article{cd7f6278-687b-4a1d-9f0d-d122c28d5b7f, abstract = {Postnatal neurogenesis takes place in two brain regions, the hippocampus and the subventricular zone (SVZ). The transcriptional cascade controlling hippocampal neurogenesis has been described in detail; however, the transcriptional control of olfactory bulb neurogenesis is still not well mapped. In this study, we provide insights into the molecular events controlling postnatal olfactory bulb neurogenesis. We first show the existence of diverse neural stem cell/progenitor populations along the SVZ-rostral migratory stream (RMS) axis, focusing on those expressing the basic helix-loop-helix (bHLH) transcription factor Mash1. We provide evidence that Mash1-derived progenies generate oligodendrocytic and neuronal precursors through the transient expression of the bHLH transcription factors Olig2 and neurogenin2 (Ngn2), respectively. Furthermore, we reveal that Ngn2-positive progenies express the T-box transcription factors Tbr2 and Tbr1, which ...
New olfactory bulb granule cells (GCs) are GABAergic interneurons continuously arising from neuronal progenitors and integrating into preexisting bulbar circuits. They receive both GABAergic and glutamatergic synaptic inputs from olfactory bulb intrinsic neurons and centrifugal afferents. Here, we investigated the spatiotemporal dynamic of newborn GC synaptogenesis in adult mouse olfactory bulb. First, we established that GABAergic synapses onto mature GC dendrites contain the GABA(A) receptor alpha2 subunit along with the postsynaptic scaffolding protein gephyrin. Next, we characterized morphologically and electrophysiologically the development of GABAergic and glutamatergic inputs onto newborn GCs labeled with eGFP (enhanced green fluorescent protein) using lentiviral vectors. Already when reaching the GC layer (GCL), at 3 d post-vector injection (dpi), newborn GCs exhibited tiny voltage-dependent sodium currents and received functional GABAergic and glutamatergic synapses, recognized ...
TY - JOUR. T1 - Olfactory bulbectomy induced oxidative and cell damage in rat. T2 - Protective effect of melatonin. AU - Tasset, Inmaculada. AU - Medina, F. J.. AU - Peña, J.. AU - Jimena, I.. AU - muñoz, M. del Carmen. AU - Salcedo, M.. AU - Ruiz, C.. AU - Feijóo, M.. AU - Montilla, P.. AU - Túnez, I.. PY - 2010. Y1 - 2010. N2 - In this study we analyzed the effects of melatonin (Mel, 1 mg/kgip) on behavioral changes as well as cell and oxidative damage prompted by bilaterally olfactory bulbectomy. Olfactory bulbectomy caused an increase in lipid peroxidation products and caspase-3, whereas it prompted a decrease of reduced glutathione (GSH) content and antioxidative enzymes activities. Additionally, olfactory bulbectomy induced behavioral changes characterized by the enhancement of immobility time in the forced swim test and hyperactivity in the open field test. All these changes were normalized by treatment of Mel (14 days). Our data show that Mel has a beneficial neuropsychiatric action ...
What triggered release from calcium stores in GC spines? Application of 50 μm APV and 100 μm Ni2+ completely blocked the synaptic Ca2+ transient in all spines examined [7 ± 10% of control; mean (ΔF/F)syn, 2 ± 3%; n = 5; p , 0.05; χ2 test] (Fig. 5B,D), although it had little effect on the corresponding EPSP amplitudes (80 ± 16% of control; p , 0.09) (Fig. 5B,C). Thus, internal stores are activated via calcium-induced calcium release (CICR) rather than via the metabotropic glutamate receptor/IP3 pathway. This manipulation also showed that other possible ligandgated sources of synaptically gated calcium, in particular calcium-permeable AMPA receptors, play no significant role.. For spines of cultured hippocampal neurons, it has been suggested that CICR carries most of the Ca2+ signal and is triggered by an NMDA-R-mediated Ca2+ signal too small for detection (Emptage et al., 1999). Could the APV-sensitive component of the Ca2+ transient in GC spines be attributable to NMDA-R triggered CICR ...
In mammals, new neurons in the adult olfactory bulb originate from a pool of neural stem cells in the subventricular zone of the lateral ventricles. Adult-born cells play an important role in odor information processing by adjusting the neuronal network to changing environmental conditions. Olfactory bulb neurogenesis is supported by several non-neuronal cells. In this review, we focus on the role of astroglial cells in the generation, migration, integration and survival of new neurons in the adult forebrain. In the subventricular zone, neural stem cells with astrocytic properties display regional and temporal specificity when generating different neuronal subtypes. Non-neurogenic astrocytes contribute to the establishment and maintenance of the neurogenic niche. Neuroblast chains migrate through the rostral migratory stream ensheathed by astrocytic processes. Astrocytes play an important regulatory role in neuroblast migration and also assist in the development of a vasculature scaffold in the
After bilateral olfactory bulbectomy in rats a significant increase of norepinephrine (NE) level in the hypothalamus was found. However, no difference was observed between hypothalamic NE turnover of bulbectomized and sham operated animals. In the amygdaloid cortex the NE level was not affected by bulbectomy. In this area, however, the ... read more NE turnover appeared to be decreased after bulbectomy. The latter finding may be related to the deficits in passive avoidance behaviour as found in bulbectomized rats. show less ...
