視丘通路主要由腦橋被蓋中的膽鹼能神經元組成,而下視丘通路主要由釋放單胺神經遞質(即多巴胺、去甲腎上腺素、血清素和組胺)的神經元組成。 [3][6] ARAS 中釋放穀氨酸的神經元相對於單胺能和膽鹼能神經元的發現要晚得多。 [8] ARAS 的穀氨酸能成分包括下視丘的一個核和多個腦幹核。 [4][8][9]下視丘外側的食慾素神經元支配上行網狀激活系統的每個組成部分並協調整個系統內的活動。 [5][10][11]
直接電刺激 ARAS 會在貓中產生疼痛反應,並引發人類對疼痛的口頭報告。[來源請求]</link>[需要引用]貓的上行網狀結構激活會導致瞳孔散大, [27]這可能是由於長期疼痛引起的。這些結果表明 ARAS 迴路與生理疼痛通路之間存在某種關係。 [27]
病理學
ARAS 的一些病理可能歸因於年齡,因為隨著年齡的增長,ARAS 的反應性似乎普遍下降。 [28]電耦合[C]的變化被認為可以解釋 ARAS 活動的一些變化:如果耦合下調,則高頻同步(伽馬帶)也會相應減少。相反,上調的電耦合會增加快節奏的同步,從而導致覺醒和快速眼動睡眠驅動力的增加。 [30]具體來說,ARAS 的破壞與以下疾病有關:
接下來,通過在中腦前部的內側和外側部分放置損傷來評估這個新發現的中繼系統的重要性。 ARAS 中腦中斷的貓進入深度睡眠並顯示出相應的腦電波。以另一種方式,上行聽覺和軀體通路受到類似干擾的貓表現出正常的睡眠和覺醒,並且可以通過物理刺激喚醒。因為這些外部刺激在到達皮層的途中會被中斷所阻礙,這表明上行傳輸必須通過新發現的 ARAS。
最後,馬貢記錄了腦幹內側部分的電位,發現聽覺刺激直接激發了網狀激活系統的部分區域。此外,坐骨神經的單次電擊刺激也激活了內側網狀結構、下視丘和視丘。 ARAS 的興奮不依賴於通過小腦迴路的進一步信號傳播,因為在去小腦和去皮後獲得了相同的結果。研究人員提出,中腦網狀結構周圍的一列細胞接收來自腦幹所有上升束的輸入,並將這些傳入信號傳遞到皮質,從而調節覺醒。 [40][22]
Iwańczuk W, Guźniczak P. Neurophysiological foundations of sleep, arousal, awareness and consciousness phenomena. Part 1. Anaesthesiol Intensive Ther. 2015, 47 (2): 162–167. PMID 25940332. doi:10.5603/AIT.2015.0015. The ascending reticular activating system (ARAS) is responsible for a sustained wakefulness state. It receives information from sensory receptors of various modalities, transmitted through spinoreticular pathways and cranial nerves (trigeminal nerve – polymodal pathways, olfactory nerve, optic nerve and vestibulocochlear nerve – monomodal pathways). These pathways reach the thalamus directly or indirectly via the medial column of reticular formation nuclei (magnocellular nuclei and reticular nuclei of pontine tegmentum). The reticular activating system begins in the dorsal part of the posterior midbrain and anterior pons, continues into the diencephalon, and then divides into two parts reaching the thalamus and hypothalamus, which then project into the cerebral cortex (Fig. 1). The thalamic projection is dominated by cholinergic neurons originating from the pedunculopontine tegmental nucleus of pons and midbrain (PPT) and laterodorsal tegmental nucleus of pons and midbrain (LDT) nuclei [17, 18]. The hypothalamic projection involves noradrenergic neurons of the locus coeruleus (LC) and serotoninergic neurons of the dorsal and median raphe nuclei (DR), which pass through the lateral hypothalamus and reach axons of the histaminergic tubero-mamillary nucleus (TMN), together forming a pathway extending into the forebrain, cortex and hippocampus. Cortical arousal also takes advantage of dopaminergic neurons of the substantia nigra (SN), ventral tegmenti area (VTA) and the periaqueductal grey area (PAG). Fewer cholinergic neurons of the pons and midbrain send projections to the forebrain along the ventral pathway, bypassing the thalamus [19, 20].
