Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LABYRINTH”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1975

Spontaneous cerebrospinal fluid otorrhea. Congenital anomaly of bony labyrinth a possible cause.

A patient had recurrent meningitis as a result of a congenital anomaly of the bony labyrinth. As far as could be traced in the literature, this was the first time that an isolated congenital anomaly of the bony labyrinth could be shown to be the origin of spontaneous cerebrospinal fluid otorrhea and the resulting recurrent meningitis. In cerebrospinal fluid otorrhea of unknown origin, tomographic x-ray examination of the bony labyrinth is of utmost importance. For the detection of the finer details is the bony structure of the labyrinth, this tomography should be done according to one of the multidirectional techniques.

Adolescent↗
PubMed1998

Comparative review of the human bony labyrinth.

The bony labyrinth inside the petrous part of the temporal bone houses the organs of hearing and balance. Being functionally linked with sensory control of body movements and located in a part of the basicranium that is closely associated with the brain, this structure is of great interest in the study of human evolutionary history. However, few aspects of its morphology have been studied in nonhuman primates. This review compares the bony labyrinth of humans with that of the great apes and 37 other primate species based on data newly acquired with computed tomography combined with previous descriptions. With body mass taken into account, consistent differences are found between the size of the semicircular canals in humans, the great apes, and other primates. In particular, the arcs of the anterior and posterior canals are larger in humans than in the African apes. The functional implications of semicircular canal dimensions for registering angular head motion are evaluated in relation to locomotor behavior. Biophysical models, comparative studies, and some neurophysiological experiments all support a link between semicircular canal size and agility, or more specifically the frequency contents of natural head movements, but the evidence on the exact nature of this link is ambiguous. It is concluded that any link between the characteristic dimensions of the human canals and locomotion will be more complex than a simple association with the broad categories of quadrupedal vs. bipedal behavior. The functionally important planar orientations of the semicircular canals are similar in humans and the African apes as well as in many other species. In contrast, other aspects of the human labyrinth differ markedly in shape, following a pattern that seems to reflect the characteristic architecture of the human basicranium. Indeed, it is found that labyrinthine and basicranial shape are interspecifically correlated in the sample, and in most respects the human morphology is consistent with the general trend among primate species. Differences in brain growth and development are proposed as the predominant factor underlying both the unique shape of the human labyrinth as well as the interspecific labyrintho-basicranial correlations.

Anatomy, Comparative↗
PubMed2006

Evolutionary changes in the cochlea and labyrinth: Solving the problem of sound transmission to the balance organs of the inner ear.

This review article examines the evolutionary adaptations in the vertebrate inner ear that allow selective activation of auditory or vestibular hair cells, although both are housed in the same bony capsule. The problem of separating acoustic stimuli from the vestibular end organs in the inner ear has recently reemerged with the recognition of clinical conditions such as superior canal dehiscence syndrome and enlarged vestibular aqueduct syndrome. In these syndromes, anatomical defects in the otic capsule alter the functional separation of auditory and vestibular stimuli and lead to pathological activation of vestibular reflexes in response to sound. This review demonstrates that while the pars superior of the labyrinth (utricle and semicircular canals) has remained fairly constant throughout evolution, the pars inferior (saccule and other otolith, macular, and auditory end organs) has seen considerable change as many adaptations were made for the development of auditory function. Among these were a relatively rigid membranous labyrinth wall, a variably rigid otic capsule, immersion of the membranous labyrinth in perilymph, a perilymphatic duct to channel acoustic pressure changes away from the vestibular organs, and different operating frequencies for vestibular versus auditory epithelia. Even in normal human ears, acoustic sensitivity of the labyrinth to loud clicks or tones is retained enough to be measured in a standard clinical test, the vestibular-evoked myogenic potential test.

Animals↗
PubMed2001

Remarks on the inner ear of elasmobranchs and its interpretation from skeletal labyrinth morphology.

