Phylogeny of a serotonin-immunoreactive neuron in the primary olfactory center of the insect brain

Local networks within the primary olfactory centers reformat odor representations from olfactory receptor neurons to second-order neurons. By studying the rules underlying mixture representation at the input to the antennal lobe (AL), the primary olfactory center of the insect brain, we recently found that mixture representation follows a strict elemental rule in honeybees: the more a component activates the AL when presented alone, the more it is represented in a mixture. We now studied mixture representation at the output of the AL by imaging a population of second-order neurons, which convey AL processed odor information to higher brain centers. We systematically measured odor-evoked activity in 22 identified glomeruli in response to four single odorants and all their possible binary, ternary and quaternary mixtures. By comparing input and output responses, we determined how the AL network reformats mixture representation and what advantage this confers for odor discrimination. We show that increased inhibition within the AL leads to more synthetic, less elemental, mixture representation at the output level than that at the input level. As a result, mixture representations become more separable in the olfactory space, thus allowing better differentiation among floral blends in nature.

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Action of Pyrethroids on Ca2+-Stimulated ATP Hydrolyzing Activities: Protein Phosphorylation-Dephosphorylation Events in Insect Brain Fractions

Membrane Receptors and Enzymes as Targets of Insecticidal Action ◽

10.1007/978-1-4684-5113-9_10 ◽

1986 ◽

pp. 189-211 ◽

Cited By ~ 1

Author(s):

J. Marshall Clark

Keyword(s):

Protein Phosphorylation ◽

Insect Brain

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Expression patterns of nicotinic subunits α2, α7, α8, and β1 affect the kinetics and pharmacology of ACh-induced currents in adult bee olfactory neuropiles

Journal of Neurophysiology ◽

10.1152/jn.00126.2011 ◽

2011 ◽

Vol 106 (4) ◽

pp. 1604-1613 ◽

Cited By ~ 28

Author(s):

Julien Pierre Dupuis ◽

Monique Gauthier ◽

Valérie Raymond-Delpech

Keyword(s):

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Expression Patterns ◽

Insect Brain ◽

Olfactory Pathway ◽

Excitatory Neurotransmitter ◽

Kenyon Cells ◽

Inward Currents ◽

Induced Currents ◽

The Brain

Acetylcholine (ACh) is the main excitatory neurotransmitter of the insect brain, where nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission. In the honeybee Apis mellifera, nAChRs are expressed in diverse structures including the primary olfactory centers of the brain, the antennal lobes (ALs) and the mushroom bodies (MBs), where they participate in olfactory information processing. To understand the nature and properties of the nAChRs involved in these processes, we performed a pharmacological and molecular characterization of nAChRs on cultured Kenyon cells of the MBs, using whole cell patch-clamp recordings combined with single-cell RT-PCR. In all cells, applications of ACh as well as nicotinic agonists such as nicotine and imidacloprid induced inward currents with fast desensitization. These currents were fully blocked by saturating doses of the antagonists α-bungarotoxin (α-BGT), dihydroxy-β-erythroidine (DHE), and methyllycaconitine (MLA) (MLA ≥ α-BGT ≥ DHE). Molecular analysis of ACh-responding cells revealed that of the 11 nicotinic receptor subunits encoded within the honeybee genome, α2, α8, and β1 subunits were expressed in adult Kenyon cells. Comparison with the expression pattern of adult AL cells revealed the supplementary presence of subunit α7, which could be responsible for the kinetic and pharmacological differences observed when comparing ACh-induced currents from AL and Kenyon cells. Together, our data demonstrate the existence of functional nAChRs on adult MB Kenyon cells that differ from nAChRs on AL cells in both their molecular composition and pharmacological properties, suggesting that changing receptor subsets could mediate different processing functions depending on the brain structure within the olfactory pathway.