Brudzynski SM. The ascending mesolimbic cholinergic system – a specific division of the reticular activating system involved in the initiation of negative emotional states. Journal of Molecular Neuroscience. July 2014, 53 (3): 436–445. PMID 24272957. S2CID 14615039. doi:10.1007/s12031-013-0179-1. Understanding of arousing and wakefulness-maintaining functions of the ARAS has been further complicated by neurochemical discoveries of numerous groups of neurons with the ascending pathways originating within the brainstem reticular core, including pontomesencephalic nuclei, which synthesize different transmitters and release them in vast areas of the brain and in the entire neocortex (for review, see Jones 2003; Lin et al. 2011). They included glutamatergic, cholinergic, noradrenergic, dopaminergic, serotonergic, histaminergic, and orexinergic systems (for review, see Lin et al. 2011). ... The ARAS represented diffuse, nonspecific pathways that, working through the midline and intralaminar thalamic nuclei, could change activity of the entire neocortex, and thus, this system was suggested initially as a general arousal system to natural stimuli and the critical system underlying wakefulness (Moruzzi and Magoun 1949; Lindsley et al. 1949; Starzl et al. 1951, see stippled area in Fig. 1). ... It was found in a recent study in the rat that the state of wakefulness is mostly maintained by the ascending glutamatergic projection from the parabrachial nucleus and precoeruleus regions to the basal forebrain and then relayed to the cerebral cortex (Fuller et al. 2011). ... Anatomical studies have shown two main pathways involved in arousal and originating from the areas with cholinergic cell groups, one through the thalamus and the other, traveling ventrally through the hypothalamus and preoptic area, and reciprocally connected with the limbic system (Nauta and Kuypers 1958; Siegel 2004). ... As counted in the cholinergic connections to the thalamic reticular nucleus ...
Schwartz MD, Kilduff TS. The Neurobiology of Sleep and Wakefulness. The Psychiatric Clinics of North America. December 2015, 38 (4): 615–644. PMC 4660253. PMID 26600100. doi:10.1016/j.psc.2015.07.002. This ascending reticular activating system (ARAS) is comprised of cholinergic laterodorsal and pedunculopontine tegmentum (LDT/PPT), noradrenergic locus coeruleus (LC), serotonergic (5-HT) Raphe nuclei and dopaminergic ventral tegmental area (VTA), substantia nigra (SN) and periaqueductal gray projections that stimulate the cortex directly and indirectly via the thalamus, hypothalamus and BF.6, 12-18 These aminergic and catecholaminergic populations have numerous interconnections and parallel projections which likely impart functional redundancy and resilience to the system.6, 13, 19 ... More recently, the medullary parafacial zone (PZ) adjacent to the facial nerve was identified as a sleep-promoting center on the basis of anatomical, electrophysiological and chemo- and optogenetic studies.23, 24 GABAergic PZ neurons inhibit glutamatergic parabrachial (PB) neurons that project to the BF,25 thereby promoting NREM sleep at the expense of wakefulness and REM sleep. ... The Hcrt neurons project widely throughout the brain and spinal cord92, 96, 99, 100 including major projections to wake-promoting cell groups such as the HA cells of the TM,101 the 5-HT cells of the dorsal Raphe nuclei (DRN),101 the noradrenergic cells of the LC,102 and cholinergic cells in the LDT, PPT, and BF.101, 103 ... Hcrt directly excites cellular systems involved in waking and arousal including the LC,102, 106, 107 DRN,108, 109 TM,110-112 LDT,113, 114 cholinergic BF,115 and both dopamine (DA) and non-DA neurons in the VTA.116, 117
Malenka RC, Nestler EJ, Hyman SE. Chapter 12: Sleep and Arousal 2nd. New York: McGraw-Hill Medical. 2009: 295. ISBN 978-0071481274. The RAS is a complex structure consisting of several different circuits including the four monoaminergic pathways ... The norepinephrine pathway originates from the locus ceruleus (LC) and related brainstem nuclei; the serotonergic neurons originate from the raphe nuclei within the brainstem as well; the dopaminergic neurons originate in ventral tegmental area (VTA); and the histaminergic pathway originates from neurons in the tuberomammillary nucleus (TMN) of the posterior hypothalamus. As discussed in Chapter 6, these neurons project widely throughout the brain from restricted collections of cell bodies. Norepinephrine, serotonin, dopamine, and histamine have complex modulatory functions and, in general, promote wakefulness. The PT in the brain stem is also an important component of the ARAS. Activity of PT cholinergic neurons (REM-on cells) promotes REM sleep. During waking, REM-on cells are inhibited by a subset of ARAS norepinephrine and serotonin neurons called REM-off cells.
