Dimensions of the Horizontal Semicircular Duct, Ampulla and Utricle in Rat and Guinea Pig

Curthoys, Ian S.; Oman, Charles M.

doi:10.3109/00016488609108601

Cited by 37 publications

(33 citation statements)

References 21 publications

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“…This is important as deviation from circularity will affect the area enclosed by the canal, a parameter that has been shown to be closely related to canal sensitivity (McVean, 1999). A more useful measure may be 2P ⁄ L, referred to as the 'average radius' of the canal by Oman et al (1987), in which L is the streamline length of fluid flow, encompassing the entire membranous duct, ampulla and utricle, and P is the plane area enclosed by L (Curthoys & Oman, 1986Lindenlaub et al 1995). This measure takes shape into account as, for a given streamline length, the greater the deviation from circularity, the smaller the value of P and hence P ⁄ L. A perfectly circular canal should have a value of 2P ⁄ L that equals R (because P = pR 2 and L = 2pR).…”

Section: Canal Shapementioning

confidence: 99%

“…This measurement is distinct from the radius of the membranous duct seen in a cross-sectional slice through the canal (r). R has been measured from fixed, dissected specimens by superimposing a circle of best fit (estimated by eye) over the course of the canal either directly (Lindenlaub et al 1995;McVean, 1999) or from photographs (Curthoys & Oman, 1986. More recently, semicircular canals have been imaged using computed tomography, obviating the need for dissection (Spoor & Zonneveld, 1998;Spoor et al 2002Spoor et al , 2007.…”

Section: Canal Sizementioning

confidence: 99%

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Semicircular canals and agility: the influence of size and shape measures

Cox

Jeffery

2009

Journal of Anatomy

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The semicircular canals of the inner ear sense angular accelerations and decelerations of the head and enable co-ordination of posture and body movement, as well as visual stability. Differences of agility and spatial sensitivity among species have been linked to interspecific differences in the relative size of the canals, particularly the radius of curvature (R) and the ratio of the canal plane area to streamline length (P ⁄ L). Here we investigate the scaling relationships of these two size variables and also out-of-plane torsion in the three semicircular canals (anterior, posterior and lateral), in order to assess which is more closely correlated with body size and locomotor agility. Measurements were computed from 3D landmarks taken from magnetic resonance images of a diverse sample of placental mammals encompassing 16 eutherian orders. Body masses were collected from the literature and an agility score was assigned to each species. The R and P ⁄ L of all three semicircular canals were found to have highly significant positive correlations with each other and no statistical difference was found between the slope of 2P ⁄ L against R and 1. This indicated that, contrary to initial hypotheses, there is little difference between 2P ⁄ L and R as measures of semicircular canal size. A measure of the in-plane circularity of the canal was obtained by dividing 2P ⁄ L by R and out-of-plane torsion was measured as angular deviation from a plane of best fit. It was predicted that deviations from in-plane and out-of-plane circularity would increase at small body size due to the constraints of fitting a proportionately larger canal into a smaller petrous bone. However, neither measurement was found to have a significant correlation with body mass, indicating that deviations from circularity (both in-plane and out-of-plane) are not sufficient to alter P ⁄ L to an extent that would impact the sensitivity of the canals. 2P ⁄ L and R were both shown to be significantly correlated with locomotor agility. The posterior canal was the least correlated with agility, suggesting that it may be generally less closely aligned to the direction of movement than the anterior canal. Of the three canals, the lateral canal was the most highly correlated with agility. In particular, it could be used to distinguish between species that move in a largely 2D environment and those that locomote in 3D space (aerial, arboreal and aquatic species). This complements previous work suggesting that the lateral canal primarily commands navigation, whereas the vertical canals control reflex adjustments. It was also found that 2P ⁄ L is substantially better correlated with agility than is R in the lateral canal. This result is intriguing given the above finding that there is no statistical difference between 2P ⁄ L and R, and requires further investigation.

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Section: Canal Shapementioning

confidence: 99%

Section: Canal Sizementioning

confidence: 99%

Semicircular canals and agility: the influence of size and shape measures

Cox

Jeffery

2009

Journal of Anatomy

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“…[35] Spurious stimulation of vestibular nerve branches other than the intended target can cause poor control of eye movement direction, corrupting attempts to independently control different ampullary nerves. (Emulation of otolith endorgan transduction represents an even greater challenge, and published attempts have yielded conflicting results, probably due to the close proximity of axons representing different directions within each macule and macular nerve.…”

Section: Introductionmentioning

confidence: 99%

A Multichannel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3-D Vestibular Sensation

Santina

Migliaccio²,

Patel³

2007

IEEE Trans. Biomed. Eng.

150

211

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Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode's targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior.

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“…The diameters of the lateral semicircular ducts, ampullae and utricles of the guinea pigs with and without EH were measured according to the landmarks which had been reported by Curthoys and Oman [8]. These landmarks are described in figure 1.…”

Section: Methodsmentioning

confidence: 99%

“…Curthoys and Oman [8] measured the sizes, cross-sectional shapes and areas of the horizontal semicircular duct, ampulla and utricle in the guinea pigs. Some articles have reported the volumes of endolymphatic spaces in the normal and EH mice, human beings and guinea pigs [9].…”

Section: Introductionmentioning

confidence: 99%

Geometrical and Volume Changes of the Membranous Vestibular Labyrinth in Guinea Pigs with Endolymphatic Hydrops

Yang

Hua³

et al. 2013

ORL

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Objective: To evaluate geometrical and volume changes of membranous vestibular labyrinths in guinea pigs after endolymphatic hydrops (EH). Methods: The membranous labyrinths of normal guinea pigs and of those with EH for 4 and 8 weeks were reconstructed after being scanned using micro-computed tomography subseqent to being stained in osmium tetroxide (OsO₄). The diameters and volumes of the semicircular ducts, ampullae, utricles and saccules were measured based on the three-dimensional models. Results: The diameters of the ampullae and utricles of EH guinea pigs were greater than those of the normal guinea pigs, while there were no significant differences in the diameters of the semicircular ducts among all groups. The volumes of ampullae, utricles and saccules of the EH groups were greater than those of the control group, but there were no changes in volumes of semicircular ducts after EH. Conclusion: The dilations of the membranous vestibular labyrinth in guinea pigs with EH mainly occur at the ampullae, utricles and saccules.

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Dimensions of the Horizontal Semicircular Duct, Ampulla and Utricle in Rat and Guinea Pig

Cited by 37 publications

References 21 publications

Semicircular canals and agility: the influence of size and shape measures

Semicircular canals and agility: the influence of size and shape measures

A Multichannel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3-D Vestibular Sensation

Geometrical and Volume Changes of the Membranous Vestibular Labyrinth in Guinea Pigs with Endolymphatic Hydrops

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