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Threshold of excitation

 
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6 8 1012141618+

This activity takes an experimental approach to introduce the notion of the threshold of excitation  in nerve cells via electrical stimulation of 5 µA, 10 µA, 20 µA, 40 µA and 80 µA.
One notes in passing the way in which the information is encoded:
Beyond the threshold of excitation, the nerve message is a signal that takes the form of a train of action potentials, the frequency of which is proportional to the intensity of the stimulation.

Click on « Start the Experiment », then select an excitation intensity.
Roll over the oscilloscope screens to obtain values.

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  • To analyze the consequences of sub-threshold, threshold and superthreshold stimulations on the value of the membrane potential of a neuron.
  • To set down   the law of « all or nothing » that characterizes the notion of action potential.
  • To understand that the nerve message is encoded in the frequencies of action potentials.