Pain Neuroscience Explained Simply

You might wonder why your pain continues even though your injury should be healed. Or why some days hurt more than others for no clear reason. Perhaps you've been told it's 'all in your head,' and you're unsure what to believe anymore. This confusion is normal, as pain is far more complex than previously understood.

Good news: Understanding pain and resuming appropriate activities can help you manage it better. The brain's role opens up new treatment possibilities, even when pain persists.

What science teaches us about the neuroscience of pain:

• Your brain plays an active role in pain; you don't consciously choose to feel pain.
• The intensity of pain does not directly reflect tissue damage.
• Context, emotions, and beliefs can influence your pain.
• Your nervous system may change, and appropriate care can improve your comfort and your ability to perform daily activities.

This guide explains the role of the brain, nerves, and context in pain. For practical ways to manage pain, see our article on pain management strategies.

How Does Your Brain Produce Pain?

Your brain helps generate pain by integrating signals from your body, your experiences, and^{the context¹⁻².} This process occurs without any conscious decision on your part.

The “single electrical wire” model is incomplete: an injury to the foot would send a message, and the brain would simply receive it. In reality, the nervous system transforms and modulates these messages. This helps explain certain types of chronic pain—pain that persists or recurs for more than three months.

Your brain takes into account signals from your body, as well as your physical condition, your emotions, and your^{experiences.¹, ²} Therefore, feeling pain is neither a conscious decision nor a lack of willpower.

Is nociception already pain?

Nociception refers to the nervous system’s processing of stimuli capable of threatening or damaging tissue; it is not the same as the pain that is felt¹. A stimulus is an event such as pressure or heat.

The Detection System

The word “nociception” comes from the Latin nocere, which means “to harm.” Nociceptive mechanisms detect and transmit information about potentially harmful stimuli. This neural activity alone is not sufficient to prove that a person is experiencing pain.

Nociceptors are the endings of certain nerve fibers. They are found primarily in the skin, muscles, and joints. These sensors can respond to three types of potentially harmful stimuli:

• Mechanical factors: pressure or stretching intense enough to damage the tissues.
• Thermal: extreme heat or cold.
• Chemical: Substances released, in particular, during inflammation or injury.

These messages travel through the nerves to the spinal cord or, for certain areas such as the face, to the brainstem. The spinal cord is a nerve cord located within the spinal column that transmits messages between the brain and the body. The brainstem is located at the base of the brain. These relay stations are involved in processing information before it is transmitted to other regions of the brain, as explained in the neuroscience chapter on nociceptors.

From the stimulus to its processing: three steps

The stimulus (pressure, heat, etc.) is transformed into an electrical signal by the nociceptors.

The electrical signal travels along the nerve fibers to the spinal cord or the brainstem. These relay stations transmit it to different regions of the brain and may already alter how it is processed.

The brain combines nerve signals with context, memories, and the body’s state. Pain can arise from this processing. There is no single conscious “yes or no” response that alone determines whether you are in pain.

Why doesn't pain always reflect the condition of your tissues?

Pain does not directly reflect the condition of the tissues, because the nervous system also processes context, emotions, and experiences. An injury can therefore cause pain that varies greatly from one person to another.

Surprising Discoveries

Research distinguishes between nerve activity, tissue damage, and the pain experienced:

Signals from the tissues contribute to pain, but their activity alone is not sufficient to determine what a person is feeling. Brain research shows that several regions are involved and that^context plays a role^{.³, ¹, ⁴}

Intense pain alone is not a reliable indicator of the severity of an injury. The condition of the tissues remains a relevant factor, but the sensitivity of the nervous system, emotions, and the situation can also influence^{pain3, 4}.

In experiments, nociceptive stimulation can increase the response of nerve cells in the brain or spinal cord, even after the stimulation has stopped. This is known as central sensitization⁵. This mechanism may contribute to persistent pain. It does not mean that nociceptor activity always decreases during prolonged pain.

The Key Message

Two people with similar injuries may experience different levels of pain. The absence of a visible injury does not mean the pain is not real; nor does mild pain rule out an injury.

In some cases of persistent pain, a more sensitive nervous system can amplify the pain without causing new damage proportional to the tissue⁶. This does not rule out the possibility of an injury. New or significantly different pain warrants an appropriate evaluation.

How do various regions of the brain contribute to pain?

Different regions of the brain work together as a network to link sensations, emotions, memories, and reactions associated with pain. There is no single center dedicated to pain.

The Neuromatrix

The neuromatrix is a proposed model for describing the brain networks that contribute to body awareness and pain². This model brings together sensations, emotions, and thoughts. It does not correspond to a single, identical map in every person.

