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Experimental Eye Research May 2023The mechanics of accommodation is a complex process that involves multiple intraocular ocular structures. Recent studies suggest that there is deformation of the sclera...
The mechanics of accommodation is a complex process that involves multiple intraocular ocular structures. Recent studies suggest that there is deformation of the sclera during accommodation that may also play a role in accommodation, influencing ciliary muscle contraction and contributing to the accommodative response. However, the type and magnitude of the deformations measured varies significantly across studies. We present high-resolution synchronous OCT measurements of the anterior sclera contour and thickness and lens thickness acquired in real-time during accommodative responses to 4D step stimuli. The lens thickness was used as an assessment of objective accommodation. No changes in nasal and temporal anterior scleral contour and scleral thickness were found during accommodation within the precision of our measurements. Our results demonstrate that there are no significant scleral deformations during accommodation.
Topics: Lens, Crystalline; Sclera; Tomography, Optical Coherence; Accommodation, Ocular; Ciliary Body
PubMed: 36958428
DOI: 10.1016/j.exer.2023.109441 -
Nature Communications Nov 2020Hearing is a crucial sense in underwater environments for communication, hunting, attracting mates, and detecting predators. However, the tools currently used to study...
Hearing is a crucial sense in underwater environments for communication, hunting, attracting mates, and detecting predators. However, the tools currently used to study hearing are limited, as they cannot controllably stimulate specific parts of the auditory system. To date, the contributions of hearing organs have been identified through lesion experiments that inactivate an organ, making it difficult to gauge the specific stimuli to which each organ is sensitive, or the ways in which inputs from multiple organs are combined during perception. Here, we introduce Bio-Opto-Acoustic (BOA) stimulation, using optical forces to generate localized vibrations in vivo, and demonstrate stimulation of the auditory system of zebrafish larvae with precise control. We use a rapidly oscillated optical trap to generate vibrations in individual otolith organs that are perceived as sound, while adjacent otoliths are either left unstimulated or similarly stimulated with a second optical laser trap. The resulting brain-wide neural activity is characterized using fluorescent calcium indicators, thus linking each otolith organ to its individual neuronal network in a way that would be impossible using traditional sound delivery methods. The results reveal integration and cooperation of the utricular and saccular otoliths, which were previously described as having separate biological functions, during hearing.
Topics: Acoustic Stimulation; Acoustics; Animals; Brain; Hearing; Larva; Neurons; Otolithic Membrane; Sound; Vibration; Zebrafish
PubMed: 33257652
DOI: 10.1038/s41467-020-19982-5 -
Neuroscience Letters Sep 2019Acquisition of cell polarity generates signaling and cytoskeletal asymmetry and thus underpins polarized cell behaviors during tissue morphogenesis. In epithelial... (Review)
Review
Acquisition of cell polarity generates signaling and cytoskeletal asymmetry and thus underpins polarized cell behaviors during tissue morphogenesis. In epithelial tissues, both apical-basal polarity and planar polarity, which refers to cell polarization along an axis orthogonal to the apical-basal axis, are essential for epithelial morphogenesis and function. A prime example of epithelial planar polarity can be found in the auditory sensory epithelium (or organ of Corti, OC). Sensory hair cells, the sound receptors, acquire a planar polarized apical cytoskeleton which is uniformely oriented along an axis orthogonal to the longitudinal axis of the cochlear duct. Both cell-intrinsic and tissue-level planar polarity are necessary for proper perception of sound. Here we review recent insights into the novel roles and mechanisms of planar polarity signaling gained from genetic analysis in mice, focusing mainly on the OC but also with some discussions on the vestibular sensory epithelia.
Topics: Animals; Cell Polarity; Ear, Inner; Hair Cells, Auditory; Hair Cells, Auditory, Inner; Humans; Organ of Corti; Stereocilia
PubMed: 31295539
DOI: 10.1016/j.neulet.2019.134373 -
Otolaryngologia Polska = the Polish... May 2020<b>Introduction: </b>Knowledge about the physiology of a healthy middle ear is essential for understanding the activity and mechanics of the ear as well as...
