Conservation and change in the tectofugal visual system of mammals: A comparative study
The tectofugal pathway (TFP; retina-optic tectum-thalamus-visual pallium) is the main visual route to the telencephalon in amniotes. In mammals and birds, the tecto-thalamic portion of this pathway exhibits a diffuse and bilateral character that is originated exclusively from tectal ganglion cells (...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | Chile |
| OAI Identifier: | oai:repositorio.anid.cl:10533/253204 |
| Acceso en línea: | https://hdl.handle.net/10533/253204 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias Naturales Otras Ciencias Naturales |
| Sumario: | The tectofugal pathway (TFP; retina-optic tectum-thalamus-visual pallium) is the main visual route to the telencephalon in amniotes. In mammals and birds, the tecto-thalamic portion of this pathway exhibits a diffuse and bilateral character that is originated exclusively from tectal ganglion cells (TGC). Thus, the TFP can be regarded as the ancestral amniote condition. However, the constancy of this trait in mammals is still uncertain, as bilateral TGC projections have only been reported in rodent species. In addition to thalamic projections, avian TGCs establish conspicuous reciprocal connections with nuclei in the isthmic and pretectal regions: the nucleus ithsmi pars parvocelullaris (Ipc) and the nucleus pretectalis principalis (PT), respectively. In mammals this association with the isthmus and pretectum has yet to be elucidated. In this project we sought to clarify three aspects of the hodological organization of the TGC-originated tectofugal pathway in mammals: First, using the diurnal rodent Octodon degus as a model, we investigated the organization of the isthmo-tectal connectivity. Second, we searched for the presence of a homologous to the avian PT. Finally, in order to make a clearer picture of the evolutionary history of the mammalian TFP we introduced the marsupial Thylamis elegans as a new comparative model to study the organization of visual pathways in basal mammals. |
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