Question

Which one of the following is TRUE for the Pain-Gate control theory?

• A. Gate is a physical structure
• B. Activity of gate cannot be closed by non-pain signals
• C. Substance P released into spinal cord does not activate other neurons that send messages through spinal gates
• D. Pain signals must pass through a gate located in the spinal cord

Hint:

Remember the heuristic: {Rub it and it hurts less} \(\Rightarrow\) non-pain (A-beta) input can close the spinal gate.

Answer 1

The Correct Option is D

Step 1: Core idea. Gate-control theory (Melzack \& Wall) proposes a {gating mechanism} in the dorsal horn of the spinal cord that modulates nociceptive input before it ascends \(\Rightarrow\) pain transmission is “gated” at the spinal level.

Step 2: Check options.
(A) False — the “gate” is a functional mechanism (interneuronal modulation), not a discrete physical gate.
(B) False — large-diameter touch/pressure fibers and descending pathways can {close} the gate (e.g., rubbing an injured area reduces pain).
(C) False — Substance P facilitates transmission to second-order neurons; it does not negate activation.
(D) True — nociceptive signals are modulated at a spinal “gate” before ascending.
Final Answer: (D)