TY - JOUR. T1 - Accumulation of stress-related proteins within the glomeruli of the rat olfactory bulb following damage to olfactory receptor neurons. AU - Hirata, Kazuho. AU - Kanemaru, Takaaki. AU - Minohara, Motozumi. AU - Togo, Akinobu. AU - Kira, Jun Ichi. PY - 2008/12/1. Y1 - 2008/12/1. N2 - The expression of stress-responsive proteins, such as nestin and a 27-kDa heat-shock protein (HSP27), was immunohistochemically examined in order to demonstrate glial responses in the rat olfactory bulb following sensory deprivation. At 3 days to 1 week after sensory deprivation, numerous nestin-expressing cells appeared within the glomerulus of the olfactory bulb. These cells were regarded as reactive astrocytes since they were immunoreactive for glial fibrillary acidic protein and showed hypertrophic features. The glomeruli, in which nestin-immunoreactive astrocytes were localized, were filled with degenerating terminals of olfactory receptor neurons and migrated microglia. A small population of ...
By using biochemical, immunological and immunohistochemical techniques, we have investigated the expression and functional activity of protease-activated receptor (PARs) 1 and 2 in the rat olfactory system. Western blot analysis of microdissected main olfactory bulb indicated the presence of both PAR1 and PAR2 in olfactory nerve-glomerular cell layer (ON-GL), external plexiform layer (EPL) and granule cell layer (GRL). In functional assays, PAR1 and PAR2 selective peptides stimulated [35S]GTPyS binding and phosphoinositide hydrolysis and inhibited cyclic AMP formation in ON-GL but not in EPL and GRL, whereas they induced RhoA activation in both ON-GL and EPL+GRL. Olfactory bulb deafferentation by lesions of the olfactory mucosa elicited a significant decrease of PAR1 and PAR2 immunoreactivity in ON-GL and a reduced stimulation of [35S]GTPyS binding by PAR selective peptides. In primary cultures of olfactory neurons both PAR1 and PAR2 were detected by immunofluorescence and their activation by ...
Hyperosmia is an increased olfactory acuity (heightened sense of smell), usually caused by a lower threshold for odor. This perceptual disorder arises when there is an abnormally increased signal at any point between the olfactory receptors and the olfactory cortex. The causes of hyperosmia may be genetic, environmental or the result of benzodiazepine withdrawal syndrome. When odorants enter the nasal cavity, they bind to odorant receptors at the base of the olfactory epithelium. These receptors are bipolar neurons that connect to the glomerular layer of the olfactory bulb, traveling through the cribriform plate. At the glomerular layer, axons from the olfactory receptor neurons intermingle with dendrites from intrinsic olfactory bulb neurons: mitrial/tufted cells and dopaminergic periglomerular cells. From the olfactory bulb, mitral/tufted cells send axons via the lateral olfactory tract (the cranial nerve I) to the olfactory cortex, which includes the piriform cortex, entorhinal cortex, and ...
The main olfactory bulb (OB) is made up of several concentric layers, forming circuitries often involving dendro-dendritic synapses. Important interactions between OB neurons occur in the external plexiform layer (EPL), where dendrites of tufted and Van Gehuchten cells form synapses with dendrites of deeper lying mitral, tufted, and granule cells. OB neurons display a variety of neurotransmitters. Here, the focus is on calcitonin gene-related peptide (CGRP), a 37-amino acid neuropeptide transmitter that is widely distributed in the central and peripheral nervous system. In the OB, CGRP-immunoreactive (ir) cell bodies were mostly observed in the mitral cell layer (MCL) of normal mice, and their number increased following colchicine treatment. Sparsely distributed CGRP-ir cell bodies were also found in the EPL and granular cell layer. Double-immunofluorescence experiments revealed a lack of co-localization between CGRP-like immunoreactivity (LI) and corticotropin-releasing factor- or galanin-LI, ...
The periglomerular region of the olfactory bulb, apart from containing the somata and stem dendrites of the cells contributing to the glomeruli, is the sole region of distribution of the periglomerular cell thin dendrites and the short-axon cell dendrites. It is also the major site of termination of all axons to the glomerular layer except the olfactory axons - i.e. tufted cell collaterals, periglomerular cell and short-axon cell axons and centrifugal fibres. Its characteristic neuropil has been studied with the electron microscope to define the cells of origin of the types of neuronal process and their synaptic relationships. Three types of axon terminals have been found: those with spherical, large flattened and small flattened vesicles, which are deduced to derive from tufted cell collaterals or centrifugal fibres, periglomerular cell and short axon-cell axons respectively; those with spherical vesicles are consistently associated with asymmetrical membrane thickenings and those with either ...
