The neurophysiological study about the control mechanism of the velopharyngeal function

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For the purpose of the neurophysiological analysis of the velopharyngeal function, the data collecting analysis device (BRC ; Maclab8) and the polygrapH system (NIHON KOHDEN : RM-6000) were purchased as the equipment that was written in the grant application in 1994 and 1995. Experiments were performed in cats. The cats were anesthetized with halothane and decerebrated. A bipolar electrode was inserted into the levator veli palatini muscle which was a major muscle elevating the soft palate.In 1994, the innoxious mechanical stimulation was applied to the tongue dorsum. Excitatory or inhibitory response was elicited in the levator veli palatini muscle by pressure stimulation to the tongue dorsum. Excitatory reflexes were elicited under low level background activity (BGA). The excitatory effect decreased with increase of BGA,the inhibitory effect was increased . Reversal levels were calculated from BGA-response curves.As stimulation sites were changed from anterior to posterior of the ora … More l cavity, the reversal level increased. This result indicated that the excitatory reflex was easily elicited from the posterior part and the inhibitory reflex was easily elicited from the anterior part of the oral cavity.We continued animal experiments in 1995. Assumed the contact style of the tongue to the palate at the chewing, swallowing and pronunciation, the simultaneous stimulation applied to the tongue dorsum and the palate. As stimulation sites were changed from anterior to posterior of the oral cavity, the reversal level in simultaneous stimulation became high. This results agreed with the response characteristic in independent tongue stimulation. When the reversal level in this simultaneous stimulation was compared with the level in the independent stimulation, the former showed a high value, and it became clear that excitement effect reinforced.It was suggested that the levator veli palatini muscle was ingeniously controlled by integrative reflexes of tongue and palatal mucosa stimulation. Less