The structure and function of the craniate inner ear is reviewed, with 33 apomorphic characters of the membranous labyrinth and associated structures identified in craniates, gnathostomes, and elasmobranchs. Elasmobranchs are capable of low-frequency semi-directional phonoreception, even in the absence of any pressure-to-displacement transducer such as ear ossicles. The endolymphatic (parietal) fossa, semicircular canals, and crista (macula) neglecta are all adapted toward phonoreception. Some (but not all) of the morphological features associated with phonoreception can be inferred from the elasmobranch skeletal labyrinth. Endocranial spaces such as the skeletal labyrinth also provide suites of morphological characters that may be incorporated into phylogenetic analyses, irrespective of how closely these spaces reflect underlying soft anatomy. The skeletal labyrinths of Squalus and Notorynchus are compared using silicone endocasts and high-resolution CT-scanning. The latter procedure offers several advantages over other techniques; it is more informative, nondestructive, preserves relationships of surrounding structures, and it can be applied both to modern and fossil material.

Animals↗
PubMed1990

Computer-aided three-dimensional reconstruction of the osseous and membranous labyrinths.

In order to obtain an adequate knowledge of the stereoscopic anatomy of the temporal bone, it is very useful to make three-dimensional reconstructions of the bone. By using the histological sections of a human temporal bone processed for routine evaluation, we have undertaken computer-aided reconstruction of the osseous and the membranous labyrinths, as well as the inner ear sensory organs. Reconstructions were done either separately or simultaneously. Owing to the "semitransparent display" function of the computer system, it was possible to observe the reconstructed membranous labyrinth through the simultaneously reconstructed osseous labyrinth, and the sensory organs through the membranous labyrinth. The results were satisfactory for understanding the spatial relationships among these structures. We also attempted computer-aided measurements of the reconstructed sensory organs and calculated the length of the organ of Corti and the angle between the saccular and the utricular maculae.

Computer Simulation↗
PubMed1985

Influence of Renshaw cells on the response gain of hindlimb extensor muscles to sinusoidal labyrinth stimulation.

The contraction of limb extensor muscles during side-down roll tilt of the animal depends upon an increased discharge of excitatory vestibulospinal (VS) neurons (alpha-response) and a reduced discharge of inhibitory reticulospinal (RS) neurons of the medulla (beta-response), both acting on ipsilateral limb extensor motoneurons. In the decerebrate cat, a modulation of the multiunit EMG activity was clearly present in forelimb extensors, but was extremely weak or absent in hindlimb extensors. Experiments performed in decerebrate cats with the deefferented GS muscle fixed at a constant length have shown that Renshaw (R)-cells, monosynaptically coupled with gastrocnemius-soleus (GS) motoneurons, were either unresponsive or displayed only very weak, small amplitude alpha-responses to sinusoidal stimulation of labyrinth receptors elicited during slow head rotation after bilateral neck deafferentation. This effect was attributed to excitatory VS volleys acting on GS motoneurons and, through their recurrent collaterals, on the related R-cells. In these instances the recurrent inhibition of the GS motoneurons contributed to the very low gain of the EMG response of the corresponding muscles to labyrinth stimulation. Intravenous injection of an anticholinesterase (eserine sulphate, 0.05-0.1 mg/kg) at a dose that in previous experiments increased the firing rate of medullary RS neurons, while decreasing the decerebrate rigidity, slightly increased the discharge rate of R-cells linked with the GS motoneurons in the animal at rest; these findings suggest that the RS system inhibits the extensor motoneurons by exciting the related R-cells. All the R-cells, which prior to the injection were either unresponsive or showed an alpha-response to head rotation (at 0.026-0.15 Hz, +/- 10 degrees), after eserine sulphate showed a beta-response for the same parameters of labyrinth stimulation. In particular, a reduced discharge of the R-cells linked with the GS motoneurons occurred during side-down head rotation as shown for the majority of the RS neurons. It appears therefore that the same R-cells, which in the normal decerebrate cat responded to the excitatory VS volleys acting through the GS motoneurons, were now decoupled from their input motoneurons during head rotation, thus behaving as if they underwent the most efficient direct excitatory control of the RS system. The reduced discharge of the R-cells linked with the GS motoneurons during side-down head rotation would lead to disinhibition of these motoneurons, thus enhancing the response gain of the corresponding muscle to labyrinth stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1980

Labyrinth and neck reflex modification of the tonic vibration reflex in the decerebrate cat.

