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Ian D Thompson - One of the best experts on this subject based on the ideXlab platform.
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the development of retinal ganglion cell Decussation patterns in postnatal pigmented and albino ferrets
European Journal of Neuroscience, 1993Co-Authors: Ian D Thompson, James Edward MorganAbstract:The Decussation patterns of retinal ganglion cells in postnatal pigmented and albino ferrets were examined by using retrograde axonal tracers. Following unilateral injections into the optic pathway of newborn pigmented ferrets, approximately 13,000 cells were labelled in the ipsilateral retina. The majority (11,500) of these were located in temporal retina. Postnatally, the numbers of cells projecting ipsilaterally from temporal retina fell by 49%. High rates of loss were observed in both the smaller uncrossed projection from nasal retina (92%) and also in the crossed projection from temporal retina (84%). After injections on the day of birth, a Decussation line was not obvious in the crossed projection: > or = 14,000 labelled cells were found in temporal retina. Double tracer studies showed that very few of these cells had axons which projected bilaterally. The numbers of ipsilaterally projecting cells labelled in neonatal albino ferrets was dramatically reduced. Only approximately 2500 were labelled in temporal retina following injections at birth. As in pigmented ferrets, about half of these cells subsequently died. The reduced uncrossed projection in albino neonates was associated with an increase in the crossed projection from temporal retina, in which approximately 21,000 cells were labelled following injections at birth. These results suggest that differential postnatal ganglion cell death establishes the adult Decussation pattern in the contralateral retinal projection but merely refines the pattern already established in the uncrossed projection. Postnatal ganglion cell death plays no significant role in generating the abnormal projections found in albino ferrets.
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albino gene dosage and retinal Decussation patterns in the pigmented ferret
Visual Neuroscience, 1991Co-Authors: Ian D Thompson, James Edwards Morgan, Glen Jeffery, Gary E BakerAbstract:We have examined the retinal Decussation patterns in pigmented ferrets that were either wild-type sable or heterozygous with one albino gene. Unilateral injections of horseradish peroxidase were made into the optic tract and labeled ganglion cells visualized in retinal wholemounts. In both wild-type and heterozygous ferrets, those ganglion cells in the temporal retina with the largest cell bodies projected only to the contralateral side of the brain. The total number of ipsilaterally projecting ganglion cells did not differ with the genotype of the animal. The numbers ranged from 5471–6759 cells. Unlike the cat, there is no difference in retinal Decussation patterns in wild-type sable ferrets and heterozygous ferrets carrying one albino gene.
Michael B Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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quantifying nerve Decussation abnormalities in the optic chiasm
bioRxiv, 2019Co-Authors: Robert J Puzniak, Khazar Ahmadi, Jorn Kaufmann, Andre Gouws, Antony B Morland, Franco Pestilli, Michael B HoffmannAbstract:Abstract Objective The human optic chiasm comprises partially crossing optic nerve fibres. Here we used diffusion MRI (dMRI) for the in-vivo identification of the abnormally high proportion of crossing fibres found in the optic chiasm of people with albinism. Methods In 9 individuals with albinism and 8 controls high-resolution 3T dMRI data was acquired and analyzed with a set of methods for signal modelling [Diffusion Tensor (DT) and Constrained Spherical Deconvolution (CSD)], tractography, and streamline filtering (LiFE, COMMIT, and SIFT2). The number of crossing and non-crossing streamlines and their weights after filtering entered ROC-analyses to compare the discriminative power of the methods based on the area under the curve (AUC). The dMRI results were cross-validated with fMRI estimates of misrouting in a subset of 6 albinotic individuals. Results We detected significant group differences in chiasmal crossing for both unfiltered DT (p=0.014) and CSD tractograms (p=0.0009) also reflected by AUC (for DT and CSD: 0.61 and 0.75, respectively) measures underlining the discriminative power of the approach. Estimates of crossing strength obtained with dMRI and fMRI were significantly correlated for CSD (R2=0.83, p=0.012). We show that in some cases using streamline filtering methods with parameters optimized for the data at hand (COMMIT-SZB in this case) in combination with CSD-base tracking can improve the detection crossing in the human optic chiasm. Conclusions Especially CSD-based tractography provides an efficient approach to detect structural abnormalities in the optic chiasm. The most realistic results were obtained with filtering methods with parameters optimized for the data had. Significance Our findings demonstrate a novel anatomy-driven approach for the individualized diagnostics of optic chiasm abnormalities. Highlights Diffusion MRI is capable of detecting structural abnormalities of the optic chiasm. Quantification of crossing strength in optic chiasm can be applied to albinism diagnostics. Optic chiasm is a powerful test model for neuroimaging methods resolving crossing fibers.
