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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↗
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↗
PubMed1997

The embryonic development of the human ethmoid labyrinth from 8-40 weeks.

The embryonic development of the human ethmoid labyrinth was studied in 24 fetal heads aged between 8 and 40 weeks of gestation under light microscopy. The uncinate process was identifiable at 8 weeks of gestation on the laterosuperior portion of the inferior turbinate; however, at this stage of development, the ethmoid bulla was not apparent. The ethmoid bulla developed on the lateral wall of the middle meatus by 12 weeks of gestation. By 14 weeks, the primordial ethmoid infundibulum and primordial maxillary sinus were seen developing between the uncinate process and the ethmoid bulla. It was obvious that the anterior and middle ethmoid cells developed from the ethmoid bulla. By 22 weeks of gestation, the first cell of the anterior ethmoid group was evident in the anterior-inferior portion of the ethmoid bulla. By 23 weeks of gestation, the first cell of the middle ethmoid group was visible in the superior portion of the ethmoid bulla. Pneumatization of the middle turbinate occurred as part of normal development of the ethmoid labyrinth. By 32 weeks of gestation, the ostium for the development of the middle turbinate cell was seen in the superior-interior portion of the middle turbinate. These observations provide new insight into the development of the ethmoid labyrinth and have important implications for the understanding of normal anatomy and developmental variants of the ethmoid labyrinth.

Embryonic and Fetal Development↗
PubMed2001

[Mathematic modeling of the shape and size of the ethmoidal labyrinth].

The present work was designed to study craniometric characteristics of ethmoidal labyrinths, facial and cerebral skeleton and to define mathematical correlation between the parameters of ethmoidal labyrinth and facial and cerebral skeleton. As a result average, minimal and maximal values of linear parameters and the parameters of the volume of ethmoidal labyrinths were calculated. Correlational, regressive and factor analyses of the craniometric characteristics studied were carried out. Significant regression equations for calculating width, height, length and volume of ethmoidal labyrinths for different types of cerebral skeleton were obtained.

Ethmoid Sinus↗
PubMed1976

EEG-studies on the phases of sleep and wakefulness after bilateral labyrinth destruction.

The dynamics of the state of wakefulness, slow and paradoxical sleep after labyrinth destruction was studied in chronic cats. The states were assessed according to the behaviour, EEG, myogram and eye movements. The labyrinth destruction was combined (chemical and mechanical). Bilateral labyrinth deafferentation results in a decrease in the duration of wakefulness from 30 to 17 per cent, p less than 0.001. At the same time paradoxical sleep increased from 4 to 8 per cent, p less than 0.001. This increase is due to both the greater average number of paradoxical sleep episodes and a higher average duration of the individual episode. The latency of the first appearance of a paradoxical sleep episode is considerably shortened after labyrinth destruction.

Animals↗
PubMed1988

Lesions in the mesencephalic reticular formation change open field and thirst motivated labyrinth behaviour of rats.

Open field behaviour and thirst motivated running through two labyrinth variants were compared before and after bilateral symmetric lesions of the anterior part of the dorsolateral parabrachial nucleus (PBl) and in the anterior mesencephalic area cuneiformis (CU), both n = 9, on 4-month-old male Long-Evans rats. CU-rats were characterized by abolished visual placing responses, aphagia or hypophagia which was limited up to the 15th postoperative day, ambulatory hyperactivity, reduced climbing and grooming, but enhanced rearing. Their preoperatively learnt thirst motivated labyrinth passage remained unimpaired but their drinking behaviour was persistently changed. They interrupted drinking several times and regularly did not empty the cups. Thirst motivation was evidently reduced after CU-lesions. PBl-rats were ambulatory hypoactive and slowed with accelerated habituation, reduced climbing and changed incline-plane behaviour. A slight hypophagia was generally overcome after the 5th postoperative day. Labyrinth performance of PBl-rats was evidently changed with significantly slower runs and impaired differentiation of the second labyrinth type in which passage duration, errors and even duration of licking were enhanced. Water intake was less reduced than in CU-rats. Both nuclei include parts of the "mesencephalic locomotor region", but contribute differently to the regulation of spontaneous and goal-directed behaviour.

Animals↗
PubMed1985

Tonic facilitatory influences of dorsal pontine reticular structures on the response gain of limb extensors to sinusoidal labyrinth and neck stimulations.

Experiments were performed to find out whether changes in resting discharge of the inhibitory reticulospinal (RS) neurons of the medulla, produced either by selective destruction or by cholinergic activation of a pontine tegmental reticular system, may modify the response gain of limb extensor muscles to given parameters of roll tilt of the animal or neck rotation. In precollicular decerebrate cats, an electrolytic lesion of the dorsal aspect of the pontine tegmentum, which slightly increased the tonic contraction of limb extensors, greatly decreased the amplitude of the multiunit EMG response of forelimb extensor muscles, i.e. of the medial head of the triceps brachii, to roll tilt of the animal and neck rotation (at 0.15 Hz, +/- 10 degrees), leading to selective stimulation of labyrinth or neck receptors. Correspondingly, the response gain of the forelimb extensors to labyrinth and neck stimulation decreased, but no change in the phase angle of the responses was observed. These findings did not depend on the increased postural activity, since they were still observed in the absence of any change in spontaneous EMG activity of the triceps brachii following the lesion. The changes in posture as well as in response gain of the forelimb extensors to labyrinth and neck stimulation produced by the pontine lesion appeared suddenly, and persisted for several hours throughout the survival period. Moreover, these changes involved mainly, but not exclusively, the limbs ipsilateral to the side of the lesion. Histological controls indicated that the structure responsible for the postural and reflex changes described above corresponded to the dorsal aspect of the pontine tegmentum located immediately ventral to the locus coeruleus (LC); this area corresponded to the peri-LC region as well as the surrounding pontine reticular formation (RF), including the dorsal aspect of the central tegmental field. This region closely corresponds to the area from which a tegmentoreticular tract, ending on the medullary inhibitory area, originates. It was previously shown that unilateral or bilateral lesion of the LC, which decreased the extensor tonus in the ipsilateral limbs, greatly enhanced the response gain of the triceps brachii to sinusoidal stimulation of labyrinth and neck receptors. These findings were attributed to suppression of an inhibitory influence that the LC exerts on the dorsal pontine reticular structures described above.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Cholinergic mechanism controlling the response gain of forelimb extensor muscles to sinusoidal stimulation of macular labyrinth and neck receptors.

