Department of Medical & Biological Engineering, Kyungpook National University, Dongduk-Ro, Jung-Gu, Daegu, Korea.
Magn Reson Imaging. 2013 Sep;31(7):1143-9. doi: 10.1016/j.mri.2013.03.003. Epub 2013 May 6.
The cochlear plays a vital role in the sense and sensitivity of hearing; however, there is currently a lack of knowledge regarding the relationships between mechanical transduction of sound at different intensities and frequencies in the cochlear and the neurochemical processes that lead to neuronal responses in the central auditory system. In the current study, we introduced manganese-enhanced MRI (MEMRI), a convenient in vivo imaging method, for investigation of how sound, at different intensities and frequencies, is propagated from the cochlear to the central auditory system. Using MEMRI with intratympanic administration, we demonstrated differential manganese signal enhancements according to sound intensity and frequencies in the ascending auditory pathway of the rat after administration of intratympanic MnCl2.Compared to signal enhancement without explicit sound stimuli, auditory structures in the ascending auditory pathway showed stronger signal enhancement in rats who received sound stimuli of 10 and 40 kHz. In addition, signal enhancement with a stimulation frequency of 40 kHz was stronger than that with 10 kHz. Therefore, the results of this study seem to suggest that, in order to achieve an effective response to high sound intensity or frequency, more firing of auditory neurons, or firing of many auditory neurons together for the pooled neural activity is needed.
耳蜗在听觉的感觉和灵敏度方面起着至关重要的作用；然而，目前对于不同强度和频率的声音在耳蜗中的机械转导与导致中枢听觉系统神经元反应的神经化学过程之间的关系知之甚少。在本研究中，我们引入了锰增强磁共振成像（MEMRI），这是一种方便的体内成像方法，用于研究不同强度和频率的声音如何从耳蜗传播到中枢听觉系统。通过鼓室内给予 MEMRI，我们在给予鼓室内 MnCl2 后，在大鼠的上行听觉通路中，根据声音强度和频率，显示了不同的锰信号增强。与没有明确声音刺激的信号增强相比，在接受 10 和 40 kHz 声音刺激的大鼠中，上行听觉通路中的听觉结构显示出更强的信号增强。此外，40 kHz 刺激频率的信号增强强于 10 kHz。因此，本研究的结果似乎表明，为了对高强度或高频声音做出有效反应，需要更多的听觉神经元放电，或者需要许多听觉神经元一起放电以产生聚合的神经活动。
