Group delay measurement from spiral ganglion cells in the basal turn of the guinea pig cochlea
作者:
Anthony W. Gummer,
Brian M. Johnstone,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1984)
卷期:
Volume 76,
issue 5
页码: 1388-1400
ISSN:0001-4966
年代: 1984
DOI:10.1121/1.391456
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Measurements of group delay were made extracellularly from spiral ganglion cells in the 3.7 to 5.0‐mm region of the guinea pig cochlea, using sinusoidally amplitude modulated tones with constant modulating frequency (100 Hz) and depth of modulation (0.19). Threshold cochlear tuning was accompanied by frequency‐dependent group delays. The group delay on the low‐frequency tail was independent of carrier frequency; the interunit variation was 0.28–1.28 ms. The difference in group delay between CF and the low‐frequency tail decreased as the CF threshold increased (−0.09±0.02 ms per 10 dB, beginning at 0.62±0.07 ms at 0 dB SPL). The group delay decreased above CF; at the units’ maximum frequency it was less than the low‐frequency tail value, and was sometimes negative. Following arterial injections of furosemide the CF threshold increased and the group delay peak decreased; the low‐frequency tail was unaffected. The group delay decreased with increasing intensity; the reduction near and above CF was not only larger than that on the low‐frequency tail, but also the change at 5–10 dB above threshold was far greater than expected from theQ10 dBof the suprathreshold iso‐rate tuning curves. A minimum‐phase analysis suggested that the group delay response above CF, together with its nonlinear behavior, can be accounted for by a high‐frequency, level‐independent, amplitude plateau, in combination with the single unit, amplitude nonlinearity which is known to exist above CF.
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