In the facilitated segment model, which factor is described as bringing postsynaptic neurons closer to the threshold?

In the facilitated segment model, which factor is described as bringing postsynaptic neurons closer to the threshold?

• A. Increased nociceptive afferentation
• B. Decreased nociceptive afferentation
• C. Increased mechanoreceptive afferentation
• D. Increased sympathetic activity

Answer: (A)

Persistent nociceptive input from a segment increases the excitability of the neurons in that spinal segment. This process, known as facilitation, makes the postsynaptic neurons more responsive; their firing threshold effectively lowers so that even smaller inputs can trigger action potentials. In the facilitated segment model, the factor that brings neurons closer to threshold is the rise in nociceptive afferentation from the affected segment. Decreasing nociceptive input would reduce this excitability, and mechanoreceptive input or sympathetic activity can modulate pain in other ways but are not the primary drivers described by this model for lowering the threshold.

Persistent nociceptive input from a segment increases the excitability of the neurons in that spinal segment. This process, known as facilitation, makes the postsynaptic neurons more responsive; their firing threshold effectively lowers so that even smaller inputs can trigger action potentials. In the facilitated segment model, the factor that brings neurons closer to threshold is the rise in nociceptive afferentation from the affected segment.

Decreasing nociceptive input would reduce this excitability, and mechanoreceptive input or sympathetic activity can modulate pain in other ways but are not the primary drivers described by this model for lowering the threshold.