I am interested in describing synaptic circuits in the olfactory bulb, the first relay station for odor processing in the brain. In the mammalian olfactory system, sensory inputs converge in the olfactory bulb in spatially segregated anatomical structure called glomeruli. Olfactory neurons expressing the same olfactory receptor project in specific glomeruli where they transmit sensory information to ~25 mitral and tufted cells, the principal output neurons of the bulb. Each glomerulus is surrounded by local juxtaglomerular neurons that shape the output of mitral and tufted cells. Juxtaglomerular cells include different types of neurons like inhibitory periglomerular cells, excitatory external tufted cells and mixed dopaminergic-GABAergic short axon cells.. My earlier work focused on intraglomerular excitatory interactions that amplify the complex and unique long-lasting synaptic response of mitral and tufted cells to an olfactory nerve input. I demonstrated the unexpected role of external tufted ...
TY - JOUR. T1 - Low-dose curcumin stimulates proliferation, migration and phagocytic activity of olfactory ensheathing cells. AU - Velasquez, Johana Tello. AU - Watts, Michelle E.. AU - Todorovic, Michael. AU - Nazareth, Lynnmaria. AU - Pastrana, Erika. AU - Diaz-Nido, Javier. AU - Lim, Filip. AU - Ekberg, Jenny A K. AU - Quinn, Ronald J.. AU - St John, James A.. PY - 2014/10/31. Y1 - 2014/10/31. N2 - One of the promising strategies for neural repair therapies is the transplantation of olfactory ensheathing cells (OECs) which are the glial cells of the olfactory system. We evaluated the effects of curcumin on the behaviour of mouse OECs to determine if it could be of use to further enhance the therapeutic potential of OECs. Curcumin, a natural polyphenol compound found in the spice turmeric, is known for its anti-cancer properties at doses over 10 μM, and often at 50 μM, and it exerts its effects on cancer cells in part by activation of MAP kinases. In contrast, we found that low-dose curcumin ...
Sprague Dawley rats (21-29 d of age) of either gender were anesthetized with chloral hydrate and decapitated in accordance with Institutional Animal Care and Use Committee and National Institutes of Health guidelines. The olfactory bulbs were removed and immersed in sucrose-artificial CSF (sucrose-aCSF) equilibrated with 95% O2-5% CO2, pH 7.38. The sucrose-aCSF had the following composition (in mm): 26 NaHCO3, 1 NaH2PO4, 2 KCl, 5 MgSO4, 0.5 CaCl2, 10 glucose, and 248 sucrose. Horizontal slices (400 μm thick) were cut with a microslicer (Ted Pella, Redding, CA). After a period of recovery at 30°C for 15 min, slices were then incubated at room temperature (22°C) in aCSF equilibrated with 95% O2-5% CO2 [composition (in mm): 124 NaCl, 26 NaHCO3, 3 KCl, 1.25 NaH2PO4, 2 MgSO4, 2 CaCl2, and 10 glucose] until they were used. For recording, a single slice was placed in a recording chamber and continuously perfused at the rate of 1.5 ml/min with normal aCSF equilibrated with 95% O2-5% CO2. All ...
In rodents, sexual behavior depends on the adequate detection of sexually relevant stimuli. The olfactory bulb (OB) is a region of the adult mammalian brain undergoing constant cell renewal by continuous integration of new granular and periglomerular neurons in the accessory (AOB) and main (MOB) olfactory bulbs. The proliferation, migration, survival, maturation, and integration of these new cells to the OB depend on the stimulus that the subjects received. We have previously shown that 15 days after females control (paced) the sexual interaction an increase in the number of cells is observed in the AOB. No changes are observed in the number of cells when females are not allowed to control the sexual interaction. In the present study we investigated if in male rats sexual behavior increases the number of new cells in the OB. Male rats were divided in five groups: 1) males that did not receive any sexual stimulation, 2) males that were exposed to female odors, 3) males that mated for 1 h and could not
Previous research suggests that volatile body odourants detected by the main olfactory epithelium (MOE) are processed mainly by the main olfactory bulb (MOB) whereas nonvolatile body odourants detected by the vomeronasal organ (VNO) are processed via the accessory olfactory bulb (AOB). We asked whether urinary volatiles from males and females differentially activate the AOB in addition to the MOB in gonadectomized mice of either sex. Exposure to urinary volatiles from opposite-sex but not same-sex conspecifics augmented the number of Fos-immunoreactive mitral and granule cells in the AOB. Volatile urinary odours from male as well as female mice also stimulated Fos expression in distinct clusters of MOB glomeruli in both sexes. Intranasal administration of ZnSO4, intended to disrupt MOE function, eliminated the ability of volatile urinary odours to stimulate Fos in both the MOB and AOB. In ovariectomized, ZnSO4-treated females a significant, though attenuated, AOB Fos response occurred after ...
