Analysis of the effects of motor command for vocalization upon auditory mechanisms in the brainstem

为了研究发声运动中发声运动指令对脑干听觉机制的影响，我们首先识别了脑干内的听觉中继神经元，并分析了发声中枢的输入及其放电特性。采用中脑导尿管周围灰质作为发声中枢，研究了与诱导发声具有相同基本频率和形成峰的听觉刺激对侧耳膜背核和腹侧核内的听觉中继神经元的放电特性。这些刺激由计算机控制的仪器重建，该仪器由该基金配备。我们首先试图确定对发声中枢的单一电击的作用以及对不同听觉刺激的作用，然后在实际发声运动中这些神经元的放电特性。大多数记录的听觉中继神经元对发声中枢的单次电击在刺激强度范围内没有反应，而刺激强度可引起发声运动。在较高的刺激强度下，部分神经元受到抑制作用，部分神经元受到兴奋作用。然而，这些差异在统计学上并不显著，所以我们还没有发表我们的结果。为了阐明发声中枢的作用，我们现在试图分析听觉刺激对放电的影响。在实际发声过程中，听觉中继神经元的放电特性尚未进行分析，因为伴随脑干的运动异常大，很难进行稳定的记录。

To investigate the effects of motor commands for vocalization upon auditory mechanisms in the brainstem during actual vocalization movement, we first identified the auditory relay neurons within the brainstem, and analyzed the inputs from the vocalization center and their discharge properties.In precollicular-postmammilary decerebrate cats, we employed the midbrain periaqueductal gray as the vocalization center, and analyzed the discharge properties of auditory relay neurons within the dorsal and ventral nuclei of the lateral remuniscus responding to the auditory stimuli that has the same fundamental frequency and formant as those of induced vocalization. These stimuli were reconstructed by the computer controlled apparatus that was equipped by this grant.We first tried to identify the responsibility to the single electrical shock delivered to the vocalization center and the responsibility to the different auditory stimuli, and then the discharge properties of these neurons during the actual vocalization movements.Most of recorded auditory relay neurons did not respond to the single shock delivered to the vocalization center within the stimulus strength which could induce vocalization movements. With higher stimulus strength, some neurons received suppressive effects and some were excitatory. However, these differences were not significant statistically, so that we did not published our results yet. To clarify the effects from the vocalization center, we are now trying to analyze the effects upon the discharges induced by the auditory stimuli. The analysis of discharge properties of auditory relay neurons during actual vocalization was not performed yet, because accompanying movements of brainstem was unexpectedly large so that stable recording was quite difficult.