Neurophysiology Nerve Impulse Simulation: PhysioEx Lab CD-ROM

1. Lab 18B Neurophysiology: Simulation of Nerve Impulses

2. PhysioEx • CD-ROM came with lab manual • You will manipulate a model of a nerve – not a single neuron, but a bundle of axons – and see what happens • 3 Exercises: • Eliciting a nerve impulse • Inhibiting a nerve impulse • Nerve conduction velocity

3. Eliciting a nerve impulse

4. Eliciting a nerve impulse • Set voltage at 1.0 by clicking + button • Click “Single Stimulus” • Increase voltage until you get a population action potential • Click “Record Data” • Increase by 0.5 and see what happens • Keep increasing until no further change • Record Data • Remember, you are not seeing a single AP, but a collection of action potentials in many axons within a nerve • Click Clear

5. Eliciting a nerve impulse • Click the glass rod and drag it over the nerve • Compare to your threshold AP (do it again to see them next to each other) • Record Data • Now drag the rod to the heater and click heat • When it turns red, drag it onto the nerve • Compare it to unheated trace • Record Data

6. Eliciting a nerve impulse • Click and drag the NaCl dropper over to the nerve and release drops – note what happens • Record Data • Now run a Single Stimulus at threshold and see how it differs from NaCl application • Clean and Clear • Repeat the drap and drop with HCl • Record Data, then compare with a Single Stimulus

7. Inhibiting a nerve impulse

8. Inhibiting a nerve impulse • Chose I.a.n.i. from Experiment drop down • Test the effect of ether by clicking and dragging it onto the nerve, then set to threshold and Stimulate • Record Data • Now click on Time (min) to change time scale to 10 min • Set interval between stimuli to 2.0 min • Make sure it is set to threshold and click Stimulate – watch how long it takes to return to normal • Click Stop, return interval to 0.0 and Clean and Clear

9. Inhibiting a nerve impulse • Test the effects of cuare, an ACh blocker by clicking and dragging onto nerve • Stimulate at threshold and see what happens • Record Data • Clean and Clear • Test effects of lidocaine by dragging it and Stimulate at threshold • Record Data

10. Nerve conduction velocity

11. Nerve conduction velocity • Choose N.C.V from Experiment drop down • Compare 4 types of nerves in terms of conduction speed • Click Pulse, switch amplifier to on • Drop ether onto worm and then drag it onto stimulating apparatus • Start at 1.0V and Stimulate, increase (by 1V) until threshold reached • Click Measure, then click + until yellow line moves to place where AP starts • Record Data • Fill in Chart 1

12. Nerve conduction velocity • Put earthworm back and repeat process for the remaining three nerves (no ethanol necessary): • Drag onto apparatus • Determine threshold • Measure and Record Data

13. Turn in • Pages PEx-39 through PEx-48 with answers and data • Due next Thursday