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Clare Rusbridge - One of the best experts on this subject based on the ideXlab platform.
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use of morphometric mapping to characterise symptomatic chiari like malformation secondary syringomyelia and associated brachycephaly in the cavalier king charles spaniel
PLOS ONE, 2017Co-Authors: Susan P Knowler, Chloe Cross, Sandra Griffiths, Jelena Jovanovik, C J Driver, Anna Tauro, Roberto M La Ragione, Zoha Kibar, Angus Mcfadyen, Clare RusbridgeAbstract:Objectives To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and Olfactory Lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010), least Olfactory bulb rotation (p = 0.003) and a protective angle (p = 0.004) compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007), shortest basioccipital (p = 0.019), but a greater distance between the atlas and basioccipital (p = 0.002) which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i) the proximity of the dens (p <0.001) ii) increased airorhynchy with a smaller, more ventrally rotated Olfactory bulb (p <0.001). Both generated `concertina' flexures of the brain and craniocervical junction. Conclusion Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise the neural parenchyma and impede cerebrospinal fluid flow.
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Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel
PLOS ONE, 2017Co-Authors: Susan P Knowler, Chloe Cross, Sandra Griffiths, Jelena Jovanovik, C J Driver, Anna Tauro, Roberto M La Ragione, Zoha Kibar, Angus Mcfadyen, Clare RusbridgeAbstract:Objectives To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and Olfactory Lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010), least Olfactory bulb rotation (p = 0.003) and a protective angle (p = 0.004) compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007), shortest basioccipital (p = 0.019), but a greater distance between the atlas and basioccipital (p = 0.002) which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i) the proximity of the dens (p
Barry W. Ache - One of the best experts on this subject based on the ideXlab platform.
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Presynaptic inhibition of Olfactory receptor neurons in crustaceans.
Microscopy Research and Technique, 2002Co-Authors: Matt Wachowiak, Lawrence B. Cohen, Barry W. AcheAbstract:Presynaptic inhibition of transmitter release from primary sensory afferents is a common strategy for regulating sensory input to the arthropod central nervous system. In the Olfactory system, presynaptic inhibition of Olfactory receptor neurons has been long suspected, but until recently could not be demonstrated directly because of the difficulty in recording from the afferent nerve terminals. A preparation using the isolated but intact brain of the spiny lobster in combination with voltage-sensitive dye staining has allowed stimulus-evoked responses of Olfactory receptor axons to be recorded selectively with optical imaging methods. This approach has provided the first direct physiological evidence for presynaptic inhibition of Olfactory receptor neurons. As in other arthropod sensory systems, the cellular mechanism underlying presynaptic afferent inhibition appears to be a reduction of action potential amplitude in the axon terminal. In the spiny lobster, two inhibitory transmitters, GABA and histamine, can independently mediate presynaptic inhibition. GABA- and histaminergic interneurons in the lobster Olfactory Lobe (the target of Olfactory receptor neurons) constitute dual, functionally distinct inhibitory pathways that are likely to play different roles in regulating primary Olfactory input to the CNS. Presynaptic inhibition in the vertebrate Olfactory system is also mediated by dual inhibitory pathways, but via a different cellular mechanism. Thus, it is possible that presynaptic inhibition of primary Olfactory afferents evolved independently in vertebrates and invertebrates to fill a common, fundamental role in processing Olfactory information. Microsc. Res. Tech. 58:365–375, 2002. © 2002 Wiley-Liss, Inc.
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DUAL INHIBITORY PATHWAYS MEDIATED BY GABA- AND HISTAMINERGIC INTERNEURONS IN THE LOBSTER Olfactory Lobe
Journal of Comparative Physiology A: Sensory Neural and Behavioral Physiology, 1997Co-Authors: Matt Wachowiak, Barry W. AcheAbstract:Antisera to GABA and histamine (HA) label distinct populations of interneurons that innervate glomeruli in the Olfactory Lobe (OL) of the spiny lobster. GABA-immunoreactive interneurons branch most heavily in the cap of the glomeruli, while HA-immunoreactive interneurons branch mostly in the glomerular subcap. Perfusing GABA or HA into the isolated brain increases the intensity of electrical stimulation of the antennular nerve necessary to elicit action potentials in OL projection neurons. The GABA receptor antagonist picrotoxin (30–100 μmol · l−1) and the HA receptor antagonist cimetidine (1–5 mmol · l−1) both reduce the stimulus intensity needed to elicit action potentials. However, cimetidine also eliminates the hyperpolarizing phase of the evoked response and reveals a delayed, prolonged excitation of up to 10 s, whereas picrotoxin enhances the hyperpolarization and, at higher concentrations, transiently suppresses all phases of the evoked response. We conclude that GABA- and HA-ergic interneurons constitute two overlapping, yet functionally distinct inhibitory pathways in the OL, an organizational feature which may be fundamental to processing at this level of the Olfactory pathway.
