Vestibular Research Laboratory, School of Psychology, The University of Sydney, NSW, Australia.
Vestibular Research Laboratory, School of Psychology, The University of Sydney, NSW, Australia.
Hear Res. 2019 Mar 1;373:59-70. doi: 10.1016/j.heares.2018.12.009. Epub 2018 Dec 24.
Phase-locking of cochlear neurons to sound has been of great value in understanding cochlear transduction. Phase-locking has also been reported previously in irregular vestibular afferents, but detailed information about it is sparse. We measured the phase-locking of guinea pig irregular otolithic neurons and canal neurons (after a semicircular canal dehiscence allowed them to respond) to both sound and vibration stimuli. Irregular vestibular afferents from both otoliths and canals have a range of preferred phase angles which systematically increase as frequency is increased from 250 Hz to above 1000 Hz. Surprisingly vestibular afferents show more precise phase-locking than comparable auditory afferents as reported by Palmer and Russell (1986), and they do so up to higher frequencies. This high precision implies a very sharp, fast threshold for evoking an action potential with minimal variability, and so has implications for the current controversy about hair-cell-afferent transmission in the vestibular system. Following recent evidence, we suggest that potassium in the unique type I-calyx synapse may be a major factor in generating this very precise phase-locking.
耳蜗神经元对声音的锁相已被证明对耳蜗转导的理解具有重要价值。先前也曾有报道称不规则前庭传入神经存在锁相现象，但关于其的详细信息却很匮乏。我们测量了豚鼠不规则耳石神经元和半规管神经元（在半规管裂开放后，它们可以做出反应）对声音和振动刺激的锁相情况。来自耳石和半规管的不规则前庭传入神经具有一系列的最佳相位角，随着频率从 250 Hz 增加到 1000 Hz 以上，这些相位角会系统地增加。令人惊讶的是，与 Palmer 和 Russell（1986）报道的可比听觉传入神经相比，前庭传入神经具有更高的锁相精度，而且它们可以在更高的频率下做到这一点。这种高精度意味着在最小变异性下引发动作电位的阈值非常尖锐、快速，因此对当前关于前庭系统毛细胞传入神经传递的争议具有重要意义。根据最近的证据，我们认为，独特的 I 型壶腹突触中的钾可能是产生这种非常精确锁相的主要因素。
