title: The perception of affective touch in Parkinson's disease and its relation to small fibre neuropathy.
abstract: Affective touch sensation is conducted by a sub-class of C-fibres in hairy skin known as C-Tactile (CT) afferents. CT afferents respond maximally to gentle skin stroking at velocities between 1 and 10 cm/s. Parkinson's disease (PD) is characterised by markedly reduced cutaneous C-fibres. It is not known if affective touch perception is influenced by C-fibre density and if affective touch is impaired in PD compared to healthy controls. We predicted that perceived pleasantness to gentle stroking in PD would correlate with C-afferent density and that affective touch perception would be impaired in PD compared to healthy controls. Twenty-four PD patients and 27 control subjects rated the pleasantness of brush stroking at an optimum CT stimulation velocity (3 cm/s) and two sub-optimal velocities (0.3 and 30 cm/s). PD patients underwent quantification of C-fibre density using skin biopsies and corneal confocal microscopy. All participants rated a stroking velocity of 3 cm/s as the most pleasant with significantly lower ratings for 0.3 and 30 cm/s. There was a significant positive correlation between C-fibre density and pleasantness ratings at 3 and 30 cm/s but not 0.3 cm/s. Mean pleasantness ratings were consistently higher in PD patients compared to control subjects across all three velocities. This study shows that perceived pleasantness to gentle touch correlates significantly with C-fibre density in PD. The higher perceived pleasantness in PD patients compared to controls suggests central sensitisation to peripheral inputs, which may have been enhanced by dopamine therapy.
authors.affiliation: Greater Manchester Neuroscience Centre, Department of Neurology, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.|Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK.
authors.forename: Lewis
authors.initials: L
authors.lastname: Kass-Iliyya
authors.affiliation: Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Leung
authors.affiliation: Greater Manchester Neuroscience Centre, Department of Neurology, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.|Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK.|School of Natural Science & Psychology, Liverpool John Moores University, Liverpool, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Marshall
authors.affiliation: School of Natural Science & Psychology, Liverpool John Moores University, Liverpool, UK.
authors.forename: Paula
authors.initials: P
authors.lastname: Trotter
authors.affiliation: Greater Manchester Neuroscience Centre, Department of Neurology, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.|Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Kobylecki
authors.affiliation: School of Natural Science & Psychology, Liverpool John Moores University, Liverpool, UK.
authors.forename: Susannah
authors.initials: S
authors.lastname: Walker
authors.affiliation: Greater Manchester Neuroscience Centre, Department of Neurology, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.
authors.forename: David
authors.initials: D
authors.lastname: Gosal
authors.affiliation: Institute of Human Development, University of Manchester, Manchester, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Jeziorska
authors.affiliation: Institute of Human Development, University of Manchester, Manchester, UK.
authors.forename: Rayaz A
authors.initials: RA
authors.lastname: Malik
authors.affiliation: School of Natural Science & Psychology, Liverpool John Moores University, Liverpool, UK.
authors.forename: Francis
authors.initials: F
authors.lastname: McGlone
authors.affiliation: Greater Manchester Neuroscience Centre, Department of Neurology, Salford Royal NHS Foundation Trust, Stott Lane, Salford, M6 8HD, UK.|Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, UK.
authors.forename: Monty A
authors.initials: MA
authors.lastname: Silverdale
mesh_terms: D004644:Emotions / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology*; D010812:Physical Stimulation / Q000379:methods; D012867:Skin / Q000294:innervation; D000071075:Small Fiber Neuropathy / Q000503:physiopathology*; D014110:Touch / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*
keywords: C-tactile afferent; cornea; hedonic; pain; skin