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Biomaterials Advances Apr 2023The outer retina consists of the light-sensitive photoreceptors, the pigmented epithelium, and the choroid, which interact in a complex manner to sustain homeostasis.... (Review)
Review
The outer retina consists of the light-sensitive photoreceptors, the pigmented epithelium, and the choroid, which interact in a complex manner to sustain homeostasis. The organisation and function of these cellular layers are mediated by the extracellular matrix compartment named Bruch's membrane, situated between the retinal epithelium and the choroid. Like many tissues, the retina experiences age-related structural and metabolic changes, which are relevant for understanding major blinding diseases of the elderly, such as age-related macular degeneration. Compared with other tissues, the retina mainly comprises postmitotic cells, making it less able to maintain its mechanical homeostasis over the years functionally. Aspects of retinal ageing, like the structural and morphometric changes of the pigment epithelium and the heterogenous remodelling of the Bruch's membrane, imply changes in tissue mechanics and may affect functional integrity. In recent years, findings in the field of mechanobiology and bioengineering highlighted the importance of mechanical changes in tissues for understanding physiological and pathological processes. Here, we review the current knowledge of age-related changes in the outer retina from a mechanobiological perspective, aiming to generate food for thought for future mechanobiology studies in the outer retina.
Topics: Humans; Aged; Pigment Epithelium of Eye; Retina; Choroid; Bruch Membrane; Macular Degeneration
PubMed: 36801797
DOI: 10.1016/j.bioadv.2023.213343 -
Acta Otorhinolaryngologica Italica :... Apr 2022
Topics: COVID-19; Humans; Nose; Otolaryngology; Pharynx; SARS-CoV-2
PubMed: 35763275
DOI: 10.14639/0392-100X-suppl.1-42-2022-06 -
Slit sense organ distribution on the legs of two species of orb-weaving spider (Araneae: Araneidae).Arthropod Structure & Development Mar 2022Biotic and abiotic mechanical stimuli are ubiquitous in the environment, and are a widely used source of sensory information in arthropods. Spiders sense mechanical...
Biotic and abiotic mechanical stimuli are ubiquitous in the environment, and are a widely used source of sensory information in arthropods. Spiders sense mechanical stimuli using hundreds of slit sense organs (small isolated slits, large isolated slits, groups of slits and lyriform organs) distributed across their bodies and appendages. These slit sense organs are embedded in the exoskeleton and detect cuticular strain. Therefore, the spatial pattern of these sensors can give clues into how mechanical stimuli from different sources might be processed and filtered as they are transmitted through the body. Here, we map the distribution of slit sense organs on the legs in two species of orb-weaving spider, A. diadematus and T. edulis, in which slit sense organ distribution has not previously been investigated. We image the spiders' legs using scanning electron microscopy, and trace the position and orientation of slits on these images to describe the distribution and external morphology of the slit sense organs. We show that both species have a similar distribution of slit sense organs, with small isolated slits occurring in consistent lines parallel to the long axis of the legs, whilst large isolated slits, groups of slits and lyriform organs appear in fixed positions near the leg joints. Our findings support what has been described in the literature for several other species of spider, which indicates that slit organ arrangement is conserved across spiders in different evolutionary lineages and with disparate hunting strategies. The dispersed distribution of small isolated slits along the whole length of the leg may be used to detect large-scale strain of the leg segment as a result of muscle activity or internal changes in haemolymph pressure.
Topics: Animals; Extremities; Microscopy, Electron, Scanning; Sense Organs; Spiders
PubMed: 35137691
DOI: 10.1016/j.asd.2022.101140 -
The Journal of International Advanced... May 2021Self-Contained Underwater Breathing Apparatus (SCUBA) diving is a popular sport. However, improper diving may injure different organs. The majority of dive-related... (Review)
Review
Self-Contained Underwater Breathing Apparatus (SCUBA) diving is a popular sport. However, improper diving may injure different organs. The majority of dive-related disorders concern otolaryngology, and may include hearing loss, tinnitus, aural fullness, disequilibrium, and vertigo. Three main inner ear pathological conditions can occur underwater: inner ear barotrauma (IEB), inner ear decompression sickness (IEDS), and alternobaric vertigo (AV). IEB results from inappropriate equalization of middle ear pressure and consequent inner ear injury produced by pressure changes within the middle ear; IEDS is characterized by the formation of gas bubbles within the vessels of the inner ear during rapid ascent; AV typically develops while ascending or performing the Valsalva maneuver and can follow asymmetrical equalization of middle ear pressure transmitted via the oval and round window membranes. The clinical pictures of these pathological conditions are partly superimposable, even if they have specific peculiarities. Before starting SCUBA diving, a fit-to-dive assessment is recommended. It should include an otolaryngologic examination with audiological assessment to evaluate nasal, middle ear, and tubal patency and to minimize the risk of IEB, IEDS, and AV. It is of utmost importance to identify individual risk factors and predisposing pathological conditions that favor inner ear injury before diving, to prevent acute events and preserve auditory and vestibular functions in SCUBA divers. This review aims to provide an overview of the pathological conditions characterized by inner ear injury in SCUBA divers, discussing their pathogenetic mechanisms, diagnostic work-up, and prevention.
