Tsoukatos J, Kiss Z H, Davis K D, Tasker R R, Dostrovsky J O
Department of Physiology, University of Toronto, Ontario, Canada.
Exp Brain Res. 1997 Feb;113(2):273-82. doi: 10.1007/BF02450325.
The firing patterns of thalamic neurons in mammals undergo a dramatic change as the animal's state changes between sleep and wakefulness. During sleep the normal tonic firing of thalamic neurons changes into a slower bursting mode characterized by repetitive activation of a low-threshold calcium (Ca2+) current. The present report describes the patterns of thalamic neuronal firing during sleep and wakefulness in one human patient. Extracellular single neuron activity was recorded during functional stereotactic surgery in the thalamus of a patient with chronic pain, who was observed to fall asleep during the recording. Evolutive power spectra of the thalamic slow wave were used in place of cortical encephalography to confirm the patient's states of sleep and wakefulness. Twenty-nine sites were observed in motor and somatosensory thalamus (Vop, Vim, and Vc) that were characterized by the presence of neurons with bursting activity when the patient was asleep. Such bursting was not observed in the patient when she was awakened. At 14 of these sites we were able to discriminate the bursting activity of single units. In each case the cell stopped firing or its bursting was replaced by a tonic firing pattern when the patient was awakened. In three cases the patient began to lapse back into sleep and the neuron resumed firing in a bursting pattern once again. None of these units had a peripheral receptive field (RF), while several other units recorded in nearby regions that did not fire in a bursting pattern during sleep had kinesthetic or cutaneous RFs. Analysis of the intraburst firing pattern revealed increasing interspike intervals (ISI) for successive action potentials in a burst and that the duration of the first ISI in the burst decreased as the number of ISIs increased. This pattern is similar to that reported to occur as a result of a calcium spike. These data have confirmed for the first time that state-dependent changes in thalamic firing exist in the human and that the physiological substrates at the thalamic level that are involved in human sleep are similar to those observed in animals.
随着动物在睡眠和觉醒状态之间转换，哺乳动物丘脑神经元的放电模式会发生显著变化。在睡眠期间，丘脑神经元正常的紧张性放电会转变为一种较慢的爆发模式，其特征是低阈值钙（Ca2+）电流的重复激活。本报告描述了一名人类患者在睡眠和觉醒期间丘脑神经元的放电模式。在一名患有慢性疼痛的患者丘脑进行功能性立体定向手术期间，记录了细胞外单个神经元的活动，该患者在记录过程中入睡。使用丘脑慢波的演化功率谱代替皮层脑电图来确认患者的睡眠和觉醒状态。在运动和体感丘脑（Vop、Vim和Vc）中观察到29个位点，其特征是患者睡眠时存在具有爆发活动的神经元。患者醒来时未观察到这种爆发活动。在其中14个位点，我们能够区分单个单元的爆发活动。在每种情况下，当患者醒来时，细胞停止放电或其爆发活动被紧张性放电模式所取代。在三个病例中，患者开始再次陷入睡眠，神经元再次恢复爆发式放电。这些单元均无外周感受野（RF），而在附近区域记录的其他几个单元在睡眠期间不呈爆发式放电，它们具有动觉或皮肤RF。对爆发内放电模式的分析显示，爆发中连续动作电位的峰间间隔（ISI）增加，并且随着ISI数量的增加，爆发中第一个ISI的持续时间缩短。这种模式类似于据报道因钙峰而出现的模式。这些数据首次证实人类丘脑存在与状态相关的放电变化，并且人类睡眠中涉及的丘脑水平的生理底物与在动物中观察到的相似。
