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This study was designed to investigate extrinsic tongue muscle activity in response to bronchopulmonary C-fiber activation following midcervical spinal contusion in the rat. Esophageal pressure and electromyogram of the extrinsic tongue muscles (genioglossus and hyoglossus) were monitored before and after inhalation of capsaicin (25 and 100 µg/mL) at the acute (3 days), subchronic (12-16 days), and chronic (52-65 days) injured stages following unilateral midcervical spinal contusion. Three days after injury, the preinspiratory burst amplitude of the extrinsic tongue muscle at baseline was significantly greater in midcervical spinal-contused animals than in sham animals. At this time, capsaicin induced a significant reduction in both preinspiratory and inspiratory activity of the extrinsic tongue muscle in sham but not contused animals at the acute stage. During the chronic injured stage, capsaicin at 100 µg/mL induced stronger suppression of preinspiratory genioglossus muscle activity in the contused animals than in sham animals. These results demonstrated that cervical spinal cord injury alters upper airway motor outputs and their reflex modulation by bronchopulmonary C-fibers. The compensatory increase in respiratory activity of the extrinsic tongue muscle early after cervical spinal cord injury may help to maintain upper airway patency. However, under the condition of chronic cervical spinal cord injury, the increased suppression of genioglossus muscle activity by bronchopulmonary C-fiber activation may increase the risk of airway obstruction following chronic cervical spinal cord injury.

An attempt has been made to clarify the exteroceptive control mechanism of extrinsic tongue muscles in cats. For this purpose, excitatory and inhibitory receptive fields of extrinsic tongue muscle motor units on the tongue surface have been investigated in urethanechloralose anesthetized or decerebrate cats.1. Styloglossal motor units responded with spike discharges to gentle stroking of the anterior part of the tongue dorsum. The receptive field of this reflex response has been classified into 5 types; ipsilateral filiform type (iF type), ipsilateral nonfiliform type (iNF type), bilateral nonfilifbrm ype (bNF type), ipsilateral filifbrm plus ipsilateral nonfliform type (iF+iNF type) and ipsilateral filifbrm plus bilateral nonfiliform type (iF+bNF type). The majority of styloglossal motor units were of the bNF type in urethane-chloralose anesthetized cats. On the other hand, motor units of the iF type dominated in decerebrate cats.2. Hyoglossal motor units were divided into two groups; ventral and dorsal. Ventral hyoglossal motor units responded with spike discharges to gentle stroking of the ipsilateral posterior part of the tongue dorsum, while dorsal hyoglossal motor units to that of the ipsilateral filiform area of the anterior tongue dorsum.3. Only a minority of genioglossal motor units responded with spike discharges to tactile stimulation of the filiform area of the anterior tongue. In most responsive genioglossal motor units, the excitatory receptive fieldwas located in the ipsi-or bilateral filiform area of the anterior tongue. In a few cats, however, the excitatory receptive field was in the ipsilateral Dosterior part of the tongue dorsum.4. Some styloglossal and hyoglossal motor units responded with spike discharges to tactile stimulation of the ventral surface of the tongue, but none of the genioglossal motor units responded to it.5. Some genioglossal and ventral hyoglossal motor units exhibited nonrespiratory spontaneous discharges, but no styloglossal and dorsal hyo-glossal motor units showed them. However, the majority of styloglossal motor units responded with spike discharges to jaw opening.6. Inhibition of spike discharges was demonstrated with styloglossal and genioglossal motor units. The inhibitory receptive field of styloglossal motor unit was located on the ipsilateral posterior part of the tongue dorsum. In most genioglossal motor units, the inhibitory receptive field was on the ipsi-, contra- or bilateral posterior part of the tongue dorsum.

Diphthongization of vocalic syllable nuclei is not a process of one kind. In Dutch, for instance, diphthongization can be of three different types, depending on whether the syllabic nucleus is a long vowel, a genuine diphthong, or a vowel + semivowel sequence. The perceptual and acoustic aspects of these differences are well documented in the literature. This paper complements the description with some articulatory data, based on electromyographic recordings of extrinsic tongue muscle activity in relation to the three types of diphthongization. [Work supported by NINCHDS grant NS 13870 and NFWO, Belgium.]