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quantifying nerve Decussation abnormalities in the optic chiasm
bioRxiv, 2019Co-Authors: Robert J Puzniak, Khazar Ahmadi, Jorn Kaufmann, Andre Gouws, Antony B Morland, Franco Pestilli, Michael B HoffmannAbstract:The human optic chiasm comprises partially crossing optic nerve fibres. Here we used diffusion MRI (dMRI) for the in-vivo identification of the abnormally high proportion of crossing fibres found in the optic chiasm of people with albinism. In 9 individuals with albinism and 8 controls high-resolution 3T dMRI data was acquired and analyzed with a set of methods for signal modeling [Diffusion Tensor (DT) and Constrained Spherical Deconvolution (CSD)], tractography, and streamline filtering (LiFE, COMMIT, and SIFT2). The number of crossing and non-crossing streamlines and their weights after filtering entered ROC-analyses to compare the discriminative power of the methods based on the area under the curve (AUC). The dMRI results were cross-validated with fMRI estimates of misrouting in a subset of 6 albinotic individuals. We detected significant group differences in chiasmal crossing for both unfiltered DT (p=0.014) and CSD tractograms (p=0.0009) also reflected by AUC measures (for DT and CSD: 0.61 and 0.75, respectively), underlining the discriminative power of the approach. Estimates of crossing strengths obtained with dMRI and fMRI were significantly correlated for CSD (R2=0.83, p=0.012). The results show that streamline filtering methods in combination with probabilistic tracking, both optimized for the data at hand, can improve the detection of crossing in the human optic chiasm. Especially CSD-based tractography provides an efficient approach to detect structural abnormalities in the optic chiasm. The most realistic results were obtained with filtering methods with parameters optimized for the data at hand. Our findings demonstrate a novel anatomy-driven approach for the individualized diagnostics of optic chiasm abnormalities.
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quantifying nerve Decussation abnormalities in the optic chiasm
NeuroImage: Clinical, 2019Co-Authors: Robert J Puzniak, Khazar Ahmadi, Jorn Kaufmann, Andre Gouws, Antony B Morland, Franco Pestilli, Michael B HoffmannAbstract:Abstract Objective The human optic chiasm comprises partially crossing optic nerve fibers. Here we used diffusion MRI (dMRI) for the in-vivo identification of the abnormally high proportion of crossing fibers found in the optic chiasm of people with albinism. Methods In 9 individuals with albinism and 8 controls high-resolution 3T dMRI data was acquired and analyzed with a set of methods for signal modeling [Diffusion Tensor (DT) and Constrained Spherical Deconvolution (CSD)], tractography, and streamline filtering (LiFE, COMMIT, and SIFT2). The number of crossing and non-crossing streamlines and their weights after filtering entered ROC-analyses to compare the discriminative power of the methods based on the area under the curve (AUC). The dMRI results were cross-validated with fMRI estimates of misrouting in a subset of 6 albinotic individuals. Results We detected significant group differences in chiasmal crossing for both unfiltered DT (p = 0.014) and CSD tractograms (p = 0.0009) also reflected by AUC measures (for DT and CSD: 0.61 and 0.75, respectively), underlining the discriminative power of the approach. Estimates of crossing strengths obtained with dMRI and fMRI were significantly correlated for CSD (R2 = 0.83, p = 0.012). The results show that streamline filtering methods in combination with probabilistic tracking, both optimized for the data at hand, can improve the detection of crossing in the human optic chiasm. Conclusions Especially CSD-based tractography provides an efficient approach to detect structural abnormalities in the optic chiasm. The most realistic results were obtained with filtering methods with parameters optimized for the data at hand. Significance Our findings demonstrate a novel anatomy-driven approach for the individualized diagnostics of optic chiasm abnormalities.
J. Casselman - One of the best experts on this subject based on the ideXlab platform.
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Combined trochlear nerve palsy and internuclear ophthalmoplegia.
Archives of neurology, 1992Co-Authors: P Vanooteghem, I. Dehaene, M Van Zandycke, J. CasselmanAbstract:• We report a case of left superior oblique palsy combined with a right internuclear ophthalmoplegia. A right mesencephalic lesion involving the trochlear nerve nucleus (or its fibers prior to Decussation) and the medial longitudinal fascicle was hypothesized. Magnetic resonance imaging showed a lesion at the suspected level.
