伏隔核（拉丁語：nucleus accumbens；英語：accumbens nucleus，NAc，NAcc），台灣譯依核[1]，又稱依伏神經核，是位於基底核與邊緣系統交接處、尾狀核頭部下方的神經核團；大腦的每側半球各有一個伏隔核，它位於尾狀核頭部、殼核的前部，側面與透明隔相接；伏隔核與嗅結節組成腹側紋狀體[2]。
伏隔核是大腦的愉悅中樞，參與獎賞、快樂、笑、成癮、侵犯、恐懼及安慰劑效果等活動[3][4][5]。
伏隔核核心的一部分主要參與慢波睡眠的誘導[6] [7] [8] [9]，也參與新運動程序的編碼[10]。伏隔核在處理恐懼（厭惡的一種形式）、衝動和安慰劑效應方面發揮較小的作用[11] [12] [13]。
伏隔核可以分作兩部分：伏隔核的核與伏隔核的殼，兩個結構有不同的形態和功能。
伏隔核的基本細胞類型是中型多棘神經元，這類神經元產生的神經遞質是γ-氨基丁酸 （GABA），一種主要的中樞神經系統的抑制性神經遞質，這些神經元也是伏隔核的主要投射或者稱輸出神經元。
隔核的95%神經元是中型多棘GABA能投射神經元，其它類型神經元還發現有無棘膽鹼能中間神經元。
2017年底，利用光遺傳學和化學遺傳學方法對齧齒類動物的研究發現，伏隔核核心中共同表達腺苷A 2A受體並投射到腹側蒼白球的間接途徑（即D2型）中型多棘神經元參與了慢波睡眠的調節。[14][15][16][17] 特別是，這些間接途徑 NAcc 核心神經元的光遺傳學激活會誘導慢波睡眠，而相同神經元的化學遺傳學激活會增加慢波睡眠發作的次數和持續時間。[15][16][17] 這些 NAcc 核心神經元的化學遺傳學抑制會抑制睡眠。[15][16]相反，NAcc 殼中表達腺苷 A 2A受體的 D2 型中型多棘神經元在調節慢波睡眠中沒有作用。 [15][16]
伏隔核的輸出神經元發出的軸突投射到蒼白球的腹側對應部分，稱作腹側蒼白球（VP），腹側蒼白球再投射到背側丘腦的背內側核。背內側核在投射到前額皮質和紋狀體，伏隔核其它輸出連接還有投射到黑質與橋腦網狀結構。
伏隔核的主要輸入包括前額皮質相關神經元，杏仁體基底外側核，以及通過中腦邊緣通道聯繫的腹側被蓋區（VTA）的多巴胺神經元。因此，伏隔核經常被描述為皮質-紋狀體-丘腦-皮質迴路的一部分。
從VTA的多巴胺能輸入被認為調節伏隔核神經元活動。這些神經末梢是高成癮性藥品如可卡因、安非他命的作用區，能引起伏隔核多巴胺濃度的大量增加。其它娛樂性藥物也是在伏隔核增加多巴胺濃度。
另外一大類輸入是從大腦海馬的腹側下托及CA1區到伏隔核背內側區域。海馬的神經元顯然與伏隔核細胞的輕微去極化相關，使得伏隔核細胞更為正電性因而更容易激發。與海馬關聯的伏隔核的激發態中型多棘神經元細胞由海馬下托與CA1區共享。海馬下托神經元能超極化(增加負電性)而CA1神經元振盪(> 50 Hz)以完成啟動。[18]
1950年代，詹姆斯·奧爾茲與Peter Milner在大白鼠的隔區植入電極，發現大白鼠選擇按壓一個刺激該電極的開關。大白鼠持續選擇此操作甚至停止了吃喝。這暗示此區域是大腦的欣快中心，然而隔核並不直接連通到伏隔核。[19]
雖然伏隔核傳統上被研究在成癮中的作用，但它在獎賞系統如食物和性等的也有重要作用。近來的研究發現伏隔核涉及由音樂調節情緒，[20] 可能是它調節多巴胺釋放的結果。伏隔核對音樂的神經認知中的節奏定時有作用，並被認為在邊緣-運動界面（Mogensen）有關鍵作用。
2007年4月，兩個研究隊伍報告通過在伏隔核插入電極以使用腦深層刺激治療幾種臨床抑鬱。[21]
2007年7月， Jon-Kar Zubieta報告伏隔核是安慰劑效應的機制中心。[22]
2012年瑞士巴塞爾大學的神經經濟學教授瓦西里·克盧恰廖夫研究發現：人類在進行一項決策並選擇從眾的時候，會激活伏隔核，使其呈現出「歡呼雀躍」的狀態。 [23]
Schwienbacher I, Fendt M, Richardson R, Schnitzler HU. Temporary inactivation of the nucleus accumbens disrupts acquisition and expression of fear-potentiated startle in rats. Brain Res. 2004, 1027 (1–2): 87–93. PMID 15494160. doi:10.1016/j.brainres.2004.08.037. 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 . More recently, Fuller's laboratory also discovered that sleep can be promoted by the activation of a gamma-aminobutyric acid-ergic (GABAergic) population of neurons located in the parafacial zone [11,12], while the role of the GABAergic A2AR-expressing neurons of the nucleus accumbens [13] and the striatum has just been revealed [14,15].
