In the context of the gate-control theory of pain, explain how the “pain gates” may be opened or closed by physiological and psychological mechanisms. Make explicit reference to the distinction between A-delta and C-fibers on the one hand, and specific spinal cord and brain areas on the other.

Question

What will be an ideal response?

Answer 1

The gate-control theory of pain differs from early theories of pain because it explicitly acknowledges that psychological factors may influence the experience of pain. The theory posits a pain gate located in a part of the dorsal horn section of the spinal cord called the substantia gelatinosa. This pain gate may be closed from the “bottom up” or from the “top down”. From the bottom up--that is, from the nociceptors and peripheral nerve fibers toward the brain--pain messages may be carried on small, myelinated A-delta fibers. Competing sensations carried along large, unmyelinated C-fibers may cause the gate in the substantia gelatinosa close. A familiar example occurs when we rub a sore area or punch a wall when we stub a toe. From the top down, signals from a brain area called the periaqueductal gray in the midbrain can cause the closure of the gate in the substantia gelatinosa. The periaqueductal gray is part of a more general central control mechanism by which relaxation, distraction and other positive mood states may close the gate in the spinal cord.