Konrad Kohler

Learn More
We examined optokinetic and optomotor responses of 450 zebrafish mutants, which were isolated previously based on defects in organ formation, tissue patterning, pigmentation, axon guidance, or other visible phenotypes. These strains carry single point mutations in >400 essential loci. We asked which fraction of the mutants develop blindness or other types(More)
Two types of photoreceptors, rods and cones, coexist in the vertebrate retina. An in-depth analysis of the retinal circuitry that transmits rod and cone signals has been hampered by the presence of intimate physical and functional connections between rod and cone pathways. By deleting the cyclic nucleotide-gated channel CNG3 we have generated a mouse(More)
The tyrosine kinase TrkB is a receptor for the neurotrophic factors brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4). Retinal ganglion cells are responsive to BDNF, and TrkB has been localized in ganglion cells as well as in a subpopulation of amacrine cells in the retina of the chicken and the rat. In the present paper, we analyzed the(More)
PURPOSE To determine a time window in the rhodopsin knockout (Rho(-/-)) mouse during which retinal function is already sufficiently developed but cone degeneration is not yet substantial, thus representing an all-cone retina. METHODS Electroretinograms (ERGs) were obtained from 14 homozygous Rho(-/-) mice and eight C57Bl/6 control mice. The same(More)
The idea of implanting microphotodiode arrays as visual prostheses has aroused controversy on its feasibility from the moment it appeared in print. We now present results which basically support the concept of replacing damaged photoreceptors with subretinally implanted stimulation devices. Network activity in degenerated rat retinae could be modulated(More)
Kynurenine aminotransferases (KATs I and II) are pivotal to the synthesis of kynurenic acid (KYNA), the only known endogenous glutamate receptor antagonist and neuroprotectant. This study is the first to identify KYNA in the rat retina and to examine immunohistochemically the distribution of KAT isoforms. As determined by HPLC, KYNA concentration in the(More)
This study was focused on the analysis of cell type differentiation and synaptogenesis as well as outer segment formation in an organotypic culture of the neonatal rat retina during a 6-14 day period of in vitro development. Moreover, the effects of the retinal pigment epithelium (RPE) on these processes were investigated. The in vitro development resulted(More)
Micro-photodiode arrays based on semiconductor chip technology are being developed to replace degenerated photoreceptor cells in the retina. Electric current is generated in tiny micro-photodiodes and delivered to the adjacent tissue by micro-electrodes. One of the main requirements of a sub-retinal implantable device is long-term stability versus corrosion(More)
Dopaminergic cells in the retina express the receptor for brain-derived neurotrophic factor (BDNF) (). To investigate whether BDNF can influence the development of the retinal dopaminergic pathway, we performed intraocular injections of BDNF during the second or third postnatal week and visualized the dopaminergic system with tyrosine hydroxylase (TH)(More)
Degradation of the retinal image by translucent occluders during postnatal development induces axial myopia in chickens, tree shrews and monkeys. Local visual deprivation produces myopia even in local regions of the eye and neither accommodation nor intact connection between the eye and the brain are necessary. Therefore, it is an important question whether(More)