Cross-modal neuroplasticity in the blind mole rat Spalax ehrenbergi: a WGA-HRP tracing study.

Spalax ehrenbergi is a subterranean rodent possessing extremely degenerated eyes but a distinguishable dorsal lateral geniculate nucleus (dLGN) which projects ipsilaterally to a fair sized striate cortex. 2-Deoxyglucose and electrophysiological studies have shown that these areas are vigorously activated by auditory input. We show here, using the neuroanatomical tracer WGA-HRP, that the major source of the auditory input to the visual system is the inferior colliculus that, in addition to all its typical auditory targets, also projects to the dLGN. The visual thalamo-cortical pathway thereupon processes auditory information. This is the first naturally blind mammal in which the origin of auditory compensatory projections have been traced and described.