Research in the Martin Lab
A fundamental problem in pain research is the lack of translation between animal models and human subjects or patients. This problem is compounded further by not taking into account factors that modulate pain such as environmental variables and social influences. Research in the Martin lab attempts to overcome these translational barriers through experiments with animal and human subjects, while also analyzing biological samples from both species. Specifically, we use animal models to probe the influences of cognitive and social factors on pain modulation, while developing novel translational models to provide proof-of-importance for human pain modulation. Research in the lab is grouped under 3 themes:
Theme 1: The effect of chronic pain on shaping brain circuits
It has been suggested that chronic pain may be a manifestation of a breakdown within the brain’s emotional circuitry and therapies that alter these circuits may be effective treatment options for chronic pain. This line of inquiry aims to highlight the importance of chronic pain in shaping brain circuits and determine the impact that these changes have on behaviour. We are primarily interested in the “top-down” modulatory circuits that profoundly change the sensory and emotional aspects of pain. Our data and the data of others suggest that chronic pain enhances neuronal excitability within distinct neural networks and resultant behavioral modifications are dependent upon where in the brain these changes occur.
Theme 2: The bidirectional interaction between pain and social factors
Social groups are quite important for pain outcomes and robustly affect pain levels in chronic pain patients. Direct effects of varying social context on laboratory pain sensitivity have been demonstrated and it is of considerable surprise to many that social context and interactions affect pain sensitivity in laboratory animals. The converse is also true: the presence of pain can affect the social interactions of laboratory animals, acting as a useful stimulus in social neuroscience studies. In fact, pain can serve a social communication function, operating as a distinct social cue. We have shown using a translational approach, that elevated stress hormones impair the social communication of pain in both mice and healthy human volunteers, and that blockade of the stress-axis can facilitate social bonding. Our recent work aims to dissect the neural circuits that are important for the self-other distinction and to determine whether these circuits modulate pain empathy, social approach to pain and social analgesia.
Theme 3: Learning-related modulation of pain processing
It has been shown that the cognitive factors that modulate pain are so influential that they regulate the therapeutic response to analgesic drugs and the pain experience itself. In particular, an important cognitive factor that is known to modify pain is the expectation of impending pain. Typically the ability to predict the likelihood of pain or other unpleasant events by learning from prior experience is an important adaptive behavior in healthy organisms and can cause disabling fear, avoidance, and stress in patients with persistent pain states. Contrary to this, we also have the ability to learn about pain relief and these expectations are what drives placebo responding. This line of research uses classical conditioning approaches to understand the learning mechanisms associated with the development of pain hypersensitivity and pain relief.