An in vivo canine model for the study of phonation physiology by midbrain stimulation

A versatile in vivo canine model is indispensable in studying the phonation function of the larynx. In this study, we attempted to build an in vivo phonation model in anesthetized dogs using stereotaxic electrical stimulation at a specific area in the midbrain. In each of the eight animals in this experiment, evoked phonation was successfully elicited by stimulating sites in the area ranging from 9 to 11 mm anterior, 3 to 5 mm lateral and 5 to 16 mm dorsal to the ear bar zero. This area was at the lateral border of the periaqueductal gray in the midbrain. The evoked-phonation process involved electrical stimulation of sites in this area, resulting in consistent responses by respiratory and laryngeal musculature accompanied by phonation. The evoked phonation could be consistently repeated. Different pitches of phonation were elicited by slightly moving the stimulation spots in this area. During evoked phonation, the subglottic aerodynamic power and individual laryngeal muscle action could be modified to study the effects of a single factor on the phonation process. The neuromuscular action for the control of phonation and the mechanical properties of the vocal folds can be investigated using an in vivo canine model.