Regenerating Optic Axons Restore Topography after Incomplete Optic Nerve Injury

摘要: Following complete optic nerve injury in a lizard, Ctenophorus ornatus, retinal ganglion cell (RGC) axons regenerate but fail to restore retinotectal topography unless animals are trained on visual task (Beazley et al. [ 1997] J Comp Neurol 370:105–120, [2003] Neurotrauma 20:1263–1270). Here we show that incomplete injury, which leaves some RGC intact, restores normal topography. Strict axon allowed us preserve one side of the (projecting medial tectum) while lesioning those other lateral tectum). Topography and response properties for both populations were assessed electrophysiologically. The majority intact retained appropriate tectum had normal, consistently brisk, reliable responses. Regenerate fell into two classes: projected topographically with responses tended habituate lacked topography, responded weakly, habituated rapidly. Axon tracing by localized application carbocyanine dyes supported electrophysiological data. soma counts axotomized populations, contrasting 30% loss after injury. Unlike mammals, where regeneration fails secondary death removes many somata, lizards experience “win–win” situation: favorably influence functional outcome regenerating ones RGCs do not succumb either primary or death. J. Comp. Neurol. 505:46–57, 2007. © 2007 Wiley-Liss, Inc.