Valencia Garcia S, Fort P. Nucleus Accumbens, a new sleep-regulating area through the integration of motivational stimuli. Acta Pharmacologica Sinica. February 2018, 39 (2): 165–166. PMC 5800466 . PMID 29283174. doi:10.1038/aps.2017.168. The nucleus accumbens comprises a contingent of neurons specifically expressing the post-synaptic A2A-receptor (A2AR) subtype making them excitable by adenosine, its natural agonist endowed with powerful sleep-promoting properties[4]. ... In both cases, large activation of A2AR-expressing neurons in NAc promotes slow wave sleep (SWS) by increasing the number and duration of episodes. ... After optogenetic activation of the core, a similar promotion of SWS was observed, whereas no significant effects were induced when activating A2AR-expressing neurons within the shell.
Oishi Y, Xu Q, Wang L, Zhang BJ, Takahashi K, Takata Y, Luo YJ, Cherasse Y, Schiffmann SN, de Kerchove d'Exaerde A, Urade Y, Qu WM, Huang ZL, Lazarus M. Slow-wave sleep is controlled by a subset of nucleus accumbens core neurons in mice. Nature Communications. September 2017, 8 (1): 734. Bibcode:2017NatCo...8..734O. PMC 5622037 . PMID 28963505. doi:10.1038/s41467-017-00781-4. Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A2A receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound.
Yuan XS, Wang L, Dong H, Qu WM, Yang SR, Cherasse Y, Lazarus M, Schiffmann SN, d'Exaerde AK, Li RX, Huang ZL. 2A receptor neurons control active-period sleep via parvalbumin neurons in external globus pallidus. eLife. October 2017, 6: e29055. PMC 5655138 . PMID 29022877. doi:10.7554/eLife.29055 . Malenka RC, Nestler EJ, Hyman SE. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience 2nd. New York: McGraw-Hill Medical. 2009: 147–148, 367, 376. ISBN 978-0-07-148127-4. VTA DA neurons play a critical role in motivation, reward-related behavior (Chapter 15), attention, and multiple forms of memory. This organization of the DA system, wide projection from a limited number of cell bodies, permits coordinated responses to potent new rewards. Thus, acting in diverse terminal fields, dopamine confers motivational salience ("wanting") on the reward itself or associated cues (nucleus accumbens shell region), updates the value placed on different goals in light of this new experience (orbital prefrontal cortex), helps consolidate multiple forms of memory (amygdala and hippocampus), and encodes new motor programs that will facilitate obtaining this reward in the future (nucleus accumbens core region and dorsal striatum). In this example, dopamine modulates the processing of sensorimotor information in diverse neural circuits to maximize the ability of the organism to obtain future rewards. ...
The brain reward circuitry that is targeted by addictive drugs normally mediates the pleasure and strengthening of behaviors associated with natural reinforcers, such as food, water, and sexual contact. Dopamine neurons in the VTA are activated by food and water, and dopamine release in the NAc is stimulated by the presence of natural reinforcers, such as food, water, or a sexual partner. ...
The NAc and VTA are central components of the circuitry underlying reward and memory of reward. As previously mentioned, the activity of dopaminergic neurons in the VTA appears to be linked to reward prediction. The NAc is involved in learning associated with reinforcement and the modulation of motoric responses to stimuli that satisfy internal homeostatic needs. The shell of the NAc appears to be particularly important to initial drug actions within reward circuitry; addictive drugs appear to have a greater effect on dopamine release in the shell than in the core of the NAc.
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 . More recently, Fuller's laboratory also discovered that sleep can be promoted by the activation of a gamma-aminobutyric acid-ergic (GABAergic) population of neurons located in the parafacial zone [11,12], while the role of the GABAergic A2AR-expressing neurons of the nucleus accumbens [13] and the striatum has just been revealed [14,15].
Valencia Garcia S, Fort P. Nucleus Accumbens, a new sleep-regulating area through the integration of motivational stimuli. Acta Pharmacologica Sinica. February 2018, 39 (2): 165–166. PMC 5800466 . PMID 29283174. doi:10.1038/aps.2017.168. The nucleus accumbens comprises a contingent of neurons specifically expressing the post-synaptic A2A-receptor (A2AR) subtype making them excitable by adenosine, its natural agonist endowed with powerful sleep-promoting properties[4]. ... In both cases, large activation of A2AR-expressing neurons in NAc promotes slow wave sleep (SWS) by increasing the number and duration of episodes. ... After optogenetic activation of the core, a similar promotion of SWS was observed, whereas no significant effects were induced when activating A2AR-expressing neurons within the shell.
Oishi Y, Xu Q, Wang L, Zhang BJ, Takahashi K, Takata Y, Luo YJ, Cherasse Y, Schiffmann SN, de Kerchove d'Exaerde A, Urade Y, Qu WM, Huang ZL, Lazarus M. Slow-wave sleep is controlled by a subset of nucleus accumbens core neurons in mice. Nature Communications. September 2017, 8 (1): 734. Bibcode:2017NatCo...8..734O. PMC 5622037 . PMID 28963505. doi:10.1038/s41467-017-00781-4. Here, we show that chemogenetic or optogenetic activation of excitatory adenosine A2A receptor-expressing indirect pathway neurons in the core region of the NAc strongly induces slow-wave sleep. Chemogenetic inhibition of the NAc indirect pathway neurons prevents the sleep induction, but does not affect the homoeostatic sleep rebound.
Yuan XS, Wang L, Dong H, Qu WM, Yang SR, Cherasse Y, Lazarus M, Schiffmann SN, d'Exaerde AK, Li RX, Huang ZL. 2A receptor neurons control active-period sleep via parvalbumin neurons in external globus pallidus. eLife. October 2017, 6: e29055. PMC 5655138 . PMID 29022877. doi:10.7554/eLife.29055 . The Journal of Neuroscience, 2001, 21:RC131:1-5 Synchronous Activity in the Hippocampus and Nucleus Accumbens In Vivo Yukiori Goto and Patricio O'Donnell
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