Reconstruction of sound driven, actively amplified and spontaneous motions within the tree cricket auditory organ

Hearing consists of a delicate chain of events. Sound is first captured by an eardrum or similar organ which is set into vibrations, these vibrations must then be transmitted to sensory cells in a manner that opens mechanosensory channels generating an electrical signal. Studying this process is challenging. Auditory vibrations are in the nano- to picometer-scale and occur at fast temporal scales of milli to microseconds. Finally, most of this process occurs within the body of the animal where it is inaccessible to conventional measurement techniques. For instance, even in crickets, a century-old auditory model system, it is unclear how sound evoked vibrations are transmitted to sensory neurons. Here, we use optical coherence tomography (OCT) to measure how vibrations travel within the auditory organ of the western tree cricket (Oecanthus californicus). We also measure the reversal of this process as mechanosensory cells generate spontaneous oscillations and amplify sound-evoked vibrations. Most importantly, we found that while the mechanosensory neurons were not attached to the peripheral sound collecting structures, they were mechanically well-coupled through acoustic trachea. Thus, the acoustic trachea are not merely conduits for sound but also perform a mechanical function. Our results generate several insights into the similarities between insect and vertebrate hearing, and into the evolutionary history of auditory amplification.

IE-Map: a novel in-vivo atlas and template of the human inner ear

Brain atlases and templates are core tools in scientific research with increasing importance also in clinical applications. Advances in neuroimaging now allowed us to expand the atlas domain to the vestibular and auditory organ, the inner ear. In this study, we present IE-Map, an in-vivo template and atlas of the human labyrinth derived from multi-modal high-resolution magnetic resonance imaging (MRI) data, in a fully non-invasive manner without any contrast agent or radiation. We reconstructed a common template from 126 inner ears (63 normal subjects) and annotated it with 94 established landmarks and semi-automatic segmentations of all relevant macroscopic vestibular and auditory substructures. We validated the atlas by comparing MRI templates to a novel CT/micro-CT atlas, which we reconstructed from 21 publicly available post-mortem images of the bony labyrinth. Templates in MRI and micro-CT have a high overlap, and several key anatomical measures of the bony labyrinth in IE-Map are in line with micro-CT literature of the inner ear. A quantitative substructural analysis based on the new template, revealed a correlation of labyrinth parameters with total intracranial volume. No effects of gender or laterality were found. We provide the validated templates, atlas segmentations, surface meshes and landmark annotations as open-access material, to provide neuroscience researchers and clinicians in neurology, neurosurgery, and otorhinolaryngology with a widely applicable tool for computational neuro-otology.

METHODOLOGY OF OBJECTIVE EVALUATION OF THE QUALITY BEARINGS BY VIBRO-ACOUSTICS AND ITS COMPARISON WITH A SUBJECTIVE METHOD

The quality of bearing production has an impact not only on their reliability and lifetime, but also on the dynamic load of the working and living environment by excessive vibration and thus also noise. The intensity of the noise emitted by a bearing which is perceived by man characterizes the quality of its production. Reducing the dynamic load of mechanical systems and their components is reflected in the working environment by reducing noise emissions and immissions. The article proposes an objective method of bearing quality assessment based on measuring vibro-acoustic parameters of dynamic load of a new bearing using FFT analysis and the magnitude of the amplitude of bearing vibration acceleration and compares it with a subjective method that also uses the human auditory organ to assess bearing quality. The results of vibro-acoustic measurements were analysed in terms of vibration intensity and the noise of the produced bearings. The proposed objective methodology was compared with the subjective evaluation of the quality of bearings and the results of this methodology matched. The proposed methodology is applicable to all types of bearings, and it is possible to automate this methodology in the production process.

Influence of music and color spectrum on the nervous system of humans and animals

Several years ago, I published articles in Russian and German languages about the influence of music on humans and animals. Then, in 1897, I again published in Russian The Influence of Music on Man and Animals. In this 2nd edition there is a more detailed description of the structure of the auditory organ, the human larynx and the hearing aid of some animals; a few remarks about notation, about more well-known musical instruments, about the meaning of music in educational, medical and social relations.

let-7 miRNAs inhibit CHD7 expression and control auditory-sensory progenitor cell behavior in the developing inner ear

ABSTRACTThe evolutionarily conserved lethal-7 (let-7) microRNAs (miRNAs) are well-known activators of proliferative quiescence and terminal differentiation. However, in the murine auditory organ, let-7g overexpression delays the differentiation of mechano-sensory hair cells (HCs). To address whether the role of let-7 in auditory-sensory differentiation is conserved among vertebrates, we manipulated let-7 levels within the chicken auditory organ: the basilar papilla. Using a let-7 sponge construct to sequester let-7 miRNAs, we found that endogenous let-7 miRNAs are essential for limiting the self-renewal of HC progenitor cells. Furthermore, let-7b overexpression experiments revealed that, similar to mice, higher than normal let-7 levels slow/delay HC differentiation. Finally, we identify CHD7, a chromatin remodeler, as a candidate for mediating the repressive function of let-7 in HC differentiation and inner ear morphogenesis. Our analysis uncovered an evolutionarily conserved let-7-5p-binding site within the chicken Chd7 gene and its human and murine homologs, and we show that let-7g overexpression in mice limits CHD7 expression in the developing inner ear, retina and brain. Haploinsufficiency of CHD7 in humans causes CHARGE syndrome and attenuation of let-7 function may be an effective method for treating CHD7 deficiency.

