声长对小鼠下丘神经元声强反应关系的影响

The Efect of Sund Dration on the Rpresentation of Aoustic Aplitude in the Muse Iferior Clliculus

目的：探讨声长（sound duration）对听神经元声音强度反应关系的影响。方法：采用在体细胞外记录方法,通过给予双耳不同声长和声强的特征频率（characteristic frequency,CF）短纯音刺激,记录4-6周BALB/c小鼠下丘神经元听反应,并分别以动作电位发放数（spike counts,SC）和第一发放延时（first spike latency,FSL）为评价指标,分析比较声长对神经元的声强反应关系的影响。结果：共记录到35个神经元反应。以发放数为评价指标,这些神经元分别表现出34%单调、26%饱和、40%非单调3种声强反应。较之发放数,FSL能更好地反映声强和声强变化,并展示出同一规律的FSL-声强反应曲线：FSL随着声强的增大而缩短。在不同声长下,所有神经元发放数-声强曲线和FSL-声强曲线基本重合,但后者变异性小。结论：声长对小鼠下丘神经元强度反应关系无明显影响;相比发放数,FSL则能更准确地反映声强和声强变化。

Objective. To explore the effect of the sound duration on the neuronal responses to the amplitudes. Methods. In 4 to 6 weeks BALB/c mice, we employed extracellular recording technique on their central nuclei of inferior colliculus. In this study, spike counts （SC） and first spike latency （FSL） were both used to evaluate the responses of neurons to the binaural acoustic stimuli which were varied with duration and amplitude at the neuronal characteristic frequency. Results： A total of 35 single neurons were recorded. The SC-mplitude functions across a population of auditory neurons are classified as the monotonic （34%）, saturated （26 %）, and non-onotonic （40 %）. For each type neuron, the iso-duration SC-amplitude functions demonstrated similar shape with wide variation. In contrast to SC, FSL decreases monotonically with the amplitude increasing. The iso-duration FSL-amplitude functions of a recorded neuron overlapped. Conclusion： Sound duration has no effect on the representation of acoustic amplitude; In contrast to SC, FSL can precisely reflect the response to acoustic amplitude and its variation.