Villablanca J R, de Andrés I, Olmstead C E
Department of Psychiatry and Biobehavioral Sciences, Department of Neurobiology, Mental Retardation Research Center and Brain Research Institute, University of California, Los Angeles 90024-1759, USA.
Neuroscience. 2001;106(4):717-31. doi: 10.1016/s0306-4522(01)00329-3.
We report the effects of permanently separating the immature forebrain from the brain stem upon sleeping and waking development. Kittens ranging from postnatal 9 to 27 days of age sustained a mesencephalic transection and were maintained for up to 135 days. Prior to postnatal day 40, the electroencephalogram of the isolated forebrain and behavioral sleep-wakefulness of the decerebrate animal showed the immature patterns of normal young kittens. Thereafter, the isolated forebrain showed alternating sleep-wakefulness electrocortical rhythms similar to the corresponding normal patterns of intact, mature cats. Olfactory stimuli generally changed forebrain sleeping into waking activity, and in cats with the section behind the third nerve nuclei, normal correlates of eye movements-pupillary activity with electrocortical rhythms were present. Behind the transection, decerebrate animals showed wakefulness, and after 20 days of age displayed typical behavioral episodes of rapid eye movements sleep and, during these periods, the pontine recordings showed ponto-geniculo-occipital waves, which are markers for this sleep stage, together with muscle atonia and rapid lateral eye movements. Typically, but with remarkable exceptions suggesting humoral interactions, the sleep-waking patterns of the isolated forebrain were dissociated from those of the decerebrate animal. These results were very similar to our previous findings in midbrain-transected adult cats. However, subtle differences suggested greater functional plasticity in the developing versus the adult isolated forebrain. We conclude that behavioral and electroencephalographic patterns of non-rapid eye movement sleep and of rapid eye movement sleep states mature independently in the forebrain and the brain stem, respectively, after these structures are separated early postnatally. In terms of waking, the findings strengthen our concept that in higher mammals the rostral brain can independently support wakefulness/arousal and, hypothetically, perhaps even awareness. Therefore, these basic sleeping-waking functions are intrinsic properties of the forebrain/brain stem and as such can develop autochthonously. These data help our understanding of some normal/borderline sleep-waking dissociations as well as peculiar states of consciousness in long term patients with brain stem lesions.
我们报告了将未成熟的前脑与脑干永久分离对睡眠和觉醒发育的影响。出生后9至27天的小猫接受了中脑横切术，并维持长达135天。在出生后40天之前，分离的前脑的脑电图和去大脑动物的行为睡眠-觉醒表现出正常幼小猫的未成熟模式。此后，分离的前脑显示出交替的睡眠-觉醒电皮质节律，类似于完整成熟猫的相应正常模式。嗅觉刺激通常会将前脑睡眠转变为觉醒活动，并且在第三神经核后方进行横切的猫中，存在眼动-瞳孔活动与电皮质节律的正常关联。在横切部位后方，去大脑动物表现出觉醒，并且在20日龄后表现出快速眼动睡眠的典型行为发作，在这些时期，脑桥记录显示出脑桥-膝状体-枕叶波，这是该睡眠阶段的标志物，同时伴有肌肉张力缺失和快速的眼球侧向运动。通常情况下，但也有明显的例外表明存在体液相互作用，分离的前脑的睡眠-觉醒模式与去大脑动物的模式相互分离。这些结果与我们之前在中脑横切的成年猫中的发现非常相似。然而，细微的差异表明发育中的分离前脑与成年分离前脑相比具有更大的功能可塑性。我们得出结论，在出生后早期这些结构分离后，非快速眼动睡眠和快速眼动睡眠状态的行为和脑电图模式分别在前脑和脑干中独立成熟。就觉醒而言，这些发现强化了我们的概念，即在高等哺乳动物中，脑前部可以独立支持觉醒/唤醒，并且假设甚至可能支持意识。因此，这些基本的睡眠-觉醒功能是前脑/脑干的内在属性，因此可以自主发育。这些数据有助于我们理解一些正常/临界的睡眠-觉醒分离以及脑干病变长期患者的特殊意识状态。
