Directional coding of three-dimensional movements by the vestibular semicircular canals

Rabbitt, Richard D.

doi:10.1007/s004220050536

Cited by 96 publications

(98 citation statements)

References 67 publications

(92 reference statements)

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“…Out-of-plane torsion was calculated as the mean angular deviation from the plane of best fit of the canal, measured from the centroid of the canal. It was predicted that torsion helps to optimize overall sensitivity by sacrificing in-plane mechanical sensitivity, as denoted by P ⁄ L, in order to shift the best fit plane closer to the plane of maximal sensitivity (Rabbitt, 1999). This predicts that P ⁄ L and torsion are negatively correlated.…”

Section: Discussionmentioning

confidence: 99%

“…Torsion can allow the canals to pick up accelerations outside its plane of best fit at the expense of in-plane sensitivity (L increases relative to P). This can be particularly important as the maximal response directions of the nerves frequently differ from the anatomical planes of the canals (Rabbitt, 1999). The misalignment between the anatomical plane and maximal response direction has been calculated to be approximately 6°in monkeys (Reisine et al 1988) and 7°i n cats .…”

Section: Canal Shapementioning

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: Discussionmentioning

confidence: 99%

Section: Canal Shapementioning

confidence: 99%

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

Cox

Jeffery

2009

Journal of Anatomy

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“…Differences between the anatomic planes of the canals and their planes of maximum sensitivity may arise from variance in the shape and size of the bony canal and the membranous duct, the departure of the canals from a strict toroidal shape, and the fluid mechanics of the endolymph system (Ghanem et al 1998;Rabbitt 1999). Divergences in the two planes (anatomic and physiologic) have been reported for several species: 4-for the horizontal canal and 5-for the posterior canal in rhesus monkey (Reisine et al 1988); 10-for the horizontal canal and 8-for the posterior canal in pigeons (Dickman 1996); and 6.5-for the horizontal canal and 10.2-for the posterior canal in cats (Blanks et al 1975b).…”

Section: Discussionmentioning

confidence: 99%

Planar Relationships of the Semicircular Canals in Two Strains of Mice

Calabrese

Hullar

2006

JARO

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The mouse is increasingly important as a subject of vestibular research. Although many studies have focused on the vestibular responses of mice to angular rotation, the geometry of their semicircular canals has not been described. High-voltage X-ray computed tomography was used to measure the anatomy of the semicircular canals of two strains of mice, C57Bl/6J and CBA/CaJ. The horizontal plane of a stereotaxic coordinate system was defined by the midpoints of the external auditory meati and the point where the incisors emerge from the maxilla. The centroids of the lumens of the bony canals were calculated, and planes that describe the canals were fit using a least-squares regression analysis to the resulting points. Vectors normal to each regressed plane were used to represent the corresponding canal's axis of rotation, and angles of these vectors relative to skull landmarks as well as to each other were calculated. The horizontal canal of the mouse was found to be angled anteriorly upward 17.8-for CBA/CaJ and 32.6-for C57Bl/6J from the reference horizontal plane. Angles between ipsilateral canals deviated up to 12.3-from orthogonal, and angles between contralateral synergistic canals (left anterior-right posterior, right anterior-left posterior, and horizontal-horizontal) deviated from parallel by up to 14.8-. The orientations of the canals within the head as well as the orientations of the canals relative to each other were significantly different between the two strains, suggesting that care must be taken in the design and interpretation of developmental and physiologic studies involving different mouse strains.

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“…Maximal endolymph displacement within a SCC occurs with head rotations in a fixed plane that is close to but not necessarily equal to the anatomical SCC plane (Ifediba et al 2007;Curthoys and Oman 1987;Rabbitt et al 2003;Rabbitt 1999) and it is dependent on the 3D geometry and cross-sectional area of the membranous SCC Zonneveld 1995, 1998). The geometry of the membranous SCC can be inferred from reconstructed bony SCCs because of the direct connection between the spatial paths of the bony and membranous labyrinth (Igarashi 1966;Curthoys et al 1977b).…”

Section: Introductionmentioning

confidence: 99%

A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

Bradshaw

Curthoys

Todd

et al. 2009

JARO

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We report a precise, simple, and accessible method of mathematically measuring and modeling the threedimensional (3D) geometry of semicircular canals (SCCs) in living humans. Knowledge of this geometry helps understand the development and physiology of SCC stimulation. We developed a framework of robust techniques that automatically and accurately reconstruct SCC geometry from computed tomography (CT) images and are directly validated using micro-CT as ground truth. This framework measures the 3D centroid paths of the bony SCCs allowing direct comparison and analysis between ears within and between subjects. An average set of SCC morphology is calculated from 34 human ears, within which other geometrical attributes such as nonplanarity, radius of curvature, and inter-SCC angle are examined, with a focus on physiological implications. These measurements have also been used to critically evaluate plane fitting techniques that reconcile many of the discrepancies in current SCC plane studies. Finally, we mathematically model SCC geometry using Fourier series equations. This work has the potential to reinterpret physiology and pathophysiology in terms of real individual 3D morphology.

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Directional coding of three-dimensional movements by the vestibular semicircular canals

Cited by 96 publications

References 67 publications

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

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

Planar Relationships of the Semicircular Canals in Two Strains of Mice

A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

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