ABSTRACT
For example, in normal-hearing mice, the general tonotopic organization of the CN and IC follows the basic mammalian scheme in normal-hearing mice: a dorsoventral progression of highto low frequencies in CN subdivisions and low-to-high frequencies in the IC, an orderly representation in cortex. However, the commonly used inbred strain, DBA/2J exhibits high-frequency hearing loss at an early age (Chapters 14, 28, and 29), and its tonotopic organization is far from typical. As shown in Figure 17.1, tonotopic organization in the CN progresses dorsoventrally from high to low frequencies, as expected in young C57BL/6J mice (which hear well at this age). By contrast, in DBA mice with high-frequency hearing loss, tonotopic variation is virtually nonexistent. Given that a number of the most commonly used inbred strains exhibit high-frequency hearing loss at some stage of life (Chapters 24, 27-29), it is wise to avoid referring to tonotopic organization or frequency representation typical of “the mouse.”
