Practice question · Multiple choice
Action potentials are all-or-none, so every spike is the same size. How does the nervous system represent the difference between a gentle touch and a hard press?
Hints
- If every spike is identical, what is left that can vary?
- Count them. Then count how many neurons are producing them.
Show the answer
D. By firing rate and by the number of neurons recruited.
Why
The all-or-none law removes amplitude as a variable, so the code moves to rate and recruitment. That is a design rather than a limitation: a signal carrying information in its size loses it as it decays, where a spike either arrives or does not. It also explains why perceived intensity is compressive, a receptor already at maximum cannot report that the stimulus grew.
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