The interaction between tonic labyrinth or neck reflexes and the tonic vibration reflex acting on the medial head of triceps in the decerebrate cat is described. Medial triceps was isotonically loaded and reflex actions were measured as changes in muscle length. Natural stimulation of the receptors giving rise to tonic labyrinth or neck reflexes can either enhance or diminish the size of a pre-existing tonic vibration reflex. It is also shown that descending activity from either the labyrinth or neck reflex systems can completely suppress the tonic vibration reflex, whereas the tonic vibration reflex was never observed to suppress an established labyrinth or neck reflex.

Animals↗
PubMed2003

The bony labyrinth of Neanderthals.

This paper presents a comprehensive comparative analysis of the Neanderthal bony labyrinth, a structure located inside the petrous temporal bone. Fifteen Neanderthal specimens are compared with a Holocene human sample, as well as with a small number of European Middle Pleistocene hominins, and early anatomically modern and European Upper Palaeolithic humans. Compared with Holocene humans the bony labyrinth of Neanderthals can be characterized by an anterior semicircular canal arc which is smaller in absolute and relative size, is relatively narrow, and shows more torsion. The posterior semicircular canal arc is smaller in absolute and relative size as well, it is more circular in shape, and is positioned more inferiorly relative to the lateral canal plane. The lateral semicircular canal arc is absolutely and relatively larger. Finally, the Neanderthal ampullar line is more vertically inclined relative to the planar orientation of the lateral canal. The European Upper Palaeolithic and early modern humans are most similar, although not fully identical to Holocene humans in labyrinthine morphology. The European Middle Pleistocene hominins show the typical semicircular canal morphology of Neanderthals, with the exception of the arc shape and inferiorly position of the posterior canal and the strongly inclined ampullar line. The marked difference between the labyrinths of Neanderthals and modern humans can be used to assess the phylogenetic affinities of fragmentary temporal bone fossils. However, this application is limited by a degree of overlap between the morphologies. The typical shape of the Neanderthal labyrinth appears to mirror aspects of the surrounding petrous pyramid, and both may follow from the phylogenetic impact of Neanderthal brain morphology moulding the shape of the posterior cranial fossa. The functionally important arc sizes of the Neanderthal semicircular canals may reflect a pattern of head movements different from that of modern humans, possibly related to aspects of locomotor behaviour and the kinematic properties of their head and neck.

Adult↗
PubMed1998

Three-dimensional reconstruction of the membranous vestibular labyrinth in the toadfish, Opsanus tau.

Membranous vestibular labyrinths from the oyster toadfish, Opsanus tau, were fixed, dissected from the animal, stained, and embedded in rectangular blocks of clear histological resin. Photomicrographs of complete embedded labyrinths were taken from six orthogonal directions and used to construct three-dimensional (3D) geometrical models of the semicircular canals, ampullae, utricular vestibule and common crus. Membraneous ducts and ampullae were modeled using a set of cross-sectional elliptical curves laced together to generate curved tubular models of each structure. The ensemble of these curved tubes was used to generate a complete 3D reconstruction of the outside surface of the membranous labyrinth. When viewed from six orthogonal directions, reconstructions closely matched the embedded tissue. Dimensions of the reconstruction and histological sections were compared to measurements of fresh tissue taken from the same animals prior to fixation and used to correct the reconstructions for tissue shrinkage. Results provide estimates of the endolymphatic volumes, local cross-sectional areas and elliptical eccentricities as well as 3D orientations of the geometric canal planes relative to the skull. Ten micrometer histological sections of the material were also prepared to measure wall thickness in various regions of the labyrinth.

Animals↗
PubMed2001

Development of the membranous labyrinth of human embryos and fetuses using computer aided 3D-reconstruction.

The last detailed description of the development of the inner ear membranous labyrinth goes back to Streeter in 1918. This investigation can be regarded to be of outstanding scientific value. However, at that time no staging system of human embryos existed. In this respect, Streeter's work is outdated. It was the aim of this study to reinvestigate the development of the membranous labyrinth in human embryos and fetuses of which the developmental stages have been determined according to the Carnegie staging system and to compare the results with the literature. Serial histologic sections in the coronal or frontal plane of the heads of human embryos and fetuses of different developmental stages were used for computer aided 3D-reconstruction of the membranous labyrinth. From the obtained results, it is concluded that the endolymphatic duct develops earlier than previously described in the literature. The induction of the differentiation of the endolymphatic duct does not correspond with the superficial ectoderm because the endolymphatic duct develops medial of the otic vesicle. The membranous labyrinth determines the form of the petrosal bone as early as in stage 19 (47-48 days post conception).