Topics: Barotrauma; Diving; Ear, Inner; Ear, Middle; Humans; Vertigo
PubMed: 34100753
DOI: 10.5152/iao.2021.8892 -
Acta Bio-medica : Atenei Parmensis Nov 2021Vernal keratocongiuntivitis (VKC) is a chronic inflammatory disease affecting the ocular conjunctiva and cornea. It is a rare and underestimated pathology, whose missed... (Review)
Review
Vernal keratocongiuntivitis (VKC) is a chronic inflammatory disease affecting the ocular conjunctiva and cornea. It is a rare and underestimated pathology, whose missed or delayed diagnosis can lead to the development of serious ocular complications. Moreover, despite VKC symptoms are well known, they can overlap and be mistaken with allergic conjunctivitis. In fact, diagnostic criteria and severity grading are not standardized yet. The pathogenesis of VKC is still controversial and it is difficult to identify a single mechanism underlying the chronic ocular inflammation. Different studies hypothesized both allergies and autoimmune diseases and also oxidative stress contribute significantly to the origin of the disease. However, the unclear pathogenesis and the lack of specific disease biomarkers make treatment a challenge. The standard therapy includes antihistamines, anti-inflammatory and immunosuppressant drugs and novel therapies are currently under investigation. However, considering treatment guidelines and recommendations are not well defined yet, therapy should be personalized on the clinical features of the patient. This paper provides an overview of the VKC and updates on the challenges that need to be addressed in the future to improve the management of the patient with this disease and improve his quality of life.
Topics: Anti-Inflammatory Agents; Conjunctiva; Conjunctivitis, Allergic; Histamine Antagonists; Humans; Quality of Life
PubMed: 34842588
DOI: 10.23750/abm.v92iS7.12419 -
Nature Communications Sep 2023Salient objects grab attention because they stand out from their surroundings. Whether this phenomenon is accomplished by bottom-up sensory processing or requires...
Salient objects grab attention because they stand out from their surroundings. Whether this phenomenon is accomplished by bottom-up sensory processing or requires top-down guidance is debated. We tested these alternative hypotheses by measuring how early and in which cortical layer(s) neural spiking distinguished a target from a distractor. We measured synaptic and spiking activity across cortical columns in mid-level area V4 of male macaque monkeys performing visual search for a color singleton. A neural signature of attentional capture was observed in the earliest response in the input layer 4. The magnitude of this response predicted response time and accuracy. Errant behavior followed errant selection. Because this response preceded top-down influences and arose in the cortical layer not targeted by top-down connections, these findings demonstrate that feedforward activation of sensory cortex can underlie attentional priority.
Topics: Animals; Male; Attention; Reaction Time; Parietal Lobe; Sensation; Sense Organs; Macaca; Visual Perception
PubMed: 37752171
DOI: 10.1038/s41467-023-41745-1 -
Journal of Neurophysiology Dec 2019Semicircular canal afferent neurons transmit information about head rotation to the brain. Mathematical models of how they do this have coevolved with concepts of how... (Review)
Review
Semicircular canal afferent neurons transmit information about head rotation to the brain. Mathematical models of how they do this have coevolved with concepts of how brains perceive the world. A 19th-century "camera" metaphor, in which sensory neurons project an image of the world captured by sense organs into the brain, gave way to a 20th-century view of sensory nerves as communication channels providing inputs to dynamical control systems. Now, in the 21st century, brains are being modeled as Bayesian observers who infer what is happening in the world given noisy, incomplete, and distorted sense data. The semicircular canals of the vestibular apparatus provide an experimentally accessible, low-dimensional system for developing and testing dynamical Bayesian generative models of sense data. In this review, we summarize advances in mathematical modeling of information transmission by semicircular canal afferent sensory neurons since the first such model was proposed nearly a century ago. Models of information transmission by vestibular afferent neurons may provide a foundation for developing realistic models of how brains perceive the world by inferring the causes of sense data.
Topics: Animals; Models, Biological; Neurons, Afferent; Semicircular Canals; Vestibule, Labyrinth
PubMed: 31693427
DOI: 10.1152/jn.00087.2019 -
PloS One 2019Proton conductivity is important in many natural phenomena including oxidative phosphorylation in mitochondria and archaea, uncoupling membrane potentials by the...
