Which statement describes the descending pain pathway?

• A. Pain signals travel from the body through the spinal cord to the brain.
• B. Brain sends signals down the spinal cord to reduce pain.
• C. The path uses only the brain and not the spinal cord.
• D. It increases pain transmission in the spinal cord.

Answer: (B)

The main idea here is descending pain modulation: the brain can dampen pain signals at the level of the spinal cord. This pathway starts in brainstem regions such as the periaqueductal gray and rostral ventromedial medulla, and sends signals down to the dorsal horn of the spinal cord. There, it activates inhibitory interneurons and engages monoaminergic systems (like norepinephrine and serotonin) and endogenous opioids. This action reduces the release of excitatory neurotransmitters from primary sensory neurons and decreases the activity of second-order neurons, leading to less pain information being transmitted toward the brain. So the statement that describes the descending pathway as the brain sending signals down the spinal cord to reduce pain captures this modulatory, analgesic effect. In contrast, pain traveling from the body up to the brain refers to the ascending pathway; and saying it involves only the brain or that it always increases pain would misrepresent this inhibitory mechanism.