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| 2. |
- Löken, Line Sofie, 1977, et al.
(författare)
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Coding of pleasant touch by unmyelinated afferents in humans.
- 2009
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Ingår i: Nature neuroscience. - : Springer Science and Business Media LLC. - 1546-1726 .- 1097-6256. ; 12:5, s. 547-8
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Tidskriftsartikel (refereegranskat)abstract
- Pleasant touch sensations may begin with neural coding in the periphery by specific afferents. We found that during soft brush stroking, low-threshold unmyelinated mechanoreceptors (C-tactile), but not myelinated afferents, responded most vigorously at intermediate brushing velocities (1-10 cm s(-1)), which were perceived by subjects as being the most pleasant. Our results indicate that C-tactile afferents constitute a privileged peripheral pathway for pleasant tactile stimulation that is likely to signal affiliative social body contact.
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| 3. |
- McGlone, Francis, et al.
(författare)
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Discriminative touch and emotional touch.
- 2007
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Ingår i: Canadian journal of experimental psychology = Revue canadienne de psychologie expérimentale. - : American Psychological Association (APA). - 1196-1961 .- 1878-7290. ; 61:3, s. 173-83
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Forskningsöversikt (refereegranskat)abstract
- Somatic sensation comprises four main modalities, each relaying tactile, thermal, painful, or pruritic (itch) information to the central nervous system. These input channels can be further classified as subserving a sensory function of spatial and temporal localization, discrimination, and provision of essential information for controlling and guiding exploratory tactile behaviours, and an affective function that is widely recognized as providing the afferent neural input driving the subjective experience of pain, but not so widely recognized as also providing the subjective experience of affiliative or emotional somatic pleasure of touch. The discriminative properties of tactile sensation are mediated by a class of fast-conducting myelinated peripheral nerve fibres--A-beta fibres--whereas the rewarding, emotional properties of touch are hypothesized to be mediated by a class of unmyelinated peripheral nerve fibres--CT afferents (C tactile)--that have biophysical, electrophysiological, neurobiological, and anatomical properties that drive the temporally delayed emotional somatic system. CT afferents have not been found in the glabrous skin of the hand in spite of numerous electrophysiological explorations of this area. Hence, it seems reasonable to conclude that they are lacking in the glabrous skin. A full understanding of the behavioural and affective consequences of the differential innervation of CT afferents awaits a fuller understanding of their function.
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| 4. |
- Olausson, Håkan, 1965, et al.
(författare)
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Functional role of unmyelinated tactile afferents in human hairy skin: sympathetic response and perceptual localization.
- 2008
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Ingår i: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale. - : Springer Science and Business Media LLC. - 1432-1106. ; 184:1, s. 135-40
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Tidskriftsartikel (refereegranskat)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.
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| 5. |
- Olausson, Håkan, 1965, et al.
(författare)
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Unmyelinated tactile afferents have opposite effects on insular and somatosensory cortical processing.
- 2008
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Ingår i: Neuroscience letters. - : Elsevier BV. - 0304-3940. ; 436:2, s. 128-32
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Tidskriftsartikel (refereegranskat)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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