Analysis of dendritic arbors of native and regenerated ganglion cells in the goldfish retina

The retinas of adult teleost fish can regenerate following injury, but litt le is known about the neuronal integration of the visual scene that is perf ormed by the regenerated retina. Using goldfish retinal ganglion cells (RGC s) as the experimental system, an evaluation of dendritic arbor structure a nd passive electrotonic properties was developed, the aim being to quantita tively test the hypothesis that native and regenerated RGC dendritic arbors have similar structural and modeled electrotonic attributes. Fractal dimen sion was chosen as the descriptor of RGC dendritic arbor complexity, and th e arbors' transfer function magnitudes were estimated using an electrically passive, equivalent-circuit analysis. For both native and regenerated RGCs , arbors qualitatively judged to be simple tended to have lower fractal dim ension values than arbors judged to be more complex. All cells had similar cut-off frequencies, and for random stimulation of greater than 25% of an R GC's population of dendritic tips, there was a positive correlation between fractal dimension and transfer function magnitude. Some regenerated RGCs h ad abnormally long primary dendrites, but neither the distributions of frac tal dimension values, nor the estimated transfer function magnitudes, were significantly different between native and regenerated RGCs. The results ap pear to support the hypothesis that structural and modeled electrotonic att ributes of regenerated goldfish RGCs are similar to those of native RGCs, s uggesting that regenerated RGCs may restore normal visual function.