Unmyelinated tactile afferents signal touch and project to insular cortex.
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.
Olausson
H
H
Department of Clinical Neurophysiology, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden. olausson@physiol.gu.se
Lamarre
Y
Y
Backlund
H
H
Morin
C
C
Wallin
B G
BG
Starck
G
G
Ekholm
S
S
Strigo
I
I
Worsley
K
K
Vallbo
A B
AB
Bushnell
M C
MC
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology; D010812:Physical Stimulation; D012867:Skin / Q000294:innervation*; D013003:Somatosensory Cortex / Q000502:physiology; D014110:Touch / Q000502:physiology*