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Lauren Poon's picture

All or None

Action potentials have been described as “all or none.” The input has to reach a specific threshold before the neuron fires. Above this point, the intensity of the signal does not matter. The neuron will send the same signal regardless of whether or not the peak is higher than the necessary threshold. That talks about the “all” part of action potentials, but what about the “none” part? Are there some inputs that never reach action potential because they’re below the threshold point? Does a person never feel these inputs? I suppose sensory inputs that fall below the threshold point prevent us from being super sensitive. For example, every single minute piece of dust that brushes against our skin does not cause us excruciating pain. It seems that the “none” part of action potentials protects us from unimportant or insignificant stimuli.

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