Fundamental study for clarifying dysphagia : The role of upper brain in inducing swallowing

长期以来，人们一直认为对咽和/或喉区的机械刺激会引起反射性的吞咽，而与皮层的情况无关。然而，视频荧光（VF）研究显示，一些食物可能在咀嚼过程中被运送到咽。有趣的是，在咀嚼过程完成之前，滴在咽部的药丸不会引起吞咽。因此，本项目旨在寻找可能影响吞咽中枢的皮质区域，对人类受试者采用脑磁图和VF，对动物采用运动学和电生理学方法。在家兔的摄食行为，从食物的摄取到吞咽，可以记录和识别。阐明了舌肌和咀嚼肌之间的协调关系，以及咀嚼过程中面部（脸颊和嘴唇）肌肉的作用。为了寻找可能与吞咽有关的皮质区域，对家兔皮质进行了系统的刺激。然后确定了燕子在咀嚼过程中被促进或抑制的区域。然而，没有具体的区域，燕子可以单独引出被确定。我们认为，在皮质发育粗糙的动物中，该区域可能局限在一个小区域，甚至自主吞咽本身也可能没有发育。脑磁图显示，在自主吞咽前2秒左右，扣带皮层处于短暂的活动状态，而在吞咽前，脑岛和脑盖处于长时间的活动状态。由于扣带皮层被认为是一个与情绪有关的区域，因此得出结论，该区域的激活可能与食物的识别过程有关。脑岛和脑盖与吞咽中枢有直接联系，因此该区域可能是吞咽皮层引出的主要区域。VF研究表明，人类在清除满嘴食物时要吞咽两到三次，这在动物研究中也有报道。

Mechanical stimulation to pharyngeal and/or laryngeal region has long been believed to elicit swallow reflexively irrespective of the cortical situation. However, videofluorographic (VF) study has revealed that some food may be transported to the pharynx during mastication. Interestingly, the bolus dropped in the pharynx does not elicit swallow till the chewing process is completed. The project was thus designed to seek possible cortical regions which could affect swallowing center, in which magneto-encephalogram and VF were applied for human subjects and kinesiological and electrophysiological methods for animals.In rabbits, the ingestive behavior, from food intake to swallowing, could be recorded and identified. The coordination between tongue and masticatory muscles and the role of facial (cheek and lip) muscles during mastication were clarified. To seek a possible cortical region for swallowing, rabbit's cortex was systematically stimulated. Then the region, where swallows were facilitated or inhibited during chewing, was identified. However, no concrete region where the swallow could be elicited solely was identified. We believe that in animals with crudely developed cortex, the region may be limited in a small area or even voluntary swallow itself may not be developed.Magneto-encephalogram showed that the cingulate cortex was active for short time about 2 sec preceding voluntary swallows and the insula and operculum were active for long period till swallows occurred. Since cingulate cortex is known as a region relating to emotion, it is concluded that the activation in this region may be related to a recognition process of food. Insula and operculum is known to have a direct connection with the swallowing center, thereafter, the region may be the main one for cortical elicitation of swallows. VF studies revealed that humans swallow two or three times when they clear the mouth of mouthful food as has been reported in animal studies.