Where in the spinal cord is the gate control mechanism located according to the theory?

• A. Dorsal horn
• B. Ventral horn
• C. Medulla
• D. Cerebellum

Answer: (A)

Pain signals are modulated right where they enter the spinal cord, in the dorsal horn. The gate control mechanism sits there, specifically in the substantia gelatinosa (lamina II). In this region, small nociceptive fibers (carrying pain) and larger non-nociceptive fibers (like touch) influence the activity of inhibitory interneurons. When non-nociceptive input is strong, these interneurons dampen the projection neurons, effectively closing the gate and reducing pain transmission to the brain. When nociceptive input dominates, the gate opens and more pain signals are sent up the spinal cord to higher centers. The other options aren’t where this gating happens: the ventral horn contains motor neurons, while the medulla and cerebellum are brain areas not acting as the spinal gate in this theory.