In Simple Terms
A movement that brings on a bout of long-lasting back pain may affect the brain differently from a brief, unpleasant heat sensation. Researchers found that a brain network linked to thoughts and memories became more active during the back-pain flare. The finding may help explain why easing pain alone does not always address its wider effects, but it does not prove that a new treatment works.
Chronic Pain Is More Than a Moment of Discomfort
Lower back pain is widespread, and the World Health Organization describes it as the leading cause of disability worldwide. Pain that lasts more than 12 weeks is classified as chronic. For some people, everyday movements that would normally seem simple can trigger sudden flares, making the condition more complicated than a passing ache that comes and goes.
That complexity does not mean the pain is unreal or imagined. The physical sensation is real, but living with it over time can also involve expecting it to return, remembering previous episodes, and trying to avoid activities that might set it off. Researchers therefore see the brain not as a passive relay for signals from the back, but as part of a system that interprets sensation and combines it with attention and experience.
Even so, pinpointing which brain circuits change specifically when movement triggers a flare of chronic pain has been a scientific challenge. Studying pain under separate, isolated conditions does not necessarily reveal what happens during a movement tied directly to a patient’s condition. To address this, the research team compared a flare brought on by moving the body with a short-lived painful sensation caused by heat.
A Movement Test and a Heat Comparison
The study included 114 people with chronic lower back pain. Each participant underwent a straight-leg raise, a clinical test used to provoke back pain in some patients. During the test, researchers tracked changes in blood flow in the brain using arterial spin labeling functional magnetic resonance imaging, known as ASL.
This technique estimates patterns of brain activity by measuring blood flow, without requiring an injected contrast agent. That mattered because the researchers wanted to follow the brain’s response in the context of a movement that triggered pain, rather than relying only on participants’ accounts after the experiment. The test brought together body movement, changes in pain, and a physiological measure of brain activity.
To compare the chronic flare with another kind of pain, participants were also exposed to an unpleasant but harmless heat sensation applied to the calf. The researchers likened it to the brief sting someone might feel after accidentally touching a hot surface. This allowed them to observe how the brain responded to pain linked to a movement associated with a chronic condition, compared with a separate, temporary heat stimulus.
The Brain Network That Went Against Expectations
The results focused on the brain’s default mode network, or DMN, sometimes called the self-related network. It is a group of connected regions in the frontal, parietal, and temporal lobes. The network is usually more active when attention turns inward, such as when someone thinks about personal experiences, identity, feelings, or thoughts. Its activity tends to decrease when attention shifts to a task or event outside the self.
When the straight-leg raise triggered a back-pain flare, activity in this network increased. During the painful heat sensation, by contrast, its activity fell, consistent with the pattern typically seen in the brain’s response to acute pain. The difference, then, was not simply how intense the sensation was, but the direction of change in a network associated with inward-focused thought.
Usually, a drop in default mode network activity helps redirect attention toward an immediate source of potential danger. The pattern observed during the chronic pain flare went the other way. Fadel Zeidan, the study’s lead researcher and a professor of anesthesiology at the University of California San Diego School of Medicine, said the team observed activation of the network during the flare, rather than the decrease reported in studies of more typical pain. The finding suggests that chronic pain episodes may involve processes beyond the handling of physical sensation alone.
But activity in a network associated with the self does not show that pain changes a person’s identity, nor does it mean that patients choose to connect pain with who they are. This is a finding about brain activity in a group of participants, offering evidence that the response to chronic pain may overlap with systems involved in inner experience. More research is needed to connect this overlap to people’s everyday lives over longer periods.
Stronger Links to the Processing of Physical Sensations
The results went beyond comparing the network’s activity during the two types of pain. Researchers found that participants with more severe back pain had stronger connections between the default mode network and the primary somatosensory cortex. This region helps process sensory signals from the body, including signals related to the back.
Greater pain intensity during the straight-leg raise was also associated with increased activity in brain regions involved in sensation and movement. These associations do not, by themselves, show that any one region causes the pain. Instead, they indicate that the severity of a flare coincided with measurable differences in brain systems involved in sensation and movement, alongside the change in the self-related network.
The team also found that increases in heart rate during the test reliably reflected the severity of a pain flare. This bodily measurement adds information to participants’ descriptions of what they felt, but it cannot replace pain assessment or serve as an independent diagnostic tool. Its value here is that it showed a link between the intensity of a person’s experience and a measurable physiological response.
