The conventional TENS usage is based on what theory?

• A. All or none
• B. Open gate
• C. Close gate
• D. No gate

Answer: (C)

The main idea being tested is how conventional TENS reduces pain through gate control of pain signals. Conventional TENS delivers high-frequency, low-intensity pulses that activate large-diameter Aβ fibers. This input excites inhibitory interneurons in the dorsal horn of the spinal cord, which dampen the transmission of nociceptive signals carried by C fibers and A-delta fibers. By increasing non-nociceptive input, the neural “gate” to the brain is closed, leading to less pain perception. That’s why the correct description is closing the gate. The other concepts don’t fit: the all-or-none idea is about whether a neuron fires at all, not about modulating pain signals; opening the gate would increase pain; and there isn’t a concept of “no gate” in this context.