Auditory pathway and auditory activation of primary visual targets in the blind mole rat (Spalax ehrenbergi): I. 2‐deoxyglucose study of subcortical centers

The blind mole rat Spalax ehrenbergi is a subterranean rodent that shows striking behavioral, structural, and physiological adaptations to fossorial life including highly degenerated eyes and optic nerves and a behavioral audiogram that indicates high specialization for low‐frequency hearing. A 2‐deoxyglucose functional mapping of acoustically activated structures, in conjunction with Nissl/Klüver‐Barrera‐stained material, revealed a typical mammalian auditory pathway with some indications for specialized low‐frequency hearing such as a poorly differentiated lateral nucleus and a well‐developed medial nucleus in the superior olive complex. The most striking finding was a marked 2‐deoxyglucose labeling of the dorsal lateral geniculate body and of cortical regions that correspond to visual areas in sighted rodents. The results render the blind mole rat a good model system for studying natural neural plasticity and intermodal compensation. In this report, we confine ourselves to the subcortical levels. The cortical level will be dealt comprehensively in a following paper.