By directly comparing the stimulation-induced Fos expression levels and patterns of all four cohorts, NH, OAD, YAD, and ND rats, we derived two main conclusions: First, the shorter the duration of deafness, the better the tonotopy of the auditory pathway, and second, with identical duration of deafness in adulthood, as in our YAD vs. OAD cohorts, age at onset of deafness and/or hearing experience appears to influence the preservation of tonotopy. This evidence concerns the gene FOS and deafness.