MASSAG model: Towards an integrative neuroscience framework linking emotional trauma, pain, and mechanisms of force-based manipulations.

The frequent comorbidity of chronic pain, affective disorders, and trauma histories suggests shared mechanisms, and opportunities for interventions that target their overlap. Force-based manipulations (FBMs) of the soft tissues such as massage and fascial manipulation are especially relevant given their dual impact on sensory and affective mechanisms. This paper synthesizes current evidence on the distributed somatosensory effects of emotional trauma, evaluating how trauma and stress reshape neural, immune, and connective tissue functions, altering sensory perception and pain processing. By elucidating known as well as plausible mechanisms, we aim to provide a foundation for advancing research on how FBMs of the soft tissues may counter stress and trauma-related alterations in the somatosensory system. We then propose the MASSAG (Mechanisms of Affective Somatosensory Soothing for Allostatic Gain) model, which is intended to provide a framework for understanding the therapeutic benefit of manual therapies and to guide future research in this field. This integrative framework conceptualizes how manipulation of the soft tissues engage both sensory-afferent and cognitive-affective pathways ideally situated to reshape predictive models of somatosensory experience and counter the long-term effects of trauma and pain.