Nuñez A, Curró Dossi R, Contreras D, Steriade M
Département de Physiologie, Faculté de Médecine, Université Laval, Quebec, Canada.
Neuroscience. 1992;48(1):75-85. doi: 10.1016/0306-4522(92)90339-4.
Recent studies have revealed that the thalamus does not only generate spindle oscillations (7-14 Hz), but that it also participates in the genesis of a slower (less than 4 Hz) rhythm within the frequency range of delta waves on the electroencephalogram. In thalamic cells, delta is an intrinsic oscillation consisting of low-threshold spikes alternating with afterhyperpolarizing potentials. It is known from electroencephalographic recordings in humans and animals that slow or delta waves prevail during late sleep stages, whereas spindle oscillations are characteristic for the early stages of sleep. We studied the dependence of spindles and delta oscillations on membrane potential, as well as the effects of spindles on delta oscillations, in thalamocortical neurons of cats under urethane anesthesia and in cerveau isolé preparations (low collicular transections). Spindles appeared at membrane potentials between -55 and -65 mV, whereas delta oscillations occurred by bringing the membrane potential between -68 and -90 mV. Spindles either evoked by cortical stimulation or occurring spontaneously in cerveau isolé preparations prevented delta oscillations. This effect was probably due to the increase in membrane conductance associated with spindles. Barbiturates also blocked delta activity in thalamocortical neurons, probably through the same mechanism. A certain degree of incompatibility between spindles and delta rhythms in thalamocortical cells may explain the prevalence of these two types of oscillations during different stages of sleep with synchronization of the electroencephalogram.
最近的研究表明，丘脑不仅能产生纺锤体振荡（7-14赫兹），还参与了脑电图上δ波频率范围内较慢（低于4赫兹）节律的产生。在丘脑细胞中，δ波是一种内在振荡，由低阈值尖峰与超极化后电位交替组成。从人类和动物的脑电图记录中可知，慢波或δ波在睡眠后期阶段占主导，而纺锤体振荡是睡眠早期阶段的特征。我们研究了在乌拉坦麻醉的猫和孤立脑标本（低位丘系横切）中，丘脑皮质神经元的纺锤体和δ振荡对膜电位的依赖性，以及纺锤体对δ振荡的影响。纺锤体出现在膜电位在-55至-65毫伏之间时，而δ振荡则是在膜电位在-68至-90毫伏之间时出现。在孤立脑标本中，由皮质刺激诱发或自发出现的纺锤体可阻止δ振荡。这种效应可能是由于与纺锤体相关的膜电导增加所致。巴比妥类药物也可能通过相同机制阻断丘脑皮质神经元的δ活动。丘脑皮质细胞中纺锤体和δ节律之间的某种程度的不相容性，可能解释了在睡眠不同阶段这两种振荡的盛行以及脑电图的同步性。
