What difference in axonal signaling determines whether we experience a mild or a strong sensation?

Question

A.  amplitude of action potentials
B.  frequency of action potentials
C.  action potential threshold
D.  conduction speed
E.  amount of neurotransmitter released per vesicle

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about axonal signaling? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?


Answer 1

B.  frequency of action potentials

Clarify Question
What is the key concept addressed by the question?
        · How is strength of axonal signaling coded in the nervous system?
What type of thinking is required?
            o This is an analyze question because you have to break neural signaling into different stages and understand which aspects of axonal signaling vary with signal strength.

Gather Content
What do you already know about axonal signaling? What other information is related to the question?
        · You already know that signals are transmitting down axons via action potentials. But what makes one signal stronger than another one? You know that action potentials are an “all-or-none” response. Once membrane potential reaches a certain threshold, then voltage-gated ion channels open up and an action potential occurs. The amplitude of the action potential does not change with increased stimulation, but the rate at which action potentials fire does change- with higher frequency of action potentials resulting from stronger stimuli. Once action potentials reach the end of the axon, neurotransmitters are released that bind to post-synaptic receptors, which can change the membrane potential and initiate an action potential in the post-synaptic neuron.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Since action potentials are all-or-none responses that do not vary in amplitude or threshold, you can eliminate amplitude and threshold as correct responses. Similarly, conduction speed and the amount of neurotransmitter released per vesicle is constant for an individual neuron. That leaves frequency of action potentials as the correct answer. Greater stimulation leads to a higher frequency of action potentials.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o Answering this question correctly depended not only on distinguishing between different properties of neurons and action potentials, but on your ability to analyze which characteristics are constant and which one would shift with intensity of stimulation. If you got an incorrect answer, did you remember that action potentials are an all-or-none event that either happens or it does not, with the threshold and amplitude being constant for a particular neuron? Did you forget that axon conduction speed is dependent upon axon width and whether it is myelinated or not? Did you realize that the amount of neurotransmitter in each vesicle is constant?