Section on Circuits, Synapses, and Molecular Signaling, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
Section on Genetics of Neuronal Signaling, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
J Comp Neurol. 2024 Nov;532(11):e70001. doi: 10.1002/cne.70001.
Cholinergic projection neurons of the nucleus basalis and substantia innominata (NBM/SI) densely innervate the basolateral amygdala (BLA) and have been shown to contribute to the encoding of fundamental and life-threatening experiences. Given the vital importance of these circuits in the acquisition and retention of memories that are essential for survival in a changing environment, it is not surprising that the basic anatomical organization of the NBM/SI is well conserved across animal classes as diverse as teleost and mammal. What is not known is the extent to which the physiology and morphology of NBM/SI neurons have also been conserved. To address this issue, we made patch-clamp recordings from NBM/SI neurons in ex vivo slices of two widely divergent mammalian species, mouse and rhesus macaque, focusing our efforts on cholinergic neurons that project to the BLA. We then reconstructed most of these recorded neurons post hoc to characterize neuronal morphology. We found that rhesus macaque BLA-projecting cholinergic neurons were both more intrinsically excitable and less morphologically compact than their mouse homologs. Combining measurements of 18 physiological features and 13 morphological features, we illustrate the extent of the separation. Although macaque and mouse neurons both exhibited considerable within-group diversity and overlapped with each other on multiple individual metrics, a combined morphoelectric analysis demonstrates that they form two distinct neuronal classes. Given the shared purpose of the circuits in which these neurons participate, this finding raises questions about (and offers constraints on) how these distinct classes result in similar behavior.
基底核和无名质（NBM/SI）的胆碱能投射神经元密集地支配外侧杏仁核（BLA），并被证明有助于基本和危及生命的体验的编码。鉴于这些回路在获取和保留对变化环境中生存至关重要的记忆方面的重要性，NBM/SI 的基本解剖组织在从硬骨鱼到哺乳动物等各种动物类群中得到很好的保守并不奇怪。尚不清楚 NBM/SI 神经元的生理学和形态学在多大程度上也得到了保守。为了解决这个问题，我们在来自两种广泛不同的哺乳动物物种（小鼠和恒河猴）的离体切片中进行了 NBM/SI 神经元的膜片钳记录，重点关注投射到 BLA 的胆碱能神经元。然后，我们对大多数记录神经元进行了事后重建，以表征神经元形态。我们发现，恒河猴 BLA 投射的胆碱能神经元比其小鼠同源物更具内在兴奋性，形态也更不紧凑。通过对 18 个生理特征和 13 个形态特征的测量，我们说明了分离的程度。尽管猕猴和小鼠神经元在组内都表现出相当大的多样性，并且在多个个体指标上相互重叠，但综合形态电分析表明它们形成了两个不同的神经元类群。鉴于这些神经元参与的回路具有共同的目的，这一发现提出了关于这些不同类群如何导致相似行为的问题（并提供了限制）。
