Lab4 Checklist

Biological Sciences 300/301, Smith College | Neurophysiology

Checklist for Lab 4: Action Potentials in
Earthworm Giant Axons

http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs/labcheck4.html

UPDATED: February 27, 2008.

1.
Background
for this lab

From the Web instructions for Lab 4, review:

The role of giant axons in invertebrates. Look at the cross section of an annelid worm's nerve cord to see the three giant axons in the cord, two lateral and one median.

Extracellular recording of action potentials, which appear as negative spikes (to a single electrode) or biphasic spikes (to a pair of electrodes connected to a differential amplifier, like our DAM50).

The controls for the SD9 stimulators.

The video showing the dissection and experimental procedures.

2. Procedures

A. Anesthetize an earthworm in dilute alcohol. See the Web pages for precautions about this method.

B. Pin out the middle of the worm and make an incision to reveal the nerve cord. See the video for guidance.

C. Put the recording electrodes in place.

D. Attempt to elicit spikes in the giants mechanically, by stroking or gently prodding the worm. (Don't linger on this step.)

E. Electrically stimulate the nerve cord through pin electrodes at one end of the worm.

(a) Capture a good screenshot of an action potential.
(b) Measure the conduction velocity.

(c) Measure and plot a strength-duration curve.

(d) Capture one or more screenshots demonstrating the refractory period.

3.
Plotting
data

At the end of the lab, post one neat summary page that you make in AppleWorks showing:

a screenshot of an evoked action potential from part (a),

the conduction velocity you calculated in part (b),

the strength-duration graph from part (c), and

a screenshot of several superimposed traces showing the refractory period (part d).

Make sure that the full names of all the team members are on the page as authors.

4.
Clean up

Rinse and dry your tools and dissecting dish. Turn off power to all equipment, including the stimulator and the DAM-50 preamplifier.

	Biological Sciences 300/301, Smith College \| Neurophysiology Checklist for Lab 4: Action Potentials in Earthworm Giant Axons http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs/labcheck4.html
	UPDATED: February 27, 2008.
1. Background for this lab	From the Web instructions for Lab 4, review: The role of giant axons in invertebrates. Look at the cross section of an annelid worm's nerve cord to see the three giant axons in the cord, two lateral and one median. Extracellular recording of action potentials, which appear as negative spikes (to a single electrode) or biphasic spikes (to a pair of electrodes connected to a differential amplifier, like our DAM50). The controls for the SD9 stimulators. The video showing the dissection and experimental procedures.
2. Procedures	A. Anesthetize an earthworm in dilute alcohol. See the Web pages for precautions about this method. B. Pin out the middle of the worm and make an incision to reveal the nerve cord. See the video for guidance. C. Put the recording electrodes in place. D. Attempt to elicit spikes in the giants mechanically, by stroking or gently prodding the worm. (Don't linger on this step.) E. Electrically stimulate the nerve cord through pin electrodes at one end of the worm. (a) Capture a good screenshot of an action potential. (b) Measure the conduction velocity. (c) Measure and plot a strength-duration curve. (d) Capture one or more screenshots demonstrating the refractory period.
3. Plotting data	At the end of the lab, post one neat summary page that you make in AppleWorks showing: a screenshot of an evoked action potential from part (a), the conduction velocity you calculated in part (b), the strength-duration graph from part (c), and a screenshot of several superimposed traces showing the refractory period (part d). Make sure that the full names of all the team members are on the page as authors.
4. Clean up	Rinse and dry your tools and dissecting dish. Turn off power to all equipment, including the stimulator and the DAM-50 preamplifier.

Biological Sciences 300/301, Smith College | Neurophysiology

Checklist for Lab 4: Action Potentials in Earthworm Giant Axons

1. Background for this lab

2. Procedures

3. Plotting data

4. Clean up

Checklist for Lab 4: Action Potentials in
Earthworm Giant Axons

1.
Background
for this lab

3.
Plotting
data

4.
Clean up