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PubMed1992

Acoustic modulation of neural activity in the preoptic area and ventral hypothalamus of the green treefrog (Hyla cinerea).

Responses of neurons in the preoptic area and ventral hypothalamus to conspecific mating calls or white noise bursts were examined in male green treefrogs (Hyla cinerea) during different seasons. In the winter, 34.3% of preoptic neurons and 46.7% of ventral hypothalamic cells demonstrated significant changes in activity level during presentation of a conspecific mating call. In contrast, only 13.3% of preoptic units and 16.7% of ventral hypothalamic cells responded to the white noise. The percentage of preoptic and hypothalamic units responding to the advertisement call did not differ significantly during the summer breeding season. Type I units exhibited a dramatic increase in activity during acoustic stimulation followed by a rapid return to baseline activity levels after stimulus offset. Type II cells showed a robust activity increase during stimulation, but maintained an intermediate activity level after stimulus offset. In the preoptic area, a third response type exhibited suppressed activity during acoustic stimulation. Although seasonal condition did not alter the percentage of acoustically responsive units within either nucleus, the proportion of Type I units in the ventral hypothalamus was greatest during the summer.

Acoustic Stimulation↗
PubMed1993

Cholinergic neurons in the pedunculopontine tegmental nucleus are involved in the mediation of prepulse inhibition of the acoustic startle response in the rat.

The amplitude of the acoustic startle response (ASR) is markedly reduced when the startle eliciting pulse is preceded by a weak, non-startling stimulus at an appropriate lead time, usually about 100 ms. This phenomenon is termed prepulse inhibition (PPI) and has received considerable attention in recent years as a model of sensorimotor gating. We report here on experiments which were undertaken in order to investigate some of the neural mechanisms of PPI. We focused on the characterization of the cholinergic innervation of the pontine reticular nucleus, caudal part (PnC), an obligatory relay station in the primary startle pathway. The combination of retrograde tracing with choline acetyltransferase-immunocytochemistry revealed a cholinergic projection from the pedunculopontine tegmental nucleus (PPTg) and laterodorsal tegmental nucleus (LDTg) to the PnC. Extracellular recording from single PnC units, combined with microiontophoretic application of the acetylcholine (ACh) agonists acetyl-beta-methylcholine (AMCH) and carbachol revealed that ACh inhibits the majority of acoustically responsive PnC neurons. Neurotoxic lesions of the cholinergic neurons of the PPTg significantly reduced PPI without affecting the ASR amplitude in the absence of prepulses. No effect on long-term habituation of the ASR was observed. The present data indicate that the pathway mediating PPI impinges upon the primary acoustic startle circuit through an inhibitory cholinergic projection from the PPTg to the PnC.

Acoustic Stimulation↗
PubMed1990

ON-OFF units in the mustached bat inferior colliculus are selective for transients resembling "acoustic glint" from fluttering insect targets.

Of 311 single units studied in the central nucleus of the inferior colliculus (ICC) in 18 mustached bats (Pteronotus parnelli), a small but significant population (13%) of cells with on-off discharge patterns to tone bursts at best frequency (BF) was found in the dorsoposterior division. In contrast to units with the same BF's but other discharge patterns, the majority of ON-OFF units were unresponsive to sinusoidally amplitude-modulated tone bursts (SAM). To define the contribution of linear and nonlinear components to the responses of ICC neurons to amplitude modulation, we tested some of these neurons with a long, seamlessly repeating pseudorandom sequence of ternary amplitude-modulated tones at BF. Wiener-like kernels were subsequently derived from cross-correlation of spikes with acoustic events in the sequence. These kernels provided estimates of neural impulse responses that proved unusual in SAM-unresponsive ON-OFF units. First, their estimated impulse response had no linear component. Second, the predicted second-order impulse responses to both increments and decrements in stimulus intensity were long (about 20 ms) and nearly identical in shape: triphasic, with the positive phase bounded by leading and trailing negative periods. The similar shape of responses to increments and decrements in these neurons suggests a full-wave rectifier. The triphasic, initially negative second-order prediction of the impulse response accounted for an unusual result in experiments measuring the recovery cycle of ON-OFF units using a pair of identical stimulus pulses separated by various time delays. This recovery cycle can be related to their response to amplitude modulation. As the delay between two brief, near-threshold BF tone bursts decreased, the response to the first tone diminished, rather than to the second. The second-order prediction of this experiment derived from impulse responses obtained with pseudorandom noise suggests that, at short interpulse intervals, the initial negative phase of the response to the later stimulus cancels the positive phase of the response to the first. Such cancellation at short interpulse intervals may help explain why the majority of ON-OFF units are unresponsive to SAM. The unusual properties of these ON-OFF units make them ideally suited to respond selectively to infrequent acoustic transients superimposed on an ongoing background of modulation. Such patterns are commonly encountered by mustached bats foraging in cluttered habitats for small, fluttering insects, which generate "acoustic glints" upon a background of modulated echoes from the surroundings (Schnitzler et al. 1983; Henson et al. 1987).

