Figure 3: Magnitude of receptor potential and CM as functions of stimulus level.

Recordings from the basal turn cochleae of CD-1Cx30^A88V/A88V and CBA/J mice in response to 5 kHz tones. (a) Techniques (in addition to those presented in Fig. 2) used to make acoustic, electrophysiological and mechanical measurements from the cochlea (modified with permission from refs 39, 40). (b) Peak-to-peak magnitude of an intracellular receptor potential recorded from a presumed supporting cell from a CD-1Cx30^A88V/A88V mouse in response to a 5 kHz tone as a function of stimulus level (representative example). (c) Magnitude of an intracellular receptor potential of a presumed OHC of a CD-1Cx30^A88V/A88V mouse in response to a 5 kHz tone as a function of stimulus level (representative example). Insets in b and c show voltage responses to 5 kHz tones made at tone onset; stimulus levels: 60 dB SPL, black; 80 dB SPL, red. Arrows, insets of b and c indicate negative peak of presumed compound action potential. (d) Compound extracellular receptor potentials (organ of Corti CM), as functions of stimulus level to 5 kHz tones, measured close to the middle row of OHCs (mean±s.d.) from cochleae of CBA/J (red, n=5) mice and CD-1Cx30^A88V/A88V (black, n=4) mice. Asterisks: significantly different (unpaired t-test, ≤0.05 two-tailed p value). Dashed line: recording noise floor for d and inset; CM responses were not seen at any level above this floor for CD-1Cx30^A88V/WT and CD-1Cx30^WT/WT mice. Dotted lines: slope of one. Inset, CM recorded from the round windows of the same group of mice (RW CM).