Background: There is continuing neurogenesis in the subventricular zone (SVZ) of the adult brain which supplies interneurons to the olfactory bulb. There is also continuing neurogenesis in the olfactory epithelium (OE) supplying new olfactory sensory neurons whose axons terminate in the olfactory bulb. These axons synapse with tyrosine hydroxylase-positive periglomerular neurons, which are the product of subventricular zone neurogenesis. Hypothesis: SVZ neurogenesis is regulated coordinately with olfactory epithelial neurogenesis. Aims: The aim is to quantify the rate of cell proliferation in the SVZ after killing the olfactory sensory neurons, which upregulates neurogenesis in the OE. Methods: Adult mice were treated with methimazole, and the tissues were examined at different times after treatment. The survival of the olfactory sensory neurons within the OE was assessed together with their terminals within glomeruli of the olfactory bulb. The loss of tyrosine hydroxylase periglomerular neurons ...
This study of the ventral olfactory bulb of larval Xenopus laevis shows for the first time the existence of a thermosensitive olfactory glomerulus. This thermosensitive olfactory glomerulus was found to be innervated by axons of olfactory sensory neurons emerging from the ipsilateral olfactory epithelium as well as from the contralateral olfactory epithelium. The perfusion of the ipsilateral or contralateral olfactory epithelium with cold, odor-free Ringer solution elicited a transient [Ca2+]i response within the axons of olfactory sensory neurons and in mitral cells. The activation of mitral cells demonstrated that the response to temperature stimulation is transmitted across the first olfactory synapse. The thermoreception was spatially restricted to this glomerulus, which did not respond to any of the tested odors. Adjacent olfactory glomeruli responded to olfactory and mechanical stimulation without showing any response to temperature changes. The spatially restricted, bilateral processing ...
TY - JOUR. T1 - Differential regulation of synaptic GABA(A) receptors by cAMP-dependent protein kinase in mouse cerebellar and olfactory bulb neurones. AU - Nusser, Zoltan. AU - Sieghart, Werner. AU - Mody, Istvan. PY - 1999/12/1. Y1 - 1999/12/1. N2 - 1. It has been demonstrated that the regulation of recombinant GABA(A) receptors by phosphorylation depends on the subunit composition. Here we studied the regulation of synaptic GABA(A) receptor function by cAMP-dependent protein kinase (PKA) in neurones expressing distinct receptor subtypes. 2. Light microscopic immunocytochemistry revealed that granule cells of the olfactory bulb express only the β3 as the β subunit variant, whereas cerebellar stellate and basket cells express only the β2 as the β subunit. 3. In cerebellar interneurones, intracellular application of 20 μM microcystin, a protein phosphatase 1/2A inhibitor, prolonged (63 ± 14%; mean ± S.E.M.) the decay time course of miniature IPSCs (mIPSCs) without significantly affecting ...
Olfactory sensory neurons project axons to the brain within the olfactory nerve, (cranial nerve I). These nerve fibers, lacking myelin sheaths, pass to the olfactory bulb of the brain through perforations in the cribriform plate, which in turn projects olfactory information to the olfactory cortex and other areas.[7] The axons from the olfactory receptors converge in the outer layer of the olfactory bulb within small (≈50 micrometers in diameter) structures called glomeruli. Mitral cells, located in the inner layer of the olfactory bulb, form synapses with the axons of the sensory neurons within glomeruli and send the information about the odor to other parts of the olfactory system, where multiple signals may be processed to form a synthesized olfactory perception. A large degree of convergence occurs, with 25,000 axons synapsing on 25 or so mitral cells, and with each of these mitral cells projecting to multiple glomeruli. Mitral cells also project to periglomerular cells and granular cells ...
Olfactory sensory neurons project axons to the brain within the olfactory nerve, (cranial nerve I). These nerve fibers, lacking myelin sheaths, pass to the olfactory bulb of the brain through perforations in the cribriform plate, which in turn projects olfactory information to the olfactory cortex and other areas.[23] The axons from the olfactory receptors converge in the outer layer of the olfactory bulb within small (≈50 micrometers in diameter) structures called glomeruli. Mitral cells, located in the inner layer of the olfactory bulb, form synapses with the axons of the sensory neurons within glomeruli and send the information about the odor to other parts of the olfactory system, where multiple signals may be processed to form a synthesized olfactory perception. A large degree of convergence occurs, with 25,000 axons synapsing on 25 or so mitral cells, and with each of these mitral cells projecting to multiple glomeruli. Mitral cells also project to periglomerular cells and granular cells ...
Olfactory sensory neurons project axons to the brain within the olfactory nerve, (cranial nerve I). These nerve fibers, lacking myelin sheaths, pass to the olfactory bulb of the brain through perforations in the cribriform plate, which in turn projects olfactory information to the olfactory cortex and other areas.[13] The axons from the olfactory receptors converge in the outer layer of the olfactory bulb within small (≈50 micrometers in diameter) structures called glomeruli. Mitral cells, located in the inner layer of the olfactory bulb, form synapses with the axons of the sensory neurons within glomeruli and send the information about the odor to other parts of the olfactory system, where multiple signals may be processed to form a synthesized olfactory perception. A large degree of convergence occurs, with 25,000 axons synapsing on 25 or so mitral cells, and with each of these mitral cells projecting to multiple glomeruli. Mitral cells also project to periglomerular cells and granular cells ...
