Eye-in-water electrophysiological mapping of goldfish with and without tectal lesions

doi:10.1016/0014-4886(77)90136-4

Experimental Neurology

Volume 56, Issue 1, July 1977, Pages 23-41

https://doi.org/10.1016/0014-4886(77)90136-4 Get rights and content

Abstract

An eye-in-water electrophysiological recording method was used to map accurately the retinotectal projection of normal goldfish, and the results were compared with those obtained using the more customary technique of recording with the eye in air. In air, the receptive fields were found not only enlarged, as expected from the extreme myopia, but were also shifted toward the periphery by as much as 25°, resulting in a sizable deficit in the map. In view of this mapping error, the eye-in-water technique was used to reinvestigate the projection plasticity previously found with the eye-in-air recording method. After ablation of the posterior half-tectum or medial quartertectum, with and without optic nerve crush, recordings were obtained in 40 fish, 1 to 18 months postsurgically. The results substantially confirmed that compression, whereby the visual field, including regions surgically deprived of their normal target zones, comes to project onto the tectal remnant in compressed retinotopic fashion, but the compression found was not homogeneous and as complete as previously thought. Rather, the degree of compression was greatest near the lesion and progressively decreased toward the opposite tectal pole where it was frequently absent. This compression difference between these tectal regions was typically a factor of two and in early postsurgical stages as great as three to four. In addition, regions of the peripheral field corresponding to the tectal lesion were found to be missing from the recorded projection even after long survival times. Some projection anomalies, not previously seen, were also observed. These findings have implications for theories on the growth of selective nerve connections.

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Cited by (51)