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Functional organization of Olfactory processing in the accessory Lobe of the spiny lobster
Journal of Comparative Physiology A, 1996Co-Authors: Matt Wachowiak, C. E. Diebel, Barry W. AcheAbstract:An isolated brain preparation was used to characterize neurons innervating the accessory Lobe (AL) of the spiny lobster (Panulirus argus). Four distinct classes of neurons responded to electrical stimulation of the Olfactory (antennular) nerve. These cells responded to electrical stimulation with a long and variable latency; they also responded to odor stimulation in a nose-brain preparation. Neurons connecting the AL with the Olfactory Lobe branched in the central AL layer and selectively innervated Olfactory Lobe glomeruli. These cells had response latencies which were significantly shorter than those of other AL neurons. Intrinsic AL interneurons were heterogeneous as a population, and most arborized in irregular but circumscribed regions of either the lateral or medial layers. The final class of neurons branched ipsilaterally in the deutocerebral neuropil and bilaterally innervated only a few AL glomeruli. The physiology and morphology of these four classes of neurons confirm an Olfactory function for the AL and identify the input and output regions of the Lobe. Based on these findings, we propose that the AL processes odor information in the context of higher order multimodal input.
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Antennular projections to the midbrain of the spiny lobster. II. Sensory innervation of the Olfactory Lobe.
The Journal of comparative neurology, 1992Co-Authors: Manfred Schmidt, Barry W. AcheAbstract:The projection pattern of antennular sensory afferents in the Olfactory Lobe (OL) of the spiny lobster, Panulirus argus, was examined by backfilling axons in the antennular nerve (AN) with biocytin. Thin, presumptive Olfactory afferents from the lateral division of the AN form a tract in the brain that diverges into a dense plexus that completely envelops the glomerular cortex of the OL. Most of the thin (diameter less than or equal to 0.3-1 microns) afferents project to single glomeruli. About 10% of the thin afferents, however, branch in the plexus and project to multiple glomeruli. A smaller number of medium-sized to thick (diameter 2-10 microns), presumably mechanosensory, afferents also innervate the OL and co-project to multiple glomeruli with the thin afferents. Afferents arborize profusely within the columnar glomeruli into very fine processes that penetrate to the base of the columns, but selectively terminate in either the cap/subcap region or in the innermost part of the base of the columns, often with conspicuous terminal boutons, forming two distinct regions of presumptive synaptic output. These results suggest that 1) The majority of the OL innervation is provided by Olfactory sensilla (aesthetascs), but that other types of sensilla provide additional, likely mechanosensory, input to the OL. 2) The projection of Olfactory afferents is not strictly uniglomerular. 3) The columnar organization of crustacean Olfactory glomeruli is functionally significant and may provide an evolutionary correlate of the recently proposed subdivision of the vertebrate Olfactory bulb into "functional columns.
Susan P Knowler - One of the best experts on this subject based on the ideXlab platform.
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use of morphometric mapping to characterise symptomatic chiari like malformation secondary syringomyelia and associated brachycephaly in the cavalier king charles spaniel
PLOS ONE, 2017Co-Authors: Susan P Knowler, Chloe Cross, Sandra Griffiths, Jelena Jovanovik, C J Driver, Anna Tauro, Roberto M La Ragione, Zoha Kibar, Angus Mcfadyen, Clare RusbridgeAbstract:Objectives To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and Olfactory Lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010), least Olfactory bulb rotation (p = 0.003) and a protective angle (p = 0.004) compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007), shortest basioccipital (p = 0.019), but a greater distance between the atlas and basioccipital (p = 0.002) which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i) the proximity of the dens (p <0.001) ii) increased airorhynchy with a smaller, more ventrally rotated Olfactory bulb (p <0.001). Both generated `concertina' flexures of the brain and craniocervical junction. Conclusion Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise the neural parenchyma and impede cerebrospinal fluid flow.
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Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel
PLOS ONE, 2017Co-Authors: Susan P Knowler, Chloe Cross, Sandra Griffiths, Jelena Jovanovik, C J Driver, Anna Tauro, Roberto M La Ragione, Zoha Kibar, Angus Mcfadyen, Clare RusbridgeAbstract:Objectives To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction. Methods This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and Olfactory Lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other. Results Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010), least Olfactory bulb rotation (p = 0.003) and a protective angle (p = 0.004) compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007), shortest basioccipital (p = 0.019), but a greater distance between the atlas and basioccipital (p = 0.002) which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i) the proximity of the dens (p
Charles D. Derby - One of the best experts on this subject based on the ideXlab platform.
