FOS and deafness: To identify a correlation between tonotopic organization of the auditory system and hearing experience prior to deafness, the topography of stimulation-induced Fos expression in AVCN (Figure 7A, dashed line), LSO (Figure 7B, dashed line), and CIC (Figure 7C, dashed line) was determined for all four experimental groups: (1) young and old NH rats, (2) OAD rats, (3) YAD rats, and (4) ND rats.