Helmut Heinsen - One of the best experts on this subject based on the ideXlab platform.
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Mid-sagittal magnetic resonance image of the equine brain.
2019Co-Authors: Martin J. Schmidt, Carola Knemeyer, Helmut HeinsenAbstract:acc: corpus callosum artery, ah: adenohypophysis, Ans: ansate sulcus, aq: mesencephalic aqueduct, boc: basioccipital bone, bsp: basisphenoidal bone, cam: ammon’s horn, cc: corpus callosum, ccc: commissure of the caudal colliculus, ccd: caudal commissure, ccma: caudal communicating artery, cho: optic chiasm, chp: choroid plexus, cig: cingulate gyrus, cin: cingulum, cl: central lobule, crt: rubro-cerebello-thalamic tract, cu: culmen, de: declive of the vermis, drp: Decussation of the rostral cerebellar peduncles, dtn: Decussation of trochlear nerve, Eng: endogenual sulcus, Enm: endomarginal sulcus, Espl: ectosplenial sulcus, flm: medial longitudinal fasciculus, fo: fornix, fol: folium of the vermis, Fp: primary fissure, Fpc: praeculminate fissure, gcc: genu of the corpus callosum, Gen: genual sulcus, icvs: intercavernous sinus, inf: infundibular stalk, ipd: interpeduncular nucleus, li: lingula of the vermis, lt: terminal lamina, mb: mamillary body, nf: fastigial nucleus, nh: neurohypophysis, no: nodulus of the vermis, obx: obex, pb: pineal body, po: pons, prr: prorean gyrus, psi: pars intermedia of the pituitary gland, py: pyramis of the vermis, pyr: pyramidal tract, rc: rostral commissure, rca: rostral cerebral artery, rcc: radiation of corpus callosum, rccl: rostrum of the corpus callosum, rpb: recess of the pineal body, roc: rostral colliculus, scc: splenium of corpus callosum, Scf: secondary fissure, scg: subcallosal gyrus, Scl: sulcus of corpus callosum, sl: lateral septal nuclei, smt: stria medullaris thalami, sn: septal nuclei, Spl: splenial sulcus, Sspl: suprasplenial sulcus, th: thalamus, tu: tuber vermis, uv: uvula of the vermis, 3: third ventricle, 4: fourth ventricle. asterisk: blind ending medullary branches, uncovered with cortex.
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Transverse magnetic resonance image of the equine brain on the level of the acoustic tubercle.
2019Co-Authors: Martin J. Schmidt, Carola Knemeyer, Helmut HeinsenAbstract:ans: ansiform lobule, ccp: caudal cerebellar peduncle, dctb: Decussation of the fibres of trapezoid body, de: declive of the vermis, dn: dentate nucleus, flm: medial longitudinal fasciculus, flo: flocculus, li: lingula of the vermis, ncd: dorsal cochlear nucleus, ndct: superior olivary nucleus, nf: fastigial nucleus, nip: interpositus nucleus, ntsn: nucleus of the spinal tract of the trigeminal nerve, nvl: lateral vestibular nuclei, nvm: medial vestibular nucleus, paf: paraflocculus, pml: paramedian lobule, py: pyramis of the vermis, rcp: rostral cerebellar peduncle, slm: sulcus limitans, tac: acoustic tubercle, tb: trapezoid body, tsnt: spinal tract of the trigeminal nerve.
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Transverse magnetic resonance image of the equine brain on the level of the rostral colliculi.
2019Co-Authors: Martin J. Schmidt, Carola Knemeyer, Helmut HeinsenAbstract:aq: mesencephalic aqueduct, bcc: brachium of the caudal colliculus, ccr: commissure of the rostral colliculus, cgs: central grey substance, crc: cerebral crus, ctt: central tegmental tract, drp: Decussation of the rostral cerebellar peduncles, Ecs: ectosylvian sulcus, Ectm: ectomarginal sulcus, Enm: endomarginal sulcus, flm: medial longitudinal fasciculus, ipd: interpeduncular nucleus, Lms: lateral mesencephalic sulcus, Mar: marginal sulcus, ml: medial lemniscus, nom: nucleus of the oculomotor nerve, pb: pineal body, Rfi: rhinal fissure, roc: rostral colliculus, snr: substantia nigra, Spl: splenial sulcus, stse: stratum sagittale externum, stsi: stratum sagittale internum, Sss: suprasylvian sulcus, V: trigeminal nerve.