When insects search for food, a sexual mate or the ideal place for laying eggs - somewhere where the hatching larvae have a good chance to survive - they have to rely on their sense of smell. They use their olfactory organs, the antennae, to detect odor molecules in their environment. These odors are processed in the so-called antennal lobe, the actual olfactory center of the insect brain, which consists of spherical structures: the olfactory glomeruli. Here, inside the olfactory glomeruli, different groups of olfactory neurons form conjunctions or synapses which enable different environmental odors to be processed.. Until now, scientists had assumed that olfactory glomeruli share a pretty homogeneous architecture and that particular functions of the different glomeruli can be attributed primarily to special olfactory receptors on the membranes of the olfactory sensory neurons. A research team of the Department of Evolutionary Neuroethology has now shown for the first time that the neuronal ...
There is ongoing neurogenesis in the subventricular zone (SVZ) of the adult brain which supplies interneurons to the olfactory bulb. There is also continuous neurogenesis in the olfactory epithelium (OE) supplying new olfactory sensory neurons whose axons terminate in the olfactory bulb. These axons synapse with tyrosine hydroxylase-positive periglomerular neurons within the olfactory bulb, which are the product of subventricular zone neurogenesis. We hypothesize that focal denervation of the olfactory sensory neurons and thereby lesioning of the presynaptic input to the Type 1 neurons would result in their degeneration, and a subsequent upregulation of subventricular zone neurogenesis. Adult mice (n=26) were treated with methimazole causing the ablation of the OE, and the tissues examined at multiple time-points after treatment. The survival of the olfactory sensory neurons within the OE was assessed together with their terminals within glomeruli of the olfactory bulb. The loss of tyrosine ...
In sensory systems, peripheral organs convey sensory inputs to relay networks where information is shaped by local microcircuits before being transmitted to cortical areas. In the olfactory system, odorants evoke specific patterns of sensory neuron activity that are transmitted to output neurons in olfactory bulb (OB) glomeruli. How sensory information is transferred and shaped at this level remains still unclear. Here we employ mouse genetics, 2-photon microscopy, electrophysiology and optogenetics, to identify a novel population of glutamatergic neurons (VGLUT3+) in the glomerular layer of the adult mouse OB as well as several of their synaptic targets. Both peripheral and serotoninergic inputs control VGLUT3+ neurons firing. Furthermore, we show that VGLUT3+ neuron photostimulation in vivo strongly suppresses both spontaneous and odour-evoked firing of bulbar output neurons. In conclusion, we identify and characterize here a microcircuit controlling the transfer of sensory information at an early
The aim of this study is to analyzed the three nervi; terminalis, vomeronasalis and olfactorius emerging from the olfactory apparatus. The lizard Chacidessepoides was collected from Sinai and was undergone to permanent histological preparation. Through the examination of the olfactory apparatus of this species resulted in the vomeronasal organ is innervated by two correlating nerves: terminal and vomeronasal nerves that originating from its sensory epithelium. The terminal nerve bears the ganglion terminale. The olfactory nerve innervates the olfactory chamber. The three nerves leave the nasal capsule through the fenestra olfactoriaadvehens as separate bundles. They enter the cranial cavity through the fenestra olfactoriaevehens. The olfactory nerve connected with the main olfactory bulb. The terminal connects with the outer layer of the brain, while the vomeronasal one joins the accessory olfactory bulb. The three nerves are perspicuous special sensory.. ...
The gaseous radical nitric oxide (NO) is generated in the conversion of L-arginine to L-citrulline by nitric oxide synthases (NOS). Being a highly mobile free radical, NO reacts with a wide range of targets. This allows NO to modulate many and various biological functions, from its cardinal role as a potent vasodilator, to neuronal signalling. In mammals, the olfactory bulbs (OB) are the first brain structures to receive and process odour information from the olfactory epithelium (OE), and are among the most prominent nitrergic areas in the rodent brain. Despite this, the acute function of NO in mammalian OBs is unknown. In this thesis, I aim to test the acute electrophysiological effect of NO on the mouse OB in vitro. Hundreds of glomeruli, discrete odour specific neuropils, are the sites of synapses between odour specific axons from the OE and mitral cells (MCs), the principal OB neurons. Glomeruli comprise the circuitry necessary to drive OB output, and are thought to be ideally suited to ...
