Region-specific contribution of ephrin-B and Wnt signaling to receptive field plasticity in developing optic tectum.

Ephrin-B/EphB and Wnts are known to regulate synapse maturation and plasticity, besides serving as axon guidance molecules, but the relevance of such synaptic regulation to neural circuit functions in vivo remains unclear. In this study, we have examined the role of ephrin-B and Wnt signaling in regulating visual experience-dependent and developmental plasticity of receptive fields (RFs) of tectal cells in the developing Xenopus optic tectum. We found that repetitive exposure to unidirectional moving visual stimuli caused varying degrees of shift in the RFs in different regions of the tectum. By acute perfusion of exogenous antagonists and inducible transgene expression, we showed that ephrin-B signaling in presynaptic retinal ganglion cells and Wnt secretion from tectal cells are specifically responsible for the enhanced visual stimulation-induced changes in neuronal responses and RFs in the ventral and dorsal tectum, respectively. Thus, ephrin-B and Wnt signaling contribute to region-specific plasticity of visual circuit functions.
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