Kalluri Radha
Caruso Department of Otolaryngology-Head and Neck Surgery, Zilkha Neurogenetics Institute, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States.
Front Neurosci. 2021 Oct 12;15:710275. doi: 10.3389/fnins.2021.710275. eCollection 2021.
The membranes of auditory and vestibular afferent neurons each contain diverse groups of ion channels that lead to heterogeneity in their intrinsic biophysical properties. Pioneering work in both auditory- and vestibular-ganglion physiology have individually examined this remarkable diversity, but there are few direct comparisons between the two ganglia. Here the firing patterns recorded by whole-cell patch-clamping in neonatal vestibular- and spiral ganglion neurons are compared. Indicative of an overall heterogeneity in ion channel composition, both ganglia exhibit qualitatively similar firing patterns ranging from sustained-spiking to transient-spiking in response to current injection. The range of resting potentials, voltage thresholds, current thresholds, input-resistances, and first-spike latencies are similarly broad in both ganglion groups. The covariance between several biophysical properties (e.g., resting potential to voltage threshold and their dependence on postnatal age) was similar between the two ganglia. Cell sizes were on average larger and more variable in VGN than in SGN. One sub-group of VGN stood out as having extra-large somata with transient-firing patterns, very low-input resistance, fast first-spike latencies, and required large current amplitudes to induce spiking. Despite these differences, the input resistance per unit area of the large-bodied transient neurons was like that of smaller-bodied transient-firing neurons in both VGN and SGN, thus appearing to be size-scaled versions of other transient-firing neurons. Our analysis reveals that although auditory and vestibular afferents serve very different functions in distinct sensory modalities, their biophysical properties are more closely related by firing pattern and cell size than by sensory modality.
听觉和前庭传入神经元的细胞膜各自包含不同的离子通道组，这导致它们内在生物物理特性的异质性。在听觉神经节和前庭神经节生理学方面的开创性工作分别研究了这种显著的多样性，但这两个神经节之间的直接比较很少。在此，对新生前庭神经节和螺旋神经节神经元通过全细胞膜片钳记录的放电模式进行了比较。两个神经节均表现出从持续放电到瞬态放电等定性相似的放电模式，这表明离子通道组成存在总体异质性。两个神经节组的静息电位、电压阈值、电流阈值、输入电阻和首次放电潜伏期范围同样广泛。两个神经节之间几种生物物理特性之间的协方差（例如，静息电位与电压阈值之间以及它们对出生后年龄的依赖性）相似。与螺旋神经节相比，前庭神经节中细胞大小平均更大且更具变异性。前庭神经节的一个亚组尤为突出，其具有超大的胞体，表现为瞬态放电模式、极低的输入电阻、快速的首次放电潜伏期，并且需要大电流幅度才能诱导放电。尽管存在这些差异，但大体积瞬态神经元的单位面积输入电阻与前庭神经节和螺旋神经节中较小体积瞬态放电神经元的相似，因此似乎是其他瞬态放电神经元的大小缩放版本。我们的分析表明，尽管听觉和前庭传入神经在不同的感觉模态中发挥着非常不同的功能，但它们的生物物理特性在放电模式和细胞大小方面的相关性比在感觉模态方面更密切。
