The Experts below are selected from a list of 102 Experts worldwide ranked by ideXlab platform
Masao Norita - One of the best experts on this subject based on the ideXlab platform.
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a light and electron microscopic analysis of the convergent retinal and visual cortical projections to the nucleus of the optic tract not in the Pigmented Rat
Neurobiology (Budapest Hungary), 1999Co-Authors: T Shintani, Kaeko Hoshino, Reiko Meguro, T Kaiya, Masao NoritaAbstract:It is generally known that the nucleus of the optic tract (NOT) subserves visuomotor relations between the retina and preoculomotor structures as the only subcortical pathway mediating optokinetic responses (OKR) in mammals. We have examined the projections from the retina and visual cortical areas (areas 17, 18a and 18b) to NOT using tracers (wheat germ agglutinin-conjugated horseradish peroxidase, WGA-HRP and cholera toxin B subunit, CTB) in order to clarify how these two different functional inputs to OKR are organized. CTB injection into the vitreous body resulted in anterograde label almost exclusively in the contralateral NOT. Ultrastructually, the size of the retinal axon terminals was small (up to 0.7 micron in diameter), contained round synaptic vesicles and pale mitochondria, and made asymmetrical synaptic contacts with both GABA-positive and GABA-negative NOT neurons. Visual cortical area 17 and the transitional area between area 17 and 18a, or between area 17 and 18b projected their axons to the ipsilateral NOT. Ultrastructually, the size of the cortical axon terminals was small (up to 0.5 micron in diameter), contained round synaptic vesicles, and made asymmetrical synaptic contacts only with GABAnegative NOT neurons. With light and electron microscopical observation, there was a considerable overlap in the cortico-NOT and retino-NOT projection pattern: GABA-negative (presumably NOT projection) neurons simultaneously receive input from both cortical and retinal terminals. From these results, it seems reasonable to postulate that inputs from visual cortical areas in the Pigmented Rat coopeRate with those from the retina in controlling OKR.
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the organization of the thalamostriatal projection from the lateral posterior thalamic nuclear complex lp in the Pigmented Rat
Neurobiology, 1998Co-Authors: S Funaki, Reiko Meguro, H Abe, Masao NoritaAbstract:We investigated the thalamostriatal projection of the Rat using biotinylated dextran amine (BDA) and wheat-germ agglutinin horseradish peroxidase (WGA-HRP). To obtain the patch/matrix compartments of the striatum (ST), we used mu-opioid receptor (MOR) immunoreaction labeling. Thus, an MOR-positive 'patch' was indicated by a darkly stained spot, while the MOR-negative 'matrix' was displayed as a non-immunoreactive region. A small injection of BDA was made in a subregion of the lateral posterior thalamic nucleus (LP). The LP-ST fibers originated in all subregions of LP and terminated in the dorsocaudal portion of ST, where the corticostriatal fibers from the visual cortex terminate (Serizawa et al. 1994). These LP-ST fibers and terminals were concentRated in the MOR-negative matrix compartment. Electron microscopic observations showed that the LP-ST terminals made asymmetrical synaptic contacts mainly (70%, n = 30) with the dendritic spines of the presumptive ST-output neurons, and fewer (30%) contacted dendritic shafts. The present results provide anatomical support for the contention that ST-output spiny neurons of the matrix that project to the pars reticulata of the substantia nigra or globus pallidus, may be influenced directly by the LP-ST projection.
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corticostriatal and corticotectal projections from visual cortical areas 17 18 and 18a in the Pigmented Rat
Archives of Histology and Cytology, 1994Co-Authors: Masahiro Serizawa, Kaeko Hoshino, John G Mchaffie, Masao NoritaAbstract:Regions of the visual cortex and the deep layers of the superior colliculus (SC) have been suggested to be functionally linked via an 'indirect' pathway through the basal ganglia. The present report demonstRates projections from the striate (area 17) and extrastriate (areas 18 and 18a) visual cortex in Long-Evans hooded Rats to the striatum (ST) and SC with anterograde (biocytin) and retrograde (WGA-HRP and fluorescent dyes) tracers. Biocytin injections into each cortical area produced markedly different patterns of labeling in ST and SC. Injections into area 17 resulted in a dense labeling in the superficial layers of SC, with little labeling present in the deep layers of SC or ST. In contrast, injections into area 18a, which produced marked labeling in the deep layers of SC with modeRate in the superficial layers, resulted in dense labeling in the caudal two-thirds of the dorsal region of ST; injections into area 18 produced numerous terminals mainly in the deep layers of SC and in the rostral two-thirds of the dorsal aspect of ST. WGA-HRP injections into ST resulted in numerous retrogradely labeled pyramidal neurons in areas 18 and 18a, but only a few labeled neurons were observed in area 17. Corticostriatal neurons in extrastriate visual cortex were distributed predominantly in layer V, with smaller numbers in layers II and III, whereas corticotectal neurons were located only in layer V of both the striate and extrastriate visual cortex. Although corticostriatal and corticotectal neurons were intermingled in layer V, no double-labeled neurons were observed following injections of different fluorescent dyes into ST and SC. It appears, therefore, that: 1) the major source of visual input to both ST and the deep layers of SC in the Rat arises not from the primary visual cortex but from extrastriate visual areas; and that 2) the projections from the extrastriate visual area to ST and SC originate from different populations of corticofugal neurons.
