Visual information is processed in birds and other vertebrates along three different chains of brain areas: the thalamofugal system, the tectofugal system, and the accessory optic system. The latter is involved in control of body orientation in space. The two other systems share other tasks like localization and identification of objects in space. In birds with laterally placed eyes like the zebra finch, the tectofugal system is the most prominent one. It conveys visual information from the eye to the optic tectum of the contralateral hemisphere, then to nucleus rotundus and further to different nuclei of the forebrain. The tasks of the brain areas following Ectostriatum are not known. We are presently investigating the role of the Neostriatum which may be involved in the processing of imprinted information (see sexual imprinting)
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The retina of birds is organized similar to that of other vertebrates. The highest density of retinal ganglion cells is found in the foveal region, which is "looking" laterally with an angle of 60 degrees from the midline. The region between the fovea and the point †of the retina "looking" towards the beak tip also comprises a higher density of retinal ganglion cells, which means this area has a higher resolution than the other retinal parts.
A speciality of the avian eye is the Pecten, a comblike protrusion reaching into the vitreous of the eye. It most probably serves as a source for nutrition of the eye.


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