Scientists chart spinal circuitry responsible for chronic pain

Researchers at the Salk Institute and Harvard University have identified a neural mechanism in the spinal cord that can send false senses of pain signals to the brain, according to a press release. Results of the researchers’ study were published online in Cell and may led to possible methods for treating pain disorders that have no clear physical cause, according to the release.

Previous research had identified two types of sensory neurons that appeared to be involved in the transmission of pain signals: pain and touch receptors. In the new study, the researchers deciphered the role played by the two neuronal cell types in the processing of pain signals in the dorsal horn, where the sensory neurons connect with the spinal cord.

The researchers discovered that a class of mechanoreceptors in the skin capable of detecting painful mechanical stimuli are part of a “feedback circuit” in which excitatory neurons that produce the hormone, somatostatin, are inhibited by dynorphin-synthesizing neurons. These neurons appeared to regulate whether touch activated the excitatory neurons to send pain signals to the brain, according to the release.

This finding may help explain how a light touch can cause discomfort in someone with allodynia, the release said. Additionally, the mechanoreceptor fibers projected to the spinal cord from a missing limb might prompt erroneous pain signals.

Reference: www.salk.edu.