Ear, Inner↗
PubMed2003

A study on the effect of inhalative formaldehyde exposure on water labyrinth test performance in rats.

We investigated the effects of repeated inhalative exposure to several formaldehyde concentrations (2 hours/day, 10 consecutive days) on the behavior of adult male and female LEW.1K rats during a period in which they learned to perform a water labyrinth task. We also examined the effects on the histology of some organ tissues. While the controls needed increasingly shorter swimming periods to complete the water labyrinth test and made fewer errors with advancing trial duration, such progress could not be observed in the learning behavior of the exposed animals. They took significantly longer swimming periods to reach the finish and made significantly more errors in comparison to the controls. The statistical comparison between the collected data in the formaldehyde exposed male and female rats reveals that females in general reached the end point of the swimming labyrinth in significantly less time. On some trial days, however, they made more mistakes than males. In the highest concentration group, no gender differences were evident in the frequency of errors. The histological examination revealed no pathological changes attributable to formaldehyde exposure. Since the water labyrinth test is used to investigate changes in memory and learning behavior in animals, we conclude that under investigational conditions, formaldehyde affects the learning behavior and the memory of male and female rats.

Administration, Inhalation↗
PubMed2006

Suppressive effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on vascular remodeling that takes place in the normal labyrinth zone of rat placenta during late gestation.

The maintenance of the placental vasculature is essential for sustaining normal fetal growth. On the basis of our previous observation that fetal death was accompanied by placental hypoxia upon exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (R. Ishimura et al., 2002a, Toxicol. Appl. Pharmacol. 185, 197-206), we here investigated the effects of TCDD on the placenta, focusing on the development of the labyrinth zone. Holtzman rats were administered a single oral dose of 1.6 mug of TCDD/kg body weight or an equivalent volume of vehicle (control) on gestation day (GD) 15, and placental tissues were analyzed on GD20. Immunohistochemical staining showed that the exposure to TCDD decreased the size of maternal blood sinusoids and caused the constriction of fetal capillaries in the placenta. In contrast, we found that vascular remodeling occurred in the labyrinth zone of normal rat placenta; that is, the vascular development in the normal labyrinth zone during the late gestation (from GD16 to GD20) showed dilated maternal blood sinusoids and fetal capillaries accompanied by a decrease in thickness and the apoptosis of trophoblasts. The present results demonstrate that this remodeling is suppressed by TCDD, which is further supported by the decreased expression level of Tie2 mRNA, the gene which is associated with vascular remodeling, and also by the decrease in the number of apoptotic trophoblasts in TCDD-exposed rats. The present study provided a new finding on the development of the vasculature in the labyrinth zone during the late gestation under normal conditions and showed the inhibition of vascular remodeling in TCDD-exposed rats.

Animals↗
PubMed1985

Radiation measurements in a labyrinth penetration at a high-energy proton accelerator.

The efficient design of access penetrations at high-energy proton accelerators is desirable for both economic and personnel protection reasons. This paper reports on a series of measurements made in a personnel access labyrinth which viewed an A1 target bombarded by 400-GeV protons from the Fermilab Tevatron. Measurements of absorbed dose in the labyrinth using tissue-equivalent ion chambers were consistent with theoretical predictions of both the relative attenuation through the penetration and the absolute magnitude near the target. The multisphere technique was used to determine the neutron energy spectrum in one section of the labyrinth. A recombination chamber was used to measure the quality factor of the radiation field in two sections of the labyrinth. Good agreement with the quality factor deduced from the multisphere result was obtained at the same measurement location.

Neutrons↗
PubMed2001

Chemical reaction-diffusion implementation of finding the shortest paths in a labyrinth.