Certain regions are specifically associated with the following functions:

• Body sensations: the somatosensory cortex, a region on the surface of the brain.
• Emotions: several regions often grouped together under the name "limbic system," including the amygdala, a small structure located deep within the brain.
• Memories: notably the hippocampus, another deep-seated structure.
• Planning and decision-making: the prefrontal cortex, located at the front of the brain.
• Movement: the motor cortex, which helps control the muscles.

These regions communicate with other parts of the nervous system. Pain involves both a sensory experience—related to what you feel—and an unpleasant emotional experience. It is therefore not limited to the strength of a nerve signal.

In a study of 30 healthy young adults, images were used to induce a positive, neutral, or negative mood. The participants walked while wearing a cuff that induced pain in the thigh. They reached the predetermined pain threshold more quickly in the negative condition than in the positive condition. Comparisons with the neutral condition showed no^clear difference7^{, 4}. This experiment demonstrates a possible influence of mood on induced pain; it does not measure the effect of a treatment on chronic pain.

The DIM/SIM Model

The DIM/SIM educational model helps identify what increases feelings of danger or safety. It is used to discuss your experience:

DIM (Danger In Me): what you associate with a danger to your body.

SIM (Safety In Me): what you associate with a sense of safety.

This model helps identify concerns, sources of support, and situations that require action. It does not allow you to calculate pain by subtracting risk indicators from safety indicators. Feeling safer can be helpful, but it does not guarantee a reduction in pain.

Factors to explore may include:

• The body: inflammation, fatigue, or poor sleep.
• Emotions and thoughts: fear, stress, or anxiety about movement.
• Social life: conflicts, isolation, or uncertainty at work.

Downward Modulation: Can Your Brain Adjust the Intensity of Pain?

Your brain can increase or decrease the processing of nociceptive signals through circuits that extend down to the spinal cord. This descending modulation can alter the pain you feel.

Your brain can increase or decrease pain

Downward modulation refers to the effect of brain circuits on the processing of signals in the spinal cord. Some circuits inhibit this processing, while others amplify it⁸.

The nervous system can reduce the processing of nociceptive signals. Opioid substances produced by the body, including endorphins, play a role in some of these mechanisms. Intense stress can sometimes temporarily reduce pain, a phenomenon known as stress-induced analgesia; this effect varies depending on the situation and the individual⁹.
A historical example also shows that pain and injury are not proportional. In Beecher’s observations of 215 seriously wounded soldiers, some reported little or no pain after arriving at the hospital. This observation does not prove a single mechanism of stress or safety.

Other descending pathways can amplify the processing of nociceptive signals. The context and the state of the nervous system influence this modulation; it does not depend solely on a perceived threat⁸.

The Pain Gate

The gate control theory compares the pathways in the spinal cord to a gate that modulates the transmission of nociceptive signals. This gate is a metaphor, not an actual structure that opens. Processing depends, in particular, on:

• Messages from the brain, via descending modulation.
• Other sensations in the same area: this helps explain why gently rubbing a painful area sometimes provides relief.
• On the Condition of the Circuits of the Nervous System.

The gate control theory has transformed our understanding of pain. Subsequent research has clarified and corrected certain details of its pathways; this model alone does not account for all pain¹⁰.

Awareness: What happens when the system becomes too reactive?

Sensitization increases the response of nerve cells to stimuli. The same stimulus can then trigger a stronger reaction, and certain touches that are usually painless may become painful.

A sensitivity that can change

Stimulation can affect nerve endings in the tissues or in the circuits of the spinal cord and brain. After certain types of stimulation, the cells’ response may remain heightened. Experiments also describe reversible changes⁵. For a person with persistent pain, however, the course of the condition depends on several factors.

Peripheral Sensitization

At the tissue level, peripheral sensitization can make nociceptors more responsive¹¹ :

• Nociceptors can be activated by less intense stimulation.
• Nociceptors may respond more strongly to the same stimulus.
• Some fibers can generate signals spontaneously, without further stimulation.

Hyperalgesia is an increased pain response to a stimulus that is normally painful.Allodynia is pain caused by a stimulus that is usually painless, such as light touch⁶. These signs may accompany sensitization, but they do not, on their own, establish its cause.

Central sensitization

Central sensitization increases the response of circuits in the spinal cord or brain. Several changes may contribute to this:

• Bone marrow cells may respond more strongly to the signals they receive.
• Some mechanisms that slow down messages may become less effective.
• Descending pathways can further amplify the messages.
• Certain regions of the brain can alter their response to incoming information.

These changes can increase and prolong the response of nerve cells. They do not all manifest in the same way in every^{person5, 11}.

