In vivo calcium imaging reveals directional sensitivity of C-low threshold mechanoreceptors

Semizoglou, Evangelia; Lo Re, Laure; Middleton, Steven J.; Perez‐Sanchez, Jimena; Tufarelli, Tommaso; Bennett, David L.; Chisholm, Kim I.

Abstract

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. Here we suggest a new approach to studying genetically labelled C-LTMRs using in vivo calcium imaging. We used an automated rotating brush stimulus and von Frey filaments, applied to the hairy skin of anaesthetized mice to mirror light and affective touch. Simultaneously we visualized changes in C-LTMR activity and confirmed that these neurons are sensitive to low-threshold punctate mechanical stimuli and brush stimuli with a strong preference for slow brushing speeds. We also reveal that C-LMTRs are directionally sensitive, showing more activity when brushed against the natural orientation of the hair. We present in vivo calcium imaging of genetically labelled C-LTMRs as a useful approach that can reveal new aspects of C-LTMR physiology.

Citation

Semizoglou, E., Lo Re, L., Middleton, S. J., Perez‐Sanchez, J., Tufarelli, T., Bennett, D. L., & Chisholm, K. I. (2025). In vivo calcium imaging reveals directional sensitivity of C-low threshold mechanoreceptors. Journal of Physiology, https://doi.org/10.1113/jp286631

• Journal Article Type: Article
• Acceptance Date: Nov 28, 2024
• Online Publication Date: Jan 15, 2025
• Publication Date: Jan 15, 2025
• Deposit Date: Jan 17, 2025
• Publicly Available Date: Jan 21, 2025
• Journal: Journal of Physiology
• Print ISSN: 0022-3751
• Electronic ISSN: 1469-7793
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1113/jp286631
• Public URL: https://nottingham-repository.worktribe.com/output/44234225
• Publisher URL: https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP286631