中央杏仁核（主要由GABAergic抑制性神经元组成）是大脑中处理“巴甫洛夫条件恐惧”的地方。在本期Nature上发表文章的两个小组，利用很不相同的、但却互补的实验方法得到了关于决定条件恐惧反应的功能架构的相似结论。他们发现，有两个微型回路涉及其中：一个是恐惧获取所必需的，另一个是条件恐惧反应是必需的。
Haubensak等人利用基因功能操纵方法识别出在门控“学得的恐惧”中扮演关键角色的GABAergic神经元的一个亚组。Ciocchi等人在活体中把电生理、光遗传学和药理学方法结合起来控制小鼠的行为，以此识别出三个不同功能的神经元类型，这些神经元嵌入在一个具有高度组织性的局部“去抑制”网络中。
推荐英文摘要：
Nature doi:10.1038/nature09553
Genetic dissection of an amygdala microcircuit that gates conditioned fear
Wulf Haubensak,Prabhat S. Kunwar,Haijiang Cai,Stephane Ciocchi,Nicholas R. Wall,Ravikumar Ponnusamy,Jonathan Biag,Hong-Wei Dong,Karl Deisseroth,Edward M. Callaway,Michael S. Fanselow,Andreas Lüthi" David J. Andersonwuwei@caltech.edu
The role of different amygdala nuclei (neuroanatomical subdivisions) in processing Pavlovian conditioned fear has been studied extensively, but the function of the heterogeneous neuronal subtypes within these nuclei remains poorly understood. Here we use molecular genetic approaches to map the functional connectivity of a subpopulation of GABA-containing neurons, located in the lateral subdivision of the central amygdala (CEl), which express protein kinase C-δ (PKC-δ). Channelrhodopsin-2-assisted circuit mapping in amygdala slices and cell-specific viral tracing indicate that PKC-δ+ neurons inhibit output neurons in the medial central amygdala (CEm), and also make reciprocal inhibitory synapses with PKC-δ? neurons in CEl. Electrical silencing of PKC-δ+ neurons in vivo suggests that they correspond to physiologically identified units that are inhibited by the conditioned stimulus, called CEloff units. This correspondence, together with behavioural data, defines an inhibitory microcircuit in CEl that gates CEm output to control the level of conditioned freezing.
