Meeting Abstract
Unlike mammals, many anamniotes exhibit lifelong growth of the retina and its target brain tissue, the optic tectum. In zebrafish, retinal ganglion cells (RGCs) project from the inner layer of the retina and form synapses with the contralateral optic tectum. In a variety of animals, tectal cell proliferation and cell death are influenced by innervation from the retina, indicating that RGC axons provide key information to control stem and progenitor cell behaviors. However, the nature of this information, trophic or synaptic, remains unknown. In this study we investigated how the loss of visual input that occurs through rearing fish in constant darkness alters stem and progenitor cell behaviors in the optic tectum relative to the presence or absence of a functional optic nerve. We demonstrate that while non-innervated lobes of fish raised in the typical light-dark cycle had significantly less proliferation than their innervated counterparts, there was not a significant difference between the innervated and non-innervated lobes of fish raised in complete darkness. These findings provide preliminary evidence that the cue supplied by RGC axons to tectal stem and progenitor cells arises from synaptic, visually-evoked activity.
