allgemeine zoologie und neurobiologie

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Retinal ganglion cells projecting to the nucleus of the optic tract and the dorsal terminal nucleus of the accessory optic system in macaque monkeys

I. Telkes, C. Distler & K.-P. Hoffmann

European Journal of Neuroscience, 12:2367-2375, 2000

Using classical neuroanatomical retrograde tracing methods we investigated retinal ganglion cells of origin of the projection to the nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT-DTN) in macaque monkeys. Our main question was to quantify the strength of the projection from the ipsilateral retina to the NOT-DTN. We therefore examined the number, distribution, and soma size of retinal ganglion cells involved in this projection. Electrophysiologically controlled small injections into the NOT-DTN revealed a clearly bilateral retinal projection mainly originating from the central retina but also involving peripheral retinal regions. Labelled cells were found nasally in the contralateral retina and temporally in the ipsilateral retina with some overlap in the fovea. The projection from the ipsilateral retina was 36%-43% of that from the contralateral retina. On average, only 1-6% of the local population of ganglion cells projected to the NOT-DTN. Small soma size and large dendritic fields imply that in monkey rarely encountered, "specialized" ganglion cells provide the direct retinal input to the accessory optic system. These results are discussed with respect to the symmetry of monocular horizontal optokinetic nystagmus in primates.




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