Chandler S H, Tal M
J Neurosci. 1986 Jun;6(6):1831-42. doi: 10.1523/JNEUROSCI.06-06-01831.1986.
The purpose of this study was to determine the critical areas of brain stem necessary for the production of cortically induced rhythmical jaw muscle activity (RJMs) in the anesthetized guinea pig. It was found that longitudinal midline transections of the lower brain stem starting at the obex and extending to the rostral third of the inferior olivary nucleus (IO) were able to abolish rhythmical EMG activity in the jaw-opener muscle (digastric) on the same side (ipsilateral) as the cortical stimulus. Under these conditions, rhythmical activity in the contralateral digastric (DIG) EMG was not affected. Midline transections extending from the rostral superior colliculus to 500 microns rostral to the trigeminal motor nucleus had no effect on cortically evoked bilateral DIG rhythmical EMG activity. Serial transverse hemisections of the left side of the medulla, starting at the obex and extending to the rostral third of the IO, reduced the amplitude of the left DIG EMG without producing significant effects in the cycle characteristics [cycle duration (CD) or burst duration (BD)] of that muscle during stimulation of the contralateral (right) cortex. Hemisections more rostral to the IO completely abolished bilateral rhythmical DIG activity induced by stimulation of the cortex on the side opposite to the transection (right cortex). Under these conditions, stimulation of the cortex on the side ipsilateral to the left hemisection (left cortex) initiated rhythmical EMG activity with normal cycle characteristics in only the contralateral (right) DIG muscle. Transverse hemisections as little as 500 microns rostral to the trigeminal motor nucleus (Mot V), which spared the pyramidal tract, had no effect on RJMs induced by stimulation of either cortex. These data suggest that each ipsilateral cortex initiates activity in neuronal oscillatory networks located exclusively in the contralateral brain stem; bilateral rhythmical DIG activity is produced by neurons in the contralateral brain stem; each side of the lower brain stem is capable of producing rhythmical DIG activity independent of the integrity of the other side; and the location of the neuronal oscillators responsible for RJMs is between the rostral IO and the trigeminal motor nucleus.
本研究的目的是确定在麻醉的豚鼠中产生皮层诱导的节律性咬肌活动（RJMs）所必需的脑干关键区域。研究发现，从闩开始并延伸至下橄榄核（IO）吻侧三分之一的低位脑干纵向中线横切能够消除与皮层刺激同侧（同侧）的开颌肌（二腹肌）中的节律性肌电图活动。在这些条件下，对侧二腹肌（DIG）的节律性活动不受影响。从吻侧上丘延伸至三叉神经运动核吻侧500微米的中线横切对皮层诱发的双侧DIG节律性肌电图活动没有影响。从闩开始并延伸至IO吻侧三分之一的延髓左侧连续横向半切，在刺激对侧（右侧）皮层期间，降低了左侧DIG肌电图的幅度，但对该肌肉的周期特征[周期持续时间（CD）或爆发持续时间（BD）]没有产生显著影响。IO吻侧更靠上的半切完全消除了由横切对侧（右侧）皮层刺激诱导的双侧节律性DIG活动。在这些条件下，刺激左侧半切同侧的皮层（左侧皮层）仅在对侧（右侧）DIG肌肉中引发具有正常周期特征的节律性肌电图活动。仅在三叉神经运动核（Mot V）吻侧500微米处进行的横向半切，保留了锥体束，对任何一侧皮层刺激诱发的RJMs均无影响。这些数据表明，每个同侧皮层在仅位于对侧脑干的神经元振荡网络中启动活动；双侧节律性DIG活动由对侧脑干中的神经元产生；低位脑干的每一侧都能够独立于另一侧的完整性产生节律性DIG活动；并且负责RJMs的神经元振荡器位于IO吻侧和三叉神经运动核之间。
