Post on 24-Feb-2016
description
Lab 4:Neurophysiology
Nervous System Organization
Earthworm
Structure of a Typical Neuron
Membrane Potential
Intracellular-70 to -60 mV
Extracellular
Nerve Impulse: Action Potential
Action Potential Propagation
Precautions
• Careful with equipment• Anesthetize the worm (change to 3 minutes)• Ground the worm (to minimize cutaneous
voltage conduction)• Use aluminum foil under apparatus• Use Loggerpro for data collection
Experimental DesignRoom Temperature• Voltage threshold: What voltage is needed to stimulate action
potential? Time between rising edge of stimulus pulse and first electrical event in the worm.
• Saturation: determine voltage that results in no further increase in activity.
• Pulse Duration: what occurs when duration is extended (0.25 sec)?• Stimulus Polarity: place anode closer to recording electrode. What
happens?• Symmetry of axons: switch anode/cathode and move amplifier.
Observe and record results.• Conduction velocity = distance/time (meters/second) (2 amplifiers)
Experimental Design
Effect of cooling • Cool the worm (in the apparatus) in
refrigerator for 10 minutes• Measure conduction velocity • Determine voltage threshold
Earthworm Chamber Set Up
Lab
Open “Earthworm AP” in LoggerPro
Sensor Confirmation Table will OpenSelect Connect Twice
Computer Screen After Stimulator Reading