Thus Labs 2 and 3 introduce extracellular nerve recording and crayfish dissection. A minor modification of that dissection is used in Lab 4, which introduces intracellular recording from the muscle innervated by the nerve that was used in Labs 2 and 3. Labs 8 and 9 combine the crayfish nerve and muscle preparations used in Labs 2 and 3. Lab 10 is a simple dissection and extracellular recording that could be done anywhere in the sequence. This lab introduces basic principles of extracellular and intracellular recording.
Students first simulate recordings using a resistor model membrane and a voltmeter.
Next, they inject a square pulse into an RC circuit and measure its time constant. In both of these exercises, emphasis is placed on quantitative measurements. Finally, amplifiers and data acquisition equipment are introduced. Students are given a weakly electric fish, from which they record by simply placing an electrode in the water. Crayfish Motor Nerve Recording Lab 2 introduces extracellular recording of the third nerve of a crayfish abdominal ganglion.