Neuroplasticity

LEARNING AND NEUROPLASTICITY

 

The brain naturally adapts its structure and function over time in response to changes in the body and environment, a phenomenon known as neuroplasticity. This has profound implications for patients suffering from chronic pain.

Our and other's previous research has found that pain is strongly influenced by psychological context such as expectancy, and that these effects are likely mediated by activity in the cerebral cortex of the brain. We are now investigating new ways of better measuring these mechanisms, to develop clinical tests and improve treatments.

 

Current projects

Biomarkers of cortical plasticity in chronic pain

Patients who suffer a particularly puzzling type of chronic pain called Complex Regional Pain Syndrome (CRPS) have been found to undergo changes in brain structure and function that are thought to contribute to pain symptoms. Some of these changes might involve brain mechanisms involved in making decisions about body sensations and translating those decisions in actions. Other changes might involve the areas of the brain that map the body representation of the affected limb. Along with colleagues at the University of Cambridge and the University of the West of England we are working on identifying better biomarkers of these changes using convenient and cheap EEG technology.

 

Can mathematical models explain brain changes that make pain worse?

Recent theories of how the brain learns from, and adapts to, sensory experiences (such as pain) offer a way of investigating the mechanisms of neuroplasticity affecting patients with chronic pain. The theories (summarised here) are based on the concept that the brain is constantly learning to better predict sensations such as pain, and that these predictions have an influence on the perception of pain. It is thought that these mechanisms could potentially cause long-lasting changes in the brain that make chronic pain worse. These theories can be tested using mathematical models that describe the mechanisms by which predictions change the perception of pain over time. In a collaborative project funded by Arthritis Research UK and involving colleagues at the University of Liverpool, University of Manchester, and the Walton Centre, we are currently investigating how plausible these mathematical methods are for understanding brain changes related to chronic pain and differences between patients in how they process pain.

 

Understanding pain catastrophising as a learnt state of belief.

Catastrophically negative thoughts about how bad pain is, or about one’s ability to cope, are supported by brain’s learning and memory systems. Such beliefs are learnt, supported or challenged over the course of a lifetime. This critical learning process can be measured, and may provide insight into the brain mechanisms supporting psychological distress and pain. We think that there may be biases in these learning processes in people who are the most vulnerable to developing chronic pain, biases which may have psychological, social or neurochemical/genetic origins. To better understand this, at the University of Liverpool we are developing methods (using laboratory-based and online tests) for studying the learning processes of “belief-updating”. Such tests may provide a novel clinical screening tool that can be used to identify people who are at risk of long-term poor outcomes from chronic pain.

 

Can learning-by-association actually make pain worse?

The brain changes its function by strengthening or weakening connections between neurons in response to sensory experiences, including those of pain. This neuroplasticity enables people to learn to get better at certain sensory tasks (“perceptual learning”), such as discriminating the difference between a painful and a non-painful feeling in the body that might indicate “bad” and “good” health respectively. Unfortunately, patients with chronic pain are often less able to make these discriminations. We are still investigating why this happens, but one hypothesis is to do with another type of learning, namely "associative" learning in which people learn to predict when pain will happen based on environmental cues. Associative learning might make people more efficient at recognising potential threats to their health, but when this learning is negatively biased (e.g. as we think underlies pain catastrophising), this could be detrimental for the person’s ability to accurately recognise and adaptively respond to changes in their state of health. To understand this better, at the University of Liverpool we are investigating whether negative biases in learning-by-association make it more difficult for people to accurately tell apart painful from non-painful sensations. If so, new treatments may be most effective if they target both types of learning process (perceptual and associative) simultaneously.

CHRISTOPHER BROWN

 

Brain mechanisms of human pain perception and behaviour

Institutional Links

Prospective collaborators and PhDs

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