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Toshima N, Schleyer M. IR76b-expressing neurons in Drosophila melanogaster are necessary for associative reward learning of an amino acid mixture. Biol Lett 2024; 20:20230519. [PMID: 38351746 PMCID: PMC10865000 DOI: 10.1098/rsbl.2023.0519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
Learning where to find nutrients while at the same time avoiding toxic food is essential for survival of any animal. Using Drosophila melanogaster larvae as a study case, we investigate the role of gustatory sensory neurons expressing IR76b for associative learning of amino acids, the building blocks of proteins. We found surprising complexity in the neuronal underpinnings of sensing amino acids, and a functional division of sensory neurons. We found that the IR76b receptor is dispensable for amino acid learning, whereas the neurons expressing IR76b are specifically required for the rewarding but not the punishing effect of amino acids. This unexpected dissociation in neuronal processing of amino acids for different behavioural functions provides a study case for functional divisions of labour in gustatory systems.
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Affiliation(s)
- Naoko Toshima
- Department Genetics of Learning and Memory, Leibniz-Institute for Neurobiology, Magdeburg 39118, Germany
- Institute for the Advancement of Higher Education, Hokkaido University, Sapporo 060-0810, Japan
| | - Michael Schleyer
- Department Genetics of Learning and Memory, Leibniz-Institute for Neurobiology, Magdeburg 39118, Germany
- Institute for the Advancement of Higher Education, Hokkaido University, Sapporo 060-0810, Japan
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Thoener J, Weiglein A, Gerber B, Schleyer M. Optogenetically induced reward and 'frustration' memory in larval Drosophila. J Exp Biol 2022; 225:276423. [PMID: 35924545 DOI: 10.1242/jeb.244565] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/27/2022] [Indexed: 11/20/2022]
Abstract
Humans and animals alike form oppositely valenced memories for stimuli that predict the occurrence versus the termination of a reward: appetitive 'reward' memory for stimuli associated with the occurrence of a reward and aversive 'frustration' memory for stimuli that are associated with its termination. We characterize these memories in larval Drosophila using a combination of Pavlovian conditioning, optogenetic activation of the dopaminergic central-brain DAN-i1864 neuron, and high-resolution video-tracking. This reveals their dependency on the number of training trials and the duration of DAN-i1864 activation, their temporal stability, and the parameters of locomotion that are modulated during memory expression. Together with previous results on 'punishment' versus 'relief' learning by DAN-f1 neuron activation, this reveals a 2x2 matrix of timing-dependent memory valence for the occurrence/ termination of reward/ punishment. These findings should aid the understanding and modelling of how brains decipher the predictive, causal structure of events around a target reinforcing occurrence.
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Affiliation(s)
- Juliane Thoener
- Leibniz Institute for Neurobiology, Department of Genetics, Magdeburg, Germany
| | - Aliće Weiglein
- Leibniz Institute for Neurobiology, Department of Genetics, Magdeburg, Germany
| | - Bertram Gerber
- Leibniz Institute for Neurobiology, Department of Genetics, Magdeburg, Germany.,Institute of Biology, Otto von Guericke University Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Michael Schleyer
- Leibniz Institute for Neurobiology, Department of Genetics, Magdeburg, Germany
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Schumann I, Berger M, Nowag N, Schäfer Y, Saumweber J, Scholz H, Thum AS. Ethanol-guided behavior in Drosophila larvae. Sci Rep 2021; 11:12307. [PMID: 34112872 PMCID: PMC8192949 DOI: 10.1038/s41598-021-91677-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 05/27/2021] [Indexed: 11/22/2022] Open
Abstract
Chemosensory signals allow vertebrates and invertebrates not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid unpleasant or even poisonous substrates. Ethanol is a substance found in the natural environment of Drosophila melanogaster. Accordingly, D. melanogaster has evolved specific sensory systems, physiological adaptations, and associated behaviors at its larval and adult stage to perceive and process ethanol. To systematically analyze how D. melanogaster larvae respond to naturally occurring ethanol, we examined ethanol-induced behavior in great detail by reevaluating existing approaches and comparing them with new experiments. Using behavioral assays, we confirm that larvae are attracted to different concentrations of ethanol in their environment. This behavior is controlled by olfactory and other environmental cues. It is independent of previous exposure to ethanol in their food. Moreover, moderate, naturally occurring ethanol concentration of 4% results in increased larval fitness. On the contrary, higher concentrations of 10% and 20% ethanol, which rarely or never appear in nature, increase larval mortality. Finally, ethanol also serves as a positive teaching signal in learning and memory and updates valence associated with simultaneously processed odor information. Since information on how larvae perceive and process ethanol at the genetic and neuronal level is limited, the establishment of standardized assays described here is an important step towards their discovery.
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Affiliation(s)
- Isabell Schumann
- Department of Genetics, Leipzig University, 04103, Leipzig, Germany
| | - Michael Berger
- Department of Biology, University of Cologne, 50674, Cologne, Germany
| | - Nadine Nowag
- Department of Genetics, Leipzig University, 04103, Leipzig, Germany
| | - Yannick Schäfer
- Department of Biology, University of Cologne, 50674, Cologne, Germany
| | | | - Henrike Scholz
- Department of Biology, University of Cologne, 50674, Cologne, Germany
| | - Andreas S Thum
- Department of Genetics, Leipzig University, 04103, Leipzig, Germany. .,Department of Genetics, Institute of Biology, Faculty of Life Sciences, Leipzig University, Talstraße 33, 04103, Leipzig, Germany.
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