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Multimodal integration and stimulus categorization in putative mushroom body output neurons of the honeybee

Royal Society Open Science ◽

10.1098/rsos.171785 ◽

2018 ◽

Vol 5 (2) ◽

pp. 171785 ◽

Cited By ~ 23

Author(s):

Martin F. Strube-Bloss ◽

Wolfgang Rössler

Keyword(s):

Visual Information ◽

Mushroom Body ◽

Visual Cues ◽

Sensory Modality ◽

Sensory Information ◽

Insect Brain ◽

Pollinating Insects ◽

Output Neurons ◽

Electrophysiological Characterization ◽

Nonlinear Integration

Flowers attract pollinating insects like honeybees by sophisticated compositions of olfactory and visual cues. Using honeybees as a model to study olfactory–visual integration at the neuronal level, we focused on mushroom body (MB) output neurons (MBON). From a neuronal circuit perspective, MBONs represent a prominent level of sensory-modality convergence in the insect brain. We established an experimental design allowing electrophysiological characterization of olfactory, visual, as well as olfactory–visual induced activation of individual MBONs. Despite the obvious convergence of olfactory and visual pathways in the MB, we found numerous unimodal MBONs. However, a substantial proportion of MBONs (32%) responded to both modalities and thus integrated olfactory–visual information across MB input layers. In these neurons, representation of the olfactory–visual compound was significantly increased compared with that of single components, suggesting an additive, but nonlinear integration. Population analyses of olfactory–visual MBONs revealed three categories: (i) olfactory, (ii) visual and (iii) olfactory–visual compound stimuli. Interestingly, no significant differentiation was apparent regarding different stimulus qualities within these categories. We conclude that encoding of stimulus quality within a modality is largely completed at the level of MB input, and information at the MB output is integrated across modalities to efficiently categorize sensory information for downstream behavioural decision processing.

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Abstract concept learning in a simple neural network inspired by the insect brain

PLoS Computational Biology ◽

10.1371/journal.pcbi.1006435 ◽

2018 ◽

Vol 14 (9) ◽

pp. e1006435 ◽

Cited By ~ 16

Author(s):

Alex J. Cope ◽

Eleni Vasilaki ◽

Dorian Minors ◽

Chelsea Sabo ◽

James A. R. Marshall ◽

...

Keyword(s):

Neural Network ◽

Concept Learning ◽

Insect Brain ◽

Abstract Concept ◽

Simple Neural Network

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The Insect Brain as a Model System for Low Power Electronics and Edge Processing Applications

2019 IEEE Space Computing Conference (SCC) ◽

10.1109/spacecomp.2019.00012 ◽

2019 ◽

Author(s):

Angel Yanguas-Gil ◽

Anil Mane ◽

Jeffrey W. Elam ◽

Felix Wang ◽

William Severa ◽

...

Keyword(s):

Low Power ◽

Power Electronics ◽

Model System ◽

Insect Brain ◽

Low Power Electronics

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Analysis of Synaptic Microcircuits in the Mushroom Bodies of the Honeybee

Insects ◽

10.3390/insects11010043 ◽

2020 ◽

Vol 11 (1) ◽

pp. 43 ◽

Cited By ~ 4

Author(s):

Claudia Groh ◽

Wolfgang Rössler

Keyword(s):

Behavioral Plasticity ◽

Future Research ◽

Mushroom Bodies ◽

Insect Brain ◽

Long Term Memory ◽

Projection Neurons ◽

Open Questions ◽

Neuronal Mechanisms ◽

Input Region ◽

Change Response

Mushroom bodies (MBs) are multisensory integration centers in the insect brain involved in learning and memory formation. In the honeybee, the main sensory input region (calyx) of MBs is comparatively large and receives input from mainly olfactory and visual senses, but also from gustatory/tactile modalities. Behavioral plasticity following differential brood care, changes in sensory exposure or the formation of associative long-term memory (LTM) was shown to be associated with structural plasticity in synaptic microcircuits (microglomeruli) within olfactory and visual compartments of the MB calyx. In the same line, physiological studies have demonstrated that MB-calyx microcircuits change response properties after associative learning. The aim of this review is to provide an update and synthesis of recent research on the plasticity of microcircuits in the MB calyx of the honeybee, specifically looking at the synaptic connectivity between sensory projection neurons (PNs) and MB intrinsic neurons (Kenyon cells). We focus on the honeybee as a favorable experimental insect for studying neuronal mechanisms underlying complex social behavior, but also compare it with other insect species for certain aspects. This review concludes by highlighting open questions and promising routes for future research aimed at understanding the causal relationships between neuronal and behavioral plasticity in this charismatic social insect.

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