19 Lab 4 – Speed of Neural Signals

Acknowledgment

This project is made possible with funding by the Government of Ontario and through eCampusOntario’s support of the Virtual Learning Strategy. To learn more about the Virtual Learning Strategy visit: https://vls.ecampusontario.ca.

PHY255 Stay-At-home Experiment 4

Speed of Signal Transduction in Neurons

What you will do

Estimate the speed of signal transduction in motor neurons through measurements of reaction times.

What you will need

• Any reaction time test app
  • o Such as this one: https://faculty.washington.edu/chudler/java/redgreen.html
• A meter stick or a measuring tape

Procedures

1. If you use the reaction time test provided above, it is possible to complete the test by pressing the space bar. (You need to hover your mouse cursor over the button to click, otherwise the space bar will not work.) Practice the test a few times before starting your data collection.
2. Create a spreadsheet for recording data.
3. Use your right index finger to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
4. Use your left index finger to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
5. Use your right little finger to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
6. Use your left little finger to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
7. Use your right big toe to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
8. Use your left big toe to measure the reaction time for 5 times. Record the reaction time in one column in the spreadsheet.
9. In the measurements above, if the slowest reaction time of a column is more than 0.1s slower than the fastest reaction time in the same column, redo the measurement for that column.
10. Use a measuring tape to measure the distance from your neck to your wrist. If you find measuring on the body is hard, you may do the measurement on a long-sleeved clothing that fits your body.
11. Use a measuring tape to measure the distance from your neck to your ankle. If you do not have a ruler that is long enough, you may do so by subtracting the height of your head (and neck) from your body height.

Data Analysis & Discussions

1. For each column of reaction times, calculate the average reaction time and its uncertainty (i.e., standard deviation of the samples).
2. Are you left-handed or right-handed? Do you see a significant (statistically significant) difference in reaction times between your left hand and your right hand?
3. Do you see a significant difference in reaction times between the index finger and the little finger of the same hand?
4. Do you see a significant difference in reaction times between your index fingers and your big toes?
5. Based on your data, calculate the average speed of signal transduction in motor neurons in the body. Briefly explain your method.
6. Did you measure the reaction time of toes with your legs extended or curled? Do more measurements and check if the posture of the leg affects the reaction. Does the result make sense? Briefly explain.
7. Should your elbow show a quicker reaction time than your index finger? Do more measurements and verify your answer. Does the result make sense? Briefly explain.

Requirements of the experimental report:

• Font size: 12
• Line spacing: 1.5
• Only write these sections: Results, Discussions, and Suggestions of improvement.
• Total marks: 20/20
• Results (12/20):
  •  Complete all the calculations that are required in the procedures and data analysis sections above.
  •  Show sample calculations.
  •  Attach graphs or tables when necessary.
  •  If you write a program for calculations, attach the code in the appendix.
• Discussions (8/20):
  •  Find the uncertainty values for each of the calculation in your results section.
  •  When comparing two average values, use the uncertainties of each value to decide whether the different is statistically significant (i.e., Student t-test).
  •  Make a reasonable conclusion of the experiment based on your results.
  •  Compare your results with literature values (and add citations).
• Suggestions of improvement (+2 bonus; total marks capped at 20/20):
  •  What other quantities can be determined with the same experimental design?
  •  What can be done to reduce the uncertainties at no cost while staying at home?
  •  Did you enjoy this experiment? What are the aspects that you dislike the most about this experiment?
• No page limit. But please try to be straightforward and concise!