Selective Nerve Block of A- or C-Afferents Confirms Dual Role in Touch Pleasantness but Not Touch-Pain Modulation

Authors

Albinni, B., Crankshaw, L. N., Jones, E., Alasha, V., Zimmerman, M., Schuster, N., Said, E., Strigo, I., Case, L. K.

Abstract

Gentle and deep pressure are distinct types of touch that often elicit pleasant sensations and modulate pain. Although touch pleasantness has traditionally been attributed to unmyelinated C-tactile afferents, growing evidence suggests an important contribution of myelinated A-fibers. However, the relative role of A- and C-fibers in touch-evoked pleasantness and pain modulation remains unclear. To test the role of A- and C-fibers in touch pleasantness, healthy adults underwent selective peripheral nerve block of the superficial radial nerve to preferentially impair either A- or C-fiber function. Touch pleasantness of brushing (Study 1; N = 24) or deep pressure (Study 2; N = 24) and touch-induced modulation of heat pain were assessed before and after the nerve block. Both nerve blocks significantly reduced the perceived pleasantness of both gentle brushing and deep pressure, supporting a substantial contribution of myelinated A-fibers and well as unmyelinated C-fibers (presumably C-tactile fibers) to affective touch. In addition, block of A-fibers did not diminish touch-induced modulation of experimental heat pain, suggesting a particular pain-inhibiting role for C-tactile fibers. These findings supply causal evidence in healthy adults that myelinated A-fibers are highly involved in touch pleasantness-alongside C-tactile fibers-but are not involved in touch-induced pain relief.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 16 Oct 2026.

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