Birgitta Eriksson - One of the best experts on this subject based on the ideXlab platform.
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effects of gabab activation and inhibition on vestibulo ocular and optokinetic responses in the Pigmented Rat
Brain Research, 1994Co-Authors: Magnus Niklasson, Richard Tham, Birgitta Larsby, Birgitta ErikssonAbstract:The effects of the GABAB agonist baclofen and the GABAB antagonist CGP 35348, given sepaRately or simultaneously, on the central vestibular system of Pigmented Rats have been evaluated. Drugs were administered either intramuscularly or intracerebroventricularly. Eye movements were recorded during vestibular, optokinetic and combined visual-vestibular stimulation. Activation of the GABAB receptors by baclofen caused a dose related disturbance of the system, manifested by (1) a decrease of the optokinetic gain, (2) a reduced ability to suppress nystagmus during conflicting vestibular and visual input, and (3) a disability to maintain the eccentric eye position upon a spontaneous saccade. All these effects could be inhibited in a dose-dependent fashion by CGP 35348, suggesting that the findings are specifically related to the GABAB receptor. Given sepaRately, the antagonist did not affect the mentioned parameters. During horizontal acceleRatory/deceleRatory stimulation in darkness baclofen caused a biphasic pattern in the dose-response curves. Small amounts of baclofen caused an increase of the gain and of the duRation of poststimulatory nystagmus, while high doses had a depressive action on the same parameters. The stimulating effect of baclofen could be inhibited or even reversed by CGP 35348, which has a depressive effect per se, similar to the effects of baclofen given in the upper range of doses.
Marta Agudobarriuso - One of the best experts on this subject based on the ideXlab platform.
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transient downregulation of melanopsin expression after retrograde tracing or optic nerve injury in adult Rats
Investigative Ophthalmology & Visual Science, 2015Co-Authors: Francisco M Nadalnicolas, Manuel Jimenezlopez, Manuel Salinasnavarro, Manuel Vidalsanz, Maria H Madeira, Caridad Galindoromero, Arturo Ortinmartinez, Ana Raquel Santiago, Marta AgudobarriusoAbstract:PURPOSE: To investigate the effect of retrograde tracing or axotomy on melanopsin mRNA expression and immunodetection in albino and Pigmented Rat retinas. METHODS: Groups were (1) intact-naive retinas; (2) optic nerve crush (ONC) analyzed at 7 days (7d) or 2 months (2m); (3) Fluorogold (FG) tracing from the superior colliculi (SCi) analyzed at 7d or 2m; (4) tracing from the intact optic nerve (ON) with FG or hydroxystilbamidine methanesulfonate (OHSt), analyzed 3d later; and (5) sham tracing from the ON or sham surgery. Brn3a and melanopsin were double stained in whole mounts to quantify and assess the distribution of orthotopic and displaced Brn3a(+) retinal ganglion cells (Brn3a(+)RGCs) and melanopsin(+)RGCs (m(+)RGCs). Freshly dissected retinas were used for melanopsin mRNA quantitative PCR. RESULTS: Tracing from the SCi did not affect the number of Brn3a(+)RGCs or m(+)RGCs counted in Pigmented Rats. However, only 55% of m(+)RGCs were immunodetected in albinos at 7d, although by 2m the m(+)RGCs counts returned to normal. Optic nerve tracing had a more dramatic effect (38% or 77% of m(+)RGCs were immunodetected in albino or Pigmented Rats) that occurred irrespectively of the tracer (OHSt or FG). This effect was not observed in the sham groups. After ONC, Brn3a(+)RGCs decreased to 37% and 8% by 7d and 2m, respectively. Melanopsin (+)RGC counts diminished to 30% at 7d, but recovered to 49% of controls by 2m. Melanopsin mRNA was downregulated after ON tracing or 7d after ONC, but did not differ from intact values 2m after ONC. CONCLUSIONS: Following ON injury or retrograde tracing there is a transient melanopsin downregulation that should be taken into account when assessing m(+)RGC survival.