Acoustic Stimulation↗
PubMed1989

Distribution and immunoreactivity of cerebral micro-hamartomas in bilateral acoustic neurofibromatosis (neurofibromatosis 2).

Bilateral acoustic neurofibromatosis (neurofibromatosis 2, NF2) accounts for less than 10% of all cases of neurofibromatosis and manifests itself with bilateral acoustic schwannomas, multiple schwannomas of spinal nerve roots, meningiomas, glial tumors and hamartomatous CNS lesions. We have observed dysplastic foci of immature neuroectodermal cells in the cerebral cortex and basal ganglia of six patients afflicted with neurofibromatosis 2, ranging from occasional clusters of immature, dysplastic cells to numerous, confluent lesions. These cells, although often polymorphic and multinuclear did not show mitotic activity or a tendency for neoplastic transformation. To determine the histogenesis of these foci, extensive immunocytochemical reactions were carried out with antibodies to a variety of glial, neuronal and non-neural cell lineages. With the exception of S-100 protein, no immunoreactivity was detectable. S-100 was consistently expressed in these foci, irrespective of their size, location, and degree of polymorphism. On the basis of cytological appearance, distribution and immunoreactivity we tentatively designate these foci as glial micro-hamartomas. Although we did not systematically analyze the CNS of patients with von Recklinghausen neurofibromatosis (neurofibromatosis 1, NF1), the present study strongly suggests that these micro-hamartomas constitute a morphological hallmark of bilateral acoustic neurofibromatosis (NF2).

Adolescent↗
PubMed1982

Acoustic tumour detection with early auditory evoked potentials and neuroradiological methods.

A total of 43 patients with surgically identified acoustic neuromas were tested. Results of early auditory evoked potentials (EAEP) and of neuroradiological methods were analysed. Abnormal EAEPs were observed in all patients. In 73% of the cases the EAEP indicated the retrocochlear site of the lesion; in 27%, however, the results did not localize the exact site of the lesion owing to a lack of waves I, II and III due to a pronounced hearing loss. Neuroradiological procedures provided an indication of the site and extent of the tumour. The number of true positives was 21 of 29 cases with polytomography of the petrous bone, 23 of 28 with computed tomography and in all cases when pontine angle cisternography and computed tomography combined with gas cisternography were performed. The EAEPs provide a screening-test for acoustic tumour detection at an early stage. Wave abnormalities indicative of a lesion at the acoustic nerve should lead to a neuroradiological investigation and are particularly valuable in cases with small intracanalicular tumours.

Adult↗
PubMed1984

Electron microscopical studies on the effect of lapsed time on the nerve endings of the outer hair cells in acoustically exposed rabbits.

Rabbits were exposed to pure tone (2 kHz, 100 dB for 2 h) and the changes in the nerve endings of the outer hair cells over a period of 1 month were studied using the electron microscope. In the afferent nerve endings mitochondria dilated and small vesicles decreased in number immediately after acoustic exposure. However, the afferent nerve endings recovered during the period of 1 month. In the efferent nerve endings mitochondria dilated and were distributed throughout the nerve endings, and small vesicles decreased in number immediately after acoustic exposure. The efferent nerve endings recovered more slowly than afferent nerve endings. In addition, the changes in the agglomerations of synaptic vesicles along the synaptic membrane and the gap-structures in the synaptic cleft in the efferent nerve endings after acoustic exposure are briefly discussed.

Acoustic Stimulation↗
PubMed1978

Reexamination of the acoustic method in measurement of Eustachian tube function.

