Retinal fibers alter tectal positional markers during the expansion of the half retinal projection in goldfish

Although widely accepted, the theory, that neurones carry immutable cytochemical markers which specify their synaptic connections, is not consistent with plastic reorganizations. Half retinal fish were therefore tested for changed markers following expansion. Optic nerve crush at the time of the half retinal ablation resulted in regeneration of a normal, restricted projection; but nerve crush following expansion (many months later) resulted in reestablishment of the expanded projection, assessed both by electrophysiological mapping and by radioautography. Since this implied changed markers, the half retina and tectum were tested independently using the ipsilateral tectum and eye as controls. In normal fish, removal of one tectum and deflection of the corresponding optic tract toward the remaining tectum resulted in regeneration of a positionally normal but ipsilateral map. In experimental fish, after the half retina had expanded its projection to the contralateral tectum, its optic tract was deflected to the control tectum. After 40 days it had regenerated a normal, restricted map indicating that the retinal markers had not changed. Such restricted projections did not expand in the presence of the normal projection even after a year or more. Similarly, the optic tract from the normal eye was deflected to cause innervation of the tectum containing the expanded half retinal projection. After 40 days, the projection regenerated from the normal eye was similar to the expanded half retinal projection. Areas of the normal retina corresponding to the missing areas of the half retina were not represented. Tectal markers had been altered by the half retinal fibers. In a final group, tecta were denervated and tested at various intervals by innervation from ipsilateral half retinal eyes. After five months of denervation, the regenerating fibers were no longer restricted to the rostral tectum but formed an expanded projection initially. Apparently tectal markers are induced by the retinal fibers, changed during expansion, and disappear during long‐term denervation.

[1]  Roger W. Sperry,et al.  OPTIC NERVE REGENERATION WITH RETURN OF VISION IN ANURANS , 1944 .

[2]  Roger W. Sperry,et al.  RESTORATION OF VISION AFTER CROSSING OF OPTIC NERVES AND AFTER CONTRALATERAL TRANSPLANTATION OF EYE , 1945 .

[3]  R. Sperry.  Patterning of Central Synapses in Regeneration of the Optic Nerve in Teleosts , 1948, Physiological Zoology.

[4]  R. Sperry,et al.  Preferential selection of central pathways by regenerating optic fibers. , 1963, Experimental neurology.

[5]  R. Sperry.  CHEMOAFFINITY IN THE ORDERLY GROWTH OF NERVE FIBER PATTERNS AND CONNECTIONS. , 1963, Proceedings of the National Academy of Sciences of the United States of America.

[6]  R. M. Gaze,et al.  Selection of appropriate tectal connections by regenerating optic nerve fibers in adult goldfish. , 1965, Experimental neurology.

[7]  M. Jacobson.  Development of neuronal specificity in retinal ganglion cells of Xenopus. , 1968, Developmental biology.

[8]  Electrophysiology of Goldfish Optic Tectum , 1971 .

[9]  M. Yoon.  Reorganization of retinotectal projection following surgical operations on the optic tectum in goldfish. , 1971, Experimental neurology.

[10]  R. M. Gaze,et al.  The Visual System and “Neuronal Specificity” , 1972, Nature.

[11]  S. Sharma.  Redistribution of visual projections in altered optic tecta of adult goldfish. , 1972, Proceedings of the National Academy of Sciences of the United States of America.

[12]  S. Roth.  A Molecular Model for Cell Interactions , 1973, The Quarterly Review of Biology.

[13]  R. Sperry,et al.  Tests for neuroplasticity in the anuran retinotectal system. , 1973, Experimental neurology.

[14]  Horder Tj.  Proceedings: Electron microscopic evidence in goldfish that different optic nerve fibres regenerate selectively through specific routes into the tectum. , 1974 .

[15]  M. Jacobson,et al.  Deployment of optic nerve fibers is determined by positional markers in the frog's tectum. , 1974, Experimental neurology.

[16]  Proceedings: Electron microscopic evidence in goldfish that different optic nerve fibres regenerate selectively through specific routes into the tectum. , 1974, The Journal of physiology.

[17]  Shin-Ho Chung,et al.  Polarity of structure and of ordered nerve connections in the developing amphibian brain , 1975, Nature.

[18]  M. Jacobson,et al.  Discontinuous mapping of retina onto tectum innervated by both eyes , 1975, Brain Research.

[19]  M. Murray.  Regeneration of retinal axons into the goldfish optic tectum , 1976, The Journal of comparative neurology.

[20]  J. Schmidt,et al.  Reversed visuomotor behavior mediated by induced ipsilateral retinal projections in goldfish. , 1977, Journal of Neurophysiology.

[21]  J. Schmidt,et al.  The paths and destinations of the induced ipsilateral retinal projection in goldfish. , 1978, Journal of embryology and experimental morphology.

[22]  S. Easter,et al.  Expansion of the half retinal projection to the tectum in goldfish: An electrophysiological and Anatomical study , 1978, The Journal of comparative neurology.