Organization of Functional Long-Range Circuits Controlling the Activity of Serotonergic Neurons in the Dorsal Raphe Nucleus

Publication date: 21 March 2017
Source:Cell Reports, Volume 18, Issue 12
Author(s): Li Zhou, Ming-Zhe Liu, Qing Li, Juan Deng, Di Mu, Yan-Gang Sun
Serotonergic neurons play key roles in various biological processes. However, circuit mechanisms underlying tight control of serotonergic neurons remain largely unknown. Here, we systematically investigated the organization of long-range synaptic inputs to serotonergic neurons and GABAergic neurons in the dorsal raphe nucleus (DRN) of mice with a combination of viral tracing, slice electrophysiological, and optogenetic techniques. We found that DRN serotonergic neurons and GABAergic neurons receive largely comparable synaptic inputs from six major upstream brain areas. Upon further analysis of the fine functional circuit structures, we found both bilateral and ipsilateral patterns of topographic connectivity in the DRN for the axons from different inputs. Moreover, the upstream brain areas were found to bidirectionally control the activity of DRN serotonergic neurons by recruiting feedforward inhibition or via a push-pull mechanism. Our study provides a framework for further deciphering the functional roles of long-range circuits controlling the activity of serotonergic neurons in the DRN.

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Teaser

Zhou et al. used slice physiological recording combined with optogenetics to systematically study the long-range functional input from six key upstream brain areas to both serotonergic and GABAergic neurons in the dorsal raphe nucleus. The results reveal the fine circuit mechanisms that functionally balance the activity of serotonergic neurons.


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