Slow Touch and Fast Nociception: Exploration of the Interactions Between Noxious and Innocuous Mechanical Touch Sensation

Human cutaneous somatosensation is a multimodal physiological process by which physical stimuli on the body surface activate neural substrates that consequently give rise to perceptions such as pressure/vibration, temperature, itch, and pain. When considering skin mechanosensation, the canonical view is that low force innocuous mechanical stimuli are encoded by cutaneous low threshold mechanosensitive receptor (LTMR) endings, innervated by fast conducting, thickly myelinated Aβ afferent nerves (Mountcastle, 2005). In contrast, higher force, potentially tissue damaging, mechanical stimuli are, according to this view, encoded by high threshold mechanosensitive receptor (HTMR) endings that receive innervation from slowly conducting thinly myelinated Aδ or unmyelinated C afferent fibres. The discovery of a system of LTMR afferents that are C-fibres has challenged this view and led to the recognition of a second ‘slow’ touch pathway, a pathway that has an affective rather than discriminative function (McGlone, Wessberg and Olausson, 2014). Conversely, the recent suggestion that fast-conducting afferent fibres innervating a type of ending previously considered to be an LTMR actually have nociceptive properties in rodents (Bai et al., 2015) has focussed attention on putative Aβ ‘fast’ nociceptive pathways. The work in this thesis investigates the neural basis for ‘slow’ touch and ‘fast pain’ in the human cutaneous somatosensory system concentrating first in the peripheral nervous system before addressing spinal pathways and higher-level consequences of a pathological lack of specific afferent fibre types. The thesis closes with an assessment of alterations in the perception of tactile sensation in a human model of allodynia.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Liverpool John Moores University

Year dc:date.issued

2019

Author dc:creator

• Marshall, A

Contributors dc:contributor

• McGlone, F
• Olausson, H
• Moore, D

• BF Psychology
• QM Human anatomy
• RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry

DOI dc:identifier.doi

https://doi.org/10.24377/LJMU.t.00010262

OAI identifier oai:identifier

oai:researchonline.ljmu.ac.uk:10262