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The Olfactory pathway mediates sheltering behavior of Caribbean spiny lobsters, Panulirus argus, to conspecific urine signals
Journal of comparative physiology. A Neuroethology sensory neural and behavioral physiology, 2007Co-Authors: Amy J. Horner, Marc J. Weissburg, Charles D. DerbyAbstract:The “noses” of diverse taxa are organized into different subsystems whose functions are often not well understood. The “nose” of decapod crustaceans is organized into two parallel pathways that originate in different populations of antennular sensilla and project to specific neuropils in the brain—the aesthetasc/Olfactory Lobe pathway and the non-aesthetasc/lateral antennular neuropil pathway. In this study, we investigated the role of these pathways in mediating shelter selection of Caribbean spiny lobsters, Panulirus argus, in response to conspecific urine signals. We compared the behavior of ablated animals and intact controls. Our results show that control and non-aesthetasc ablated lobsters have a significant overall preference for shelters emanating urine over control shelters. Thus the non-aesthetasc pathway does not play a critical role in shelter selection. In contrast, spiny lobsters with aesthetascs ablated did not show a preference for either shelter, suggesting that the aesthetasc/Olfactory pathway is important for processing social odors. Our results show a difference in the function of these dual chemosensory pathways in responding to social cues, with the aesthetasc/Olfactory Lobe pathway playing a major role. We discuss our results in the context of why the noses of many animals contain multiple parallel chemosensory systems.
Veronica Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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Positioning sensory terminals in the Olfactory Lobe of Drosophila by Robo signaling.
Development (Cambridge England), 2004Co-Authors: Dhanisha J. Jhaveri, Sumiti Saharan, Anindya Sen, Veronica RodriguesAbstract:Olfactory receptor neurons and the interneurons of the Olfactory Lobe are organized in distinct units called glomeruli. We have used expression patterns and genetic analysis to demonstrate that a combinatorial code of Roundabout (Robo) receptors act to position sensory terminals within the Olfactory Lobe. Groups of sensory neurons possess distinct blends of Robo and Robo3 and disruption of levels by loss-of-function or ectopic expression results in aberrant targeting. In the wild type, most of the neurons send collateral branches to the contralateral Lobe. Our data suggests that guidance of axons across brain hemispheres is mediated by Slit-dependent Robo2 signaling. The location of sensory arbors at distinct positions within the Lobe allows short-range interactions with projection neurons leading to formation of the glomeruli.
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Sensory neurons of the Atonal lineage pioneer the formation of glomeruli within the adult Drosophila Olfactory Lobe.
Development (Cambridge England), 2002Co-Authors: Dhanisha J. Jhaveri, Veronica RodriguesAbstract:The first centers for processing of odor information by animals lie in the Olfactory Lobe. Sensory neurons from the periphery synapse with interneurons in anatomically recognizable units, termed glomeruli, seen in both insects and vertebrates. The mechanisms that underlie the formation of functional maps of the odor-world in the glomeruli within the Olfactory Lobe remains unclear. We address the basis of sensory targeting in the fruitfly Drosophila and show that one class of sensory neurons, those of the Atonal lineage, plays a crucial role in glomerular patterning. Atonal-dependent neurons pioneer the segregation of other classes of sensory neurons into distinct glomeruli. Furthermore, correct sensory innervation is necessary for the arborization of projection neurons into glomeruli and for the elaboration of processes of central glial cells into the Lobe.
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Mechanisms underlying Olfactory neuronal connectivity in Drosophila-the atonal lineage organizes the periphery while sensory neurons and glia pattern the Olfactory Lobe.
Developmental biology, 2000Co-Authors: Dhanisha J. Jhaveri, Anindya Sen, Veronica RodriguesAbstract:Patterning of the antennal Lobe of adult Drosophila occurs through a complex interaction between sensory neurons, glia, and central neurons of larval and adult origin. Neurons from the Olfactory sense organs are organized into distinct fascicles lined by glial cells. The glia originate from one of the three types of sensory lineages-specified by the proneural gene atonal. Gain-of-function as well as loss-of-function analysis validates a role for cells of the Atonal lineage in the ordered fasciculation of sensory neurons. Upon entry of the antennal nerve to central regions, sensory neurons at first remain closely associated with central glia which lie around the periphery of the Lobe anlage. Coincident with the arrival of sensory neurons into the brain, glial precursors undergo mitosis and neural precursors expressing Dachshund appear around the Lobe. Sensory neurons and glial cells project into the Lobe at around the same time and are likely to coordinate the correct localization of different glomeruli. The influence of sensory neurons on the development of the Olfactory Lobe could serve to match and lock peripheral and central properties important for the generation of Olfactory behavior.
