Responses of irregularly discharging chinchilla semicircular canal vestibular-nerve afferents during high-frequency head rotations

Timothy Hullar, Charles C. Della Santina, Timo Hirvonen, David M. Lasker, John P. Carey, Lloyd B. Minor

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

Mammalian vestibular-nerve afferents innervating the semicircular canals have been divided into groups according to their discharge regularity, gain at 2-Hz rotational stimulation, and morphology. Low-gain irregular afferents terminate in calyx endings in the central crista, high-gain irregular afferents synapse more peripherally in dimorphic (bouton and calyx) endings, and regular afferents terminate in the peripheral zone as bouton-only and dimorphic endings. The response dynamics of these three groups have been described only up to 4 Hz in previous studies. Reported here are responses of chinchilla semicircular canal vestibular-nerve afferents to rotational stimuli at frequencies up to 16 Hz. The sensitivity of all afferents increased with increasing frequency with the sensitivity of low-gain irregular afferents increasing the most and matching the high-gain irregular afferents at 16 Hz. All afferents increased their phase lead with respect to stimulus velocity at higher frequencies with the highest leads in low-gain irregular afferents and the lowest in regular afferents. No attenuation of sensitivity or shift in phase consistent with the presence of a high-frequency pole over the range tested was noted. Responses were best fit with a torsion-pendulum model combined with a lead operator (τ HF1s + 1)(τHF2s + 1). The discharge regularity of individual afferents was correlated to the value of each afferent's lead operator time constants. These findings suggest that low-gain irregular afferents are well suited for encoding the onset of rapid head movements, a property that would be advantageous for initiation of reflexes with short latency such as the vestibulo-ocular reflex.

Original languageEnglish (US)
Pages (from-to)2777-2786
Number of pages10
JournalJournal of Neurophysiology
Volume93
Issue number5
DOIs
StatePublished - May 2005
Externally publishedYes

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Chinchilla
Vestibular Nerve
Semicircular Canals
Head
Vestibulo-Ocular Reflex
Head Movements
Synapses
Reflex
Lead

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

Responses of irregularly discharging chinchilla semicircular canal vestibular-nerve afferents during high-frequency head rotations. / Hullar, Timothy; Della Santina, Charles C.; Hirvonen, Timo; Lasker, David M.; Carey, John P.; Minor, Lloyd B.

In: Journal of Neurophysiology, Vol. 93, No. 5, 05.2005, p. 2777-2786.

Research output: Contribution to journalArticle

Hullar, Timothy ; Della Santina, Charles C. ; Hirvonen, Timo ; Lasker, David M. ; Carey, John P. ; Minor, Lloyd B. / Responses of irregularly discharging chinchilla semicircular canal vestibular-nerve afferents during high-frequency head rotations. In: Journal of Neurophysiology. 2005 ; Vol. 93, No. 5. pp. 2777-2786.
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