Convergence of afferents from the SLN and GPN in cat medullary swallowing neurons

• Published in: Brain research bulletin 1995, Vol.37 (4), p.397-404
• Main Authors: Ootani, Shinji, Umezaki, Toshiro, Shin, Takemoto, Murata, Yuzo
• Format: Article
• Language: English
• Subjects: Afferent Pathways - cytology; Afferent Pathways - physiology; Afferent Pathways - ultrastructure; Afferents; Anatomy; Animals; Biological and medical sciences; Cats; Central nervous system; Deglutition - physiology; Electrophysiology; Female; Fundamental and applied biological sciences. Psychology; Glossopharyngeal Nerve - cytology; Glossopharyngeal Nerve - ultrastructure; GPN; Histocytochemistry; Horseradish Peroxidase; Laryngeal Nerves - cytology; Laryngeal Nerves - ultrastructure; Male; Medulla Oblongata - cytology; Medulla Oblongata - physiology; Medulla Oblongata - ultrastructure; Microscopy, Electron; Neurons, Afferent - physiology; Neurons, Afferent - ultrastructure; Nucleus tractus solitarius; Presynaptic Terminals - physiology; Presynaptic Terminals - ultrastructure; SLN; Solitary Nucleus - cytology; Solitary Nucleus - physiology; Swallowing; Vertebrates: nervous system and sense organs
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/0361-9230(95)00018-6

We demonstrated the convergence of information from the pharyngeal and laryngeal mucosa, transmitted by the glossopharyngeal nerve (GPN) and superior laryngeal nerve (SLN), in the nucleus of the tractus solitarius (NTS). First, the distribution of terminals of the GPN and SLN in the NTS was examined by an HPR tracing technique in cats, and the synapse formation of these neurons with NTS neurons was demonstrated by electron microscopy. The HRP-labeled SLN and GPN terminals were localized in a small area of the interstitial subnucleus of the NTS, slightly rostral to the obex, forming synapses with NTS neurons. Next, using extracellular recording in anesthetized cats, we determined whether or not swallowing-related neurons in the medulla oblongata receive peripheral inputs. Convergence of peripheral sensory inputs from the SLN and GPN was observed in more than 80% of the NTS cells. These results suggest that the NTS is not only a sensory-relay nucleus but also integrates information necessary for eliciting protective reflexes of the upper airway, such as swallowing.