An experimental technique for finding the shortest paths in a labyrinth is elaborated on based on chemical reaction-diffusion media. The system designed has hybrid architecture that combines an information-processing reaction-diffusion medium performing operations of high computational complexity with a digital computer carrying out supplementary operations. Two principal points are assumed as a basis for this design. They are the following: a light-sensitive Belousov-Zhabotinsky-type reagent chosen as a reaction-diffusion medium that offers the opportunity to simulate a labyrinth and spread wave evolution by its images stored in the medium; fast light-induced phase wave processes that spread through the labyrinth in seconds instead of the dozens of minutes typical of trigger waves inherent in reaction-diffusion media. Images of consecutive wave-spreading steps are stored in the memory of a digital computer. These images are used to determine the shortest paths based on the additional procedure of testing for the connectedness of labyrinth fragments.

Journal Article↗
PubMed2002

Example of a chaotic crystal: the labyrinth.

Labyrinthine structures often appear as the final steady state of pattern forming systems. Being disordered, they exhibit the same kind of short range positional order as the Newell-Pomeau turbulent crystal. Labyrinths can be seen as a limit case of the texture of disordered rolls with a coherence length of the same order as the wavelength. In the various two-dimensional model equations we looked at, labyrinths and parallel rolls are steady states for the same parameters, their occurrence depending on the initial conditions. Comparing the stability of these two structures, we find that in variational models their energy is very close, rolls always being more stable than labyrinths. For the nonvariational model we propose a numerical experiment which displays a well defined bifurcation from parallel rolls to labyrinths as the more stable state.

Journal Article↗
PubMed1967

The content and localization of catecholamines in the carotid labyrinths and aortic arches of Rana temporaria.

1. The catecholamine content of the carotid labyrinth of Rana temporaria was estimated by two different methods, and compared with that of the aortic arch. In both tissues adrenaline was found as the dominant amine, with traces of dopamine and noradrenaline detectable in the labyrinth only.2. Per gram of fresh tissue, the labyrinth usually contained more adrenaline than the aortic arch.3. On microscopic examination, the aortic arch was found to contain nerve fibres which fluoresced after treatment with formaldehyde, whereas within the carotid labyrinth the formaldehyde-induced fluorescence was localized in the cytoplasm of clusters of small cells. This fluorescence resembled that exhibited by glomus cells in the mammalian carotid body.

Animals↗
PubMed1981

The effect of cerebellectomy on the tonic labyrinth and neck reflexes in the decerebrate cat.

1. Tonic labyrinth and neck reflexes were studied separately and in combination in the decerebrate cat before and after acute cerebellectomy. Reflex effects were observed as changes in the length of the medial head of triceps in both forelimbs. 2. In the decerebrate cat with an intact cerebellum the tonic labyrinth reflexes, elicited by side-up and side-down head rotations, produced asymmetric length changes in the medial head of triceps in both forelimbs, as described by Lindsay, Roberts & Rosenberg (1976). After cerebellectomy, head movements in either direction produced reflex shortenings in the medial triceps in both forelimbs, in contrast to the normal reciprocal reflex length changes. The presence of the cerebellum is thus required for the occurrence of the normal asymmetric labyrinth reflexes. 3. The direction of the neck reflexes remained unchanged by cerebellectomy. 4. It is suggested that the postural disturbances following cerebellar damage may partly result from the change in the form of the tonic labyrinth reflexes, which in combination with the tonic neck reflexes would no longer act in a stabilizing manner on the trunk.

Animals↗
PubMed1990

Labyrinth learning impairment in patients with early symptoms of presenile dementia.

21 patients (54 +/- 7 years old) with early cognitive deficit (ECD) during the presenile stage of presumptive primary degenerative dementia (mild stage) and 14 patients (54 +/- 4 years old) with early cognitive deficit with a background of cardiovascular disease (CVD) were examined in a labyrinth learning test of Milner (modified by Roth). 15 patients in the ECD group made 3 times more errors to negative fields (p less than 0.01), about 10 times more errors to positive fields (p less than 0.01) and needed treble the amount of time for passing through the labyrinth (p less than 0.01) compared with a healthy control group (51 +/- 4 years). A further 6 patients of the ECD group had no success in performing the labyrinth test. The CVD group was not different from the control group in making errors, but slower (p less than 0.05). The labyrinth test is found suitable for a more precise diagnosis of early cognitive deficit in the early stage of a primary degenerative dementia of the Alzheimer type.

Cognition Disorders↗