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Communications Biology Sep 2022The olfactory nerve map describes the topographical neural connections between the olfactory epithelium in the nasal cavity and the olfactory bulb. Previous studies have...
The olfactory nerve map describes the topographical neural connections between the olfactory epithelium in the nasal cavity and the olfactory bulb. Previous studies have constructed the olfactory nerve maps of rodents using histological analyses or transgenic animal models to investigate olfactory nerve pathways. However, the human olfactory nerve map remains unknown. Here, we demonstrate that high-field magnetic resonance imaging and diffusion tensor tractography can be used to visualize olfactory sensory neurons while maintaining their three-dimensional structures. This technique allowed us to evaluate the olfactory sensory neuron projections from the nasal cavities to the olfactory bulbs and visualize the olfactory nerve maps of humans, marmosets and mice. The olfactory nerve maps revealed that the dorsal-ventral and medial-lateral axes were preserved between the olfactory epithelium and olfactory bulb in all three species. Further development of this technique might allow it to be used clinically to facilitate the diagnosis of olfactory dysfunction.
Topics: Animals; Humans; Magnetic Resonance Imaging; Mice; Olfactory Bulb; Olfactory Mucosa; Olfactory Nerve; Olfactory Pathways
PubMed: 36068329
DOI: 10.1038/s42003-022-03794-y -
Diagnostic and Interventional Imaging Oct 2013Any dysfunction in olfaction requires a radiological exploration comprising the nasal cavity, the anterior base of the skull, in particular the frontal and temporal... (Review)
Review
Any dysfunction in olfaction requires a radiological exploration comprising the nasal cavity, the anterior base of the skull, in particular the frontal and temporal lobes. MRI is the reference examination, due to the frontal plane and the T1, T2 volume maps. In the child, aplasia of the olfactory bulbs falls within a polymalformation (CHARGE) or endocrine (Kallman) context. In the adult, rhino sinus disease and meningiomas are the most common etiologies. Frontal or temporal impairment: tumoral or vascular and neurodegenerative disorders (Parkinson's disease) may accompany a loss of olfaction.
Topics: Adult; CHARGE Syndrome; Child; Cranial Nerve Neoplasms; Diagnosis, Differential; Frontal Lobe; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Kallmann Syndrome; Magnetic Resonance Imaging; Olfaction Disorders; Olfactory Bulb; Olfactory Nerve; Olfactory Nerve Diseases; Parkinson Disease; Temporal Lobe
PubMed: 23932763
DOI: 10.1016/j.diii.2013.06.006 -
Journal of Korean Neurosurgical Society Feb 2009Intracranial schwannomas preferentially arise from the vestibular branch of the eighth nerve, and rarely from the trigeminal nerve, facial nerve, and lower cranial...
Intracranial schwannomas preferentially arise from the vestibular branch of the eighth nerve, and rarely from the trigeminal nerve, facial nerve, and lower cranial nerves. Anterior cranial fossa schwannomas are extremely uncommon and few details about them have been reported. The patient was a 39-year-old woman whose chief complaints were anosmia and frontal headache for 2 years. The gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) showed an extra-axial mass from ethmoid sinus to right frontal base region near the midline, with solid enhancement in lower portion and multicystic formation in upper portion. The tumor was totally resected via basal subfrontal approach. At operation, the tumor had cystic portion with marginal calcification and the anterior skull base was destructed by the tumor. The olfactory bulb was involved, and the tumor capsule did not contain neoplastic cells. The histopathological diagnosis was schwannoma. We report a rare case of anterior cranial fossa schwannoma with literature review.
PubMed: 19274121
DOI: 10.3340/jkns.2009.45.2.103 -
Anatomical Record (Hoboken, N.J. : 2007) Mar 2019The olfactory nerve constitutes the first cranial pair. Compared with other cranial nerves, it depicts some atypical features. First, the olfactory nerve does not form a...
The olfactory nerve constitutes the first cranial pair. Compared with other cranial nerves, it depicts some atypical features. First, the olfactory nerve does not form a unique bundle. The olfactory axons join other axons and form several small bundles or fascicles: the fila olfactoria. These fascicles leave the nasal cavity, pass through the lamina cribrosa of the ethmoid bone and enter the brain. The whole of these fascicles is what is known as the olfactory nerve. Second, the olfactory sensory neurons, whose axons integrate the olfactory nerve, connect the nasal cavity and the brain without any relay. Third, the olfactory nerve is composed by unmyelinated axons. Fourth, the olfactory nerve contains neither Schwann cells nor oligodendrocytes wrapping its axons. But it contains olfactory ensheathing glia, which is a type of glia unique to this nerve. Fifth, the olfactory axons participate in the circuitry of certain spherical structures of neuropil that are unique in the brain: the olfactory glomeruli. Sixth, the axons of the olfactory nerve are continuously replaced and their connections in the central nervous system are remodeled continuously. Therefore, the olfactory nerve is subject to lifelong plasticity. Finally seventh, the olfactory nerve can be a gateway for the direct entrance of viruses, neurotoxins and other xenobiotics to the brain. In the same way, it can be used as a portal of entry to the brain for therapeutic substances, bypassing the blood-brain barrier. In this article, we analyze some features of the anatomy and physiology of the first cranial pair. Anat Rec, 302:405-427, 2019. © 2018 Wiley Periodicals, Inc.