<b>Introduction: </b>Knowledge about the physiology of a healthy middle ear is essential for understanding the activity and mechanics of the ear as well as the basics of ossiculoplasty. Trauma of the epithelial lining of the tympanic cavity as well as the ossicular chain may be the result of chronic inflammation and surgery. Depending on the observed changes of the middle ear lining, there are several types of distinguished chronic inflammatory changes: simple, with cholesteatoma, with the formation of inflammatory granulation tissue, in course of specific diseases. <br><b>Purpose: </b>The aim of the article is presentation of the microstructure and vasculature of the ossicular chain in the Scanning Electron Microscope. Particular attention is drawn to the anatomical aspects of the structure and connections of auditory ossicles as vital elements for reconstruction of the conduction system of the middle ear. <br><b>Material and method: </b>The analysis covered auditory ossicles standardly removed in accordance with the methodology of the investigated surgical procedures. The preparations were evaluated in a scanning electron microscope. <br><b>Results: </b>The exposure of bone surface promotes deep erosion. The advanced process of destruction of bone surface in the case of chronic otitis media correlates with a significant degree of damage to both the lining covering the auditory ossicles and that surrounding articular surfaces. <br><b>Conclusions: </b>(1) The ossicles in the image of the Scanning Electron Microscope are covered with lining. It passes from the surface of the ossicles to the vascular bundles, forming vascular sheaths; (2) Damage to lining continuity on the surface of the auditory ossicles promotes the rapid destruction of bone tissue in the inflammatory process; (3) The dimensions of the individual ossicles are respectively: malleus - 8.36 +/- 0.01, incus - 8.14 +/- 0.0, stapes - 3.23 +/- 0.01 mm. Behavior of the anatomical length of ossicular chain during tympanoplasty appears to be essential to maintaining adequate vibration amplitude of the conductive system of the middle ear.
Topics: Ear Ossicles; Ear, Middle; Female; Humans; Male; Microscopy, Electron, Scanning; Otitis Media; Tympanoplasty
PubMed: 32636350
DOI: 10.5604/01.3001.0014.1373 -
BMC Biology Feb 2021Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These sense organs have characteristic shapes...
Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory, and gustatory reception. These sense organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of sense organs is regulated by specific combinations of transcription factors. In other arthropods, however, sense organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how sense organ diversity has evolved and whether the principles underlying subtype identity in D. melanogaster are representative of other insects. Here, we provide evidence that such principles cannot be generalised, and suggest that sensory organ diversification followed the recruitment of sensory genes to distinct sensory organ specification mechanism. RESULTS: We analysed sense organ development in a nondipteran insect, the flour beetle Tribolium castaneum, by gene expression and RNA interference studies. We show that in contrast to D. melanogaster, T. castaneum sense organs cannot be categorised based on the expression or their requirement for individual or combinations of conserved sense organ transcription factors such as cut and pox neuro, or members of the Achaete-Scute (Tc ASH, Tc asense), Atonal (Tc atonal, Tc cato, Tc amos), and neurogenin families (Tc tap). Rather, our observations support an evolutionary scenario whereby these sensory genes are required for the specification of sense organ precursors and the development and differentiation of sensory cell types in diverse external sensilla which do not fall into specific morphological and functional classes. CONCLUSIONS: Based on our findings and past research, we present an evolutionary scenario suggesting that sense organ subtype identity has evolved by recruitment of a flexible sensory gene network to the different sense organ specification processes. A dominant role of these genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of sense organs, probably modulated by positional cues.
Topics: Animals; Gene Expression; Larva; RNA Interference; Sense Organs; Tribolium
PubMed: 33546687
DOI: 10.1186/s12915-021-00948-y -
The Journal of Physiology Nov 2022
Topics: Retinal Rod Photoreceptor Cells; Retinal Cone Photoreceptor Cells; Electroretinography; Retina; Dark Adaptation
PubMed: 36083438
DOI: 10.1113/JP283652 -
Journal of Integrative Neuroscience Jan 2024Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia. While the diagnosis of PD primarily... (Review)
Review
Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms such as tremors, rigidity, and bradykinesia. While the diagnosis of PD primarily relies on clinical assessments and neurological examination, there has been growing interest in exploring non-invasive imaging techniques to aid in early detection and monitoring of the disease. In recent years, retinal imaging has emerged as a promising tool for studying PD due to the close anatomical and functional similarities between the retina and the brain. Retinal imaging methods, such as spectral domain optical coherence tomography and optical coherence tomography angiography, enable non-intrusive visualization and measurement of retinal structures and blood vessels. These techniques hold the promise of capturing alterations in retinal structure and function that could potentially mirror the underlying pathological mechanisms in PD. This review article aims to provide an overview of the current understanding of retinal changes in PD and the potential utility of retinal imaging as a diagnostic and monitoring tool.
