When you experience severe pain, like breaking or shattering a bone, the pain isn’t just felt at the sight of the injury.
There is an entire network of receptors in your body running from the site of the injury, through your nervous system, along the spine and into the brain that reacts to tell you how much pain you are feeling.
This system goes into high alert when the injury occurs, and then usually resets as you heal.
However, sometimes, the system doesn’t reset, and even though the injury has mended, nerve damage has caused your brain to be permanently altered.
It means you still feel the pain, even though the injury has fully healed.
Dr. Gerald Zamponi, Ph.D., from University of Calgary and researchers at Stanford University, California, have been examining which brain circuits are changed by injury, in order to develop targeted therapies to reset the brain to stop chronic pain.
The team utilized optogenetics to study the neuron connections in the brains of mice.
Optogenetics allow scientists to use light to target and control individual neurons in the brain.
With this tool, researchers are able to map a pathway showing which neurons are communicating with each other to process a pain signal and then communicate this information all the way back through the spine where painful stimuli are first processed.
Much of the research for chronic pain has been focused on the spinal cord and targeting nerve fibers where the pain response is processed.
Treatment with current pain relief medications is often ineffective and can have serious side effects.
This new understanding of the pain signaling circuit may allow scientists to develop new drug therapies and targeted brain stimulation treatments to address chronic nerve pain, and hopefully provide relief for pain sufferers.
Working with mice, the team has proven that targeting certain pathways in the brain can interfere with the pain signal and stop pain sensation.
They expect the results the lab has seen in mice will be comparable in humans.
While the human brain is very complex, the communication network is similar in the animal brain.
The team is already applying this research to investigate how this brain circuit interacts with other parts of the brain involved in more complex behaviours like the interaction between pain pathways and addiction, depression, and anxiety.
The findings are published in Nature Neuroscience.