The CNS can discriminate between strong and weak stimuli as strong stimuli __________.

• A. hyperpolarize the neuron
• B. increase the amplitude of action potentials
• C. increase the frequency of action potentials
• D. shift threshold

Answer: (C)

Verified step by step guidance

1. Understand the role of the central nervous system (CNS) in processing stimuli. The CNS interprets the intensity of stimuli based on the frequency of action potentials generated.
2. Recall that action potentials are all-or-none events, meaning their amplitude remains constant regardless of stimulus strength. Therefore, amplitude is not a factor in discriminating stimulus strength.
3. Consider the concept of frequency coding. Strong stimuli result in a higher frequency of action potentials, allowing the CNS to perceive them as more intense.
4. Eliminate options that do not align with the physiological mechanism of action potential generation. Hyperpolarization of the neuron would decrease the likelihood of action potential generation, and shifting the threshold would alter the conditions needed for an action potential to occur, but not directly relate to stimulus strength.
5. Conclude that the CNS discriminates between strong and weak stimuli by the frequency of action potentials, as this is the mechanism that conveys the intensity of the stimulus to the CNS.