How Pain Can Reach Beyond the Flare
The pattern of brain activity may help explain, in part, why the burden of chronic pain is not limited to the minutes when someone feels an ache. Worry about another flare, memories of earlier episodes, and fear of a particular movement can all affect how a person gets through the day. Some people may hesitate to take part in familiar activities because they have been hurt before or expect the pain to return.
These aspects do not make pain any less physical; they place it within a broader experience. A pain signal may be present, but how it is interpreted, where attention goes, and the feelings and expectations connected to it can all help shape its effects on daily life. This broader picture fits with the observation that a network linked to inward attention became more active during the movement-triggered flare. However, the study alone cannot explain how these connections form in each person or establish that everyone with back pain has the same experience.
That is why comparing a chronic flare with a heat stimulus matters: the brain did not respond in the same way to every painful sensation. Activity in the network decreased after the brief pain, while the movement-triggered flare was associated with increased activity. The context, the persistence of the condition, and a patient’s past experiences with pain may help explain the difference, but larger studies are needed to determine the role of each factor.
What the Findings Could Mean for Treatment
Many treatments aim to reduce the sensation of pain or limit the transmission of pain signals. But if chronic pain flares also involve networks that contribute to personal experience and inward attention, an approach focused only on sensation may not address everything that makes the condition affect a person’s life. The study gives researchers a scientific reason to explore this possibility; it does not show that current treatments are ineffective or that an alternative treatment has been proven to work.
In recent work, Zeidan and his colleagues have discussed studying mindfulness meditation and the compound psilocybin as part of research into pain. Mindfulness meditation trains people to notice thoughts and sensations in the present moment without immediately judging them. Psilocybin, a psychoactive compound, is being studied in scientific settings to explore how pain interacts with past experiences, emotions, and expectations. These approaches remain under investigation. Their inclusion in this research should not be taken as a treatment recommendation or proof that they are effective for back pain.
The idea behind this line of research is not necessarily to erase every pain signal, but to investigate whether the brain’s way of responding to pain can be changed so that the experience has less control over thought and everyday activity. This remains a hypothesis that requires careful clinical testing, comparisons with other approaches, and follow-up with participants to find out how much improvement occurs, how long it lasts, and whether the effects differ from person to person.
Zeidan’s Laboratory for the Study of Pain, Health, and Mindfulness at the University of California San Diego School of Medicine is conducting clinical trials that use brain imaging to examine whether meditation or psilocybin-based interventions change neural processes associated with inward-focused thought. The research goal is to find out whether these approaches affect how people experience pain, not to assume that they eliminate pain or are suitable for every patient.
Study Limitations and What Comes Next
The study offers an important picture of brain responses in 114 patients during a specific test, but it does not show that activation of the default mode network causes pain to persist. Nor can a brain scan taken during a laboratory experiment capture all the complexities of living with the condition over weeks or months. It is important to distinguish an association between pain severity and brain activity from proof of cause and effect—or evidence of a treatment that can change the pattern.
Future research will need to test whether the same pattern appears in other groups, how it changes over time, and how it relates to symptoms getting better or worse. Proposed interventions must also be assessed in appropriate clinical trials before practical conclusions can be drawn. Brain imaging offers a window into what accompanies a pain flare inside the brain, but it cannot provide a ready-made treatment on its own.
The study was published on October 5, 2026, in the British Journal of Anaesthesia. Contributors from the University of California San Diego School of Medicine included Morgan Gianola, John Dean, Conan Chen, Daniel Barrows, Gabriel Renier, Thomas Liu, and Fadel Zeidan. Part of the research was funded by the National Center for Complementary and Integrative Health at the National Institutes of Health through grant R01AT009693, and by the university’s Sanford Institute for Empathy and Compassion. The researchers reported no conflicts of interest.
The Bottom Line
The University of California San Diego team found that a movement-triggered flare of chronic back pain may come with a different brain response from a brief, painful heat sensation. A network associated with inner experience became more active during the flare and less active during the heat stimulus. Pain severity was also linked to changes in regions involved in sensation and movement, and people with more severe pain showed stronger connections between the self-related network and the primary somatosensory cortex. The findings do not establish a new treatment, but they broaden our understanding of chronic pain as an experience that may involve attention, memories, and expectations as well as physical sensation—and point to the need for research on how pain affects everyday life.