Fraser, Scott E. and Hunt, R. Kevin (1986) A physiological measure of shifting connections in the Rana pipiens retinotectal system. Journal of Embryology and Experimental Morphology, 94 . pp. 149-161. ISSN 0022-0752 http://resolver.caltech.edu/CaltechAUTHORS:FRAdev86
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The retinotectal connections of developing Rana tadpoles and froglets have been studied using light-pipe techniques to directly assay the pattern of the projection from the retina to the tectum. The projection site of the retina surrounding the optic nerve head was determined at two different stages of development (late larval and metamorphic frog) on the same animal. Small electrolytic marker lesions were used to mark the tectal sites to which the optic nerve head projected at these two times. Comparison of the positions of the two lesions gives a direct measure of the shift in the projection during the interlesion time interval of one week. The results indicate a shift in the projection of 275 µm week–1 in late larval life. Previous work in Xenopus using the light-pipe techniques indicated a qualitatively similar shift during equivalent stages of development, but significantly smaller in magnitude. In the present study, topographic postsynaptic units could be recorded at all stages investigated, indicating functional synapses between the optic nerve fibres and the tectum. Thus, these studies offer evidence of a significant shift in the functional connection pattern of the amphibian retinotectal map during development, in agreement with the recent anatomical data from other laboratories on the Rana and goldfish visual system.
|Additional Information:||Published by The Company of Biologists 1986. (Accepted 10 January 1986) We thank Marija Duda for assistance with the histology in portions of this study, and Drs M. Bronner-Fraser, N. O'Rourke and J. Schmidt for their comments on the manuscript. Supported by grants from NIH (NS14807 to R.K.H.) and from NSF (BNS 8023638 to S.E.F.). A preliminary report of some of this work has appeared (Fraser, 1983b).|
|Subject Keywords:||Rana pipiens, retinotectal system, connections, projection nerve fibre, visual system, synapse|
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|Deposited On:||22 Sep 2008 00:18|
|Last Modified:||26 Dec 2012 10:18|
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