In order to assess the reliability of the acoustic method in examination of Eustachian tube function, 30 subjects with normal, obstructive or patent tubes were examined twice, by the acoustic method, and by the aerodynamic method which we have developed. The reliability of the aerodynamic method has been confirmed by repeated clinical examinations. 60% of the results of the acoustic method were found to disagree with both the results of the aerodynamic method and the clinical findings of the tested ears. One cause of this disagreement was shown to be the influence of motion accompanying deglutition upon the sound transmission.

Acoustic Stimulation↗
PubMed1981

Metrizamide cisternography in the diagnosis of acoustic neurinomas.

Seventy-three cisternographies with metrizamide were performed on 69 patients, mainly for diagnosis of an acoustic neurinoma. Of the 31 patients with pathological findings on cisternography 26 underwent surgery for 23 acoustic neurinomas, one neurinoma of the facial nerve, and two meningiomas. For diagnosing small tumours of the cerebellopontine cistern, cisternography is superior to all other neuroradiological methods. Tomography of the porus acusticus internus and CT scanning are the initial radiological methods in patients with signs of cerebellopontine angle lesions; if no lesion is disclosed by these two methods cisternography with metrizamide should be performed to exclude a small tumour, particularly a small acoustic neurinoma.

Adolescent↗
PubMed1976

Selective breeding for acoustic priming.

Data on eight generations of selective breeding for acoustic priming efficacy are reported. The realized heritability of this trait is approximately 0.2-0.3, indicating that the trait is determined in part by genetic factors. Animals selectively bred for acoustic priming do not differ in terms of first-trial (i.e., non-priming-induced) audiogenic seizures. These data suggest that acoustic priming and first-trial audiogenic seizures are controlled by different genetic mechanisms.

Acoustic Stimulation↗
PubMedDate not supplied

Reaction of cats to species-specific acoustic signals during electrical stimulation of the hypothalamus before and after ablation of the sensorimotor region of the cortex.

The possibility of the formation under chronic experimental conditions of a reaction of a selective character to species-specific acoustic signals (SAS) of the agonistic type, presented to cats against the background of subthreshold electrical stimulation of hypothalamic divisions, was demonstrated. Reactions appropriate to the SAS presented appeared only in those animals in which threshold electrical stimulation evoked directed aggressive reactions. Partial bilateral ablation of the sensorimotor region of the cortex (SMC) did not influence the selective character of the reaction to the SAS, but led to a change by comparison with the preoperative period in the relationship of the motoric and acoustic reactions of the agonist type to conjoint acoustic and electrical stimulation.

Acoustic Stimulation↗
PubMed1996

Long-term follow-up of the residual intracanalicular tumours after subtotal removal of acoustic neurinomas.

We examined growth potential of residual intracanalicular tumours left from subtotal removal of large acoustic neurinomas. Eleven patients were followed-up by magnetic resonance (MR) imaging. The interval between surgery and MR study ranged from 12 to 29 years (median, 16 years). MR images of two patients showed no evidence of tumour remnant, and in six a small tumour was localized in the internal auditory canal. The other three showed an intracanalicular tumour protruding slightly towards the intracranial portion. This result suggests that the intracanalicular residual tumours have less risk of regrowth after subtotal removal of acoustic neurinomas. It is advisable to choose intracapsular, subtotal removal without opening the internal auditory canal in the treatment of acoustic neurinoma, if it is large in size and there is a high risk of nerve injury.

Adult↗
PubMed1990

Acoustic artifacts and reverberation shadows in gallbladder sonograms: their cause and clinical implications.

From among more than 7000 sonographic examinations of the gallbladder performed over a period of 2 years, different types of acoustic artifacts were observed in 42 patients. Artifacts originated in the gallbladder wall in 37 cases and within the lumen in 5 cases. Eighteen patients had symptoms related to the hepatobiliary area. Twenty-four patients were fully asymptomatic although cholelithiasis was demonstrated in 8. In 21 cases (50%) some type of gallbladder pathology was associated with the presence of acoustic artifacts. Thirteen patients were cholecystectomized and the associated gallbladder pathology consisted of cholelithiasis (N = 5), cholesterolosis (N = 2), adenomyomatosis (N = 2), emphysematous cholecystitis (N = 2), and acute cholecystitis (N = 2). In 3 of these patients a sonographic/pathologic correlation was established. Only 5 of the 18 symptomatic patients presented acoustic artifacts in an otherwise normal gallbladder. Recognition of those pathological conditions favorable to the appearance of artifacts and reverberation shadows is extremely useful for differentiating merely clinically irrelevant anomalies from those that require prompt management.

