In Vivo Development of Neuronal Structure and Function

Excerpt

The formation of the nervous system requires a coordinated development of neuronal morphology and synaptic physiology. We have used the frog retinotectal system to examine the development of brain structure and function. The retinotectal system of frogs is well known for its developmental and experience-dependent synaptic plasticity. As the animal grows, retinotectal axon arbors migrate considerable distances within the contralateral optic tectum in order to maintain a high degree of refinement in the retinotopic map. The capacity of the arbors to move within the tectal neuropil indicates that the retinotectal synapses and axon arbor branches are dynamic. The maintenance of retinotopy despite the axonal mobility indicates that there must be a mechanism which controls sites of synapse formation and stabilization. Considerable evidence supports the hypothesis that N-methyl-d-aspartate (NMDA) receptor activity is required to maintain the retinotopic map (Cline 1991), but it is still not clear how activity influences the neuronal...