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whole number distribution and co expression of brn3 transcription factors in retinal ganglion cells of adult albino and Pigmented Rats
PLOS ONE, 2012Co-Authors: Francisco M Nadalnicolas, Manuel Jimenezlopez, Manuel Salinasnavarro, Paloma Sobradocalvo, Juan J Alburquerquebejar, Manuel Vidalsanz, Marta AgudobarriusoAbstract:The three members of the Pou4f family of transcription factors: Pou4f1, Pou4f2, Pou4f3 (Brn3a, Brn3b and Brn3c, respectively) play, during development, essential roles in the differentiation and survival of sensory neurons. The purpose of this work is to study the expression of the three Brn3 factors in the albino and Pigmented adult Rat. Animals were divided into these groups: i) untouched; ii) fluorogold (FG) tracing from both superior colliculli; iii) FG-tracing from one superior colliculus; iv) intraorbital optic nerve transection or crush. All retinas were dissected as flat-mounts and subjected to single, double or triple immunohistofluorescence The total number of FG-traced, Brn3a, Brn3b, Brn3c or Brn3 expressing RGCs was automatically quantified and their spatial distribution assessed using specific routines. Brn3 factors were studied in the general RGC population, and in the intrinsically photosensitive (ip-RGCs) and ipsilateral RGC sub-populations. Our results show that: i) 70% of RGCs co- express two or three Brn3s and the remaining 30% express only Brn3a (26%) or Brn3b; ii) the most abundant Brn3 member is Brn3a followed by Brn3b and finally Brn3c; iii) Brn3 a-, b- or c- expressing RGCs are similarly distributed in the retina; iv) The vast majority of ip-RGCs do not express Brn3; v) The main difference between both Rat strains was found in the population of ipsilateral-RGCs, which accounts for 4.2% and 2.5% of the total RGC population in the Pigmented and albino strain, respectively. However, more ipsilateral-RGCs express Brn3 factors in the albino than in the Pigmented Rat; vi) RGCs that express only Brn3b and RGCs that co-express the three Brn3 members have the biggest nuclei; vii) After axonal injury the level of Brn3a expression in the surviving RGCs decreases compared to control retinas. Finally, this work strengthens the validity of Brn3a as a marker to identify and quantify Rat RGCs.
Magnus Niklasson - One of the best experts on this subject based on the ideXlab platform.
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effects of gabab activation and inhibition on vestibulo ocular and optokinetic responses in the Pigmented Rat
Brain Research, 1994Co-Authors: Magnus Niklasson, Richard Tham, Birgitta Larsby, Birgitta ErikssonAbstract:The effects of the GABAB agonist baclofen and the GABAB antagonist CGP 35348, given sepaRately or simultaneously, on the central vestibular system of Pigmented Rats have been evaluated. Drugs were administered either intramuscularly or intracerebroventricularly. Eye movements were recorded during vestibular, optokinetic and combined visual-vestibular stimulation. Activation of the GABAB receptors by baclofen caused a dose related disturbance of the system, manifested by (1) a decrease of the optokinetic gain, (2) a reduced ability to suppress nystagmus during conflicting vestibular and visual input, and (3) a disability to maintain the eccentric eye position upon a spontaneous saccade. All these effects could be inhibited in a dose-dependent fashion by CGP 35348, suggesting that the findings are specifically related to the GABAB receptor. Given sepaRately, the antagonist did not affect the mentioned parameters. During horizontal acceleRatory/deceleRatory stimulation in darkness baclofen caused a biphasic pattern in the dose-response curves. Small amounts of baclofen caused an increase of the gain and of the duRation of poststimulatory nystagmus, while high doses had a depressive action on the same parameters. The stimulating effect of baclofen could be inhibited or even reversed by CGP 35348, which has a depressive effect per se, similar to the effects of baclofen given in the upper range of doses.
Francisco M Nadalnicolas - One of the best experts on this subject based on the ideXlab platform.