Topics: Humans; Parkinson Disease; Retina; Tomography, Optical Coherence; Brain
PubMed: 38287853
DOI: 10.31083/j.jin2301023 -
Lin Chuang Er Bi Yan Hou Tou Jing Wai... Apr 2021As isolated anatomical position, limited labyrinthine artery supply, and blood-labyrinth barrier hampers systemic drug delivery to the inner ear. The efficient... (Review)
Review
As isolated anatomical position, limited labyrinthine artery supply, and blood-labyrinth barrier hampers systemic drug delivery to the inner ear. The efficient concentration of drug treatment is unsatisfactory and there's possible side effects after systemic administration. Intratympanic injection of drug can bypass the blood-labyrinth and permeated to the hair cells or synaptic area via the round-or oval window of the cochlea. Efficacy and safety of pharmacotherapy has become increasingly relied on the inner ear delivery carrier system. The goal of this review focus on the anatomical barrier that need to be overcome in the intratympanic applications, the improvement of drug retention and specific targets, and the safety of novel drug carriers, these emerging strategies of local drug delivery promise novel and better guidance for the clinical application.
Topics: Cochlea; Drug Carriers; Drug Delivery Systems; Ear, Inner; Round Window, Ear
PubMed: 33794643
DOI: 10.13201/j.issn.2096-7993.2021.04.022 -
Scientific Reports May 2023An adequate blood supply to meet the energy demands is essential for any tissue, particularly for high energy demand tissues such as the retina. A critical question is:...
An adequate blood supply to meet the energy demands is essential for any tissue, particularly for high energy demand tissues such as the retina. A critical question is: How is the dynamic match between neuronal demands and blood supply achieved? We present a quantitative assessment of temporal and spatial variations in perfusion in the macular capillary network in 10 healthy human subjects using a non-invasive and label-free imaging technique. The assessment is based on the calculation of the coefficient of variation (CoV) of the perfusion signal from arterioles, venules and capillaries from a sequence of optical coherence tomography angiography images centred on the fovea. Significant heterogeneity of the spatial and temporal variation was found within arterioles, venules and capillary networks. The CoV values of the capillaries and smallest vessels were significantly higher than that in the larger vessels. Our results demonstrate the presence of significant heterogeneity of spatial and temporal variation within each element of the macular microvasculature, particularly in the capillaries and finer vessels. Our findings suggest that the dynamic match between neuronal demands and blood supply is achieved by frequent alteration of local blood flow evidenced by capillary perfusion variations both spatially and temporally in the macular region.
Topics: Humans; Hemodynamics; Macula Lutea; Fovea Centralis; Retina; Veins
PubMed: 37160984
DOI: 10.1038/s41598-023-33490-8 -
International Journal of Molecular... Feb 2023Parkinson's disease (PD) is a neurodegenerative condition characterized by the progressive deterioration of dopaminergic neurons in the central and peripheral autonomous... (Review)
Review
Parkinson's disease (PD) is a neurodegenerative condition characterized by the progressive deterioration of dopaminergic neurons in the central and peripheral autonomous system and the intraneuronal cytoplasmic accumulation of misfolded α-synuclein. The clinical features are the classic triad of tremor, rigidity, and bradykinesia and a set of non-motor symptoms, including visual deficits. The latter seems to arise years before the onset of motor symptoms and reflects the course of brain disease. The retina, by virtue of its similarity to brain tissue, is an excellent site for the analysis of the known histopathological changes of PD that occur in the brain. Numerous studies conducted on animal and human models of PD have shown the presence of α-synuclein in retinal tissue. Spectral-domain optical coherence tomography (SD-OCT) could be a technique that enables the study of these retinal alterations in vivo. The objective of this review is to describe recent evidence on the accumulation of native or modified α-synuclein in the human retina of patients with PD and its effects on the retinal tissue evaluated through SD-OCT.
Topics: Animals; Humans; alpha-Synuclein; Brain; Parkinson Disease; Retina; Tremor
PubMed: 36901822
DOI: 10.3390/ijms24054391