UCL (UK) — Scientists have unlocked details of the brain’s “pain map” for the hand, and say the findings may shed light on the processes at work in chronic pain.
The hand map is the first to reveal how finely-tuned the brain is to pain. Researchers used fMRI techniques in conjunction with laser stimuli to the fingers to plot the exact response to pain across areas of the brain.
“The results reveal that pain can be finely mapped in the brain,” says lead author Flavia Mancini of the Institute of Cognitive Neuroscience at University College London. “While many studies have examined the brain response to pain before, our study is the first to map pain responses for the individual digits of the human hand.”
Using an fMRI brain imaging technique originally created to map the visual field, researchers were able to distinguish the brain’s responses to painful laser heat stimuli on each finger in seven healthy participants, and to study their organization in the brain.
This enabled the team to produce a fine-grained map showing how pain in the right hand results in certain parts of the brain being activated in the primary somatosensory cortex, an area in the left hemisphere of the brain which is involved in processing bodily information.
When comparing this pain map to ones generated by non-painful touch to the right hand, the researchers found that the two were very similar, with each map aligning with one another in each of the seven volunteers tested. The team’s findings are published in the Journal of Neuroscience,.
“The cells in the skin that respond to pain and the cells that respond to touch have very different structures and distributions, so we were surprised to find that the maps of pain and of touch were so similar in the brain,” Mancini says. “The striking alignment of pain and touch maps suggests powerful interactions between the two systems.”
The pain maps could be used to provide markers for the location of pain in the human brain, enabling clinicians to see how patients’ brains reorganize following chronic pain.
“We know that the organization of other sensory maps in the brain is altered in patients with chronic pain,” says Patrick Haggard, professor in the UCL Institute of Cognitive Neuroscience. “Our method could next be used to track the reorganization of brain maps that occurs in chronic pain, providing new insights into how the brain makes us feel pain. Therefore, measuring the map for pain itself is highly important.”