Differences in parvalbumin and calbindin chemospecificity in the centers of the turtle ascending auditory pathway revealed by double immunofluorescence labeling

► PV-immunoreactivity predominates in first-order and mesencephalic auditory centers. ► CB-immunoreactivity predominates in rostral auditory centers. ► The change of chemospecificity has been proved in the lemniscal auditory pathway. ► Differentiation of auditory centers into core and belt decreases rostrally. ► Co-localization of PV and CB decreases nonlinearly in the caudo-rostral direction.