Individual Differences and Similarities in How Pain is Represented in the Brain
Post by Lincoln Tracy
The takeaway
Brain regions receiving direct spinothalamic input display more consistent pain representations between different individuals. These regions have the potential to be used as targets for personalized clinical interventions.
What's the science?
Pain is a complex and multidimensional experience. Certain brain regions have consistently been reported to play a role in pain processing, while other regions have been less consistently linked. Researchers suspect pain arises from activity in a variety of brain pathways, which may differ from person to person. However, it is currently unclear as to which brain regions have more consistent versus variable representations of pain across individuals. This week in Nature Neuroscience, Kohoutová and colleagues used a personalized brain mapping approach to identify brain regions with high or low interindividual variability in their relationship to pain.
How did they do it?
The authors obtained existing functional magnetic resonance imaging data from 404 individuals who had previously participated in one of 13 experimental pain studies across two independent laboratories. They then used these data to undertake personalized brain mapping of pain through predictive modeling. From these models, they sought to identify which brain regions were important for pain prediction. They also sought to explore how much variability each of the identified brain regions (either individually or as a collective) displayed in terms of pain prediction between individual participants. Finally, the authors validated their findings by replicating the analyses in a novel dataset of 124 individuals.
What did they find?
The authors identified 21 pain-predictive brain regions, including the anterior midcingulate cortex, the dorsolateral prefrontal cortex, and the cerebellum. When they compared the individual variability of these important regions, certain regions (e.g., the ventromedial prefrontal cortex) displayed high levels of variability between individuals, while other regions (e.g., the posterior midcingulate cortex) displayed lower levels of variance. This indicates substantial variability in the role of these regions in pain between individuals. Similar results were observed when considering the brain regions as a collective (i.e., multivariable analysis) rather than individually. The ventrolateral prefrontal cortex, the vermis, and the ventromedial prefrontal cortex showed the highest individual variability. In contrast, the posterior midcingulate cortex, the supplementary motor area, and the sensorimotor cortex were the most stable regions among individuals. Importantly, these findings were replicated when the analyses were repeated in a novel and independent dataset. Taken together, these findings indicate that the relationship between brain regions and pain perception at the individual level is more complicated than how they are usually summarized at the group level.
What's the impact?
This study found that various brain regions display differing levels of variability in pain representation between individuals. These findings enhance our understanding of how individuals process pain differently. Knowing which brain regions contribute to pain processing at the individual level could assist treatment decision-making processes for people with chronic pain.