Distinct protocerebral neuropils associated with attractive and aversive female-produced odorants in the male moth brain.

Jonas Hansen Kymre,Christoffer Nerland Berge,Bente Gunnveig Berg,Xi Chu,XiaoLan Liu,XinCheng Zhao,GuiRong Wang,Elena Ian

doi:10.7554/elife.65683

Abstract

The pheromone system of heliothine moths is an optimal model for studying principles underlying higher-order olfactory processing. In Helicoverpa armigera, three male-specific glomeruli receive input about three female-produced signals, the primary pheromone component, serving as an attractant, and two minor constituents, serving a dual function, that is, attraction versus inhibition of attraction. From the antennal-lobe glomeruli, the information is conveyed to higher olfactory centers, including the lateral protocerebrum, via three main paths - of which the medial tract is the most prominent. In this study, we traced physiologically identified medial-tract projection neurons from each of the three male-specific glomeruli with the aim of mapping their terminal branches in the lateral protocerebrum. Our data suggest that the neurons' widespread projections are organized according to behavioral significance, including a spatial separation of signals representing attraction versus inhibition - however, with a unique capacity of switching behavioral consequence based on the amount of the minor components.

Highlights

Olfactory circuits serve a central role in encoding and modulating sensory input from the natural surroundings
Pheromone-evoked behaviors are linked to a hardwired circuit in the lateral protocerebrum, including the lateral horn (Ito et al, 2014, Martin et al, 2011)
We found that the connectivity between the MGC units and the targeted protocerebral neuropils of each PN displayed an interesting pattern (Fig. 3 – figure supplement 1H), where different neuropils served as output regions for distinct groups of MGC-PN types: 1) the ventrolateral protocerebrum (VLP)

Summary

Introduction

Olfactory circuits serve a central role in encoding and modulating sensory input from the natural surroundings. Understanding how these chemosensory circuits translate signals with different hedonic valences into behavior is an essential issue in neuroscience. Pheromone-evoked behaviors are linked to a hardwired circuit in the lateral protocerebrum, including the lateral horn (Ito et al, 2014, Martin et al, 2011). This brain region shares many neural principles with the mammalian cortical amygdala (Miyamichi et al, 2011; Sosulski et al, 2011). Signals inducing different behaviors, such as pheromones versus food odors, are segregated in the lateral protocerebrum both in fruit fly and moths

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Results

Conclusion