Retinal Developmental and Visual System Mutants
Here we characterize the sweeping reorganization of retinal connections to the superior colliculus of fetal cats. This paper was published by R. W. Williams and Leo Chalupa in The Journal of Neuroscience 2:604–622. This web edition includes revisions, annotations, and several new figures.
Interrupting binocular interactions early in development by removing one eye results in an increase in numbers of retinal gangliion cell axons originating from the spared eye. In this collaboration with Zaineb Henderson, Leo Chalupa and I verified that numbers of ganglion cells are increased and assessed how these surplus cells are distributed. This paper was published in Neuroscience 12: 1139–1146 (1984).
This review by Leo Chalupa and R. W. Williams summarizes work on visual system development in cat carried out in Leo Chalupa’s laboratory from about 1980 through 1984. It includes our only published account of the development of retinal projections to the thalamus. Published in Development of Visual Pathways in Mammals.
First of a set of papers on the achiasmatic mutation in dogs. In these remarkable achiasmatic mutants, all retinal ganglion cell axons have an uncrossed projection. The anatomical and functional repercussions of this decussation error are fascinating. This paper is our initial analysis of the mutation and was published by Robert Williams, Dale Hogan, and Preston Garraghty in Nature 367:637–639 (1993).
In this study Dale Hogan and I test whether the retina or optic chiasm is the likely site of mutant gene action in achiasmatic mutant dogs. Retinas of mutants were examined to discover any associated changes in retinal structure. Thre are some differences, but we still suspect that the chiasm is the site of gene action. The paper was originally published in 1995 in The Journal of Comparative Neurology 352:367-380.
What happens when both eyes connect to only one side of the brain? This paper by Dale Hogan, Preston Garraghty, and Robert Williams describes the bizarre, but functional, consequences of having only half an optic chiasm. Published in The Journal of Neuroscience. This is an Adobe Acrobat pdf file.
A paper by Rob Williams and Dan Goldowitz on clones of retinal cells in aggregation chimeras. Published in Proceeding of the National Academy of Science (1992).
A controversial review published in Trends in Neuroscience in 1992. In this article Dan Goldowitz and I reanalyzed data on retinal clones generated by David Turner and Constance Cepko. Based on several Monte Carlo simulations and on our own studies of clones in retinas of chimeric mice, we argued that lineage has a definite role in cell determination in retina—that lineage restriction has to be considered a probabilistic process rather than as an absolute switch. At the time, the ideas outlined in this review were not received with enthusiasm (read our critics: their letters are included). Now the main idea in this article has been largely assimilated.
A review by Dan Goldowitz and colleagues on clones of retinal cells in aggregation chimeras published in Progress in Brain Research (1996).
A visually-stunning and technical complex paper with a simple message—the expression of the tyrosinase enzyme in the pigment epithelium is critical to axon navigation by retinal ganglion cells. Now we would like to know how pigmentation, and the lack of pigmentation, modulates ganglion cell differentiation and the growth of their axons. Published in Developmental Biology by Dennis S. Rice and colleagues. This is an Adobe Acrobat pdf file.
I am probably the third person to have rediscovered that the rim of the human retina is jam-packed with cones. This is also true of baboons, talapoins, and some (but not all) macaque species (RW Williams, unpublished). The functional significance of this cone-rich rim is still in doubt, but my favorite hypothesis or speculation is that the cone rim may be the visual system's equivalent of a rapid-response network. Visual Neuroscience 6:403.
A paper by Dennis S. Rice and colleagues on the belly spot and tail mutation. Bst is an autosomal dominant mutation of an unknown gene that is associated with variable optic nerve aplasia. This is a short gene mapping study published in Mammalian Genome 6:546.
Neurogenetics at University of Tennessee Health Science Center