2026-09-18T19:22:18Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/296772026-06-06T01:04:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Rahul Sarpeshkar.
Lu, Timothy K. (Timothy Kuan-Ta), 1981-
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2006-03-24T16:14:19Z
2006-03-24T16:14:19Z
2003
2003
http://hdl.handle.net/1721.1/29677
53834016
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references (leaves 144-146).
Outer hair cells (OHCs) generate active forces in the mammalian cochlea. Acting as cochlear amplifiers, OHCs can counteract viscous drag, generating high gain at characteristic frequencies and allowing for the sharp frequency selectivity and sensitivity observed in mammals. Excitatory displacement of the basilar membrane causes depolarization of OHC membrane potentials which results in contraction. The motor protein prestin is driven by receptor potentials. However, low-pass filtering by the plasma membrane should severely attenuate the receptor potential at high frequencies (> 100 kHz) where mammalian hearing has been observed. Thus, an open question is how OHCs can respond at these high frequencies despite their low frequency cutoff. Inspired by the use of feedback in mechanical and electrical systems to accelerate slow poles, I demonstrate that negative feedback from the coupling of two mechanical modes of vibration can lead to a membrane time constant speedup and a sharpening of the mechanical response.
y Timothy K. Lu.
M.Eng.
S.B.
146 leaves
5173220 bytes
5173026 bytes
application/pdf
application/pdf
eng
Massachusetts Institute of Technology
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http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
A feedback analysis of outer hair cell dynamics
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<Abstract>Outer hair cells (OHCs) generate active forces in the mammalian cochlea. Acting as cochlear amplifiers, OHCs can counteract viscous drag, generating high gain at characteristic frequencies and allowing for the sharp frequency selectivity and sensitivity observed in mammals. Excitatory displacement of the basilar membrane causes depolarization of OHC membrane potentials which results in contraction. The motor protein prestin is driven by receptor potentials. However, low-pass filtering by the plasma membrane should severely attenuate the receptor potential at high frequencies (> 100 kHz) where mammalian hearing has been observed. Thus, an open question is how OHCs can respond at these high frequencies despite their low frequency cutoff. Inspired by the use of feedback in mechanical and electrical systems to accelerate slow poles, I demonstrate that negative feedback from the coupling of two mechanical modes of vibration can lead to a membrane time constant speedup and a sharpening of the mechanical response.</Abstract>
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