Instrumentation for Laboratory Exercises in Basic Electrophysiology *

The apparatus described below was used during the past year to provide first-year medical and graduate students with an opportunity to observe and study for themselves basic phenomena characteristic of the excitable tissues in general and nerve in particular. The apparatus represents the culmination of numerous attempts on our part to design and develop an arrangement that would be relatively simple to operate and sufficiently rugged to stand up under inexperienced hands, and which would be cheap to build and easy to maintain. In our experience, this "set up" has proven so satisfactory from the point of view of both students and teachers that we have been encouraged to recommend its use to others. The description of the apparatus is supplemented by an outline of a laboratory exercise which has proven particularly successful in clarifying some of the fundamental principles involved in an appreciation of the activity of nerve fibers. The entire apparatus (Fig. 1 ) is made up of five basic units: ( 1 ) the electrode chamber that contains the nerve under study, (2 ) the thyratron stimulator that excites the nerve fiber, (3) a delayer device that serves to separate in time the stimulus artifact and the action potential, (4) the amplifier, and (5) the oscilloscope.