1 Mechanics of the Unusual Basilar Membrane in Gerbil Santosh Kapuria, IIT Delhi Charles Steele, Stanford Sunil Puria, Stanford

2 Microstructure of BM Detailed anatomy Guinea pig: S Iurato (1962) Cat: LM Cabazudo (1978) Gerbil: Schweitzer L, Lutz C, Hobbs M, Weaver SP (1996) Point load measurements Human: Békésy (1960) Guinea pig: Gummer WA, Johnstone BM, Armstrong NJ (1981) Miller, C (1985) Gerbil: Olson EE, Mountain DC (1994) Naidu, RC, Mountain DC (1998) Emadi G, Richter CP, Dallos P (2004)

3 Iurato 1962,gp

4 I- Beam

Beam with constraints 5

6 Gerbil organ of Corti Arc of BM Edge, et al. (1998)

7 Gerbil OC (Corrales, 2006) 7

8 Beam model for BM

9 Arch model

10 Buckling of arch

Olson and Mountain

Emadi et al

13 Emadi, et al. (2004)

Point load on arch 14

15 Pressure loading without Pillar stiffness

16 Frequency map

17

18 Fast4 model of OC

Gerbil 2.75 mm, 1 kHz, wavelength = 10 mm 19

Gerbil 2.75, with pressure amplitudes 20

Gerbil at 2.75 mm, add axial flow amplitudes 21

Gerbil at 2.75 mm, add axial flow amplitudes with viscosity 22

23 Gerbil at BF, add axial viscosity

24 Acknowledgement q Fulbright Fellowship to SK q NIH RO1 DC007910

25 Close up, showing cilia and tip links

2607/07/2011 Lubrication theory HS TM IHC tip of cilium gapTM gapHS qHS qTM pressL1 pressIS Fluid displacement FD FD gapHS gapTM = – pressL1– pressIS qHS qTM perm * d/dt Edge, et al. (1998)