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transient downregulation of melanopsin expression after retrograde tracing or optic nerve injury in adult Rats
Investigative Ophthalmology & Visual Science, 2015Co-Authors: Francisco M Nadalnicolas, Manuel Jimenezlopez, Manuel Salinasnavarro, Manuel Vidalsanz, Maria H Madeira, Caridad Galindoromero, Arturo Ortinmartinez, Ana Raquel Santiago, Marta AgudobarriusoAbstract:PURPOSE: To investigate the effect of retrograde tracing or axotomy on melanopsin mRNA expression and immunodetection in albino and Pigmented Rat retinas. METHODS: Groups were (1) intact-naive retinas; (2) optic nerve crush (ONC) analyzed at 7 days (7d) or 2 months (2m); (3) Fluorogold (FG) tracing from the superior colliculi (SCi) analyzed at 7d or 2m; (4) tracing from the intact optic nerve (ON) with FG or hydroxystilbamidine methanesulfonate (OHSt), analyzed 3d later; and (5) sham tracing from the ON or sham surgery. Brn3a and melanopsin were double stained in whole mounts to quantify and assess the distribution of orthotopic and displaced Brn3a(+) retinal ganglion cells (Brn3a(+)RGCs) and melanopsin(+)RGCs (m(+)RGCs). Freshly dissected retinas were used for melanopsin mRNA quantitative PCR. RESULTS: Tracing from the SCi did not affect the number of Brn3a(+)RGCs or m(+)RGCs counted in Pigmented Rats. However, only 55% of m(+)RGCs were immunodetected in albinos at 7d, although by 2m the m(+)RGCs counts returned to normal. Optic nerve tracing had a more dramatic effect (38% or 77% of m(+)RGCs were immunodetected in albino or Pigmented Rats) that occurred irrespectively of the tracer (OHSt or FG). This effect was not observed in the sham groups. After ONC, Brn3a(+)RGCs decreased to 37% and 8% by 7d and 2m, respectively. Melanopsin (+)RGC counts diminished to 30% at 7d, but recovered to 49% of controls by 2m. Melanopsin mRNA was downregulated after ON tracing or 7d after ONC, but did not differ from intact values 2m after ONC. CONCLUSIONS: Following ON injury or retrograde tracing there is a transient melanopsin downregulation that should be taken into account when assessing m(+)RGC survival.
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whole number distribution and co expression of brn3 transcription factors in retinal ganglion cells of adult albino and Pigmented Rats
PLOS ONE, 2012Co-Authors: Francisco M Nadalnicolas, Manuel Jimenezlopez, Manuel Salinasnavarro, Paloma Sobradocalvo, Juan J Alburquerquebejar, Manuel Vidalsanz, Marta AgudobarriusoAbstract:The three members of the Pou4f family of transcription factors: Pou4f1, Pou4f2, Pou4f3 (Brn3a, Brn3b and Brn3c, respectively) play, during development, essential roles in the differentiation and survival of sensory neurons. The purpose of this work is to study the expression of the three Brn3 factors in the albino and Pigmented adult Rat. Animals were divided into these groups: i) untouched; ii) fluorogold (FG) tracing from both superior colliculli; iii) FG-tracing from one superior colliculus; iv) intraorbital optic nerve transection or crush. All retinas were dissected as flat-mounts and subjected to single, double or triple immunohistofluorescence The total number of FG-traced, Brn3a, Brn3b, Brn3c or Brn3 expressing RGCs was automatically quantified and their spatial distribution assessed using specific routines. Brn3 factors were studied in the general RGC population, and in the intrinsically photosensitive (ip-RGCs) and ipsilateral RGC sub-populations. Our results show that: i) 70% of RGCs co- express two or three Brn3s and the remaining 30% express only Brn3a (26%) or Brn3b; ii) the most abundant Brn3 member is Brn3a followed by Brn3b and finally Brn3c; iii) Brn3 a-, b- or c- expressing RGCs are similarly distributed in the retina; iv) The vast majority of ip-RGCs do not express Brn3; v) The main difference between both Rat strains was found in the population of ipsilateral-RGCs, which accounts for 4.2% and 2.5% of the total RGC population in the Pigmented and albino strain, respectively. However, more ipsilateral-RGCs express Brn3 factors in the albino than in the Pigmented Rat; vi) RGCs that express only Brn3b and RGCs that co-express the three Brn3 members have the biggest nuclei; vii) After axonal injury the level of Brn3a expression in the surviving RGCs decreases compared to control retinas. Finally, this work strengthens the validity of Brn3a as a marker to identify and quantify Rat RGCs.