Lee R S, Steffensen S C, Henriksen S J
Department of Neuropharmacology, The Scripps Research Institute, La Jolla, California 92037, USA.
J Neurosci. 2001 Mar 1;21(5):1757-66. doi: 10.1523/JNEUROSCI.21-05-01757.2001.
Although mesolimbic dopamine (DA) transmission has been implicated in behavioral and cortical arousal, DA neurons in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) are not significantly modulated by anesthetics or the sleep-wake cycle. However, VTA and SN non-DA neurons evince increased firing rates during active wakefulness (AW) and rapid eye movement (REM) sleep, relative to quiet wakefulness. Here we describe the effects of movement, select anesthetics, and the sleep-wake cycle on the activity of a homogeneous population of VTA GABA-containing neurons during normal sleep and after 24 hr sleep deprivation. In freely behaving rats, VTA GABA neurons were relatively fast firing (29 +/- 6 Hz during AW), nonbursting neurons that exhibited markedly increased activity during the onset of discrete movements. Adequate anesthesia produced by administration of chloral hydrate, ketamine, or halothane significantly reduced VTA GABA neuron firing rate and converted their activity into phasic 0.5-2.0 sec ON/OFF periods. VTA GABA neuron firing rate decreased 53% during slow-wave sleep (SWS) and increased 79% during REM, relative to AW; however, the discharging was not synchronous with electrocortical alpha wave activity during AW, delta wave activity during SWS, or gamma wave activity during REM. During deprived SWS, there was a direct correlation between increased VTA GABA neuron slowing and increased delta wave power. These findings indicate that the discharging of VTA GABA neurons correlates with psychomotor behavior and that these neurons may be an integral part of the extrathalamic cortical activating system.
尽管中脑边缘多巴胺（DA）传递与行为和皮层觉醒有关，但腹侧被盖区（VTA）和黑质致密部（SNc）中的DA神经元不会受到麻醉剂或睡眠-觉醒周期的显著调节。然而，相对于安静觉醒，VTA和SN中的非DA神经元在主动觉醒（AW）和快速眼动（REM）睡眠期间的放电频率增加。在此，我们描述了运动、特定麻醉剂以及睡眠-觉醒周期对正常睡眠期间和24小时睡眠剥夺后VTA中一组均匀的含GABA神经元活动的影响。在自由活动的大鼠中，VTA GABA神经元放电相对较快（AW期间为29±6 Hz），为非爆发性神经元，在离散运动开始时活动显著增加。水合氯醛、氯胺酮或氟烷给药产生的充分麻醉显著降低了VTA GABA神经元的放电频率，并将其活动转变为0.5 - 2.0秒的阶段性开/关周期。相对于AW，VTA GABA神经元放电频率在慢波睡眠（SWS）期间降低了53%，在REM期间增加了79%；然而，其放电在AW期间与皮层电活动的α波、SWS期间的δ波活动或REM期间的γ波活动并不同步。在剥夺SWS期间，VTA GABA神经元放电减慢增加与δ波功率增加之间存在直接相关性。这些发现表明，VTA GABA神经元的放电与精神运动行为相关，并且这些神经元可能是丘脑外皮层激活系统的一个组成部分。
