feel. The questions include, "Are you angry, happy, tired, etc?"

Tracking - Subjects are graded on how accurately they use a track ball (or mouse) follow a moving object on the computer screen.

Spatial Matrix - Subjects respond to tell whether a group of squares is the same as a group previously presented.

Continuous Recognition Memory - Subject indicates whether a number is the same as one previously memorized.

Switching Task - In one test the subject indicates which hand of a mannequin holds a matching symbol. In another, the subject indicates whether the sum of three numbers given is greater or less than 5.

Dual Task - The subject performs two tests simultaneously

3. Conduct the experiment with longer test periods and more data collected during each test period. (Conduct the tests every five minutes during a 30 minute bed rest period.) How do the results compare with previous results?

Background for Teachers:

Prerequisites:

Student test subjects must be dressed appropriately and be able to read letters of the English alphabet.

Timekeepers must be able to read a clock or stopwatch accurately.

Scorekeepers must be able to count and tally the results accurately.

Each student must be able to calculate the cognitive index using the formula provided. Each student must also be able to find the average of several test scores, and graph data they collect.

Vocabulary:

• microgravity-a condition in which the force of gravity is reduced so objects float as if weightless.
  
• cognition-The process and ability of knowing and understanding.
  
• blood pressure-the pressure of the blood on the walls of the arteries.
  
• model-In science a model is a creation or description which attempts to simulate and/or understand a true relationship in nature. A model is rarely without faults in its attempt to describe the true process and arrangement in nature.
  
• head down tilted bed rest-the condition of a person lying with a 6° head down tilt and not being allowed to sit up or stand for a specified period of time

Skills:

• collecting, recording and analyzing data.
  
• timing and score keeping.
  
• understanding and using the scientific method.

Concepts:

The tilted bed rest model is used by researchers at NASA to simulate microgravity. The model assumes that a test subject lying with his or her feet up causing higher blood pressure in the headis similar to an astronaut in space having higher blood pressure in the upper body due to reduced gravity.

Students investigate the effect of tilted bed rest on their cognitive performance. Students must identify variables and assess the effectiveness of this experiment for determining how an increase in blood pressure affects cognitive abilities (quickly and accurately recognize patterns in a list of letters).

The tests conducted using the bed rest model will help us to understand how the human body works on Earth and in space.

Additional Background information:

From NASA Publication, "Life and Microgravity Science Spacelab Mission: Human Research Pilot Study" Six Month Report; April 1996.

The priority of the Life and Microgravity Spacelab Mission investigation is the evaluation of the function and structure of muscle and organ systems essential to muscular activity. These include the bone, lung, endocrine, and central nervous systems. The ground based pilot study used the six degree head down tilt bed rest model to simulate space flight. Muscle structure and function were evaluated directly by a set of six "muscle" experiments. A second set of three "metabolism" experiments evaluated pulmonary function, energy metabolism, and bone. A third set of three experiments assessed the performance of the central nervous system before, during and after 17 days of bed rest.. The study mimicked the experimental procedures as closely as possible and used equipment available for ground based research as well as some of the equipment for the mission.

The study took place between June 19 and August 28, 1995 at the NASA Ames Human Research Facility in Moffet Field, California. There were eight test subjects whose ages varied from 34 to 50 years of age. During the 17 day bed rest portion of the study, all testing, showering, and excretory functions were carried out in the six degree head down tilt position. Standing or sitting up was not permitted. During the orientation, control and recovery periods, all subjects remained active and ambulatory.

The value of carrying out this ground based performance of the flight investigation is that it provides the opportunity to test the full set of experiments in a combined sequence prior to the actual flight. In this way, procedures can be refined, timelines can be optimized and potential conflicts and incompatibilities discovered and resolved before launch. It also provides investigators with simulation data for comparison with flight data to validate the suitability of the bed rest model in simulating microgravity on each physiological system under investigation.

This activity was edited by: Gregory Steerman (Lawrence Hall of Science)