Which neuron is responsible for the final delivery of pain information to the cerebral cortex?

Which neuron is responsible for the final delivery of pain information to the cerebral cortex?

• A. First Order Neuron
• B. Third Order Neuron
• C. Second Order Neuron
• D. Fourth Order Neuron

Answer: (B)

Pain signals travel through a three-neuron chain, with the last hop delivering the signal to the cortex. After peripheral nociceptors send the message to the spinal cord, the second-order neurons carry it up to the thalamus. The neurons that actually bring this information from the thalamus onto the cerebral cortex are used to project to the cortex; these are the third-order neurons. They originate in the thalamus (behind the relay nuclei, like the ventral posterior nucleus) and send projections to the primary somatosensory cortex, where pain is consciously perceived and localized. This thalamocortical relay is what makes the pain signal reach the cortex in a way the brain can interpret. The first-order neurons simply bring the signal into the spinal cord, and the second-order neurons relay it to the thalamus; there isn’t a standard fourth-order neuron in this pathway.

Pain signals travel through a three-neuron chain, with the last hop delivering the signal to the cortex. After peripheral nociceptors send the message to the spinal cord, the second-order neurons carry it up to the thalamus. The neurons that actually bring this information from the thalamus onto the cerebral cortex are used to project to the cortex; these are the third-order neurons. They originate in the thalamus (behind the relay nuclei, like the ventral posterior nucleus) and send projections to the primary somatosensory cortex, where pain is consciously perceived and localized. This thalamocortical relay is what makes the pain signal reach the cortex in a way the brain can interpret.

The first-order neurons simply bring the signal into the spinal cord, and the second-order neurons relay it to the thalamus; there isn’t a standard fourth-order neuron in this pathway.