This PRO lesson illustrates action potentials as they function through the conduction of cockroach ventral nerve cords.
By administering soft puffs of air to the "anal cerci" one can provoke and view action potentials as they travel in axons through the ventral nerve cord. The cerci have hundred of tiny hairs connected to individual mechanoreceptors. The small hairs respond to touch and small changes in air currents. The cockroach uses this information to evade predators.
In this lesson, stainless steel needle electrodes are placed under the cockroach ventral nerve cord to record the nerve response to stimulation. A puff of air is presented to the cerci and the response is recorded. This particular lesson shows the information being passed along the ventral nerve cord. The axons traveling through the nerve result in amplitude data spikes during recording, allowing one to study this phenomenon up close.
EXPERIMENTAL OBJECTIVES
Stimulate the cerci by puffs of air and touch.
Record the response to the stimulation.
Compare cercal response, left side vs. right.
Determine the number of cercal hairs that must be stimulated to produce a ventral nerve response.
TASKS PERFORMED BY THE STUDENT
Pith the cockroach.
Excise the cuticles.
Remove the gut, trachea, and muscles running parallel with the ventral nerve cord.
Record baseline.
Record while using a pipette to direct air puffs to the cerci.
Record while using a small probe to stimulate an increasing number of cercal hairs to produce a ventral nerve response.
KEY FEATURES
Add event markers throughout the recording.
The software automates the calibration procedure for the student. There are no knobs and dials to confuse the student.
Graph template files ensure consistent setup for subsequent Subjects or repeated trials—plus, you can easily add your own lesson plan to the onscreen journal.
The lesson will also work as part of a group study.
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