J Neurophysiol (March 1, 2003). 10.1152/jn.00256.2002
Submitted on Submitted 8 April 2002; accepted in final form 23 October 2002

Receptive Field Properties of Unmyelinated Tactile Afferents in the Human Skin

 ¹Department of Physiology, Göteborg University, SE-40530 Göteborg; and  ²Department of Clinical Neurophysiology, Sahlgrenska University Hospital, SE-41345 Göteborg, Sweden

Wessberg, Johan, Håkan Olausson, Katarina Wiklund Fernström, and Åke B. Vallbo. Receptive Field Properties of Unmyelinated Tactile Afferents in the Human Skin. J. Neurophysiol. 89: 1567-1575, 2003. We recorded, with the microneurography technique, single-unit impulses from nine cutaneous mechanoreceptive afferents with conduction velocities in the C range and receptive fields in the hairy skin of the forearm. The units responded with high impulse rates to light touch and had low monofilament thresholds. The geography of receptive fields was explored with a scanning method: a lightweight probe with a small and rounded tip was made to scan the field area in a series of closely adjacent tracks while single-unit activity was recorded. The fields of the nine units varied considerably in size as well as complexity. The individual field consisted of one to nine small responsive spots distributed over an area of 1-35 mm² when explored with a moving indentation of 5 mN. The fields were roughly round or oval in shape with no preferred orientation. The size of the response differed between individual sensitive spots in a field, suggesting a highly nonuniform terminal organization. The properties of the fields seem consistent with a role of tactile C afferents to provide information about pleasant touch and skin-to-skin contacts to central structures controlling emotions and affiliative behavior.