Wiring Specificity and Synaptic Diversity in the Mouse Lateral Central Amygdala.
The central amygdala (CeA) nucleus, a subcortical structure composed of mostly GABA-releasing (GABAergic) neurons, controls fear expression via projections to downstream targets in the hypothalamus and brainstem. The CeA consists of the lateral (CeL) and medial (CeM) subdivisions. The CeL strongly gates information transfer to the CeM, the main output station of the amygdala, but little is known about the functional organization of local circuits in this region. Using cluster analysis, we identified two major electrophysiologically distinct CeL neuron classes in mouse amygdala slices, the early-spiking (ES) and late-spiking (LS) neurons. These two classes displayed distinct autaptic transmission. Compared with LS neurons, ES neurons had strong and depressing autapses, which enhanced spike-timing precision. With multiple patch-clamp recordings, we found that CeL neurons made chemical, but not electrical, synapses. Analysis of individual connections revealed cannabinoid type 1 receptor-mediated suppression of the ES, but not of the LS cell output synapse. More interestingly, the efficacy of the ES→LS or LS→ES synapse was ~2-fold greater than that of the LS→LS or ES→ES synapse. When tested at 20 Hz, synapses between different neurons, but not within the same class, were markedly depressing and were more powerful to sculpt activity of postsynaptic neurons. Moreover, neurons of different classes also form synapses with higher degree of connectivity. We demonstrate that ES and LS neurons represent two functionally distinct cell classes in the CeL and interactions between presynaptic and postsynaptic neurons dictate synaptic properties between neurons.


CONCLUSIONS
The central lateral amygdala (CeL) is a key node in fear circuits, but the functional organization of local circuits in this region is largely unknown. The CeL consists of mostly GABAergic inhibitory neurons with different functional and molecular features. Here, we report that the presynaptic cell class determines functional properties of autapses and cannabinoid-mediated modulation of synaptic transmission between neurons, whereas presynaptic versus postsynaptic cell classes dictate the connectivity, efficacy, and dynamics of GABAergic synapses between any two neurons. The wiring specificity and synaptic diversity have a great impact on neuronal output in amygdala inhibitory networks. Such synaptic organizing principles advance our understanding of the significance of physiologically defined neuronal phenotypes in amygdala inhibitory networks.
Institute of Neuroscience.
Wen-Hsien
http://orcid.org/0000-0002-8078-5463
WH
Hou
Institute of Neuroscience.
Ning
N
Kuo
Institute of Biomedical Informatics, National Yang-Ming University, Taipei 112, Taiwan.
Ge-Wei
http://orcid.org/0000-0002-8357-3853
GW
Fang
Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
Hsien-Sung
http://orcid.org/0000-0003-2657-3635
HS
Huang
Institute of Biomedical Informatics, National Yang-Ming University, Taipei 112, Taiwan.
Kun-Pin
KP
Wu
Institute of Molecular Psychiatry, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
Andreas
http://orcid.org/0000-0003-3127-287X
A
Zimmer
Department of Medicine, MacKay Medical College, New Taipei City 252, Taiwan, and Department of Anesthesiology, MacKay Memorial Hospital, Taipei 104, Taiwan jkcheng@usa.net cclien@ym.edu.tw.
Jen-Kun
http://orcid.org/0000-0003-2384-7856
JK
Cheng
Institute of Neuroscience, Institute of Brain Science, Brain Research Center, and jkcheng@usa.net cclien@ym.edu.tw.
Cheng-Chang
http://orcid.org/0000-0002-6692-9942
CC
Lien
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D066274:Central Amygdaloid Nucleus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D026902:Potassium Channel Blockers
autapse; connectivity; depression; facilitation; short-term plasticity; synapse specificity