Information flow, cell types and stereotypy in a full olfactory connectome

Schlegel, Philipp; Bates, Alexander Shakeel; Stürner, Tomke; Jagannathan, Sridhar R.; Drummond, Nikolas; Hsu, Joseph; Capdevila, Laia Serratosa; Javier, Alexandre; Marin, Elizabeth C.; Barth-Maron, Asa; Tamimi, Imaan F M; Li, Feng; Rubin, Gerald M.; Plaza, Stephen M.; Costa, Marta; Jefferis, Gregory

doi:10.7554/elife.66018

Cited by 132 publications

(224 citation statements)

References 128 publications

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“…Learned valence of stimuli is therefore thought to be encoded as a skew in the activity of the population of MBONs. However, despite recent progress [23,[41][42][43][44], the way in which the learned valence is read out by the downstream networks and used to select actions and the way in which innate and learned valences are integrated is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Circuits for integrating learned and innate valences in the insect brain

Eschbach

Fushiki

Winding

et al. 2021

eLife

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Animal behavior is shaped both by evolution and by individual experience. Parallel brain pathways encode innate and learned valences of cues, but the way in which they are integrated during action-selection is not well understood. We used electron microscopy to comprehensively map with synaptic resolution all neurons downstream of all mushroom body (MB) output neurons (encoding learned valences) and characterized their patterns of interaction with lateral horn (LH) neurons (encoding innate valences) in Drosophila larva. The connectome revealed multiple convergence neuron types that receive convergent MB and LH inputs. A subset of these receives excitatory input from positive-valence MB and LH pathways and inhibitory input from negative-valence MB pathways. We confirmed functional connectivity from LH and MB pathways and behavioral roles of two of these neurons. These neurons encode integrated odor value and bidirectionally regulate turning. Based on this, we speculate that learning could potentially skew the balance of excitation and inhibition onto these neurons and thereby modulate turning. Together, our study provides insights into the circuits that integrate learned and innate valences to modify behavior.

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Section: Introductionmentioning

confidence: 99%

Circuits for integrating learned and innate valences in the insect brain

Eschbach

Fushiki

Winding

et al. 2021

eLife

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“…As of 2021, scientists at the Janelia labs of the Howard Hughes Medical Institute are in the process of imaging the full nervous system of a male fly, including both the brain and the VNC. However, apart from a few circuits compared in two animals (Takemura et al, 2015;Schlegel et al, 2021), we lack duplicate connectomes that could reveal the constancy of the connectome in either sex.…”

Section: Whole-animal Concernsmentioning

confidence: 99%

A connectome is not enough – what is still needed to understand the brain ofDrosophila?

Scheffer

Meinertzhagen

2021

Journal of Experimental Biology

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Understanding the structure and operation of any nervous system has been a subject of research for well over a century. A near-term opportunity in this quest is to understand the brain of a model species, the fruit fly Drosophila melanogaster. This is an enticing target given its relatively small size (roughly 200,000 neurons), coupled with the behavioral richness that this brain supports, and the wide variety of techniques now available to study both brain and behavior. It is clear that within a few years we will possess a connectome for D. melanogaster: an electron-microscopy-level description of all neurons and their chemical synaptic connections. Given what we will soon have, what we already know and the research that is currently underway, what more do we need to know to enable us to understand the fly's brain? Here, we itemize the data we will need to obtain, collate and organize in order to build an integrated model of the brain of D. melanogaster.

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“…OSN axons project to the antennal lobe in the brain ( Figure 1B ). Neurons expressing the same olfactory receptor converge onto specific glomeruli, where they synapse with projection neurons that carry sensory information to higher brain centers ( Grabe and Sachse, 2018 ; Schlegel et al, 2021 ). Each hair houses the dendrites of 1–4 OSNs, flanked by four support cells, which together comprise a sensillum.…”

Section: Insect Olfactory System Basicsmentioning

confidence: 99%

Olfactory Receptor Gene Regulation in Insects: Multiple Mechanisms for Singular Expression

Mika

Benton

2021

Front. Neurosci.

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The singular expression of insect olfactory receptors in specific populations of olfactory sensory neurons is fundamental to the encoding of odors in patterns of neuronal activity in the brain. How a receptor gene is selected, from among a large repertoire in the genome, to be expressed in a particular neuron is an outstanding question. Focusing on Drosophila melanogaster, where most investigations have been performed, but incorporating recent insights from other insect species, we review the multilevel regulatory mechanisms of olfactory receptor expression. We discuss how cis-regulatory elements, trans-acting factors, chromatin modifications, and feedback pathways collaborate to activate and maintain expression of the chosen receptor (and to suppress others), highlighting similarities and differences with the mechanisms underlying singular receptor expression in mammals. We also consider the plasticity of receptor regulation in response to environmental cues and internal state during the lifetime of an individual, as well as the evolution of novel expression patterns over longer timescales. Finally, we describe the mechanisms and potential significance of examples of receptor co-expression.

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Information flow, cell types and stereotypy in a full olfactory connectome

Cited by 132 publications

References 128 publications

Circuits for integrating learned and innate valences in the insect brain

Circuits for integrating learned and innate valences in the insect brain

A connectome is not enough – what is still needed to understand the brain ofDrosophila?

Olfactory Receptor Gene Regulation in Insects: Multiple Mechanisms for Singular Expression

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