Broniatowski Michael, Grundfest-Broniatowski Sharon, Nelson David R, Dessoffy Raymond, Shields Robert W, Strome Marshall
Department of Otolaryngology and Communicative Disorders, The Cleveland Clinic Health Sciences Center of the Ohio State University, USA.
Ann Otol Rhinol Laryngol. 2002 Jun;111(6):542-52. doi: 10.1177/000348940211100611.
This study explores the relationship between voice production and intrinsic laryngeal muscle (ILM) activities as expressed by orderly recruitment of their specific motor units. In 5 dogs, both the recurrent laryngeal nerve (RLN) and the vagus nerve (cranial nerve X) were stimulated via tripolar electrodes with stimulating frequencies (Fs) of 10 to 60 Hz and 0 to 7 mA during application of symmetric 600 Hz, 7 to 0 mA blocking currents. The fundamental frequency (Fo) and the intensity (I) of sounds generated by tracheal insufflation of humidified air were recorded while electromyograms of the cricothyroideus (CT), thyroarytenoideus (TA), and posterior cricoarytenoideus (PCA) were obtained via surface electrodes. Contractions of the CT were concurrently induced by stimulating the superior laryngeal nerve (SLN). The recruitment rates were highly specific and were affected by which nerve was stimulated. For the RLN, PCA ramping was lowest for Fs of < or =50 Hz. For Fs of 10 to 30 Hz, the recruitment rate of the TA was significantly steeper than that for the other ILMs, and the CT had the highest rate for Fs of 40 to 50 Hz. Conversely, for the vagus nerve, PCA recruitment was highest for Fs of > or =30 Hz. The average Fo was significantly higher with the RLN than with the vagus nerve. When the TA recruited faster than the CT (ie, via the RLN, but not the vagus nerve), the Fo was higher. While only CT ramping was significantly related to changes in sound intensity, there was a trend toward a decrease when PCA ramping was higher than CT ramping, as occurred when only the vagus nerve was stimulated. Stimulation of the SLN always increased Fo and loudness. We conclude that changes in Fo occur mainly through RLN-mediated CT and TA contraction. Loudness is controlled by the CT. The PCA exerts reciprocal coupling on both functions via the vagus nerve, and they are boosted across the board by the SLN. These findings may allow artificial manipulation of voice.
本研究探讨了发声与喉内肌（ILM）活动之间的关系，这种关系通过其特定运动单位的有序募集来体现。在5只犬中，在施加对称的600Hz、7至0mA阻断电流期间，通过三极电极以10至60Hz的刺激频率（Fs）和0至7mA刺激喉返神经（RLN）和迷走神经（第十对脑神经）。在通过表面电极获取环甲肌（CT）、甲杓肌（TA）和后环杓肌（PCA）的肌电图时，记录通过向气管内吹入湿化空气产生的声音的基频（Fo）和强度（I）。通过刺激喉上神经（SLN）同时诱导CT收缩。募集率具有高度特异性，并且受刺激的神经影响。对于RLN，当Fs≤50Hz时，PCA的斜坡式募集最低。当Fs为10至30Hz时，TA的募集率明显比其他ILM更陡峭，而当Fs为40至50Hz时，CT的募集率最高。相反，对于迷走神经，当Fs≥30Hz时，PCA的募集最高。RLN刺激时的平均Fo明显高于迷走神经刺激时。当TA的募集比CT快时（即通过RLN，但不是迷走神经），Fo更高。虽然只有CT的斜坡式募集与声音强度的变化显著相关，但当PCA的斜坡式募集高于CT的斜坡式募集时（如仅刺激迷走神经时发生的情况），有强度降低的趋势。刺激SLN总是会增加Fo和响度。我们得出结论，Fo的变化主要通过RLN介导的CT和TA收缩发生。响度由CT控制。PCA通过迷走神经对这两种功能施加相互耦合作用，并且它们都通过SLN得到增强。这些发现可能允许对声音进行人工操控。
