The all-or-none law governing neuronal action potentials is a foundational physiological principle established by foundational neuroscience textbook definitions, rendering formal citation unnecessary.
The claim states a basic physiological truism that once a depolarization threshold is reached, an action potential fires with a consistent amplitude regardless of the stimulus strength. Under STEP 0 instructions, facts that are trivially true by definition or direct everyday observation in standard science are classified as COMMON_KNOWLEDGE, requiring no citations.