Topics: Animals; Brain; Cranial Nerves; Humans; Olfactory Nerve; Olfactory Receptor Neurons
PubMed: 29659152
DOI: 10.1002/ar.23816 -
Acta Anatomica 1998The olfactory system is a highly plastic region of the nervous system. Continuous remodeling of neuronal circuits in the olfactory bulb takes place throughout life as a... (Review)
Review
The olfactory system is a highly plastic region of the nervous system. Continuous remodeling of neuronal circuits in the olfactory bulb takes place throughout life as a result of constant turnover of primary sensory olfactory neurons in the periphery. Glycoconjugates are very important in olfactory development, regeneration and function. This article deals with different aspects of glycobiology relevant for the olfactory system. Various anatomical, developmental and functional subdivisions of the olfactory system have been labeled with exogenous lectins. The application of reverse lectin histochemistry resulted in the visualization of endogenous lectins, involved in fasciculation of olfactory axons. Numerous glycoproteins, among them members of the immunoglobulin superfamily, the cadherins and integrins as well as different glycolipids and proteoglycans can act as surface adhesion molecules in the olfactory system. The olfactory-specific form of the sialoglycoprotein neural cell adhesion molecule is implicated in olfactory neuronal and axonal guidance. Glycoconjugates including laminin, fibronectin and proteoglycans are abundant components of the olfactory extracellular matrix, influencing neurite outgrowth and cellular migration. Immunohistochemical labeling has revealed occurrence of the carbohydrate differentiation antigen, playing a role in neurulation and morphogenesis of the very early olfactory system. The synaptic vesicle glycoprotein, appearing also early in olfactory development, is used as a marker of olfactory tumors. Finally, membrane and transmembrane glycoconjugates as well as secreted glycoconjugates may act as olfactory receptor molecules.
Topics: Animals; Cell Adhesion; Cell Differentiation; Cell Movement; Glycoconjugates; Histocytochemistry; Lectins; Mice; Neurons; Olfactory Bulb; Olfactory Nerve; Olfactory Pathways; Vomeronasal Organ
PubMed: 9780362
DOI: 10.1159/000046461 -
Cell Transplantation 2014Olfactory ensheathing cells (OECs) are unique glia cells restricted to the primary olfactory system including the olfactory mucosa, olfactory nerve, and the outer nerve... (Review)
Review
Olfactory ensheathing cells (OECs) are unique glia cells restricted to the primary olfactory system including the olfactory mucosa, olfactory nerve, and the outer nerve layer of the olfactory bulb. OECs guide growing olfactory axons from the neurons of the nasal cavity olfactory mucosa to the olfactory bulb to connect both the peripheral nervous system (PNS) and central nervous system (CNS). Based on these specialized abilities of OECs, transplantation of OECs to injury sites has been widely investigated for their potential therapeutic applications in neural repair in different injuries. In this article, we reviewed the properties of OECs and their roles in olfactory regeneration and in treatment of different injuries including spinal cord injury, PNS injury, and stroke and neurodegenerative diseases.
Topics: Animals; Cell Adhesion Molecules; Nerve Regeneration; Nervous System Diseases; Neuroglia; Olfactory Bulb; Olfactory Mucosa; Olfactory Nerve; Regenerative Medicine; Spinal Cord Injuries
PubMed: 24816451
DOI: 10.3727/096368914X678508 -
PLoS Neglected Tropical Diseases Jan 2020The infectious disease melioidosis is caused by the bacterium Burkholderia pseudomallei. Melioidosis is characterised by high mortality and morbidity and can involve the...
The infectious disease melioidosis is caused by the bacterium Burkholderia pseudomallei. Melioidosis is characterised by high mortality and morbidity and can involve the central nervous system (CNS). We have previously discovered that B. pseudomallei can infect the CNS via the olfactory and trigeminal nerves in mice. We have shown that the nerve path is dependent on mouse strain, with outbred mice showing resistance to olfactory nerve infection. Damage to the nasal epithelium by environmental factors is common, and we hypothesised that injury to the olfactory epithelium may increase the vulnerability of the olfactory nerve to microbial insult. We therefore investigated this, using outbred mice that were intranasally inoculated with B. pseudomallei, with or without methimazole-induced injury to the olfactory neuroepithelium. Methimazole-mediated injury resulted in increased B. pseudomallei invasion of the olfactory epithelium, and only in pre-injured animals were bacteria found in the olfactory nerve and bulb. In vitro assays demonstrated that B. pseudomallei readily infected glial cells isolated from the olfactory and trigeminal nerves (olfactory ensheathing cells and trigeminal Schwann cells, respectively). Bacteria were degraded by some cells but persisted in other cells, which led to the formation of multinucleated giant cells (MNGCs), with olfactory ensheathing cells less likely to form MNGCs than Schwann cells. Double Cap mutant bacteria, lacking the protein BimA, did not form MNGCs. These data suggest that injuries to the olfactory epithelium expose the primary olfactory nervous system to bacterial invasion, which can then result in CNS infection with potential pathogenic consequences for the glial cells.
