Unmyelinated tactile afferents have opposite effects on insular and somatosensory cortical processing.
A previous functional magnetic resonance imaging (fMRI) study of an A-beta deafferented subject (GL) showed that stimulation of tactile C afferents (CT) activates insular cortex whereas no activation was seen in somatosensory cortices. Psychophysical studies suggested that CT afferents contribute to affective but not to discriminative aspects of tactile stimulation. We have now examined cortical processing following CT stimulation in a second similarly deafferented subject (IW), as well as revisited the data from GL. The results in IW showed similar activation of posterior insular cortex following CT stimulation as in GL and so strengthen the view that CT afferents underpin emotional aspects of touch. In addition, CT stimulation evoked significant fMRI deactivation in somatosensory cortex in both subjects supporting the notion that CT is not a system for discriminative touch.
Olausson
Håkan W
HW
Department of Clinical Neurophysiology, Sahlgrenska University Hospital, Blå stråket 7, S-41345 Gothenburg, Sweden. olausson@physiol.gu.se
Cole
Jonathan
J
Vallbo
Ake
A
McGlone
Francis
F
Elam
Mikael
M
Krämer
Heidrun H
HH
Rylander
Karin
K
Wessberg
Johan
J
Bushnell
M Catherine
MC
D000344:Afferent Pathways / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000502:physiology*; D004644:Emotions / Q000502:physiology; D005260:Female; D006179:Gyrus Cinguli / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010812:Physical Stimulation / Q000379:methods; D011601:Psychophysics; D013003:Somatosensory Cortex
D010100:Oxygen