Glaucoma is the term used to describe a group diseases characterised by a specific type of damage to the optic nerve head (ONH) known as cupping and a characteristic type of visual field loss. This loss is associated with progressive atrophy and loss of the retinal ganglion cells. Glaucoma is a leading cause of irreversible blindness in the world. This project was aimed at investigating olfactory ensheathing cells (OEC), a population of radial glia proven to be neuroprotective in central and peripheral nerve injury models, and their potential to protect the retinal ganglion cells in glaucoma. We studied the interactions of RGC and OEC in culture. We show that OEC can straighten, ensheath and bundle RGC neurites as well as support the survival of RGC and their synapses in culture. We also show that OEC endocytose dead RGC in culture. We modified a rat model of glaucoma (where paramagnetic microbeads are injected into the anterior chamber of the rat eyes) and characterised the early and late ...
Rhythmic patterns of neuronal activity have been found at multiple levels of various sensory systems. In the olfactory bulb or the antennal lobe, oscillatory activity exhibits a broad range of frequencies and has been proposed to encode sensory information. However, the neural mechanisms underlying …
The consequences of ongoing neurogenesis have long been the subject of speculation. New neurons in the dentate gyrus of the hippocampus seem to be added throughout juvenile and adult life, suggesting that they do not replace neurons that die (36). Alternatively, work in the song-control system of birds has shown that neuronal replacement occurs in some nuclei, perhaps to play a role in song learning (37). Concerning olfaction, one possibility is that new interneurons are simply added to the bulbs, as they are in the hippocampus. Yet, although increases in the number of interneurons have been reported in the adult, substantial granule cell death has also been observed, suggesting that newly generated neurons may replace dying ones (38).. This ongoing recruitment of interneurons may also open new opportunities to investigate the cellular basis for olfactory processing and its functional plasticity. The presence of a pool of new neurons accompanied by the emergence of new synapses could play a role ...
Olfactory ensheathing cells (OECs) are a type of specialized glial cell currently considered as having a double function in the nervous system: one regenerative, and another immune. OEC cultures resulted in continuous NF-B activation. The IFN-induced increase of iNOS manifestation was reversed in infected OECs. OECs are susceptible to infection, which can suppress their cytotoxic mechanisms in order to survive. We suggest that, in contrast to microglia, OECs might serve as safe focuses on for pneumococci, providing a more stable environment for evasion of the immune system. Olfactory ensheathing cells (OECs) are a type of specialized glial cell that accompany and ensheath the primary olfactory axons through the olfactory pathway, from your olfactory epithelium to Natamycin small molecule kinase inhibitor the olfactory tract. OECs are crucial for olfactory axonal assistance and outgrowth inside the developing and adult olfactory program1,2. This real estate of OECs makes them a superb candidate ...
The mammalian the olfactory bulb (OB) maintains a continuous inflow of new neurons to its circuitry throughout adulthood. The role of these newborn neurons in
Orthodromic stimulation of axons in the olfactory nerve from sensory receptor cells excites periglomerular neurons in the input layer of the bulb, modeled by a KIe set ( Figure 2, A), producing an excitatory bias. The root locus ( Figure 4, A, Mode 1e) is nearly parallel to the real axis, because the frequency is invariant, and the decay rate increases with increased amplitude, as does the PSTH of the periglomerular cells ( Figure 2, A). Antidromic stimulation of output axons from the bulb that monosynaptically excite bulbar inhibitory neurons but not periglomerular neurons produces an inhibitory bias. The amplitude of the AEP to single shock stimulation of the olfactory tract increases with input intensity, but the decay rate is unchanged, and the frequency decreases ( Figure 4, A, Mode 1i) because the excitatory bias is lacking. The effect of increasing intensity of antidromic stimuli to the bulb is to increase the AEP initial amplitude above the background activity. The same effect results by ...
In the present study, we have shown that Robo proteins are expressed in cultured OECs and exhibit enriched distribution at the leading edge. A Slit-2 gradient indeed strongly repelled the migration of these cultured OECs. To our knowledge, this is the first guidance factor discovered to repel OEC migration. Because Slit-2 is highly expressed in the apical cells of OE, it is likely that it might help Robo-expressing OECs and olfactory axons migrate out of the OE through chemorepulsion during early development. Slits expressing in the OB might also regulate the stop and scattering of OECs that have arrived at the surface of the OB. OECs have been reported to pioneer the olfactory sensory nerves and provide a conductive substrate for the growth of olfactory sensory axons during development (Tennent and Chuah, 1996; Tisay and Key, 1999). An intriguing possibility is that the guidance of OECs by Slits might contribute to the guidance of axons because of the close interaction between neurons and glia. ...