Topics: Animals; Antithyroid Agents; Burkholderia pseudomallei; Genes, Reporter; Giant Cells; Humans; Melioidosis; Methimazole; Mice; Mice, Transgenic; Olfactory Bulb; Olfactory Nerve; Respiratory Mucosa; S100 Calcium Binding Protein beta Subunit
PubMed: 31978058
DOI: 10.1371/journal.pntd.0008017 -
Journal of Bioenergetics and... Feb 2019Most animals depend upon olfaction to find food, mates, and to avoid predators. An animal's olfactory circuit helps it sense its olfactory environment and generate... (Review)
Review
Most animals depend upon olfaction to find food, mates, and to avoid predators. An animal's olfactory circuit helps it sense its olfactory environment and generate critical behavioral responses. The general architecture of the olfactory circuit, which is conserved across species, is made up of a few different neuronal types including first-order receptor neurons, second- and third-order neurons, and local interneurons. Each neuronal type differs in their morphology, physiology, and neurochemistry. However, several recent studies have suggested that there is intrinsic diversity even among neurons of the same type and that this diversity is important for neural function. In this review, we first examine instances of intrinsic diversity observed among individual types of olfactory neurons. Next, we review potential genetic and experience-based plasticity mechanisms that underlie this diversity. Finally, we consider the implications of intrinsic neuronal diversity for circuit function. Overall, we hope to highlight the importance of intrinsic diversity as a previously underestimated property of circuit function.
Topics: Animals; Humans; Interneurons; Neuronal Plasticity; Olfactory Nerve; Olfactory Receptor Neurons
PubMed: 30604088
DOI: 10.1007/s10863-018-9779-3 -
International Journal of Molecular... Jan 2017The peripheral nervous system (PNS) exhibits a much larger capacity for regeneration than the central nervous system (CNS). One reason for this difference is the... (Review)
Review
The peripheral nervous system (PNS) exhibits a much larger capacity for regeneration than the central nervous system (CNS). One reason for this difference is the difference in glial cell types between the two systems. PNS glia respond rapidly to nerve injury by clearing debris from the injury site, supplying essential growth factors and providing structural support; all of which enhances neuronal regeneration. Thus, transplantation of glial cells from the PNS is a very promising therapy for injuries to both the PNS and the CNS. There are two key types of PNS glia: olfactory ensheathing cells (OECs), which populate the olfactory nerve, and Schwann cells (SCs), which are present in the rest of the PNS. These two glial types share many similar morphological and functional characteristics but also exhibit key differences. The olfactory nerve is constantly turning over throughout life, which means OECs are continuously stimulating neural regeneration, whilst SCs only promote regeneration after direct injury to the PNS. This review presents a comparison between these two PNS systems in respect to normal physiology, developmental anatomy, glial functions and their responses to injury. A thorough understanding of the mechanisms and differences between the two systems is crucial for the development of future therapies using transplantation of peripheral glia to treat neural injuries and/or disease.
Topics: Animals; Cell Transplantation; Homeostasis; Humans; Immunomodulation; Inflammation; Nerve Regeneration; Neuroglia; Olfactory Bulb; Olfactory Nerve; Peripheral Nerve Injuries; Schwann Cells; Sensory Receptor Cells; Signal Transduction
PubMed: 28146061
DOI: 10.3390/ijms18020287 -
Sensors (Basel, Switzerland) Jan 2023A new hypothesis for the mechanism of olfaction is presented. It begins with an odorant molecule binding to an olfactory receptor. This is followed by the quantum...
A new hypothesis for the mechanism of olfaction is presented. It begins with an odorant molecule binding to an olfactory receptor. This is followed by the quantum biology event of inelastic electron tunneling as has been suggested with both the vibration and swipe card theories. It is novel in that it is not concerned with the possible effects of the tunneled electrons as has been discussed with the previous theories. Instead, the high energy state of the odorant molecule in the receptor following inelastic electron tunneling is considered. The hypothesis is that, as the high energy state decays, there is fluorescence luminescence with radiative emission of multiple photons. These photons pass through the supporting sustentacular cells and activate a set of olfactory neurons in near-simultaneous timing, which provides the temporal basis for the brain to interpret the required complex combinatorial coding as an odor. The Luminescence Hypothesis of Olfaction is the first to present the necessity of or mechanism for a 1:3 correspondence of odorant molecule to olfactory nerve activations. The mechanism provides for a consistent and reproducible time-based activation of sets of olfactory nerves correlated to an odor. The hypothesis has a biological precedent: an energy feasibility assessment is included, explaining the anosmia seen with COVID-19, and can be confirmed with existing laboratory techniques.
Topics: Humans; Smell; Luminescence; COVID-19; Olfactory Receptor Neurons; Odorants; Receptors, Odorant
PubMed: 36772376
DOI: 10.3390/s23031333