Editor’s note: Portions of this article were republished with permission. Original article “A Final Approach to Pain,” by Frank Stephenson and Jan Godown, originally appeared in Florida State University’s Research and Review.
Current research being conducted at the University of Illinois (UIC) suggests that some of us may be born more susceptible to pain.
Researchers have long debated whether response to pain is purely emotional or a result of a combination of factors. Do our state of mind and previous experiences play a role in how we react to pain? Do fear and ignorance? Do men seem more tolerant of pain than women because they’ve been taught that they shouldn’t display emotion?
While these factors are valid, UIC researchers believe there’s more to it and hope that their research discovers which genes are responsible for pain tolerance and susceptibility.
UIC’s researchers treated mice with a lab-engineered version of Herpes Simplex Virus type 1 containing the gene that triggers the production of the pain -blocking protein Preproenkephalin. Results of the study showed that this gene worked on both slow- burning pain and sharp pain and altered the level at which the mice reacted to the pain.
However, researchers at Florida State University (FSU) caution against taking the single-minded approach that pain is genetically determined. In fact, they are convinced that how we experience pain is caused by combination of genetic, anatomical, hormonal, lifestyle, and cultural factors.
Medical schools generally teach that pain is a straightforward response to injury. Abnormal amounts of pressure, heat and certain chemicals in injured tissue trigger a response in surrounding nerve fibers that are expressly designed to handle so-called “pain signals.” These fibers are said to send “pain messages” toward the brain through a specific region in the spinal cord that controls the duration and intensity of these pain messages.
The general thought is that this area of the spinal cord is controlled by nerve impulses from all of the body’s five senses. The pain messages that pass through this area become the raw material that the brain uses to create the sensation of pain. Under the right circumstances, all signals can be cut off, resulting in no pain.
Dr. Karen Berkley, Professor in FSU’s Neuroscience Program, argues that this general theory has been grossly misrepresented, and that it refuted the idea that nerve fibers from the body handle so-called “pain messages.” What these fibers really do, she says, is deliver messages to the spinal cord – not about pain, but merely about stimulating events occurring to the body.
Once this information arrives at the spinal cord, it is subject to modification by interactions within the spinal cord itself and by information coming down from the brain, says Berkley. This modified information is then relayed to many parts of the brain where it gets modified even more by information arriving from other sensory organs. The result may or may not be the perception of pain.
What this means, somewhat ironically, is that pain is a perceptual creation that is in fact always “in the head,” so to speak. What is important, says Berkley, is that this means that injury or disease does not necessarily produce pain, and that pain can occur without any injury or threatening stimulus.
Next week – Part II: Feeling No Pain