The olfactory tubercle differs in location and relative size between humans, non-human primates, rodents, birds, and other animals. In most cases, the olfactory tubercle is identified as a round bulge along the basal forebrain anterior to the optic chiasm and posterior to the olfactory peduncle.[7] In humans and non-human primates, visual identification of the olfactory tubercle is not easy because the basal forebrain bulge is small in these animals.[8] With regard to functional anatomy, the olfactory tubercle can be considered to be a part of three larger networks. First, it is considered to be part of the basal forebrain, the nucleus accumbens, and the amygdaloid nuclei because of its location along the rostral ventral region of the brain, that is, the front-bottom part. Second, it is considered to be part of the olfactory cortex because it receives direct input from the olfactory bulb. Third, it is also considered to be part of the ventral striatum based on anatomy, neurochemical, and ...
parameters_odour_baseline.hoc // Olfactory bulb network model: parameters file // for odour input. // Andrew Davison, The Babraham Institute, 2000. nmitx = 6 // 1st dimension of mitral cell array nmity = 6 // 2nd dimension of mitral cell array nglom = nmitx*nmity // total number of mitral cells g2m = 12 // ngranx = nmitx*g2m // 1st dimension of granule cell array ngrany = nmity*g2m // 2nd dimension of granule cell array mitsep = 1.0 // um // mitral cell separation gransep = mitsep/g2m // granule cell separation seed = 0 // seed for random number generator rmax = ngranx*0.5 // maximum range of synaptic connections synpermit = 500 // synapses per mitral cell thresh = -10 // mV // threshold for detecting spikes edelay = 1.8 // ms // time delay of mitral-,granule synapses conducdel = 0 // ms // conduction delay in secondary dendrites idelay = 0.6 // ms // time delat of granule-,mitral synapses AMPAweight = 1e-3 // uS // } NMDAweight = 7e-4 // uS // } synaptic conductances iweight = 6e-4 // uS // } ...
We recently demonstrated that the growth promoting effects of ensheathing cells are not limited to olfactory receptor neurons but are also seen in other populations of neurons. Particularly exciting, our recent studies demonstrate that the ensheathing cells remain pluri-potential and that when implanted into demyelinated spinal cord can adopt a myelinating phenotype which remyelinates the axons and contributes to a restoration of normal conduction velocities.. In parallel studies we are examining the molecular and synaptic organization of the olfactory bulb glomeruli. Using RT-PCR we are mapping the distribution of subsets of olfactory receptor cell axons in glomeruli to gain insights into the topography of odor-ligand maps in the olfactory bulb. In addition, working with colleagues, we are using a GFP tag to test hypotheses regarding the specificity of synaptic organization within glomeruli. Second, using antibodies synaptic vesicle related proteins and confocal microscopy we have begun to ...
The olfactory system, particularly the olfactory epithelium, presents a unique opportunity to study the regenerative capabilities of the brain, because of its ability to recover after damage. In this study, we ablated olfactory sensory neurons with methimazole and followed the anatomical and functional recovery of circuits expressing genetic markers for I7 and M72 receptors (M72-IRES-tau-LacZ and I7-IRES-tau-GFP). Our results show that 45 days after methimazole-induced lesion, axonal projections to the bulb of M72 and I7 populations are largely reestablished. Furthermore, regenerated glomeruli are re-formed within the same areas as those of control, unexposed mice. This anatomical regeneration correlates with functional recovery of a previously learned odorant-discrimination task, dependent on the cognate ligands for M72 and I7. Following regeneration, mice also recover innate responsiveness to TMT and urine. Our findings show that regeneration of neuronal circuits in the olfactory system can be
import itertools import numpy # below creates symmetrical arrays add_columns=[1] B=[200] #range(20,780,20)# /1.0 # 0.0 20.0 ... 620.0 #(start, stop, step) S=[60, 120, 180, 240, 320, 640] #range(20,780,20) #/1.0 # [50 50 ... 50 50] both=list(itertools.product(B,S)) print both # adding a columns array. This is actually the number of additional columns # in each case # add_columns = [1, 2, 4, 6] add_columns = [1] # just one additional column # create asymmetrical array where S,B # # go from B=0 to max_B # for each B value include only S,B # #B=numpy.zeros(0,dtype=float,order=C) #delta_S = 10 # for S #delta_B = 60 # for B #max_B = 300 #big_B = B #big_S = B #for new_B in range(delta_B, max_B+delta_B, delta_B): # for new_S in range(delta_S,new_B+delta_S,delta_S): # big_B=numpy.append(big_B,numpy.array([new_B])) # big_S=numpy.append(big_S,numpy.array([new_S])) # override for special cases Shaina requested: #big_B=[50, 50, 400, 400] #big_S=[50, 400, 50, 400] #big_B=[100, 100, 300, 300] #big_S=[100, ...
Olfaction is a faculty that is remarkably sensitive to changes in function and may even be an early sign of ongoing neurodegeneration (Huisman et al., 2003, Hawkes et al., 2003). There have been debates about the way the subventricular zone (SVZ) sends new neurons to the olfactory bulb in humans. A highly publicized Nature paper suggested that there was not a so-called rostral migratory stream (RMS) in humans (Sanai et al., 2004). Now, this paper by Curtis and colleagues finds that indeed there is a form of RMS also in humans. Moreover, it demonstrates how this RMS structure is a close homologue to other mammalian olfactory systems.. This study shows for the first time that the adult human brain contains a rostral migratory stream of neuroblasts extending from the subventricular zone (SVZ) to the olfactory bulb. The authors further demonstrate that, unlike rodents and primates but more like rabbits, the human RMS is organized around a lateral ventricular extension reaching the core of the ...
