Palmer A R, Russell I J
Hear Res. 1986;24(1):1-15. doi: 10.1016/0378-5955(86)90002-x.
The high-frequency limit of phase-locking has been measured in fibres of the auditory nerve in the guinea-pig. It is shown that phase-locking begins to decline at about 600 Hz and is no longer detectable above 3.5 kHz which is about 1 octave lower than in the cat, squirrel monkey and some birds. Direct measurements of the cochlear afferent fibre synaptic delay are consistent with indirect estimates from phase-locking, both giving values of 0.7-0.8 ms. Measurements of the receptor potentials of inner hair-cells in the guinea pig cochlea indicate that as the stimulus frequency is increased there is a progressive decrease in the a.c. component compared to the steady depolarization. The cause of this decline is the low-pass filtering of the a.c. component by the hair-cell membrane. The cut-off and slope of the decline in the a.c. component is consistent with the suggestion that this process is the limiting factor in cochlear nerve fibre phase-locking. The implications of these findings for interspecies variation in phase-locking cut-off, for cochlear mechanisms and for the encoding of complex sounds are discussed.
在豚鼠听神经纤维中测量了锁相的高频极限。结果表明，锁相在约600 Hz时开始下降，在3.5 kHz以上不再可检测到，这比猫、松鼠猴和一些鸟类低约1个八度。耳蜗传入纤维突触延迟的直接测量结果与从锁相得到的间接估计一致，两者给出的值均为0.7 - 0.8毫秒。对豚鼠耳蜗内毛细胞受体电位的测量表明，随着刺激频率增加，与稳定去极化相比，交流成分逐渐减少。这种下降的原因是毛细胞膜对交流成分的低通滤波。交流成分下降的截止频率和斜率与该过程是耳蜗神经纤维锁相的限制因素这一观点一致。讨论了这些发现对锁相截止的种间差异、耳蜗机制以及复杂声音编码的影响。