The body, emotions, and social life can influence persistent pain. Long-term stress, intense anxiety about the pain, or social isolation can all play a role in a person’s experience of pain¹¹. This does not mean that each factor, on its own, causes central sensitization.

Neuroplasticity: How Can Your Nervous System Change?

Neuroplasticity allows the nervous system to change its connections and responses as a result of experience. These changes can contribute to increased sensitivity, but also to recovery.

Your brain can change

Neuroplasticity refers to the nervous system’s capacity for change. To say that the system “learns” or “unlearns” pain is a metaphor. It does not mean that you have deliberately learned to feel pain.

Some changes in sensitivity are reversible in experiments⁵. In clinical settings, exercise, education, and support for managing stress can help patients resume their activities. However, improvement does not prove that a specific brain mechanism has been reversed.

What approaches can help people cope better with pain?

Graduated exposure involves gradually performing, in appropriate steps, movements that you fear or avoid. This approach, used in physical therapy, aims to reduce fear and make activities easier¹². Pain education combined with exercise can also help in the short term¹³. In a trial involving 44 people with chronic lower back pain, graded exposure reduced several fears more effectively than graded activity or a wait-and-see approach. The benefit regarding functional limitations remained unclear. The steps are chosen based on your situation and abilities.

Pain education, combined with exercise, can help some people with persistent musculoskeletal pain—that is, pain related to muscles, joints, or nearby structures. A review included five trials involving 460 people. It reported an additional average reduction of 2.09 out of 10 compared with exercise alone over the first 12 weeks¹³. The certainty of this finding is low. Two trials also included longer follow-up periods, but their results were not included in this calculation.

Long-term stress can affect pain¹¹. Calm breathing, relaxation, and appropriate physical activity are possible ways to manage this stress; however, they do not guarantee that the pain will go away. In a trial involving 342 adults with chronic lower back pain, a program combining meditation and yoga, along with cognitive-behavioral therapy, resulted in greater improvements in pain-related discomfort and functional limitations at 26 weeks compared to standard care. These programs combined several elements; their results do not demonstrate the effect of breathing techniques alone.

Sleep and pain can influence each other. A review of studies that tracked participants over time links sleep problems to an increased risk of persistent pain. It also links pain to short-term sleep problems; however, the long-term implications of this relationship remain unclear¹⁴. It is important to prioritize sleep, without concluding that it alone explains pain.

What does this mean for you?

Understanding the nervous system helps you recognize that your pain is real and choose treatments that are appropriate for your body, your activities, and your situation. This understanding does not make the pain a choice.

Pain is always real

Tissue damage, nerve damage, or changes in how signals are processed can contribute to pain. Several mechanisms may occur simultaneously. In all these cases, the pain is real. The brain’s role does not mean that the pain is imaginary.

In some people, changes in nerve processing can sustain pain even when tissue or nerve damage is insufficient to explain it. This is referred to as nociplastic mechanisms. The brain, the spinal cord, and factors originating from the rest of the body can contribute to this⁴.

Opportunities for Improvement

Therapy can help you make progress in several areas:

• An injury or visible changes in the tissues alone do not determine how much pain you will experience in the future.
• Your sensitivity and abilities may change.
• Appropriate exercise, support for your concerns, stress management, and sleep are areas you can work on with your healthcare team.

An approach that takes your entire situation into account

Physical therapy for chronic pain may combine education, progressive exercise, and attention to concerns, stress, and social life. The treatment plan takes into account your tissues, the nervous system, and your goals.

What should we take away from this?

Pain is a real experience that depends on the body and the nervous system’s processing of signals. It does not directly measure tissue damage and is not the result of a conscious choice.

• Nociception is a neural response to potentially harmful stimuli; it is not the same as the pain that is felt.
• The brain integrates signals from the body, context, and experiences. The DIM/SIM model helps us discuss danger and safety without factoring in pain.
• Downward modulation can increase or decrease the processing of messages and influence pain.
• Raising awareness can make the system more responsive. Some changes may be reversed, though there is no guarantee for every individual.
• Neuroplasticity allows the nervous system to change. Appropriate care can improve quality of life and enable people to engage in activities.

Pain that persists after an injury can still improve. A tailored plan can help you move, resume activities, and better manage your pain. Progress varies from person to person.

Pain that persists or recurs for more than three months is considered chronic. It may be a condition in its own right or may accompany another^{condition15, 6}. This distinction helps guide the evaluation and care.

Additional Resources

These resources explain chronic pain, how it differs from acute pain, the role of emotions, ways to manage it, and nerve-related pain.

• Understanding Chronic Pain: A Complete Guide
• Acute pain vs. chronic pain
• The Psychology of Pain
• Pain Management Strategies
• Neuropathic pain

References

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