Somatosensory gating is dependent on the rate of force recruitment in the human orofacial system.
OBJECTIVE
Functional orofacial behaviors vary in their force endpoint and rate of recruitment. This study assessed the gating of orofacial cutaneous somatosensation during different cyclic lip force recruitment rates. Understanding how differences in the rate of force recruitment influences trigeminal system function is an important step toward furthering the knowledge of orofacial sensorimotor control.


METHODS
Lower lip vibrotactile detection thresholds (LL-VDTs) were sampled in response to sinusoidal inputs delivered to the lip vermilion at 5, 10, 50, and 150 Hz while adult participants engaged in a baseline condition (no force), 2 low-level lip force recruitment tasks differing by rate (0.1 Hz or 2 Hz), and passive displacement of the lip as a control to approximate the mechanosensory consequences of voluntary movement.


RESULTS
LL-VDTs increased significantly for test frequencies at or below 50 Hz during voluntary lip force recruitment. LL-VDT shifts were positively related to changes in the rate of lip force recruitment, whereas passively imposed displacements of the lip were ineffective in shifting LL-VDTs.


CONCLUSIONS
These findings are considered in relation to published reports of force-related sensory gating in orofacial and limb systems and the potential role of somatosensory gating along the trigeminal system during orofacial behaviors.
Andreatta
Richard D
RD
Department of Rehabilitation Sciences, Divison of Communication Sciences and Disorders, University of Kentucky, 900 South Limestone Street, Wethington 120-F, Lexington, KY 40536, USA. richard.andreatta@uky.edu
Barlow
Steven M
SM
D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008046:Lip / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010812:Physical Stimulation; D011601:Psychophysics; D012684:Sensory Thresholds; D017603:Signal Detection, Psychological; D055698:Touch Perception / Q000502:physiology*; D014732:Vibration; D055815:Young Adult