Mechanically evoked cortical potentials: A physiological approach to assessment of anorectal sensory pathways

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Title: Mechanically evoked cortical potentials: A physiological approach to assessment of anorectal sensory pathways
Authors: Carrington, E. V.Evers, JudithScott, S. M.Knowles, C. H.O'Connell, P. R.Jones, James F. X.
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Date: 30-Dec-2015
Online since: 2021-11-19T16:20:32Z
Abstract: Background: Normal defaecation involves activation of anorectal mechanoreceptors responsive to pressure and stretch. The aim of this study was to develop selective anal and rectal mucosal light-touch stimulation suitable for measurement of cortical evoked potentials (EPs) in order to explore the sensory arm of these pathways. New method: A novel device was manufactured to deliver selective rectal and/or anal light-touch stimulation using a shielded inter-dental brush mounted on a rotating stepper motor (1 Hz, 1 ms, 15° rotation). Resultant somatosensory EPs recorded with a 32-channel cortical multi-electrode array were compared to those elicited by electrical anorectal stimulation (2 mm anal plug electrode [1 Hz, 1 ms, 10 V]). Results: Eighteen anaesthetized female Wistar rats (body mass 180-250 g) were studied. Electrical and mechanical stimulation provoked similar maximal response amplitudes (electrical anorectal 39.0 μV[SEM 5.5], mechanical anal 42.2 μV[8.1], mechanical rectal 45.8 μV[9.0]). Response latency was longer following mechanical stimulation (electrical anorectal 8.8 ms[0.5], mechanical anal 16.4 ms[1.1], mechanical rectal 18.3 ms[2.5]). The extent of activated sensory cortex was smaller for mechanical stimulation. Sensory inferior rectal nerve activity was greater during anal compared to rectal mechanical in a subgroup of 4 rats. Evoked potentials were reproducible over 40 min in a subgroup of 9 rats. Comparison with existing methods: Cortical EPs are typically recorded in response to non-physiological electrical stimuli. The use of a mechanical stimulus may provide a more localized physiological method of assessment. Conclusions: To the authors' knowledge these are the first selective brush-elicited anal and rectal EPs recorded in animals and provide a physiological approach to testing of anorectal afferent pathways.
Funding Details: Science Foundation Ireland
Funding Details: Bowel Disease Research Foundation
Type of material: Journal Article
Publisher: Elsevier
Journal: Journal of Neuroscience Methods
Volume: 256
Start page: 198
End page: 202
Copyright (published version): 2015 Elsevier
Keywords: Intestinal mucosaRectumSomatosensory cortexAnimalsWistar ratsEquipment designPhysical stimulationTouchSomatosensory evoked potentialsAnalFemaleElectrical equipment and suppliesTouch perceptionThree-dimensional printing
DOI: 10.1016/j.jneumeth.2015.09.006
Language: en
Status of Item: Peer reviewed
ISSN: 0165-0270
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Appears in Collections:Electrical and Electronic Engineering Research Collection
Medicine Research Collection

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