Acoustics↗
PubMed1980

Acoustic neuroma surgery. Translabyrinthine-transtentorial approach via the middle cranial fossa.

In our approach for acoustic tumors, the method of Morrison and King and that of Bochenek and Kukwa have been modified into one method. This modified method is basically a neuro-otological-neurosurgical team approach, extending the operative field by drilling the temporal bone and cutting the superior petrosal sinus, tentorium, and posterior fossa dura according to the size of the tumor. Therefore, for tumors slightly protruding into the posterior fossa from the prous of the internal auditory canal, only the bone adjacent to it is removed (Bochenek et al's method). For larger tumors, labyrinthectomy and mastoidectomy with the separation of the superior petrosal sinus and the tentorium and posterior fossa dura are also performed. In Morrison et al.'s method, the translabyrinthine approach is done first and the middle cranial fossa approach is performed thereafter. In contrast, in the modified method, drilling the bone from the middle cranial fossa to the tip of the mastoid--labyrinthectomy and mastoidectomy--is the first thing done after elevating the temporal lobe and revealing the middle cranial fossa, and the internal auditory canal is opened thereafter. Thirty-five cases of acoustic tumors and other cerebello-pontine angle tumors were operated on during the past 3.5 years through the middle cranial fossa. Among 30 cases of acoustic tumors, eight cases in which the tumors were confined to the internal auditory canal were operated on through the middle cranial fossa. In four cases, Bochenek et al's method was performed in which bones adjacent to the internal auditory canal and a part of the labyrinth are removed without cutting the superior petrosal sinus. In 23 cases including five cerebellopontine angle tumors, the modified translabyrinthine-transtentorial approach through the middle cranial fossa was done. This modification has the advantage that severe postoperative complications are less frequent. The surgical technique and the results are discussed.

Adolescent↗
PubMed2000

Principles of active acoustic control in gradient coil design.

The new principles of active acoustic control in gradient coil design are introduced and theoretical expressions are developed for the far field acoustic output for a coil system comprising four or more flat rectangular coil sectors. Each sector consists of a split plate arrangement in which are embedded two windings, an outer primary winding and a narrow inner re-entrant loop control winding immediately adjacent to and surrounding the split or air gap. The wire spacing of the control winding is made small so as not to affect substantially the magnetic field created by the primary winding. Experimental results are produced for one sector which show an average difference in acoustic output of 34.9 dB when the control winding is appropriately driven. The theoretical expressions developed are used to fit the experimental data and indicate good agreement with regard to the form of the output response.

Acoustics↗
PubMed1997

Dentistry and speech production. Correlations between the morphology of the articulation zone and acoustics exemplified in /s/ articulation.

Many factors are thought to be responsible for misarticulation. Maxillomandibular or dental irregularities play an important role as one of these factors. Correlations between morphological changes in dental status and speech disorders are well known, but different opinions are discussed in the literature. A reciprocal relationship between dysfunction and various dental irregularities is assumed. The objective of our review and experimental investigations was to document the influence of dental irregularities on speech articulation as exemplified by the second articulation zone and /s/ articulation. The second articulation zone was experimentally changed by application of dental cement to the palatal surface of the upper incisors. Various words were spoken before and just after the change to the frontal teeth. The /s/ articulations were acoustically analyzed by means of sonography and compared with each other. Although this modification of the teeth, which was identical in all probands, leads to /s/ misarticulation from the standpoint of auditory analysis, interindividual differences were recorded by acoustic means. It is thus possible to differentiate objectively between acoustically correct and incorrect /s/ articulation. Speech and articulation are, however, such complex mechanisms that it is impossible to characterize them by simple causal connections with maxillomandibular or dental irregularities.

Acoustics↗
PubMedDate not supplied

A hypothesis regarding vascular acoustic emission accompanying arterial injury induced by balloon angioplasty.

