Core[edit]

The?nucleus accumbens core?(NAcc core) is the inner substructure of the nucleus accumbens.

Location:?The nucleus accumbens core is part of the?ventral striatum, located within the basal ganglia.?Cell types:?The core of the NAcc is made up mainly of medium spiny neurons containing mainly D1-type or D2-type dopamine receptors. The D1-type medium spiny neurons mediate reward-related cognitive processes,[5][35][36]?whereas the D2-type medium spiny neurons mediate aversion-related cognition.[6]?The neurons in the core, as compared to the neurons in the shell, have an increased density of dendritic spines, branch segments, and terminal segments. From the core, the neurons project to other sub-cortical areas such as the globus pallidus and the substantia nigra.

（在globus pallidus中，外側(cè)蒼白球活動抑制底丘腦核從而不去興奮內(nèi)側(cè)蒼白球，也就是說外側(cè)蒼白球活動的效果是不興奮內(nèi)側(cè)蒼白球，對于行為來說，外側(cè)蒼白球活動是有利于行為的產(chǎn)生，而內(nèi)側(cè)蒼白球的活動是不利于行為的產(chǎn)生；在黑質(zhì)中，reticulata部分活動不利于行為的產(chǎn)生，而compacta部分活動利于行為的產(chǎn)生。那么nucleus accumbens core中的D1-type medium spiny neurons與D2-type medium spiny neurons很有可能是分別投射到上述列舉的結(jié)構(gòu)，具體為D2-type medium spiny neurons投射抑制軸突到外側(cè)蒼白球、compacta部分，mediate aversion-related cognition；D1-type medium spiny neurons投射抑制軸突到內(nèi)側(cè)蒼白球、reticulata部分，mediate reward-related cognitive processes，這時reticulata部分被一定程度抑制，這是可以一定程度反映在眼球轉(zhuǎn)動和生理欲望的出現(xiàn)上，也就是說得到reward時，眼球很容易出現(xiàn)轉(zhuǎn)動現(xiàn)象，至少是不那么直勾勾，pedunculopontine nucleus也不那么被抑制，能夠投射出更多的aectylcholine遞質(zhì)進行廣泛影響，從而不自覺地產(chǎn)生心理活動（類似于，哥們兒，得大獎了，說一下獲獎感言吧。顯然根據(jù)自身經(jīng)驗，得到reward時，內(nèi)心總會有明確的感受出現(xiàn)，所以會問出感受如何的話。）。這意味著VTA通過多巴胺系統(tǒng)可以同時主導(dǎo)reward-related cognitive processes和aversion-related cognition，不過這種aversion-related cognition是區(qū)別于lateral habenula

導(dǎo)致的懲罰行為，因為lateral habenula同時抑制多巴胺系統(tǒng)、serotonin系統(tǒng)、acetylcholine系統(tǒng)，或者說個體之間逗鬧中的躲避、害怕行為就是由VTA主導(dǎo)aversion-related cognition產(chǎn)生的。而nucleus accumbens core?中的D2-type medium spiny neurons又屬于sleep-promoting nuclei，即可以被adenosine興奮，產(chǎn)生睡眠傾向。我觀察到秀秀兩歲半之前存在這樣的現(xiàn)象：她太調(diào)皮，我極為大聲呵斥她，她會郁悶地跑去蒙頭，然后很快就睡過去了，這種情況出現(xiàn)過很多次，她的睡眠行為與被大聲呵斥而多巴胺系統(tǒng)被打壓有因果關(guān)系。類似的，我也聽說過很多別人受委屈而去蒙頭睡覺的例子，我覺得其中的機制很有可能就是VTA被委屈抑制，然后nucleus accumbens core?中的D2-type medium spiny neurons能夠?qū)denosine敏感，再加上蒙頭導(dǎo)致血管中二氧化碳濃度增加，從而增加了raphe nucleus的活動，從而降低了大腦皮層與丘腦的放電量，進一步降低了arousal system接收大腦皮層的信號量，導(dǎo)致adenosine興奮各處的sleep-promoting nuclei，導(dǎo)致人進入睡眠狀態(tài)。）

?GABA?is one of the main neurotransmitters in the NAcc, and?GABA receptors?are also abundant.[27][29]

Function:?The nucleus accumbens core is involved in the cognitive processing of?motor function?related to reward and reinforcement and the regulation of?slow-wave sleep.[4][11][12][13]?Specifically, the core encodes new motor programs which facilitate the acquisition of a given reward in the future.[4]?The indirect pathway (i.e., D2-type) neurons in the NAcc core which co-express?adenosine A2A?receptors?activation-dependently promote slow-wave sleep.[11][12][13]?The NAcc core has also been shown to mediate?general Pavlovian-instrumental transfer, a phenomenon in which a classically conditioned stimulus modifies operant behavior.[32][9][10]

這一篇文章中干貨內(nèi)容十足，揭示幾種重要的行為內(nèi)在機制，而且可以用來驗證的手段可謂遍地都是，隨手就有，畢竟這里涉及到了sleep-promoting nuclei和reward-related cognitive processes和aversion-related cognition。而且，我還給出了解剖學(xué)上連接結(jié)構(gòu)的預(yù)測，即D1-type?medium spiny neurons 和D2-type medium?spiny neurons投射到basal forebrain中的具體位置，從而對應(yīng)著reward-related cognitive processes和aversion-related cognition。