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Dynamic change

Dynamic change. Dynamic change: the range of stimulus levels over which a change in level produces a change in a neuron’s discharge rate Dynamic range of ANF: <35 dB at CF DR reduced when embedding in noisy background. Human can discriminate 100-dB range of stimulus (behavior test)

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Dynamic change

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  1. Dynamic change • Dynamic change: the range of stimulus levels over which a change in level produces a change in a neuron’s discharge rate • Dynamic range of ANF: <35 dB at CF • DR reduced when embedding in noisy background

  2. Human can discriminate 100-dB range of stimulus (behavior test) • Possible reasons: Olivocochlear efferent system • Hypothesis: sound-evoked efferent activity may exert an greater influence on DR in awake animals than in anesthetized ones

  3. PSTH from single-unit in VCN Pri-Notch Chopper Units Onset Unit Pri-like

  4. Dynamic Range

  5. Comparison of DR(in quiet environment)

  6. Noise-inducedshiftof CF rate-level function (from VCN chopper unit) Noise-induced horizontal shift Larger shift at awake cats (p< 0.0001)

  7. Noise-inducedshift(cont) Chopper < pri-like at lower level Awake chopper vs awake pri-like vs anesthetized

  8. Noise-induced compression Less compression in awake cats Anesthetized cats could not respond at background of >50 dB because of saturation

  9. Adaptation in noisy environment Adaptation SR

  10. Noise-induced compression Awake chopper vs awake pri-like vs anesthetized

  11. Noise-induced shifts & compression:Awake vs Behaving

  12. Summary • Larger shift & less compression: higher DR in VCN units of awake cats than in ANFs in anesthetized cats or VCN units in decerebrate cats • Otherwise most characteristics are similar (awake vs anesthetized in quite, PST response type)

  13. Explanation: the cochlea and auditory nerve are unaffected by anesthesia. • Olivocochlear system (or other descending systems) could very well be affected by anesthesia • Descending systems are important for intensity coding and detection in background noise.

  14. COCB effects on ANF of anesthetized cats With COCB stimulation, higher Shift & lower compression higher DR Winslow et al 1987

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