Stress-induced structural damage is often accompanied by sound release. This behavior is known as acoustic emission (AE). We hypothesize that vascular injury such as that produced by balloon angioplasty is associated with AE. Postmortem human peripheral arterial specimens were randomly partitioned into test (n = 10) and control segments (n = 10). Test segments were inserted into a pressurization circuit and subjected to two consecutive hydrostatic pressurizations. Amplitude, frequency, and energy content of the AE signals released during pressurization were quantified. Test and matched control segments subsequently underwent identical histological processing. Pressure-induced tissue trauma was estimated via computerized histomorphometric analysis of the resulting slides (n = 100). Vascular acoustic emission (VAE) signals exhibited an amplitude range of +/- 5.0 mu bars and were observed to occur during periods of increasing intraluminal pressure. The VAE signal power within the monitored bandwidth was concentrated below 350 Hz. More than 25 times as much VAE energy was released during the first pressurization as during the second: 1,855 +/- 513.8 mJ vs. 73 +/- 44.9 mJ (mean +/- SEM, p < 0.006). Estimates of circumferential intimal wall stress at AE onset averaged 170 kPa, slightly below reported values of arterial tissue rupture strength. Histomorphometric estimates of tissue trauma was greater for the test than their matched control segments (p < 0.0001). These preliminary data suggest that detectable acoustic energy is released by vascular tissue subjected to therapeutic stress levels. Histological analysis suggest that the underlying source of sound energy may be related to tissue trauma, independent of histological preparation artifacts. From this preliminary work, we conclude that VAE may be a fundamental property accompanying vascular tissue trauma, which may have applications to improving balloon angioplasty outcomes.

Acoustics↗
PubMed2000

[Effect of microneurosurgical operation in acoustic neurinoma on symptoms of vertigo and tinnitus].

After exstirpation of an acoustic neuroma one trends to concentrated on the preservation of hearing and facial function. But how does the surgical removal for an acoustic neuroma, influence the symptoms of tinnitus and vertigo? Our report follows a retrospective evaluation of 78 patients. Based on these results we will also discuss aspects of the origin of these symptoms. Our patients suffered from tinnitus at a rate of 73% preoperatively and 59% postoperatively. With increasing tumor size tinnitus occurred less often, therefore we considered the size of the tumor exclusively. Also, an intraoperative dissection of the cochlear nerve often did not result in an improvement of the symptoms. Vertigo was stated prooperatively in 44% of the cases, postoperatively in 22%. Again as with tinnitus, there was an inverse relationship between the size of the tumor and the severity of the symptoms. In conclusion a deafferention-like syndrome has to be considered as the major causative factor for the tinnitus in patients with acoustic neuromas. However, in the vertigo cases, the symptoms seem to be caused vestibularily due to the increasing tumor and then after a temporary compensation a cerebellar ataxia occurred which the patients often perceive as vertigo.

Adolescent↗
PubMed2000

[Similarity of monozygotic twins regarding vocal performance and acoustic markers and possible clinical significance].

Auditory similarities in voices of monozygotic twins have already been described in the literature. However, is there a clinical relevance? Thus, the present study was designed to identify parameters of vocal performance and acoustic features which are significantly more similar in monozygotic twins than in non-related persons. In our hypothesis, comparable prerequisites for an increased vocal load in a profession or in an artistic education of the voice could be due to these similarities. We compared intra-pair differences with data from a control group. Moreover, we examined the correlation of intra-pair differences with the age of the monozygotic twins. A greater difference in older twin pairs than in younger pairs could show the effect of an exogene influence. In addition to the few phoniatric studies in twins in the literature, we used current methods for acoustic analysis. We examined seven parameters of vocal performance and three acoustic features in 31 monozygotic twin pairs (median age 36 years, range 18-75 years) and compared them with 30 control group pairs, which consisted of non-related persons of the same age and sex, newly combined from the group of monozygotic twins ("statistical twins"). We found significant differences in seven of ten parameters (vocal range, highest and lowest vocal fundamental frequency, fundamental speaking frequency, maximum voice intensity, number of partials, vibrato of intensity; U-test by Mann-Whitney). No correlation of the differences of the identical twins with age was found in the examined parameters. The voices of identical twins are significantly more similar than those of non-related persons regarding the above mentioned features. Thus, the suitability of the voices of monozygotic twins for professions with a high demand on voice is comparable. Results of the group comparison correlate largely with the literature. The missing correlation with age could be due to the fact that the environmental effects were not measurable, and/or the development of the voice is more influenced by genetic effects.

Adolescent↗