Twin-Pulse Facilitation Measured as Twitch Ratios at the! Frog Nerve/Gastrocnemius Preparation ! Richard S. Manalis and Jonathan L. Miller— Department of Biology, Goshen College, Goshen, Indiana Introduction!
Learning & Memory are related to synaptic efficacy which the present study brings to the undergraduate physiology laboratory. TWIN-PULSE FACILITATION has been widely used to study one aspect of short-term synaptic plasticity at a wide variety of synapses using electrophysiological methods. Here we show that measurements of muscle twitches from the easily prepared sciatic nerve/gastrocnemius preparation of the frog can allow one to perform experiments involving TWIN-PULSE FACILITATION. The advantages of measuring muscle twitches over electrophysiological parameters are as follows: 1. Students with minimal background can quickly learn to prepare the nerve/muscle preparation for physiological recording and for experimentation dealing with synaptic efficacy. 2. Muscle twitch recordings are population responses, which tend to average out individual variation. 3. Under certain experimental conditions (see Fig. 6), one can make deductions about synaptic transmission from muscle twitch measurements. 4. Most electrophysiological studies at the frog neuromuscular junction require that contractions NOT occur, which makes it almost impossible to obtain population responses and to observe recruitment. LabScribe software and hardware (iWorx) were used for digital recording and stimulation. Twin-pulse facilitation was studied by applying a dualstimulus pulse, consisting of a conditioning (C) pulse followed by a test (T) pulse, to the sciatic nerve, and dividing the peak T twitch by the peak C twitch to obtain the T/C ratio, our measure of facilitation. The interval between the two stimulus pulses is the CT interval (ms). A critical part of our nerve stimulation protocol was the use of trains of stimuli (Fig. 6). A given train usually consisted of 5 identical dual-pulses...
Please join StudyMode to read the full document