Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts 02215.
Graduate Program in Neuroscience, Boston University School of Medicine, Boston, Massachusetts 02215.
J Neurosci. 2020 Oct 21;40(43):8306-8328. doi: 10.1523/JNEUROSCI.0860-20.2020. Epub 2020 Sep 28.
The delicate balance among primate prefrontal networks is necessary for homeostasis and behavioral flexibility. Dorsolateral prefrontal cortex (dlPFC) is associated with cognition, while the most ventromedial subgenual cingulate area 25 (A25) is associated with emotion and emotional expression. Yet A25 is weakly connected with dlPFC, and it is unknown how the two regions communicate. In rhesus monkeys of both sexes, we investigated how these functionally distinct areas may interact through pregenual anterior cingulate area 32 (A32), which is strongly connected with both. We found that dlPFC innervated the deep layers of A32, while A32 innervated all layers of A25, mostly targeting spines of excitatory neurons. Approximately 20% of A32 terminations formed synapses on inhibitory neurons in A25, notably the powerful parvalbumin inhibitory neurons in the deep layers, and the disinhibitory calretinin neurons in the superficial layers. By innervating distinct inhibitory microenvironments in laminar compartments, A32 is positioned to tune activity in columns of A25. The circuitry of the sequential pathway indicates that when dlPFC is engaged, A32 can dampen A25 output through the parvalbumin inhibitory microsystem in the deep layers of A25. A32 thus may flexibly recruit or reduce activity in A25 to maintain emotional equilibrium, a process that is disrupted in depression. Moreover, pyramidal neurons in A25 had a heightened density of NMDARs, which are the targets of novel rapid-acting antidepressants. Pharmacologic antagonism of NMDARs in patients with depression may reduce excitability in A25, mimicking the effects of the neurotypical serial pathway identified here. The anterior cingulate is a critical hub in prefrontal networks through connections with functionally distinct areas. Dorsolateral and polar prefrontal areas that are associated with complex cognition are connected with the anterior cingulate in a pattern that allows them to indirectly control downstream activity from the anterior cingulate to the subgenual cingulate, which is associated with heightened activity and negative affect in depression. This set of pathways provides a circuit mechanism for emotional regulation, with the anterior cingulate playing a balancing role for integration of cognitive and emotional processes. Disruption of these pathways may perturb network function and the ability to regulate cognitive and affective processes based on context.
灵长类动物前额叶网络的微妙平衡对于维持体内平衡和行为灵活性是必要的。背外侧前额叶皮层(dlPFC)与认知有关,而最腹侧的前扣带回亚区 25(A25)与情绪和情绪表达有关。然而,A25 与 dlPFC 的连接较弱,目前尚不清楚这两个区域如何进行通讯。在雄性和雌性恒河猴中,我们研究了这两个功能不同的区域如何通过强烈连接这两个区域的前扣带回 32 区(A32)进行相互作用。我们发现,dlPFC 支配 A32 的深层,而 A32 支配 A25 的所有层,主要针对兴奋性神经元的棘突。约 20%的 A32 终末形成 A25 中抑制性神经元的突触,特别是深层的强大的 parvalbumin 抑制性神经元和浅层的 disinhibitory calretinin 神经元。通过支配 A25 层间不同的抑制性微环境,A32 能够调节 A25 柱的活动。该序列通路的电路表明,当 dlPFC 被激活时,A32 可以通过 A25 深层的 parvalbumin 抑制微系统来抑制 A25 的输出。因此,A32 可以灵活地招募或减少 A25 的活动,以维持情绪平衡,而在抑郁症中,这个过程会被打乱。此外,A25 中的锥体神经元具有更高密度的 NMDAR,NMDAR 是新型快速作用抗抑郁药的靶标。抗抑郁药物对抑郁症患者 NMDAR 的药理学拮抗作用可能会降低 A25 的兴奋性,模拟这里确定的神经典型串联通路的作用。扣带回是前额叶网络中的一个关键枢纽,通过与功能不同的区域的连接。与复杂认知相关的背外侧和极性前额叶区域与扣带回的连接方式允许它们间接控制扣带回下游的活动到亚区扣带回,这与抑郁症中活动增加和负性情绪有关。这组通路提供了一种情绪调节的回路机制,扣带起到了整合认知和情绪过程的平衡作用。这些通路的破坏可能会扰乱网络功能和根据上下文调节认知和情感过程的能力。