Which statement best describes gate control theory of pain?

Which statement best describes gate control theory of pain?

• A. Pain signals bypass the spinal cord.
• B. Stimulation of A-delta fibers inhibits pain.
• C. Stimulation of A-beta fibers inhibits pain from A-delta and C fibers.
• D. Endogenous opioids increase nociception.

Answer: (C)

Gate control theory describes how non-painful input can dampen pain signals at the spinal cord level, effectively closing the gate to nociceptive transmission. When large-diameter A-beta fibers are stimulated by touch or rubbing, they activate inhibitory interneurons in the dorsal horn that suppress the transmission of pain signals carried by smaller A-delta and C fibers to the next neurons that ascend to the brain. This is why rubbing a bumped knee or applying a massage can lessen pain. The best statement captures this mechanism: stimulation of A-beta fibers inhibits pain from A-delta and C fibers. Pain signals do not bypass the spinal cord; they are modulated there before reaching the brain. Stimulating A-delta fibers would tend to increase, not inhibit, pain since they carry fast nociceptive input. Endogenous opioids reduce nociception by inhibiting transmission, not increase it.

Gate control theory describes how non-painful input can dampen pain signals at the spinal cord level, effectively closing the gate to nociceptive transmission. When large-diameter A-beta fibers are stimulated by touch or rubbing, they activate inhibitory interneurons in the dorsal horn that suppress the transmission of pain signals carried by smaller A-delta and C fibers to the next neurons that ascend to the brain. This is why rubbing a bumped knee or applying a massage can lessen pain.

The best statement captures this mechanism: stimulation of A-beta fibers inhibits pain from A-delta and C fibers. Pain signals do not bypass the spinal cord; they are modulated there before reaching the brain. Stimulating A-delta fibers would tend to increase, not inhibit, pain since they carry fast nociceptive input. Endogenous opioids reduce nociception by inhibiting transmission, not increase it.