In a facilitated segment (SDF), which statement is true?

In a facilitated segment (SDF), which statement is true?

• A. Sympathetic activity is decreased by nociceptive afferentation
• B. Sympathetic activity is increased by increased mechanoreceptive afferentation
• C. Post synaptic neurons are brought closer to the threshold by increased nociceptive afferentation
• D. The threshold of a post synaptic neuron is increased by mechanoreceptive afferentation

Answer: (C)

In a facilitated segment, persistent nociceptive input keeps the dorsal horn neurons hyperresponsive, so synaptic transmission is amplified and a smaller input can trigger firing. This lowers the threshold of postsynaptic neurons, making them fire more easily. That’s why the true statement is that increased nociceptive afferentation brings postsynaptic neurons closer to the threshold. Mechanoreceptive input, through gate-control mechanisms, generally dampens nociception rather than driving neurons toward threshold, and sympathetic activity can be influenced by nociception in a segmental reflex, not simply decreased. So the key idea is that ongoing nociceptive input lowers the postsynaptic threshold in a facilitated segment.

In a facilitated segment, persistent nociceptive input keeps the dorsal horn neurons hyperresponsive, so synaptic transmission is amplified and a smaller input can trigger firing. This lowers the threshold of postsynaptic neurons, making them fire more easily. That’s why the true statement is that increased nociceptive afferentation brings postsynaptic neurons closer to the threshold. Mechanoreceptive input, through gate-control mechanisms, generally dampens nociception rather than driving neurons toward threshold, and sympathetic activity can be influenced by nociception in a segmental reflex, not simply decreased. So the key idea is that ongoing nociceptive input lowers the postsynaptic threshold in a facilitated segment.