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, Judith; Scott, S. M.; Knowles, C. H.; O'Connell, P. R.; Jones, James F. X.||Permanent link:||http://hdl.handle.net/10197/12665||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 mucosa; Rectum; Somatosensory cortex; Animals; Wistar rats; Equipment design; Physical stimulation; Touch; Somatosensory evoked potentials; Anal; Female; Electrical equipment and supplies; Touch perception; Three-dimensional printing||DOI:||10.1016/j.jneumeth.2015.09.006||Language:||en||Status of Item:||Peer reviewed||ISSN:||0165-0270||This item is made available under a Creative Commons License:||https://creativecommons.org/licenses/by-nc-nd/3.0/ie/|
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