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Neural correlates of sensory specializations in birds
- Author / Creator
- Gutierrez-Ibanez, Cristian
A basic tenet of comparative studies of the brain is that the larger size of any neural structure is related to the need for progressing more complex or larger quantities of information, the so call Jerison's “principle of proper mass”.
Base on this principle, variation of the absolute and relative size of the brain, as well as variation in individual regions, has been correlated with motor, sensory and cognitive specializations. A large amount of these comparative studies have been focused on birds. Birds have become powerful models in many aspects of neurobiology as they display a large diversity of sensory, behavioural, motor and cognitive specializations. This provides the perfect opportunity to study changes in the brain related to these specializations.
This dissertation seeks to further advance our understanding of the principles that govern brain evolution using birds as a model. We performed five studies on the variation of cytoarchitectonic organization, relative volume and cell numbers in different sensory nuclei in birds. We found differences in the relative size of somatosensory, auditory and visual nuclei among birds. We show the independent enlargement of a somatosensory nucleus in three groups of birds related to different feeding behaviors. Our results also show variation in the relative size of nuclei that belong to parallel visual and auditory pathways within owls (Strigiforms). Additionally, we performed a comparison of the cytoarchitectonic organization, size and cell numbers in the isthmo optic nucleus in a large sample of birds which throws new light on the function of the projection from the isthmo optic nucleus to the retina. Lastly, we use a combination of phylogenetically corrected principal component analysis and evolutionary rates of change to show that the relative size of 9 visual nuclei evolve in a combination of concerted and mosaic manner. The current dissertation adds greatly to our knowledge of the forces that drive differences in morphology and cytoarchitecture of the brain between different species.
- Graduation date
- Fall 2013
- Type of Item
- Doctor of Philosophy
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