Proton conductivity is important in many natural phenomena including oxidative phosphorylation in mitochondria and archaea, uncoupling membrane potentials by the antibiotic Gramicidin, and proton actuated bioluminescence in dinoflagellate. In all of these phenomena, the conduction of protons occurs along chains of hydrogen bonds between water and hydrophilic residues. These chains of hydrogen bonds are also present in many hydrated biopolymers and macromolecule including collagen, keratin, chitosan, and various proteins such as reflectin. All of these materials are also proton conductors. Recently, our group has discovered that the jelly found in the Ampullae of Lorenzini- shark's electro-sensing organs- is the highest naturally occurring proton conducting substance. The jelly has a complex composition, but we proposed that the conductivity is due to the glycosaminoglycan keratan sulfate (KS). Here we measure the proton conductivity of hydrated keratan sulfate purified from Bovine Cornea. PdHx contacts at 0.50 ± 0.11 mS cm -1, which is consistent to that of Ampullae of Lorenzini jelly at 2 ± 1 mS cm -1. Proton conductivity, albeit with lower values, is also shared by other glycosaminoglycans with similar chemical structures including dermatan sulfate, chondroitin sulfate A, heparan sulfate, and hyaluronic acid. This observation supports the relationship between proton conductivity and the chemical structure of biopolymers.
Topics: Animals; Cattle; Cornea; Electric Conductivity; Glycosaminoglycans; In Vitro Techniques; Keratan Sulfate; Palladium; Protons; Sense Organs; Sharks
PubMed: 30849116
DOI: 10.1371/journal.pone.0202713 -
Anatomical Record (Hoboken, N.J. : 2007) Jan 2020Here I review, compare, and contrast the neurobiology and behavior of the common, eastern mole (Scalopus aquaticus) and the star-nosed mole (Condylura cristata). These... (Review)
Review
Here I review, compare, and contrast the neurobiology and behavior of the common, eastern mole (Scalopus aquaticus) and the star-nosed mole (Condylura cristata). These two species are part of the same family (Talpidae) and have similar body size and general morphology. But they differ in sensory specializations, complexity of neocortical organization, and behavior. The star-nosed mole has an elaborate mechanosensory organ-the star-consisting of 22 epidermal appendages (rays) covered with 25,000 touch domes called Eimer's organs. This densely innervated structure is represented in the neocortex in three different somatosensory maps, each visible in flattened neocortical sections as a series of 11 modules representing the 11 rays from the contralateral body. The 11th ray is greatly magnified in primary somatosensory cortex (S1). Behavioral studies show the star is moved in a saccadic manner and the 11th ray is a high-resolution tactile fovea, allowing star-nosed moles to forage on small prey with unprecedented speed and efficiency. In contrast, common mole noses lack Eimer's organs, their neocortex contains only two cortical maps of the nose, and they cannot localize small prey. Yet common moles have exceptional olfactory abilities, sniffing in stereo to rapidly localize discrete odor sources originating from larger prey. In addition, common moles are shown to track odorant trails laid down by moving prey. These results highlight the surprising abilities of species once thought to be simple, and the usefulness of diverse species in revealing general principles of brain organization and behavior. Anat Rec, 2019. © 2019 American Association for Anatomy.
Topics: Animals; Behavior, Animal; Brain Mapping; Mechanoreceptors; Moles; Sense Organs; Smell; Touch; Touch Perception
PubMed: 30614659
DOI: 10.1002/ar.24057 -
Eye (London, England) Jun 2023Retinitis pigmentosa (RP) is the commonest inherited retinal dystrophy. It is characterized by progressive photoreceptor degeneration and cell death and ongoing neuronal... (Review)
Review
Retinitis pigmentosa (RP) is the commonest inherited retinal dystrophy. It is characterized by progressive photoreceptor degeneration and cell death and ongoing neuronal and vascular impairment. In recent years, pathophysiological alterations of the choroid have begun to be appreciated in RP. Thus, representing a potential diagnostic and therapeutic biomarker. In particular, choroidal thickness and the choroidal vascularity index can be used to understand the pathogenesis of disease and evaluate new therapeutic possibilities. Photoreceptor changes seen in eyes with RP are directly correlated to a decrease of choroidal flow, leading to a strong association between relative choroidal ischemia and visual impairment. In this review we analyse the literature on choroidal thickness and choroidal vascularity index in patients with RP and assess whether these markers may reflect progression of disease from an anatomical and functional point of view.
Topics: Humans; Tomography, Optical Coherence; Visual Acuity; Choroid; Retinitis Pigmentosa; Biomarkers
PubMed: 36207507
DOI: 10.1038/s41433-022-02270-5