Audiogenic Startle Reflex of Man and Its Relationship to Startle Syndromes

Wilkins, D. E.; Hallett, Mark; Wess, Maximilian

doi:10.1093/brain/109.3.561

Cited by 148 publications

(68 citation statements)

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“…This process of adaptation, called habituation (18), typically consists of attenuated muscle activity and related kinematic changes. Startle responses also habituate rapidly to repeated startling stimuli (2,8,16,17,21,38,44), and the time course of this habituation is similar to that observed after repeated whole body accelerations. On the basis of this similarity, it was first proposed (1,2,29) and more recently shown (5) that the initially elevated, prehabituation muscle response during the first whole body acceleration is in part a startle response.…”

supporting

confidence: 63%

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

Blouin

Siegmund²,

Inglis³

2007

Journal of Applied Physiology

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Blouin JS, Siegmund GP, Inglis JT. Interaction between acoustic startle and habituated neck postural responses in seated subjects. J Appl Physiol 102: 1574 -1586, 2007. First published December 14, 2006; doi:10.1152/japplphysiol.00703.2006.-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. posture; neck muscle reflexes; habituation POSTURAL RESPONSES RAPIDLY adapt with repeated exposures to the same perturbation in standing (2,19,24), seated (3, 34), and supine (2) individuals. This process of adaptation, called habituation (18), typically consists of attenuated muscle activity and related kinematic changes. Startle responses also habituate rapidly to repeated startling stimuli (2,8,16,17,21,38,44), and the time course of this habituation is similar to that observed after repeated whole body accelerations. On the basis of this similarity, it was first proposed (1, 2, 29) and more recently shown (5) that the initially elevated, prehabituation muscle response during the first whole body acceleration is in part a startle response.Startle responses can be evoked by sudden tactile, vestibular, or auditory stimuli (45) but are most often studied using acoustic stimuli. Axial and appendicular muscles respond to acoustic startle (16), but the strongest and most consistent response occurs in the neck muscles, particularly the sternocleidomastoid (SCM) muscle (8). Since consistent neck muscle responses are also evoked by forward accelerations ...

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supporting

confidence: 63%

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

Blouin

Siegmund²,

Inglis³

2007

Journal of Applied Physiology

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“…Wilkins et al (2) proposed the classification of "exaggerated startle reflex" for patients in whom startle reflexes occur at a normal latency but are abnormally enhanced by virtue of a lower threshold and reduced habituation, features found in this patient (see videotape segment). At present, it is unknown whether the primary abnormality in such cases lies in the neural circuits that mediate startle or in one of the inputs that may modulate the reflex (7).…”

Section: Fig 1 Records Of Electromyographic (Emg) Activity In a Sermentioning

confidence: 97%

Exaggerated startle reflexes in an elderly woman

Colebatch¹,

Barrett²,

Lees³

1990

Movement Disorders

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A 76-year-old woman with a 5-year history of excessive startle is reported. Electrophysiological recordings were made of muscle activation after acoustic and proprioceptive stimulation. The findings are discussed in relation to current knowledge of the startle reflex and classification of startle syndromes. It is concluded that this patient is best regarded as having a pathological exaggeration of the normal startle reflex rather than other causes of stimulus-sensitive muscle jerks.

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“…From there the reflex responses propagate up the brainstem and down the spinal cord along the reticulobulbar and reticulospinal tracts [4,23]. Auditory startle responses (ASRs) are most prominent in the muscles in the face, neck and shoulders, and less marked in the lower body [4].…”

Section: Introductionmentioning

confidence: 99%