The ROBO1 gene encodes a member of the Neural Cell Adhesion Molecule (NCAM) family, a subset of the Immunoglobulin superfamily (IgSF). The ROBO1 protein functions as an integral membrane receptor for SLIT1 and SLIT2, and is involved in axon guidance and cell migration. It is particularly involved in axonal navigation at the ventral midline of the neural tube, thus ensuring appropriate nervous system development. The protein is also engaged in the biological processes of chemorepulsion involved in postnatal olfactory bulb interneuron migration, cell migration involved in sprouting angiogenesis, inhibition of mammary gland epithelial cell proliferation and inhibition of the chemokine-mediated signaling pathway. Researchers have noted the presence of a splice variant, designated DUTT1, that differs in function from ROBO1. While ROBO1 plays a role in neuronal development, DUTT1 is believed to be involved in tumor suppression. Haploinsufficiency of the ROBO1 gene has been suggested to predispose ...
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Mammals possess an olfactory system of inordinate discriminatory power. We are studying how the diversity and specificity of olfactory perception is accomplished. Analysis of the patterns of expression of the odorant receptor genes, coupled with earlier electrophysiologic experiments, have provided a logic for olfactory discrimination. Individual olfactory sensory neurons express only one of a thousand receptor genes. Neurons expressing a given receptor, although randomly distributed in domains in the epithelium, project their axons to a small number of topographically fixed loci or glomeruli in the olfactory bulb. These data support a model of olfactory coding in whichdiscrimination of odor quality would result from the detection of specific spatial patterns of activity in the olfactory bulb.. HHMI. ...
Đây là một trong những cách dưỡng da tốt nhất cho làn da bị mụn và bị hao tổn do môi trường. Bạn có thể sử dụng nhiều loại mặt nạ đắp mặt từ thiên nhiên khác nhau, tuy nhiên bạn chỉ nên lựa chọn các loại mặt nạ phù hợp nhất với làn da của mình. Hãy xuy sét cẩn thận khi lựa chọn loại mặt nạ vì nó có thể gây kích ứng da khi bạn sử dụng đấy.. Thời gian tốt nhất để đắp mặt nạ là khoảng 15 phút, đừng để mặt nạ đắp mặt quá lâu vì nó có thể sẽ gây biến chất các loại vitamin và chất dưỡng da có trong mặt nạ. Bạn cũng có thể tận dụng khoảng thời gian đắp mặt nạ để thư giãn hoặc xem phim giải trí.. Một số loại mặt nạ đắp mặt tốt cho làn da như dưa leo, ngọc trai, bùn …có thể phù hợp với đại đa số làn da của bạn. Một số nhãn hiệu mặt nạ tốt ...
Đây là một trong những cách dưỡng da tốt nhất cho làn da bị mụn và bị hao tổn do môi trường. Bạn có thể sử dụng nhiều loại mặt nạ đắp mặt từ thiên nhiên khác nhau, tuy nhiên bạn chỉ nên lựa chọn các loại mặt nạ phù hợp nhất với làn da của mình. Hãy xuy sét cẩn thận khi lựa chọn loại mặt nạ vì nó có thể gây kích ứng da khi bạn sử dụng đấy.. Thời gian tốt nhất để đắp mặt nạ là khoảng 15 phút, đừng để mặt nạ đắp mặt quá lâu vì nó có thể sẽ gây biến chất các loại vitamin và chất dưỡng da có trong mặt nạ. Bạn cũng có thể tận dụng khoảng thời gian đắp mặt nạ để thư giãn hoặc xem phim giải trí.. Một số loại mặt nạ đắp mặt tốt cho làn da như dưa leo, ngọc trai, bùn …có thể phù hợp với đại đa số làn da của bạn. Một số nhãn hiệu mặt nạ tốt ...
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Olfactory sensory neurons express a wide variety of axon-sorting molecules to establish proper neural circuitry. This protocol...
During olfactory discrimination, odors often activate clusters of olfactory bulb glomeruli and mitral/tufted (M/T) cells that together could signal the odor ...
The main olfactory epithelium (MOE) is a complex organ containing several functionally distinct subpopulations of sensory neurons. One such subpopulation is distinguished by its expression of the guanylyl cyclase GC-D. The axons of GC-D-expressing (GC-D+) neurons innervate 9-15 necklace glomeruli encircling the caudal main olfactory bulb (MOB). Chemosensory stimuli for GC-D+ neurons include two natriuretic peptides, uroguanylin and guanylin, and CO2. However, the biologically-relevant source of these chemostimuli is unclear: uroguanylin is both excreted in urine, a rich source of olfactory stimuli for rodents, and expressed in human nasal epithelium; CO2 is present in both inspired and expired air. To determine whether the principal source of chemostimuli for GC-D+ neurons is external or internal to the nose, we assessed the consequences of removing external chemostimuli for afferent activity to the necklace glomeruli. To do so, we performed unilateral naris occlusions in Gucy2d-Mapt-lacZ +/- mice