The development of eye movements in the zebrafish (Danio rerio)

Abstract

We investigated the development of oculomotor activity in zebrafish embryos and larvae of ages postfertilization (hpf). The optokinetic response (OKR: smooth 48-96 hrs tracking movements evoked by a rotating striped drum) improved steadily after its onset at and by had a achieved a gain (eye velocity/drum velocity) of 0.9, comparable 73 hpf, 96 hpf to adult performance. Reset movements (the fast phase of optokinetic nystagmus) developed over The vestibuloocular reflex (VOR: compensatory eye movements evoked by 75-81 hpf. passive rotation of the head) developed over and the associated reset movements, 74-81 hpf, overThe VOR was qualitatively normal in dark-reared fish, which excludes an 76-81 hpf. essential role for visual experience in its early development. Spontaneous saccadic movements (the fast shift of eye position) appeared between 81 and and at had maximum 96 hpf, 96 hpf velocities that were comparable to adults.These results are compared to, and found to be incompatible with, two earlier ideas of motor development: behavioral "differentiation" and "encephalization."

Early lens development in the zebrafish: A three‐dimensional time‐lapse analysis

“…The posterior suture was visible at 48 hpf and formed before the anterior suture, which was similar to chick embryonic lens development in which the posterior suture forms at embryonic day 6, 1-2 days before the anterior suture (Shestopalov and Bassnett, 2000). The complete umbilical suture was obvious by 3dpf, when the lens became a functional optical element in the visual pathway (Easter and Nicola, 1996). The formation of primary fiber cells was one of the first differences between zebrafish and mammalian lens development.…”

“…The zebrafish has emerged more recently as an organism with unique advantages over other vertebrate models for studying the visual system (Schmitt and Dowling, 1994;Easter and Nicola, 1996;Glass and Dahm, 2004;Fadool and Dowling, 2008). Rapid development outside of a womb, transparency of early embryos, robust reproduction, and relative ease of genetic manipulation allow for experimental studies in vivo that would be impractical in mammalian species.…”

“…Instead of invagination and vesicle formation, the zebrafish lens develops as a solid mass of cells that delaminates from the surface ectoderm (Schmitt and Dowling, 1994;Easter and Nicola, 1996). The process of development and differentiation of lens epithelium, primary fibers, and secondary fibers without a lens vesicle stage remains poorly understood.…”

Behavioral genetic approaches to visual system development and function in zebrafish

“…The retina becomes mature enough to support visually mediated responses by 68 hpf (Easter and Nicola, 1996), and electroretinograms (ERG) have been recorded as early as 72 hpf (Branchek, 1984). The earliest visual behavior is the visual startle response (Kimmel et al, 1974).…”

“…Larvae respond to a sudden decrease in illumination by a rapid body movement, presumably as an adaptive behavior to escape a looming predator. This behavioral response starts at around 68 hpf (Easter and Nicola, 1996), just at the time when outer segments of photoreceptors and synaptic ribbons have formed in the retina (Branchek and Bremiller, 1984;Schmitt and Dowling, 1999). It becomes impractical to test the visual startle response after 4 dpf, because older larvae display spontaneous motor activity, making it difficult to distinguish between visually elicited and spontaneous body movements.…”