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Doppler Optical Coherence Microscopy of the Cochlea

DOCM is a technique that enables simultaneous measurements of both the reflectivity and the velocity of structures internal to the organ of Corti. A low-coherence light source is used in an interferometric setup to measure the reflectivity of structures throughout the organ of Corti. The image to the left shows the reflectivity of various cochlear structures, with hotter colors representing higher reflectivity. The basilar membrane, outer hair cells, tectorial membrane, tunnel of Corti, and other cochlear structures are all visible. At each point, the interferometer is also operated in a manner similar to that of a laser velocimeter, allowing the velocities of points throughout the organ of Corti to be measured. In the fixed cochlea shown here, the velocities (plotted to the right) in response to vibration of the temporal bone are all nearly identical. This same technique can be used to measure the motion of an unfixed or living cochlea in response to sound stimulation.