Outer hair cells act as nonlinear amplifiers with bidirectional lateral feedback

Evidence

The schematic diagram shown in Fig. 3.27a indicates the structure of the electrical circuit usually described as heing equivalent to the hydromechanical network in the inner ear, regarding displacement of the basilar membrane. This network, however, was transferred into the dual network (Fig. 3.27b), to enable study with voltages instead of currents. The possibility of a resonating tectorial membrane is ignored by assuming that its damping is large enough to integrate its influence into the elements of the approximation. The outer haircells are assumed in this model to act only as nonlinear amplifiers, the outputs of which strongly influence the input to the inner hair cells and feed back to the vibration of the basilar membrane, not only at the same location hut also at adjacent places in both directions. To account for this lateral spread, additional feedback to the next two neighbouring sections on both sides is installed, with a reduced effectiveness of half of the direct feedback for the first and one quarter for the second neighbour. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 345

Categorization

• XREF: The lateral-feedback-with-decaying-strength structure mirrors lateral inhibition schemes in neural network modeling and on-center/off-surround receptive fields.
• DEFINE: Explains how lateral coupling (feedback to neighboring sections at half and quarter strength) is operationalized in the hardware model.