Lin L D, Murray G M, Sessle B J
Faculty of Dentistry, University of Toronto, Ontario, Canada.
Arch Oral Biol. 1998 Feb;43(2):133-41. doi: 10.1016/s0003-9969(97)00101-5.
Rhythmical jaw movements can be evoked by intracortical microstimulation within four physiologically defined regions, one of which is the primary face somatosensory cortex (face SI). It has been proposed that these regions may be involved in the selection and/or control of masticatory patterns generated at the brainstem level. The aim here was to determine if mastication is affected by reversible, cooling-induced inactivation of the face SI. Two cranial chambers were chronically implanted in two monkeys (Macaca fascicularis) to allow access bilaterally to the face SI. A thermode was placed on the dura or pia overlying each SI that had been shown with micro-electrode recordings to receive intraoral inputs. A hot or cold alcohol-water solution was pumped through the thermodes while the monkey chewed a small piece of apple or a sultana during precool (thermode temperature, 37 degree C), cool (2-4 degrees C), and postcool (37 degrees C) conditions. Electromyographic (EMG) activity was recorded intramuscularly from the masseter, genioglossus, and anterior digastric. Cooling of SI impaired rhythmical jaw and tongue movements and EMG activity associated with mastication in one monkey (H5), and modified the pattern of EMG activity in the other (H6). The total masticatory time (i.e., time taken for chewing and manipulation of the bolus before swallowing) was increased. This was due principally to an increase in the oral transport time (i.e., time taken for manipulation of bolus after chewing and before swallowing: monkey H6, control, 2.7 sec; cool, 5.2 sec, p < 0.05); the bolus was manipulated by the tongue during this period before swallowing. Within the chewing time (i.e., time during which chewing occurred), cooling resulted in a significant increase in anterior digastric muscle duration, a significant delay in the onset of masseter EMG activity, and a significant increase in the variance of genioglossus EMG duration. The data support the view that the face SI plays a part in modulating the central pattern generator for mastication.
在四个生理定义区域内，通过皮质内微刺激可诱发节律性下颌运动，其中一个区域是主要面部躯体感觉皮层（面部体感区SI）。有人提出，这些区域可能参与脑干水平产生的咀嚼模式的选择和/或控制。本研究的目的是确定面部体感区SI的可逆性、冷却诱导失活是否会影响咀嚼。在两只猕猴（食蟹猴）身上长期植入两个颅腔，以便双侧进入面部体感区SI。将一个加热电极置于覆盖每个已通过微电极记录显示可接收口腔内输入的体感区SI的硬脑膜或软脑膜上。在预冷（加热电极温度37摄氏度）、冷却（2 - 4摄氏度）和冷却后（37摄氏度）条件下，当猴子咀嚼一小片苹果或一颗葡萄干时，将热或冷的酒精 - 水溶液泵入加热电极。从咬肌、颏舌肌和二腹肌前腹进行肌内肌电图（EMG）活动记录。冷却体感区SI会损害一只猴子（H5）的节律性下颌和舌头运动以及与咀嚼相关的EMG活动，并改变另一只猴子（H6）的EMG活动模式。总的咀嚼时间（即吞咽前咀嚼和处理食团所需的时间）增加。这主要是由于口腔运输时间增加（即咀嚼后吞咽前处理食团所需的时间：猴子H6，对照组为2.7秒；冷却组为5.2秒，p < 0.05）；在此期间，食团在吞咽前由舌头处理。在咀嚼时间内（即发生咀嚼的时间段），冷却导致二腹肌前腹肌肉持续时间显著增加，咬肌EMG活动开始显著延迟，颏舌肌EMG持续时间的方差显著增加。这些数据支持面部体感区SI在调节咀嚼中枢模式发生器中起作用的观点。