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Dorsal magnetic resonance image of the equine brain on the level of the optic chiasm.
2019Co-Authors: Martin J. Schmidt, Carola Knemeyer, Helmut HeinsenAbstract:ah: adenohypophysis, bsa: basilar artery, ccba: caudal cerebellar artery, ccma: caudal communicating artery, cho: optic chiasm, cst: corticospinal tract, cvs: cavernus sinus, dcml: Decussation of medial lemniscus, dctb: Decussation of the fibres of trapezoid body, icvs: intercavernous sinus, inf: infundibular stalk, ir: infundibular recess, max: maxillary nerve, ml: medial lemniscus, nh: neurohypophysis, oli: olivary nucleus, opn: optic nerve, pcm: peduncles of the mammillary body, po: pons, rca: rostral cerebral artery, tb: trapezoid body, VII: facial nerve, VIII: vestibulocochleal nerve.
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Parasagittal magnetic resonance image of the equine brain on the level of the columns of the fornix.
2019Co-Authors: Martin J. Schmidt, Carola Knemeyer, Helmut HeinsenAbstract:cam: ammon’s horn, cc: corpus callosum, ccc: commissure of the caudal colliculus, ccd: caudal commissure, cec: central canal, cf: column of fornix, cgs: central grey substance, cho: optic chiasm, chp: choroid plexus, cl: central lobule, cn: caudate nucleus, cu: culmen, drp: Decussation of the rostral cerebellar peduncles, dtd: dorsal tegmental Decussation, dtn: Decussation of trochlear nerve, Eng: endogenual sulcus, flm: medial longitudinal fasciculus, fmt: mammillo-thalamic fascicle, fo: fornix, Fp: primary fissure, Fpc: praeculminate fissure, ftp: transverse fibres of the pons, Gen: genual sulcus, hit: habenulo-interpeduncular tract, li: lingula of the vermis, mb: mamillary body, ml: medial lemniscus, nf: fastigial nucleus, no: nodulus of the vermis, olf: olfactory fibres, oli: olivary nucleus, omn: oculomotor nerve, opn: optic nerve, po: pons, py: pyramis of the vermis, rc: rostral commissure, rcc: radiation of corpus callosum, rccl: rostrum of the corpus callosum, Rfi: rhinal fissure, rn: red nucleus, roc: rostral colliculus, scc: splenium of corpus callosum, Scf: secondary fissure, sm: medial septal nuclei, smt: medullary stria of the thalamus, Spl: splenial sulcus, sre: straight sinus, tb: trapezoid body, uv: uvula of the vermis, vtd: ventral tegmental Decussation, 4: fourth ventricle.
James Edward Morgan - One of the best experts on this subject based on the ideXlab platform.
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the development of retinal ganglion cell Decussation patterns in postnatal pigmented and albino ferrets
European Journal of Neuroscience, 1993Co-Authors: Ian D Thompson, James Edward MorganAbstract:The Decussation patterns of retinal ganglion cells in postnatal pigmented and albino ferrets were examined by using retrograde axonal tracers. Following unilateral injections into the optic pathway of newborn pigmented ferrets, approximately 13,000 cells were labelled in the ipsilateral retina. The majority (11,500) of these were located in temporal retina. Postnatally, the numbers of cells projecting ipsilaterally from temporal retina fell by 49%. High rates of loss were observed in both the smaller uncrossed projection from nasal retina (92%) and also in the crossed projection from temporal retina (84%). After injections on the day of birth, a Decussation line was not obvious in the crossed projection: > or = 14,000 labelled cells were found in temporal retina. Double tracer studies showed that very few of these cells had axons which projected bilaterally. The numbers of ipsilaterally projecting cells labelled in neonatal albino ferrets was dramatically reduced. Only approximately 2500 were labelled in temporal retina following injections at birth. As in pigmented ferrets, about half of these cells subsequently died. The reduced uncrossed projection in albino neonates was associated with an increase in the crossed projection from temporal retina, in which approximately 21,000 cells were labelled following injections at birth. These results suggest that differential postnatal ganglion cell death establishes the adult Decussation pattern in the contralateral retinal projection but merely refines the pattern already established in the uncrossed projection. Postnatal ganglion cell death plays no significant role in generating the abnormal projections found in albino ferrets.