IE-Map: A novel in-vivo atlas template of the human inner ear

Brain atlases and templates are core tools in scientific research with increasing importance also in clinical applications. Advances in neuroimaging now allowed us to expand the atlas domain to the vestibular and auditory organ, the inner ear. In this study, we present IE-Map, an in-vivo template and atlas of all known substructures of the human labyrinth derived from multi-modal high-resolution magnetic resonance imaging data in a non-invasive manner (no contrast agent or radiation). We reconstructed a common template from 126 inner ears (63 normal subjects) and annotated it with 94 established landmarks and semi-automatic segmentations. Quantitative substructure analysis revealed a correlation of labyrinth parameters with total intracranial volume. No effects of gender or laterality were found. We provide the validated templates, atlas segmentations, surface meshes and landmark annotations as open-access material, to provide neuroscience researchers and clinicians in neurology, neurosurgery, and otorhinolaryngology with a widely applicable tool for computational neurootology.

What determines the number of auditory sensilla in the tympanal hearing organs of Tettigoniidae? Perspectives from comparative neuroanatomy and evolutionary forces

Insects have evolved complex receptor organs for the major sensory modalities. For the sense of hearing, the tympanal organ of Tettigoniidae (bush crickets or katydids) shows remarkable convergence to vertebrate hearing by impedance conversion and tonotopic frequency analysis. The main auditory receptors are scolopidial sensilla in the crista acustica. Morphological studies established that the numbers of auditory sensilla are species-specific. However, the factors determining the specific number of auditory sensilla are not well understood. This review provides an overview of the functional organization of the auditory organ in Tettigoniidae, including the diversification of the crista acustica sensilla, a list of species with the numbers of auditory sensilla, and a discussion of evolutionary forces affecting the number of sensilla in the crista acustica and their sensitivity. While all species of Tettigoniidae studied so far have a crista acustica, the number of sensilla varies on average from 15–116. While the relative differences or divergence in sensillum numbers may be explained by adaptive or regressive changes, it is more difficult to explain a specific number of sensilla in the crista acustica of a specific species (like for the model species Ancistrura nigrovittata, Copiphora gorgonensis, Gampsocleis gratiosa, Mecopoda elongata, Requena verticalis, or Tettigonia viridissima): sexual and natural selection as well as allometric relationships have been identified as key factors influencing the number of sensilla. Sexual selection affects the number of auditory sensilla in the crista acustica by the communication system and call patterns. Further, positive allometric relationships indicate positive selection for certain traits. Loss of selection leads to evolutionary regression of the auditory system and reduced number of auditory sensilla. This diversity in the auditory sensilla can be best addressed by comparative studies reconstructing adaptive or regressive changes in the crista acustica.

Research of influence of working conditions on workers in foundries

The working conditions of workers in foundries and their impact on occupational illness are considered. The results of the distribution of occupational diseases in the casting departments and according to professions working in foundries are given. It was found that the working conditions of foundrymen lead to such occupational diseases as silicosis and dust bronchitis, vibration disease and neuritis of the auditory organ. It is noted that about 60% of vibration disease, about 40% of neuritis of the auditory organ, about 80% of silicosis and dust bronchitis from the total number of similar occupational diseases in machine-building enterprises account for workers in foundries.

Let-7 miRNAs control auditory sensory progenitor behavior in the vertebrate inner ear

ABSTRACTThe evolutionary conserved lethal-7 (let-7) family of microRNAs (miRNAs) is a well-known activator of terminal mitosis and differentiation. Surprisingly, we previously found that overexpression of let-7 miRNAs in the murine auditory organ accelerated the terminal mitosis of auditory sensory progenitors (pro-sensory cells) but failed to stimulate their differentiation into mechano-sensory hair cells (HCs). To further address the role of let-7 miRNAs in auditory sensory differentiation, we conducted gain and loss of function experiments in the developing chicken auditory organ, the basilar papilla (BP). Using a sponge approach, we show that the disruption of let-7 miRNA function in the developing BP delays pro-sensory cell exit and delays differentiation of auditory HCs, revealing that endogenous let-7 miRNAs limit pro-sensory cell self-renewal in the developing BP. However, consistent with the role of let-7 miRNAs in the murine auditory organ, let-7b overexpression in the developing BP delayed HC differentiation, suggesting that too low or too high let-7 miRNA levels disrupt HC differentiation. Furthermore, we provide evidence that the repressive role of let-7 miRNAs in HC differentiation may be due to its targeting of the chromatin remodeler CHD7. Mutation in the human CHD7 gene causes CHARGE syndrome, which amongst others is characterized by inner ear and hearing deficits. Using target prediction algorithms, we uncovered a highly predictive and evolutionary conserved let-7 binding site within the Chd7 transcript. Consistent with being a target of let-7 repression, we demonstrate that let-7b overexpression significantly reduced CHD7 protein expression in to the developing BP. Furthermore, utilizing an inducible let-7g transgenic mouse model, we show that let-7 miRNAs negatively regulate CHD7 protein expression in developing murine cochlear, retinal and brain tissue. CHD7 is dosage dependent and the here described regulation by let-7 miRNAs may be critical to fine tune CHD7 protein levels during sensory and neuronal development.SIGNIFICANCEThe evolutionary highly conserved let-7 miRNAs are essential for proper timing of cell state transitions during embryogenesis. Even though abundantly expressed in the vertebrate auditory organ, surprisingly little is known about their function in auditory sensory differentiation. Here, we demonstrate that endogenous let-7 miRNAs are essential for limiting auditory sensory progenitor (pro-sensory) cell self-renewal. Furthermore, we find that precocious let-7 miRNAs expression interferes with auditory hair cell differentiation and identify chromatin remodeler CHD7 as a potential target gene of let-7 repressive function in HC differentiation.