title: Functional role of unmyelinated tactile afferents in human hairy skin: sympathetic response and perceptual localization.
abstract: In addition to A-beta fibres the human hairy skin has unmyelinated (C) fibres responsive to light touch. Previous functional magnetic resonance imaging (fMRI) studies in a subject with a neuronopathy who specifically lacks A-beta afferents indicated that tactile C afferents (CT) activate insular cortex, whereas no response was seen in somatosensory areas 1 and 2. Psychophysical tests suggested that CT afferents give rise to an inconsistent perception of weak and pleasant touch. By examining two neuronopathy subjects as well as control subjects we have now demonstrated that CT stimulation can elicit a sympathetic skin response. Further, the neuronopathy subjects' ability to localize stimuli which activate CT afferents was very poor but above chance level. The findings support the interpretation that the CT system is well suited to underpin affective rather than discriminative functions of tactile sensations.
authors.affiliation: Department of Clinical Neurophysiology, Sahlgrenska University Hospital, Blå stråket 7, 413 45, Göteborg, Sweden. olausson@physiol.gu.se
authors.forename: Håkan
authors.initials: H
authors.lastname: Olausson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cole
authors.forename: Karin
authors.initials: K
authors.lastname: Rylander
authors.forename: Francis
authors.initials: F
authors.lastname: McGlone
authors.forename: Yves
authors.initials: Y
authors.lastname: Lamarre
authors.forename: B Gunnar
authors.initials: BG
authors.lastname: Wallin
authors.forename: Heidrun
authors.initials: H
authors.lastname: Krämer
authors.forename: Johan
authors.initials: J
authors.lastname: Wessberg
authors.forename: Mikael
authors.initials: M
authors.lastname: Elam
authors.forename: M Catherine
authors.initials: MC
authors.lastname: Bushnell
authors.forename: Ake
authors.initials: A
authors.lastname: Vallbo
mesh_terms: D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D005260:Female; D005542:Forearm; D006197:Hair / Q000502:physiology*; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008875:Middle Aged; D009443:Neuritis / Q000503:physiopathology*; D010465:Perception / Q000502:physiology*; D010812:Physical Stimulation; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology; D012867:Skin / Q000503:physiopathology; D012879:Skin Physiological Phenomena; D014110:Touch / Q000502:physiology*