Restoration of visual function following optic nerve regeneration in bluegill (Lepomis macrochirus) × pumpkinseed (Lepomis gibbosus) hybrid sunfish

Abstract

Simple (dorsal light reflex) and complex (predator-prey interactions) visually mediated behaviors were used concurrently with morphological examination to assess restoration of visual function following optic nerve crush in bluegill (Lepomis macrochirus) x pumpkinseed (Lepomis gibbosus) hybrid sunfish. Regenerating optic nerve axons projected into the stratum opticum-stratum fibrosum et griseum superficiale by week 2, the stratum griseum centrale by week 4, and stratum album centrale by week 6. Initial projections into the laminae were diffuse and less stratified compared to controls. By week 12, the projection pattern of regenerating nerve fibers closely resembled the innervation of normal tecta. Visual improvements were correlated with increasing projections into the tectum. The dorsal light reflex improved from a 45 degrees vertical deviation following nerve crush to 4.5 degrees by week 16. Initial predator-prey interactions were exclusively mediated by the control eye. As regeneration progressed, there was a gradual expansion of the visual field. The reaction distance and attack angles within the visual field of the experimental eye were initially less than controls, however, these differences disappeared by week 10. Improvements in visual function were closely correlated with an increase of regenerating ganglion cell axons into the optic tectum indicating sufficient synaptogenesis to mediate both simple and complex visual behavior.

Interspecific Resource Competition between the Invasive Round Goby and Three Native Species: Logperch, Slimy Sculpin, and Spoonhead Sculpin

“…The bars for strike angles are subdivided into unsuccessful (open) and successful strikes (solid). strikes outside the maximum range of the lateral line were most probably triggered by visual cues (Richmond et al 2004;Callahan and Mensinger 2007). The mechanosensory lateral line detects displace-ments in the local water field.…”

Visual function in regenerating teleost retina following surgical lesioning

“…was the first to document the restoration of function following optic nerve transection. More recent studies have demonstrated the capacity of severed optic nerve fibers to reform highly topographical projections and restore visual function~Meyer, 1977visual function~Meyer, , 1980Schmidt & Edwards, 1983;Northmore & Masino, 1984;Meyer et al, 1985;Callahan & Mensinger, 2007!. Retinal regeneration provides a more complex problem, because it involves the genesis of entire classes of retinal neurons, including new central projections to the tectum. Although, the regenerative potential of the teleost retina has been well documented~Raymond et al., 1988;Hitchcock et al, 1992;Cameron & Easter, 1995;Raymond & Hitchcock, 1997;Hitchcock & Raymond, 2004!, little work has been done to assess the visual capability of the regenerated tissue.…”

Complementary research models and methods to study axonal regeneration in the vertebrate retinofugal system

“…This tilted position will gradually return to the normal horizontal posture upon the regeneration process. Thus, measuring the angle between the horizon and the imaginary line connecting the center of both eyes in a frontal view is a simple method to evaluate functional recovery after optic nerve damage, which does not require specialized software or hardware equipment (Callahan and Mensinger 2007;Lindsey and Powers 2007;Diekmann et al 2015a). Under normal conditions, the swimming position is already significantly improved within 2 weeks after ONC (Diekmann et al 2015a).…”