Interaction between acoustic startle and habituated neck postural responses in seated subjects

Blouin, Jean-Sébastien, Siegmund, Gunter P. and Inglis, J. Timothy (2007) Interaction between acoustic startle and habituated neck postural responses in seated subjects. Journal of Applied Physiology, 102 4: 1574-1586. doi:10.1152/japplphysiol.00703.2006

Author Blouin, Jean-Sébastien
Siegmund, Gunter P.
Inglis, J. Timothy
Title Interaction between acoustic startle and habituated neck postural responses in seated subjects
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 1522-1601
Publication date 2007-04
Sub-type Article (original research)
DOI 10.1152/japplphysiol.00703.2006
Volume 102
Issue 4
Start page 1574
End page 1586
Total pages 13
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Language eng
Subject 1109 Neurosciences
Formatted abstract
Postural and startle responses rapidly habituate with repeated exposures to the same stimulus, and the first exposure to a seated forward acceleration elicits a startle response in the neck muscles. Our goal was to examine how the acoustic startle response is integrated with the habituated neck postural response elicited by forward accelerations of seated subjects. In experiment 1, 14 subjects underwent 11 sequential forward accelerations followed by 5 additional sled accelerations combined with a startling tone (124-dB sound pressure level) initiated 18 ms after sled acceleration onset. During the acceleration-only trials, changes consistent with habituation occurred in the root-mean-square amplitude of the neck muscles and in the peak amplitude of five head and torso kinematic variables. The subsequent addition of the startling tone restored the amplitude of the neck muscles and four of the five kinematic variables but shortened onset of muscle activity by 9–12 ms. These shortened onset times were further explored in experiment 2, wherein 16 subjects underwent 11 acceleration-only trials followed by 15 combined acceleration-tone trials with interstimulus delays of 0, 13, 18, 23, and 28 ms. Onset times shortened further for the 0- and 13-ms delays but did not lengthen for the 23- and 28-ms delays. These temporal and spatial changes in EMG can be explained by a summation of the excitatory drive converging at or before the neck muscle motoneurons. The present observations suggest that habituation to repeated sled accelerations involves extinguishing the startle response and tuning the postural response to the whole body disturbance.
Keyword Posture
Neck muscle reflexes
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Health and Rehabilitation Sciences Publications
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