The multiunit EMG activity of the triceps brachii was recorded in precollicular decerebrate cats during roll tilt of the animal or neck rotation at the frequencies of 0.026-0.15 Hz and at the peak amplitude of 10 degrees, leading to selective stimulation of labyrinth or neck receptors. The first harmonic component of the EMG responses to labyrinth stimulation was characterized by an increased activity during side-down tilt of the animal and a decreased activity during side-up tilt; however, just the opposite changes were elicited for the same directions of neck rotation. The peak of the responses was closely related to the extreme animal or neck displacement, thus being attributed to stimulation of position-sensitive macular labyrinth and receptors. Moreover, the modulation as well as the gain of the EMG responses were small in amplitude. Intravenous injections of an anticholinesterase at a dose which in some instances slightly decreased the extensor tonus as well as the background activity of the triceps brachii (eserine sulphate, 0.05-0.075 mg/kg), greatly enhanced the response gain of this extensor muscle to animal tilt or neck rotation at the parameters reported above. This finding was also observed in the absence of any decrease in spontaneous EMG activity of the extensor muscle after injection of the anticholinesterase. In no instance did the phase angle of the response change following these injections. The increased gain of the EMG response of the forelimb extensor muscle to sinusoidal stimulation of labyrinth and neck receptors was first observed 5-10 min after the injection and reached the highest value in about one hour. This effect, was not only time-dependent, but also state-dependent. In fact, the increase in response gain described above either did not occur or was negligible during the sudden recovery of the extensor rigidity which occurred either spontaneously or after somatosensory stimulations. The effects elicited by eserine sulphate were reversed within seconds by a 0.1-0.5 mg/kg dose of atropine sulphate, an anticholinergic drug. It is postulated that for the same labyrinthine or neck signal giving rise to excitatory vestibulospinal volleys acting on extensor motoneurons, the amplitude of the EMG modulation of limb extensor muscles depends on the activity of a cholinergic system.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

High resolution Gd-DTPA MR imaging of the inner ear in 60 patients with idiopathic vestibular neuritis: no evidence for contrast enhancement of the labyrinth or vestibular nerve.

Sixty patients with acute idiopathic vestibular neuritis (confirmed by clinical examination and caloric irrigation) were evaluated in a prospective study by high resolution magnetic resonance imaging (hr-MRI) between days 3 and 30 after onset of symptoms. We used a 1.5 Tesla imager with an axial and coronal T1-weighted 2D-fast low angle shot-, T2-weighted turbo spin echo-, and an axial T2-weighted 3D-constructive interference in steady-state sequence for MRI. None of the patients' MRIs exhibited contrast enhancement of the labyrinth, vestibulocochlear nerve, or vestibular ganglion, even when high doses of gadolinium (0.2 mmol/kg) were used. In contrast, several previous studies demonstrated contrast enhancement of the vestibulocochlear nerve/labyrinth in herpes zoster oticus, labyrinthitis, and Cogan's syndrome or of the facial nerve in Bell's palsy. On the basis of our MRI findings, we speculate that idiopathic vestibular neuritis is neither a viral infection directly affecting the nerve (such as herpes zoster) nor a labyrinthitis. An autoimmunological disease of the labyrinth, which should involve only the anterior and horizontal semicircular canals, is also unlikely. A subacute reactivation of a latent viral infection--as discussed for Bell's palsy--is compatible with our MRI findings. The observed differences between contrast enhancement of the facial nerve in Bell's palsy and the vestibulocochlear nerve in vestibular neuritis may be due to their dissimilar anatomy: contrary to the vestibular nerve, the facial nerve has very prominent circumneural arteriovenous structures. Hyperemia within these vascular structures may cause the contrast enhancement seen in Bell's palsy.

Acute Disease↗
PubMed1980

Pathology of congenital syphilitic labyrinthitis.

An alarming increase in the incidence of syphilitic labyrinthitis has prompted us to review the pathology of this condition. The temporal bones of two patients with congenital syphilis of the ear were studied histopathologically. They showed diffuse osteitic changes in the otic capsule associated with severe hydrops and degeneration of the membranous labyrinth. The posterosuperior wall of the external auditory canal as well as the auditory ossicles showed numerous connective tissue filled spaces surrounded by thin bony trabeculae. These lesions probably represent healed luetic osteitis. There was severe degeneration of the sensorineural structures in the cochlea. A finding of particular interest was the infiltration and fibrous obliteration of the ductus endolymphaticus in both cases. The significance of these findings in relation to the pathophysiology and treatment of syphilitic labyrinthitis is emphasized.

Bone Resorption↗