Authors: Richard D Andreatta Steven M Barlow
Publish Date: 2002/12/19
Volume: 149, Issue: 1, Pages: 75-82
Abstract
By virtue of the direct coupling between circumoral skin and the underlying orofacial musculature mechanosensation associated with precise orofacial force control may contribute significantly to processes associated with perception proprioception and sensorimotor control in this region The purpose of this study was to assess lower lip LL vibratory detection thresholds of adult subjects during the simultaneous performance of a visually guided and continuous lip motor control task Vibrotactile inputs were delivered to the right LL vermilion at test frequencies of 5 10 50 150 250 and 300 Hz The psychophysical detection task was performed simultaneously with the three force control conditions a nullforce baseline condition an active force control task performed with the right index finger and an active force control task performed with the lip musculature For the active tasks subjects were instructed to use their analog force signal lip or finger to continuously perform a visually guided precision force task by tracking a 2 Hz sinusoidally moving target calibrated to a peaktopeak force load of 02 N Both the analog force signal and the targettracking signal were displayed in realtime on an oscilloscope Results showed a statistically significant elevation of LL vibrotactile detection thresholds for test frequencies below 50 Hz during the simultaneous performance of the lip force control task Disassociating the site of motor control from the location of sensory stimulation active control task was effective in normalizing the elevations in LL vibrotactile thresholds thus demonstrating that the threshold elevation during the lip force task was not solely an artifact of the added attentional load resulting from combining a perceptual task with a motor control requirement These findings are discussed in relation to published reports of movementrelated sensory gating in limb systems and the possible significance that this phenomenon may have for perception and proprioception in the orofacial systemDeep gratitude is expressed to Dr Donald Finan and Mr Amitava Biswas for their assistance with signal processing routines software development and technical issues Many thanks are also given to Kelly Rosamond for her administrative assistance in preparation of this manuscript This project was supported in part by a grant from the National Institute on Deafness and Other Communication Disorders National Institutes of Health USA R01 DC0036508 and by NeuroLogic Incorporated Lawrence KS USA
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