C-low threshold mechanoreceptors: a novel target for health-tech in an increasingly touch-deprived world.

This article describes the putative role of a population of unmyelinated cutaneous nerves that respond optimally to a caressing touch. Massaging touch is of course 'digital', dating back to its use by ancient civilizations for its therapeutic properties, where it was found to promote healing, relieve pain, reduce stress and improve overall well-being. What was then non-verifiable 'alternative medicine' is now verifiable 'touch medicine' with the discovery of a population of cutaneous mechanosensitive c-low threshold mechanoreceptors (C-LTMRs) that preferentially encode gentle dynamic touch, projecting centrally to dorsal posterior insular cortex. They are understood to provide a singular vital protective function across the lifespan, from the nurturing touch of the mother to end-of-life palliative care. Early life touch deprivation causes lifelong adverse neurodevelopmental consequences, with recent evidence finding a potential neuroregenerative and neuroprotective role for C-LTMR stimulation in dementia, brain damage, stress resilience and schizophrenia. By analogy with the vital role vitamins play in physical health, affective touch and its neuronal substrate, the C-LTMRs, can be described as 'vitamin-T' for neurological health. A case is made here for their therapeutic influence in functional neurological disorders. This article is part of the discussion meeting issue 'Digital healthcare for the management of functional neurological disorders'.