Biological Sciences 300/301, Smith College | Neurophysiology

Checklist for Lab 6: Electroretinogram of the Crayfish Eye

http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs/labcheck6.html

UPDATED: March 11, 2008

1.
Background
for this lab

From the Web instructions for Lab 6, review:

  • The electroretinogram (ERG) as an extracellular recording of a graded receptor potential.
  • The anatomical structure of the crayfish eye.
  • The role of second messengers in linking the response to light to the opening of a channel.
  • How to work with neutral density filters.
  • The video showing the experimental procedures.

2. Procedures

A. Examine the strobe pulse.

B. Set up the DAM50 amplifier for recording slow events.

C. Remove an eye, place it in the recording chamber, and record and save one or two good examples of the ERG.

D. Measure the latency, duration, and amplitude of the ERG.

E. Collect data for a plot of flash intensity vs. ERG amplitude and latency.

F. Demonstrate dark- and light-adaptation.

3.
Plotting
data

At the end of the lab, post one or two summary pages (with your team's full names on it) that have:

(1) a good screenshot of the ERG, brought into an AppleWorks page and labeled. Also include the measurements you made of the ERG's amplitude at the electrodes, the latency, and the duration. On the same page, you may (optionally) include several representative screenshots of the ERG for different stimulus intensities.

(2) A graph plotting the relative stimulus intensity (ND filter values) against:

  • the two measurements (bright-to dim-stimuli, and the reversed order of dim-to-bright) of the amplitude of the ERG ( in mV or µV at the electrode) for each intensity, and their average;
  • on the same graph, the latency between the flash and the ERG, using another vertical axis and different symbols to indicate latency in msec.

(3) The table of dark- and light-adaptation responses as a text box on your AppleWorks page.

4.
Clean up

At the end of the afternoon, rinse the eye chamber in tap water. Gather any files on your computer's desktop into your own group's folder. Turn off all equipment, including the DAM-50 amplifiers.