When neurons fire and transmit messages, they

• A. begin slowly, then gradually increase in velocity.
• B. begin rapidly, then gradually slow down.
• C. do so in an all-or-none fashion.
• D. sometimes transmit information partially, depending on signal strength.

Answer: (C)

Verified step by step guidance

1. Understand the concept of 'all-or-none' principle in neural firing: Neurons either fire at full strength or not at all, similar to a light switch being either on or off.
2. Recognize that the 'all-or-none' principle means that once the threshold is reached, the neuron will fire completely, regardless of the strength of the stimulus beyond the threshold.
3. Consider the process of action potential: When a neuron fires, it generates an action potential that travels down the axon to communicate with other neurons.
4. Differentiate between the 'all-or-none' principle and other options: Neurons do not gradually increase or decrease in firing speed; they either fire or they don't.
5. Apply this understanding to the problem: The correct answer is that neurons fire in an all-or-none fashion, meaning they do not transmit information partially or vary in speed based on signal strength.