Late LEO: A New System for the Study of Neuroplasticity in Xenopus

  • Scott E. Fraser
Part of the NATO Advanced Study Institutes Series book series (NSSA, volume 27)


The left eye of stage 56 Xenopus tadpoles was removed. Electrophysiologic analysis of the retina to tectum projection, two to nine months later, established that the normal right eye to left (contralateral) tectum projection remained, but an additional right eye to right (ipsilateral) tectum projection was present. This anomalous ipsilateral projection was mediated by direct retina-to-tectum innervation, as shown by single-unit analysis, latency measurements, tectal lesion studies, and histological reconstruction. This anomalous projection was confined to peripheral regions of the retina that were concurrently taking part in the normal contralateral retinotectal projection. Unlike the contralateral projection from this peripheral retina, the ipsilateral projection had expanded to cover the entire dorsal surface of the right tectum. That the same region of retina can project differently to the two tecta establishes a role for fiber-fiber interaction in the development of the retinotectal map.


Optic Nerve Optic Tectum Optic Nerve Fiber Contralateral Projection Ipsilateral Projection 
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Copyright information

© Plenum Press, New York 1979

Authors and Affiliations

  • Scott E. Fraser
    • 1
  1. 1.Jenkins Department of BiophysicsThe Johns Hopkins UniversityBaltimoreUSA

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