JournalNeural Excitability, Synapses, and Glia

Low-threshold spiking interneurons perform feedback inhibition in the lateral amygdala

Identifcation of feedback interneurons. A: An illustration of a serial paired recordings which involves recording of an interneuron (shown in red) while probing at least four principal potential synaptic partners (shown in black) in a bidirectional manner. B: A representative recording from a feedback interneuron bidirectionally connected to its principal neuron synaptic partner. The image in the inset illustrates the distance between recorded neurons. For ease of illustration, the recorded neurons are shown with arrows colored correspondingly. Averaged electrophysiological traces from the recording showing connectivity in principal neuron—>feedback interneuron (top traces) and feedback interneuron—>principal neuron (bottom traces) direction.

Amygdala plays crucial roles in emotional learning. The lateral amygdala (LA) is the input station of the amygdala, where learning related plasticity occurs. The LA is cortical like in nature in terms of its cellular make up, composed of a majority of principal cells and a minority of interneurons with distinct subtypes defined by morphology, intrinsic electrophysiological properties and neurochemical expression profile. The specific functions served by LA interneuron subtypes remain elusive. This study aimed to elucidate the interneuron subtype mediating feedback inhibition. Electrophysiological evidence involving antidromic activation of recurrent LA circuitry via basolateral amygdala stimulation and paired recordings implicate low-threshold spiking interneurons in feedback inhibition. Recordings in somatostatin-cre animals crossed with tdtomato mice have revealed remarkable similarities between a subset of SOM+ interneurons and LTS interneurons. This study concludes that LTS interneurons, most of which are putatively SOM+, mediate feedback inhibition in the LA. Parallels with cortical areas and potential implications for information processing and plasticity are discussed.

Ünal, Ç.T., Ünal, B., and Bolton, M.M. (2020). Low-threshold spiking interneurons perform feedback inhibition in the lateral amygdala. Brain Struct Funct 225, 909–923.
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