Saper CB, Fuller PM. Wake-sleep circuitry: an overview. Current Opinion in Neurobiology. June 2017, 44: 186–192. PMC 5531075. PMID 28577468. doi:10.1016/j.conb.2017.03.021. Parabrachial and pedunculopontine glutamatergic arousal system Retrograde tracers from the BF have consistently identified one brainstem site of input that is not part of the classical monoaminergic ascending arousal system: glutamatergic neurons in the parabrachial and pedunculopontine nucleus ... Juxtacellular recordings from pedunculopontine neurons have found that nearly all cholinergic neurons in this region, as well as many glutamatergic and GABAergic neurons, are most active during wake and REM sleep [25], although some of the latter neurons were maximally active during either wake or REM, but not both. ... [Parabrachial and pedunculopontine glutamatergic neurons] provide heavy innervation to the lateral hypothalamus, central nucleus of the amygdala, and BF
Pedersen NP, Ferrari L, Venner A, Wang JL, Abbott SG, Vujovic N, Arrigoni E, Saper CB, Fuller PM. Supramammillary glutamate neurons are a key node of the arousal system. Nature Communications. November 2017, 8 (1): 1405. Bibcode:2017NatCo...8.1405P. PMC 5680228. PMID 29123082. doi:10.1038/s41467-017-01004-6. Basic and clinical observations suggest that the caudal hypothalamus comprises a key node of the ascending arousal system, but the cell types underlying this are not fully understood. Here we report that glutamate-releasing neurons of the supramammillary region (SuMvglut2) produce sustained behavioral and EEG arousal when chemogenetically activated.
Malenka RC, Nestler EJ, Hyman SE. Chapter 12: Sleep and Arousal 2nd. New York: McGraw-Hill Medical. 2009: 295. ISBN 978-0071481274. Orexin neurons are located in the lateral hypothalamus. They are organized in a widely projecting manner, much like the monoamines (Chapter 6), and innervate all of the components of the ARAS. They excite the REM-off monoaminergic neurons during wakefulness and the PT cholinergic neurons during REM sleep. They are inhibited by the VLPO neurons during NREM sleep.
Cherasse Y, Urade Y. Dietary Zinc Acts as a Sleep Modulator. International Journal of Molecular Sciences. November 2017, 18 (11): 2334. PMC 5713303. PMID 29113075. doi:10.3390/ijms18112334. The regulation of sleep and wakefulness involves many regions and cellular subtypes in the brain. Indeed, the ascending arousal system promotes wakefulness through a network composed of the monaminergic neurons in the locus coeruleus (LC), histaminergic neurons in the tuberomammilary nucleus (TMN), glutamatergic neurons in the parabrachial nucleus (PB) ...
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VandenBos, Gary R (編). animal hypnosis. APA dictionary of psychology 2nd (Washington, DC: American Psychological Association). 2015: 57. ISBN 978-1433819445. doi:10.1037/14646-000. a state of motor nonresponsiveness in nonhuman animals, produced by stroking, salient stimuli, or physical restraint. It is called 「hypnosis」 because of a claimed resemblance to human hypnosis and trance
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