There is dual tactile innervation of the human hairy skin: in addition to fast-conducting myelinated afferent fibers, there is a system of slow-conducting unmyelinated (C) afferents that respond to light touch. In a unique patient lacking large myelinated afferents, we found that activation of C tactile (CT) afferents produced a faint sensation of pleasant touch. Functional magnetic resonance imaging (fMRI) analysis during CT stimulation showed activation of the insular region, but not of somatosensory areas S1 and S2. These findings identify CT as a system for limbic touch that may underlie emotional, hormonal and affiliative responses to caress-like, skin-to-skin contact between individuals.
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http://dx.doi.org/10.1038/nn896 | DOI Listing |
J Physiol
January 2025
School of Life Sciences, The University of Nottingham, Queen's Medical Centre, Nottingham, UK.
C-low threshold mechanoreceptors (C-LTMRs) in animals (termed C-tactile (CT) fibres in humans) are a subgroup of C-fibre primary afferents, which innervate hairy skin and respond to low-threshold punctate indentations and brush stimuli. These afferents respond to gentle touch stimuli and are implicated in mediating pleasant/affective touch. These afferents have traditionally been studied using low-throughput, technically challenging approaches, including microneurography in humans and teased fibre electrophysiology in other mammals.
View Article and Find Full Text PDFNeuroscience
January 2025
Department of Orofacial Pain and Jaw Function, Malmö University, Malmö, Sweden; Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark; Scandinavian Center for Orofacial Neurosciences (SCON), Malmö, Sweden.
Occlusal tactile acuity (OTA) and bite force are essential components of the sensorimotor control of oral behaviors. While these variables have been studied independently, it has not yet been revealed whether compressive force impacts the occlusal perception mediated by the mechanoreceptive afferents in the periodontal ligament. The present study examined the effect of repetition and maximum bite force on OTA by testing nine aluminum foils of different thicknesses together with a sham test with no foil, three times each, in randomized order in 36 healthy individuals.
View Article and Find Full Text PDFJ Integr Neurosci
December 2024
IRCCS Centro Neurolesi Bonino-Pulejo, 98124 Messina, Italy.
The evidence on how touch-based therapy acts on the brain activity opens novel cues for the treatment of chronic pain conditions for which no definitive treatment exists. Touch-based therapies, particularly those involving C-tactile (CT)-optimal touch, have gained increasing attention for their potential in modulating pain perception and improving psychological well-being. While previous studies have focused on the biomechanical effects of manual therapy, recent research has shifted towards understanding the neurophysiological mechanisms underlying these interventions.
View Article and Find Full Text PDFArthritis Res Ther
December 2024
Department of Medicine, University of California, 9500 Gilman Dr. MC 0663, La Jolla, San Diego, CA, USA.
Background: In the murine K/BxN serum transfer rheumatoid arthritis (RA) model, tactile allodynia persists after resolution of inflammation in male and partially in female wild type (WT) mice, which is absent in Toll-like receptor (TLR)4 deficient animals. We assessed the role of TLR4 on allodynia, bone remodeling and afferent sprouting in this model of arthritis.
Methods: K/BxN sera were injected into male and female mice with conditional or stable TLR4 deletion and controls.
Curr Biol
December 2024
Department of Integrative Biology and Physiology, Brain Research Institute, University of California, Los Angeles, CA 90024, USA. Electronic address:
Many young mammals exhibit a characteristic 'transport response' upon being picked up by their mother. New research reveals the specific tactile mechanisms and afferents underlying this critical early-life response in rat pups.
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