| Hair Cells:
Tricks to enhance response |
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| • | Inner
hair cells: MAIN SOURCE of afferent signal in |
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| auditory
(VIII) nerve. (~ 10 afferents per hair cell) |
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| • | Outer
hair cells: primarily |
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| get
EFFERENT inputs. |
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| Control
stiffness, amplify |
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| membrane
vibration. |
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| (5,000,000
X range) |
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| • | To
enhance frequency tuning: |
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| – | Mechanical
resonance of hair bundles: Like a tuning fork, hair |
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| bundles
of cells near base of cochlea are short and stiff, vibrating |
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| at
high frequencies; hair bundles near the tip of the cochlea are |
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| long
and floppy, vibrating at low frequencies. |
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| – | Electrical
resonance of cell membrane potential (in mammals?) |
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| – | An
AMAZING feat of development. |
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| • | Synaptic
transmission speed (10 ms): |
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| – | Synaptic
density: for speed? (normal synapse: 1 to 100s of ms) |
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