A recent study found that each person has a unique "pain fingerprint" in the brain, which can vary from person to person. The study, conducted by the University of Essex in collaboration with the Pain Neuroscience Group at Ludwig Maximilians University of Munich, found that rapid oscillations in brain waves associated with brief pain and touch varied significantly across scans.
Historically, these brain waves, known as gamma oscillations, were thought to represent the brain's perception of pain. However, early studies focused mainly on collective data and often ignored differences between individuals, sometimes even treating these differences as mere "noise" in the scans.
Dr. Elia Valentini of the Department of Psychology found that gamma oscillations varied greatly in time, frequency and location, and incredibly, some people showed no waves at all.
Dr. Valentini said: "Not only have we discovered for the first time extreme variability in gamma responses between individuals, we have also shown that individual response patterns are stable across time. This pattern of population variability and individual stability may apply to other brain responses, and characterizing it may allow us to identify individual pain fingerprints in brain activity."
The study, published in the Journal of Neurophysiology, was able to map the pattern in another lab participant, showing that the phenomenon can be replicated.
The study looked at data from a total of 70 people. The experiment was divided into two studies, using lasers to produce pain. Overall, the experiments found that the subjects' gamma waves were "very stable," producing similar individual patterns when stimulated.
Interestingly, some subjects had no gamma wave response when they were recorded feeling pain, while others had a large response.
It is not known at this stage why this difference occurs, but it is hoped that this will serve as a springboard for future research.
Dr. Valentini added: "I think we need to go back to square one, because the results of past studies on the relationship between pain and gamma oscillations are not representative of all participants. Unfortunately, this small number may have influenced the study results and led to misleading conclusions about the functional significance of these responses. We are not saying that gamma oscillations have no role in pain perception, but if we keep quantifying gamma oscillations as we have done so far, we certainly cannot find its true role."
The researchers hope this study will change the way gamma oscillations are measured in other sensory areas as well.