Chang F C
Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425.
Brain Res. 1992 Feb 7;571(2):281-92. doi: 10.1016/0006-8993(92)90666-w.
The modulatory influences of behaviors and states of arousal on bulbar respiratory-related unit (RRU) discharge patterns were studied in an unanesthetized, freely behaving guinea pig respiratory model system. When fully instrumented, this model system permits concurrent monitoring and recording of (i) single units from either Bötzinger complex or nucleus para-ambiguus; (ii) electrocorticogram; and, (iii) diaphragmatic EMG. In addition to being used in surveys of RRU discharge patterns in freely behaving states, the model system also offered a unique opportunity in investigating the effects of pentobarbital on RRU discharge patterns before, throughout the course of, and during recovery from anesthesia. In anesthetized preparations, a particular RRU discharge pattern (such as tonic, incrementing or decrementing) typically displayed little, if any notable variation. The most striking development following pentobarbital was a state of progressive bradypnea attributable to a significantly augmented RRU cycle duration, burst duration and an increase in the RRU spike frequencies during anesthesia. In freely behaving states, medullary RRU activities rarely adhered to a fixed, immutable discharge pattern. More specifically, the temporal organization (such as burst duration, cycle duration, and the extent of modulation of within-burst spike frequencies) of RRU discharge patterns regularly showed complex and striking variations, not only with states of arousal (sleep/wakefulness, anesthesia) but also with discrete alterations in electrocorticogram (ECoG) activities and a multitude of on-going behavioral repertoires such as volitional movement, postural modification, phonation, mastication, deglutition, sniffing/exploratory behavior, alerting/startle reflexes. Only during sleep, and on occasions when the animal assumed a motionless, resting posture, could burst patterns of relatively invariable periodicity and uniform temporal attributes be observed. RRU activities during sniffing reflex is worthy of further note in that, based on power spectrum analyses of concurrently recorded ECoG activities, this particular discharge pattern was clearly associated with the activation of a 6-10 Hz theta rhythm. These findings indicated that bulbar RRU activity patterns are subject to change by not only behaviors and sleep/wakefulness cycles, but also a variety of modulatory influences and feedback/feedforward biases from other central and peripheral physiological control mechanisms.
在一个未麻醉、自由活动的豚鼠呼吸模型系统中，研究了行为和觉醒状态对延髓呼吸相关单位（RRU）放电模式的调节影响。当完全安装仪器后，该模型系统允许同时监测和记录：（i）来自包钦格复合体或疑核旁核的单个单位；（ii）脑电图；以及（iii）膈肌肌电图。除了用于调查自由活动状态下RRU的放电模式外，该模型系统还为研究戊巴比妥在麻醉前、麻醉过程中和麻醉恢复期间对RRU放电模式的影响提供了独特的机会。在麻醉制剂中，特定的RRU放电模式（如紧张性、递增或递减）通常几乎没有明显变化（如果有变化的话）。戊巴比妥给药后最显著的变化是逐渐出现呼吸过缓状态，这归因于麻醉期间RRU周期持续时间、爆发持续时间显著增加以及RRU尖峰频率增加。在自由活动状态下，延髓RRU活动很少遵循固定不变的放电模式。更具体地说，RRU放电模式的时间组织（如爆发持续时间、周期持续时间以及爆发内尖峰频率的调制程度）不仅随觉醒状态（睡眠/清醒、麻醉），而且随脑电图（ECoG）活动的离散变化以及许多正在进行的行为 repertoire（如自主运动、姿势改变、发声、咀嚼、吞咽、嗅探/探索行为、警觉/惊吓反射）而经常显示出复杂而显著的变化。只有在睡眠期间以及动物处于静止休息姿势时，才能观察到具有相对不变周期性和均匀时间属性的爆发模式。嗅反射期间的RRU活动值得进一步关注，因为基于同时记录的ECoG活动的功率谱分析，这种特定的放电模式显然与6 - 10 Hzθ节律的激活有关。这些发现表明，延髓RRU活动模式不仅受行为和睡眠/清醒周期的影响，还受其他中枢和外周生理控制机制的各种调节影响以及反馈/前馈偏差的影响。
