Abstract
Interconnections between the olfactory bulb and the amygdala are a major pathway for triggering strong behavioral responses to a variety of odorants. However, while this broad mapping has been established, the patterns of amygdala feedback connectivity and the influence on olfactory circuitry remain unknown. Here, using a combination of neuronal tracing approaches, we dissect the connectivity of a cortical amygdala (PmCo) feedback circuit innervating the mouse accessory olfactory bulb (AOB). Optogenetic activation of PmCo feedback mainly results in feed-forward mitral cell (MC) inhibition through direct excitation of GABAergic granule cells (GC). In addition, LED-driven activity of corticofugal afferents increases the gain of MC responses to olfactory nerve stimulation. Thus, through corticofugal pathways, the PmCo likely regulates primary olfactory and social odor processing.
Significance Statement Olfactory inputs are relayed directly through the amygdala to hypothalamic and limbic system nuclei regulating essential responses in the context of social behavior. However, it is not clear whether and how amygdala circuits participate in the earlier steps of olfactory processing at the level of the olfactory bulb. Unraveling the organization of this circuitry is critical to understand the function of amygdala circuits. Combining cre-dependent viral tracing with optogenetic-assisted patch clamp electrophysiology, the present work maps the synaptic connectivity and physiology of a cortical amygdala pathway innervating primary olfactory circuits.
Footnotes
Author reports no conflict of interest.
This work was supported by NIH grants R01 NIDA020140 (J.G.C.), and R01 DC012050 (J.G.C.). Core support was provided by the CNMC IDDRC Imaging and Microscopy Core (NIH IDDRC U54 HD090257). D.D. and E.R. were supported by grants from the German Science Foundation (Du 354/8-2, CRC-1134).
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
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