1
Laboratory 2: Compound Action Potentials
(25 points)
Name: _________________________________
Exercise 1:
Attach a copy of a compound action potential (CAP) recorded from your nerve preparation.
Exercise 2:
Data:
Stimulus
Amplitude (V)
CAP
Amplitude (mV)
Stimulus
Amplitude (V)
CAP
Amplitude (V)
0.00
0.00
0.30
3.5
0.05
0.00
0.35
3.4
0.10
3.1
0.40
3.7
0.15
3.4
0.45
3.6
0.20
3.5
0.50
3.7
0.25
3.5
Attach a properly formatted Excel graph that shows a plot of the stimulus amplitude (independent
variable) vs. CAP amplitude (dependent variable) with a best-fit line through the points (draw by hand…)
1. Which stimulus voltage represents the threshold voltage? Explain physiologically why you chose this
voltage…
2. Which stimulus voltage represents the maximum recruitment voltage? Explain physiologically why
you chose this voltage…
3. The graph represents the generation and propagation of action potentials along numerous axons with
varying thresholds. Would you expect the curve to look any different if you could run the same
experiment with a single neuron? Explain… (Hint: all-or-none law of AP generation…)
BI 336 – Advanced Human Anatomy and Physiology
Western Oregon University
2
Exercise 3:
Data:
Distance between recording electrode placements:
Time delay between recording electrode placements:
4
(mm)
0. 3
(msec)
4. Calculate the compound action potential velocity (m / s): (Remember: Velocity = distance / time)
Exercise 4:
Data:
Distance between recording electrode placements:
Time delay between recording electrode placements:
4
(mm)
0. 4
(msec)
5. Calculate the compound action potential velocity (m / s): (Remember: Velocity = distance / time)
6. Compare your results from Exercise 3 with your results from Exercise 4. Does the conduction
velocity change when the sciatic nerve is cooled? What properties of the ion channels may change
with temperature?
BI 336 – Advanced Human Anatomy and Physiology
Western Oregon University
3
Exercise 5:
Data:
Time between
stimuli (ms)
1st
CAP (V)
2nd
CAP (V)
Time between
stimuli (ms)
1st
CAP (V)
2nd
CAP (V)
8
1.8
1.7
4
2.0
1.5
7
2.0
1.7
3
2.0
1.0
6
1.9
1.8
2
2.0
0.6
5
2.0
1.7
1
1.9
0.0
Attach a properly formatted Excel graph that shows a plot of the time between stimuli (independent
variable) vs. 2nd CAP amplitude (dependent variable) with a best-fit line through the points (draw by
hand…).
7. At which frequency do you begin to observe the second stimulation occurring during the relative
refractory period for the axons in the sciatic nerve? Explain why you chose this frequency…
8. At which frequency do you begin to observe the second stimulation occurring during the absolute
refractory period for the axons in the sciatic nerve? Explain why you chose this frequency…
BI 336 – Advanced Human Anatomy and Physiology
Western Oregon University