Sleep loss impairment of arousal and cognition: role of the basal forebrain

 描述（由申请人提供）： 睡眠不足会导致认知能力受损和白天过度嗜睡。这些睡眠不足的症状现在被认为是导致事故率和工作效率下降的主要原因。小鼠将被用来模拟两种类型的人类睡眠缺失，这些睡眠缺失会导致白天嗜睡和认知障碍：1）完全睡眠剥夺，这可能是由于轮班工作或紧急工作等职业需求而发生；2）睡眠碎片化，这是一种在包括睡眠呼吸暂停在内的许多临床疾病中出现的睡眠障碍模式。睡眠碎片化会破坏睡眠的连续性并干扰睡眠的恢复作用。尽管睡眠碎片化并没有大大减少总睡眠时间，但我们假设睡眠碎片化的生理和行为后果将与完全睡眠剥夺相似。该提案的总体目标是了解基底前脑 (BF) 神经元在睡眠不足引起的觉醒和警觉性缺陷中的作用。为了实现这一目标，将使用小鼠来测试 BF GABA 能小清蛋白 (PV) 和胆碱能阳性神经元增强觉醒/警觉性、注意力和皮质激活的假设。 BF PV 和胆碱能神经元均被假设通过其皮质投射促进唤醒。因此，我们预测激活这些促进觉醒的 BF 神经元可以减少睡眠不足引起的损伤。基于初步数据，我们进一步假设 BF PV 神经元相对于 BF 胆碱能神经元将更有效地增强觉醒、注意力和皮质激活；预计 PV 神经元也能更有效地减少在睡眠剥夺小鼠中观察到的这些措施的损伤。大量证据表明，BF 含有皮质投射和促进觉醒的神经元，这些神经元对于皮质激活和觉醒非常重要（例如，BF 中的大的非特异性细胞体病变会产生类似昏迷的状态）。然而，直到最近，光遗传学方法才可用于精确确定大脑中神经递质特异性神经元的作用。 Aim 1 中 BF 神经元的光遗传学抑制预计会模拟睡眠缺失的影响，证明 BF PV 和胆碱能神经元在睡眠缺失引起的损伤中的必要性。目标 2 将确定：a) BF 神经元的兴奋是否足以增强非睡眠剥夺小鼠的觉醒、注意力和皮质激活，b) BF 神经元的兴奋将减少睡眠缺失引起的觉醒、注意力和皮质激活损伤。目标 3 将测量光遗传学鉴定的 BF 神经元的单个单位活动，以确认它们的放电模式与其在调节自然睡眠和觉醒以及调节皮质活动对感觉刺激的反应中的生理作用一致。以下初步数据支持这些假设和预测： 1. PV 神经元的抑制降低了觉醒度、新物体识别任务中的注意力以及诱发的皮质激活的测量；因此，抑制 BF PV 神经元的影响与睡眠不足对这些指标的影响非常相似。 2. BF PV 神经元的兴奋产生觉醒和皮质激活，并且觉醒期间 BF PV 单元活性增加。与 BF PV 神经元相比，胆碱能神经元的兴奋似乎会产生更具调节性、更慢且更弱的行为和生理反应。如果成功，所提出的实验将证明 BF 单元活动、皮质激活、觉醒/唤醒和注意力之间的机制联系。因此，这些发现将指导针对皮质下唤醒促进神经元的治疗干预措施的开发，以治疗退伍军人群体中普遍存在的睡眠障碍的后果。

 DESCRIPTION (provided by applicant): Sleep loss leads to impaired cognitive performance and excessive daytime sleepiness. These symptoms of sleep loss are now recognized as major contributors to accident rates and decreased workplace productivity. Mice will be used to model two types of human sleep loss that produce daytime sleepiness and cognitive impairments: 1) Total sleep deprivation, which can occur due to vocational demands such as shift work or emergency work, and, 2) Sleep fragmentation, a pattern of sleep disturbance seen in many clinical disorders including sleep apnea. Sleep fragmentation disrupts the continuity of sleep and interferes with the restorative effects of sleep. Despite the fact that total sleep time is not greatly reduced by sleep fragmentation, we hypothesize that the physiological and behavioral consequences of sleep fragmentation will be similar to those of total sleep deprivation. The overall goal of this proposa is to understand the role of basal forebrain (BF) neurons in sleep loss induced deficits in wakefulness and vigilance. To accomplish this goal, mice will be used to test the hypothesis that BF GABAergic parvalbumin (PV) and cholinergic - positive neurons enhance wakefulness/alertness, attention, and cortical activation. Both BF PV and cholinergic neurons are hypothesized to be arousal promoting via their cortical projections. Hence, we predict that activation of these arousal promoting BF neurons can reduce sleep-loss induced impairments. Based on preliminary data, we further hypothesize that BF PV neurons will more potently enhance wakefulness, attention, and cortical activation relative to BF cholinergic neurons; PV neurons are also predicted to more effectively reduce the impairments in these measures observed in sleep deprived mice. Abundant evidence indicates that the BF contains cortically projecting and wakefulness promoting neurons that are important for cortical activation and wakefulness (e.g., large non-specific cell body lesions in BF produce a coma-like state). However, only recently have optogenetic methods been available to precisely determine the role of neurotransmitter specific neurons in the brain. Optogenetic inhibition of BF neurons in Aim 1 is predicted to simulate the effects of sleep loss, demonstrating the necessity of BF PV and cholinergic neurons in the sleep loss induced impairments. Aim 2 will determine if: a) excitation of BF neurons is sufficient to enhance wakefulness, attention, and cortical activation in non sleep deprived mice, and, b) excitation of BF neurons will reduce sleep loss induced impairments in wakefulness, attention, and cortical activation. Aim 3 will measure the single unit activity of optogenetically identified BF neurons to confirm that their discharge pattern is consistent with their proposed physiological role in the regulation of natural sleep and wakefulness, and in the mediation of the cortical activity responses to sensory stimuli. The following preliminary data support these hypotheses and predictions: 1. Inhibition of PV neurons reduces measures of wakefulness, attention in the novel object recognition task, and evoked cortical activation; thus, the effects of inhibition of BF PV neurons closely resemble the effects f sleep loss on these measures. 2. Excitation of BF PV neurons produces wakefulness and cortical activation and BF PV unit activity is increased during wakefulness. Compared to BF PV neurons, excitation of cholinergic neurons appears to produce a more modulatory, slower and less powerful behavioral and physiological response. If successful, the experiments proposed will demonstrate mechanistic links between BF unit activity, cortical activation, wakefulness/arousal, and attention. Thus, these findings will guide the development of therapeutic interventions targeting the subcortical arousal promoting neurons to treat the consequences of sleep disorders which are prevalent in the Veteran population.