[The visual cortex of Tupaia: an alternative model?]

The tree shrew has become an interesting animal for research in neurobiology because of its unique structural and functional properties, in particular in its visual system. Some of these properties are described and discussed here as far as they are related to the functional architecture of the primary visual cortex: The representation of the ocularity, the ON and OFF responses, the development of the retino-geniculo-cortical projection, and synaptogenesis. From these data it appears that the tree shrew forms an important exception to the functional organization as it is found in standard experimental animals like cats and monkeys. It challenges a deeper thought on a common basis for both types of organization and development.