Intraocular BDNF promotes ectopic branching, alters motility and stimulates abnormal collaterals in regenerating optic fibers
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Citation Excerpt :
The tecta were exposed by excising the cranium covering the midbrain region and aspirating any overlying fat deposits. Fish were then immobilized in a holder similar to those used in electrophysiological studies (Meyer, 1977). Fish were respired by a tube placed in the mouth through which aerated water was pumped over the gills.
A great deal of effort has been invested in using trophic factors and other bioactive molecules to promote cell survival and axonal regeneration in the adult central nervous system. Far less attention has been paid to investigating potential effects that trophic factors may have that might interfere with recovery. In the visual system, BDNF has been previously reported to prevent regeneration. To test if BDNF is inherently incompatible with regeneration, BDNF was given intraocularly during optic nerve regeneration in the adult goldfish. In vivo imaging and anatomical analysis of selectively labeled axons were used as a sensitive assay for effects on regeneration within the tectum. BDNF had no detectable inhibitory effect on the ability of axons to regenerate. Normal numbers of axons regenerated into the tectum, exhibited dynamic growth and retractions similar to controls, and were able to navigate to their correct target zone in the tectum. However, BDNF was found to have additional effects that adversely affected the quality of regeneration. It promoted premature branching at ectopic locations, diminished the growth rate of axons through the tectum, and resulted in the formation of ectopic collaterals. Thus, although BDNF has robust effects on axonal behavior, it is, nevertheless, compatible with axonal regeneration, axon navigation and the formation of terminal arbors.
Investigating regeneration and functional integration of CNS neurons: Lessons from zebrafish genetics and other fish species
2011, Biochimica et Biophysica Acta - Molecular Basis of Disease
Zebrafish possess a robust, innate CNS regenerative ability. Combined with their genetic tractability and vertebrate CNS architecture, this ability makes zebrafish an attractive model to gain requisite knowledge for clinical CNS regeneration. In treatment of neurological disorders, one can envisage replacing lost neurons through stem cell therapy or through activation of latent stem cells in the CNS. Here we review the evidence that radial glia are a major source of CNS stem cells in zebrafish and thus activation of radial glia is an attractive therapeutic target. We discuss the regenerative potential and the molecular mechanisms thereof, in the zebrafish spinal cord, retina, optic nerve and higher brain centres. We evaluate various cell ablation paradigms developed to induce regeneration, with particular emphasis on the need for (high throughput) indicators that neuronal regeneration has restored sensory or motor function. We also examine the potential confound that regeneration imposes as the community develops zebrafish models of neurodegeneration. We conclude that zebrafish combine several characters that make them a potent resource for testing hypotheses and discovering therapeutic targets in functional CNS regeneration. This article is part of a Special Issue entitled Zebrafish Models of Neurological Diseases.
Growth dynamics and morphology of regenerating optic fibers in tectum are altered by injury conditions: An in vivo imaging study in goldfish
2008, Experimental Neurology
The dynamic behavior of axons in systems that normally regenerate may provide clues for promoting regeneration in humans. When the optic nerve is severed in adult goldfish, all axons regenerate back to the tectum to reestablish accurate connections. In adult mammals, regeneration can be induced in optic and other axons but typically few fibers regrow and only for short distances. These conditions were mimicked in the adult goldfish by surgically deflecting 10–20% of optic fibers from one tectum into the opposite tectum which was denervated of all other optic fibers by removing its corresponding eye. At 21–63 days, DiI was microinjected into retina to label a few fibers and the fibers were visualized in the living fish for up to 5–7 h. The dynamic behavior and morphology of these regenerating deflected fibers were analyzed and compared to those regenerating following optic nerve crush. At 3–4 weeks, deflected fibers were found to form more branches and to maintain many more branches than crushed fibers. Although both deflected and crushed fibers exhibited stochastic growth and retraction, deflected fibers spent more time growing but grew for less distance. At 2 months, both deflected and crushed fibers became much more stable. These results show that the morphology and behavior of fibers regenerating into the same target tissue can be substantially altered by the injury conditions, that is, they show state-dependent plasticity. The morphology and behavior of the deflected fibers suggest they were impaired in their capacity to grow to their correct targets.
Changing Pax6 expression correlates with axon outgrowth and restoration of topography during optic nerve regeneration
2006, Neuroscience
Citation Excerpt :
Twelve sections equally spaced across the retina were examined, representing 17% of the total retinal area for zebrafish, and 8% for lizard. In normal fish, topography was as previously reported with the temporal–nasal retinal axis projecting to the rostral–caudal tectal one and the dorso-ventral retinal axis projecting to the lateral–medial tectal one (Meyer, 1977; Sajovic and Levinthal, 1982; Fig. 1A). Receptive field sizes were small and symmetrical (radius: 3.19±0.46; circumference: 3.21±0.77; Fig. 1A, B).
Pax6, a member of the highly conserved developmental Pax gene family, plays a crucial role in early eye development and continues to be expressed in adult retinal ganglion cells (RGCs). Here we have used Western blots and immunohistochemistry to investigate the expression of Pax6 in the formation and refinement of topographic projections during optic nerve regeneration in zebrafish and lizard. In zebrafish with natural (12-h light/dark cycle) illumination, Pax6 expression in RGCs was decreased during axon outgrowth and increased during the restoration of the retinotectal map. Rearing fish in stroboscopic illumination to prevent retinotopic refinement resulted in a prolonged decrease in Pax6 levels; return to natural light conditions resulted in map refinement and restoration of normal Pax6 levels. In lizard, RGC axons spontaneously regenerate but remain in a persistent state of regrowth and do not restore topography; visual training during regeneration, however, allows a stabilization of connections and return of topography. Pax6 was persistently decreased in untrained animals but remained increased in trained ones. In both species, changes in expression were not due to cell division or cell death. The results suggest that decreased Pax6 expression is permissive for axon regeneration and extensive searching, while higher levels of Pax6 are associated with restoration of topography.
cAMP regulates axon outgrowth and guidance during optic nerve regeneration in goldfish
2005, Molecular and Cellular Neuroscience
Citation Excerpt :
The area sampled (100 μm length × 20 μm width × 6 locations) corresponded to 2.5% of total retinal area. To examine the extent of topographic order, fish were prepared for in vivo recording 1 to 2 days after the final intra-vitreal injection and maintained under light anaesthesia (Meyer, 1977; Rodger et al., 2004). A small circle of skull (approximately 2 mm in diameter) was removed with iridial scissors to expose the tectum.
Increased cAMP improves neuronal survival and axon regeneration in mammals. Here, we assess cAMP levels and identify activated pathways in a spontaneously regenerating central nervous system. Following optic nerve crush in goldfish, almost all retinal ganglion cells (RGC) survive and regenerate retinotectal topography. Goldfish received injections of a cAMP analogue (CPT-cAMP), a protein kinase A (PKA) inhibitor (KT5720), both compounds combined, or PBS (control). RGC survival in experimental groups was unaffected at any stage. The rate of axon regeneration was accelerated by the activator and decelerated both by the inhibitor and by combined injections, suggesting a PKA-dependent pathway. In addition, errors in regenerate retinotectal topography were observed when agents were applied in vivo and RGC response to the guidance cue ephrin-A5 in vitro was altered by the inhibitor. Our results highlight that therapeutic manipulation of cAMP levels to enhance axonal regeneration in mammals must ensure that topography, and consequently function, is not disrupted.
The balance of NMDA- and AMPA/kainate receptor-mediated activity in normal adult goldfish and during optic nerve regeneration
2005, Experimental Neurology
Retinotectal topography is established during development and relies on the sequential recruitment of glutamate receptors within postsynaptic tectal cells. NMDA receptors underpin plastic changes at early stages when retinal ganglion cell (RGC) terminal arbors are widespread and topography is coarse; AMPA/kainate receptors mediate fast secure neurotransmission characteristic of mature circuits once topography is refined. Here, we have examined the relative contributions of these receptors to visually evoked activity in normal adult goldfish, in which retinotectal topography is constantly adjusted to compensate for the continual neurogenesis and the addition of new RGC arbors. Furthermore, we examined animals at two stages of optic nerve regeneration. In the first, RGC arbors are widespread and receptive fields large resulting in coarse topography; in the second, RGC arbors are pruned to reduce receptive fields leading to refined topography. Antagonists were applied to the tectum during multiunit recording of postsynaptic responses. Normal goldfish have low levels of NMDA receptor-mediated activity and high levels of AMPA/kainate. When coarse topography has been restored, NMDA receptor-mediated activity is increased and that of AMPA/kainate decreased. Once topography has been refined, the balance of NMDA and AMPA/kainate receptor-mediated activity returns to normal. The data suggest that glutamatergic neurotransmission in normal adult goldfish is dual with NMDA receptors fine-tuning topography and AMPA receptors allowing stable synaptic function. Furthermore, the normal operation of both receptors allows a response to injury in which the balance can be transiently reversed to restore topography and vision.

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^☆: Gratefully acknowledged are the encouragement and discussions with Roger Sperry, the manuscript criticisms by Margaret Scott, and the histological assistance of Josephine Macenka. The work was supported by the F. P. Hixon Fund of the California Institute of Technology and U.S. Public Health Service Grant MH-03372 to R. W. Sperry.

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Eye-in-water electrophysiological mapping of goldfish with and without tectal lesions☆

Abstract

Vision Res.

Exp. Neurol.

J. Comp. Neurol.

Exp. Neurol.

J. Physiol. (London)

Interactions between optic fibers in their regeneration to specific sites in the goldfish tectum

J. Physiol. (London)

The visual system and “neuronal specificity”

Nature (London)

Axial differences in the reinnervation of the goldfish optic tectum by regenerating optic nerve fibers

Exp. Brain Res.