Browsing by Subject "Superior colliculus"

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    Localization of choline acetyltransferase and tyrosine hydroxylase immunoreactivities in the superior colliculus of the microbat, Rhinolophus ferrumequinum
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) Jeong, Se Jin; Jeon, Chang Jin
    The purpose of this study was to determine whether the superior colliculus (SC) of the microbat has the same neurochemical makeup as that of other mammals. We examined the organization of choline acetyltransferase (ChAT)- and tyrosine hydroxylaseimmunoreactive (TH-IR) fibers/cells using standard immunohistochemistry with antibodies against ChAT and TH. ChAT-IR fibers observed in the superficial layers were denser than those in the deeper layers, and these fibers were classified into two types: small varicose fibers and large varicose fibers. ChAT-IR cells were predominantly located in the superficial layers with diverse morphologies. Among the well-known sources of cholinergic fibers in the mammalian SC, pedunculopontine tegmental nucleus (PPTN) and laterodorsal tegmental nucleus (LDTN) contained strongly labeled ChAT-IR cells, while no cholinergic structures were found in the parabigeminal nucleus (PBG) in the microbat brain. TH-immunoreactivity was found within fibers but not within cells. The density of TH-IR fibers was high in the zonal layer, moderate in the superficial gray and optic layers, and low in the deeper layers. Well-labeled TH-IR cells were also observed within area 13 and the locus coeruleus, known as the sources of catecholaminergic fibers in other mammalian SC. Although there are some cytoarchitectural variations among species, our results clearly showed elaborately organized ChAT-IR and TH-IR fibers/cells in the microbat SC. Our findings will contribute significantly to the understanding of actively constructed microbat visual systems
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    Optogenetic Stimulation of the Superior Colliculus Confers Retinal Neuroprotection in a Mouse Glaucoma Model
    (Society for Neuroscience, 2019-03-20) Geeraerts, Emiel ; Claes, Marie ; Dekeyster, Eline; Salinas Navarro, Manuel Ángel; De Groef, Lies ; Van den Haute, Chris ; Scheyltjens, Isabelle ; Baekelandt, Veerle ; Arckens, Lutgarde ; Moons, Lieve ; Anatomía Humana y Psicobiología; Facultades de la UMU::Facultad de Medicina
    Glaucoma is characterized by a progressive loss of retinal ganglion cells (RGCs) in the eye, which ultimately results in visual impairment or even blindness. Because current therapies often fail to halt disease progression, there is an unmet need for novel neuroprotective therapies to support RGC survival. Various research lines suggest that visual target centers in the brain support RGC functioning and survival. Here, we explored whether increasing neuronal activity in one of these projection areas could improve survival of RGCs in a mouse glaucoma model. Prolonged activation of an important murine RGC target area, the superior colliculus (SC), was established via a novel optogenetic stimulation paradigm. By leveraging the unique channel kinetics of the stabilized step function opsin (SSFO), protracted stimulation of the SC was achieved with only a brief light pulse. SSFO-mediated collicular stimulation was confirmed by immunohistochemistry for the immediate-early gene c-Fos and behavioral tracking, which both demonstrated consistent neuronal activity upon repeated stimulation. Finally, the neuroprotective potential of optogenetic collicular stimulation was investigated in mice of either sex subjected to a glaucoma model and a 63% reduction in RGC loss was found. This work describes a new paradigm for optogenetic collicular stimulation and a first demonstration that increasing target neuron activity can increase survival of the projecting neurons.
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    Retinal afferents on Golgi-identified vertical neurons in the superior colliculus of the rabbit. A Golgi-EM,
    (Murcia : F. Hernández, 1993) Ortega, F.; Doñate-Oliver, F.; Grandes, P.
    The characteristics and distribution pattem of retinal afferent terminals making synaptic contacts on narrow field vertical neurons in the stratum griseum superficiale of the rabbit superior colliculus were studied using the Golgi-gold substitution technique in combination with either autoradiographic or degenerative methods. At the level of light microscopy, identified gold-toned vertical neurons showed similar features to those previously described by others. Although their axons were frequently seen rising from the basal dendritic tuft, they could also emerge from an apical dendrite, but rarely from the cell body. The electron rnicroscopic study revealed that these neurons received radiolabelled or degenerated profiles with typical features of retinal terminals, while more proximal parts seemed to receive fewer terminals but of larger size. Axo-somatic synaptic junctions were very rare and, interestingly, retinal terminals were not seen forming synapses on the basal dendritic arborization. The present results indicate that the narrow field vertical cells are targets for retinotectal projection.