Neuroimaging mechanisms in pain: from discovery to translation
Here, I will describe neuroimaging studies that have largely focussed on identifying mechanisms relevant to translation—to the clinic, industry, or other areas of society where pain is highly relevant.
Figure 1A describes an approach to “forward” translational science involving neuroimaging. A mechanism is identified as relevant or interesting in a preclinical model, verified in humans—sometimes in an experimental medicine model of core symptoms—and then ultimately verified in the patient or translated as a biomarker for monitoring or targeting in a patient, or use in industry. Of course, a “reverse” translational science approach is equally meaningful. A symptom is identified by the bedside in a patient and its underpinning mechanism discovered by investigative studies in experimental medicine models as well as preclinical models. In reality, we go around this loop in a perpetual forward and reverse manner thereby improving our preclinical and experimental models, refining our techniques for exploration, as well as our understanding, with the ultimate goal of improving outcomes. This is translation in practice. It is my view that neuroimaging provides valuable information at the experimental medicine “proof of concept” stage and increasingly at all stages of these forward and reverse translational processes. Indeed, as Figure 1B highlights, sometimes neuroimaging tells you something unexpected about a patient's pain and this can be a powerful driver for new measures to assess their pain as well as provide new targets for intervention. Here, I will provide examples that illustrate the varying ways that neuroimaging can contribute to this “translation in practice.” The principle behind this philosophy being that we will have more confidence in a mechanism if it is identified cross-species and across spatial scales (from cells to networks to patients to populations).