Plural of excitability; multiple instances or types of the quality of being easily excited or stimulated.
From 'excitable' (able to be excited) + '-ity' (quality), plural formed with '-ies,' showing different versions of responsiveness to stimulation.
In neuroscience, scientists measure the excitabilities of different neurons—some brain cells barely respond to signals, while others fire at the slightest stimulus, which explains why some people are naturally more energetic or anxious.
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