Nonaka S, Takahashi R, Enomoto K, Katada A, Unno T
Department of Otolaryngology, Asahikawa Medical School, Nishikagura, Japan.
Neurosci Res. 1997 Dec;29(4):283-9. doi: 10.1016/s0168-0102(97)00097-7.
The Lombard reflex occurs when a speaker increases his vocal effort while speaking in the presence of ambient noise. The purpose of this study was to clarify whether the Lombard reflex can be evoked during controlled vocalization in an animal model. In decerebrate cats, repetitive electrical stimulation was applied to the midbrain periaqueductal gray (PAG) to evoke vocalization. Pure tone auditory stimulation was delivered through a loudspeaker. The activities of the laryngeal adductor muscle, diaphragm and external oblique abdominal muscle and the voice intensity were measured during PAG stimulation, in the presence and absence of the auditory stimulation. To clarify the effects of the auditory laryngeal reflex on the activity of laryngeal adductor motoneurons, the amplitude of the laryngeal reflex evoked by single shock stimulation of the superior laryngeal nerve was also measured during respiration, in the presence and absence of auditory stimulation. The sound made by the cats due to PAG-induced vocalization was augmented by exposure to auditory stimulation, and the activities of the laryngeal adductor muscle and external oblique abdominal muscle were also augmented. During respiration, auditory stimulation also increased the amplitude of the laryngeal reflex evoked in the laryngeal adductor muscle. These results demonstrate that the essential neuronal mechanisms for evoking the Lombard reflex exist within the brainstem.
当说话者在存在环境噪声的情况下说话时增加发声努力时，会出现伦巴德反射。本研究的目的是阐明在动物模型的受控发声过程中是否能诱发伦巴德反射。在去大脑猫中，对中脑导水管周围灰质（PAG）施加重复性电刺激以诱发发声。通过扬声器给予纯音听觉刺激。在有和没有听觉刺激的情况下，在PAG刺激期间测量喉内收肌、膈肌和腹外斜肌的活动以及声音强度。为了阐明听觉喉反射对喉内收运动神经元活动的影响，在有和没有听觉刺激的情况下，在呼吸期间也测量了由喉上神经单次电击刺激诱发的喉反射的幅度。猫因PAG诱发的发声所发出的声音在暴露于听觉刺激时增强，喉内收肌和腹外斜肌的活动也增强。在呼吸期间，听觉刺激也增加了喉内收肌中诱发的喉反射的幅度。这些结果表明，诱发伦巴德反射的基本神经机制存在于脑干内。
