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Updated: Jul 6, 2026

Using Facial Electromyography to Assess Facial Muscle Reactions to Experienced and Observed Affective Touch in Humans
Published on: March 15, 2019
Unmyelinated tactile afferents have opposite effects on insular and somatosensory cortical processing
Håkan W Olausson1, Jonathan Cole, Ake Vallbo
1Department of Clinical Neurophysiology, Sahlgrenska University Hospital, Blå stråket 7, S-41345 Gothenburg, Sweden. olausson@physiol.gu.se
Abstract:
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.
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