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Ronald L Davis - One of the best experts on this subject based on the ideXlab platform.
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Brain transcriptome changes in the aging Drosophila melanogaster accompany Olfactory Memory performance deficits.
PLOS ONE, 2018Co-Authors: Rodrigo Pacifico, Courtney M. Macmullen, Erica Walkinshaw, Xiaofan Zhang, Ronald L DavisAbstract:Cognitive decline is a common occurrence of the natural aging process in animals and studying age-related changes in gene expression in the brain might shed light on disrupted molecular pathways that play a role in this decline. The fruit fly is a useful neurobiological model for studying aging due to its short generational time and relatively small brain size. We investigated age-dependent changes in the Drosophila melanogaster whole-brain transcriptome by comparing 5-, 20-, 30- and 40-day-old flies of both sexes. We used RNA-Sequencing of dissected brain samples followed by differential expression, temporal clustering, co-expression network and gene ontology enrichment analyses. We found an overall decline in expression of genes from the mitochondrial oxidative phosphorylation pathway that occurred as part of aging. We also detected, in females, a pattern of continuously declining expression for many neuronal function genes, which was unexpectedly reversed later in life. This group of genes was highly enriched in Memory-impairing genes previously identified through an RNAi screen. We also identified deficits in short-term Olfactory Memory performance in older flies of both sexes, some of which matched the timing of certain changes in the brain transcriptome. Our study provides the first transcriptome profile of aging brains from fruit flies of both sexes, and it will serve as an important resource for those who study aging and cognitive decline in this model.
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Elongator complex is required for long-term Olfactory Memory formation in Drosophila
Learning & Memory, 2018Co-Authors: Dinghui Yu, Molee Chakraborty, Seth M. Tomchik, Ronald L DavisAbstract:The evolutionarily conserved Elongator Complex associates with RNA polymerase II for transcriptional elongation. Elp3 is the catalytic subunit, contains histone acetyltransferase activity, and is associated with neurodegeneration in humans. Elp1 is a scaffolding subunit and when mutated causes familial dysautonomia. Here, we show that elp3 and elp1 are required for aversive long-term Olfactory Memory in Drosophila RNAi knockdown of elp3 in adult mushroom bodies impairs long-term Memory (LTM) without affecting earlier forms of Memory. RNAi knockdown with coexpression of elp3 cDNA reverses the impairment. Similarly, RNAi knockdown of elp1 impairs LTM and coexpression of elp1 cDNA reverses this phenotype. The LTM deficit in elp3 and elp1 knockdown flies is accompanied by the abolishment of a LTM trace, which is registered as increased calcium influx in response to the CS+ odor in the α-branch of mushroom body neurons. Coexpression of elp1 or elp3 cDNA rescues the Memory trace in parallel with LTM. These data show that the Elongator complex is required in adult mushroom body neurons for long-term behavioral Memory and the associated long-term Memory trace.
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functional neuroanatomy of drosophila Olfactory Memory formation
Learning & Memory, 2014Co-Authors: Tugba Guvenozkan, Ronald L DavisAbstract:New approaches, techniques and tools invented over the last decade and a half have revolutionized the functional dissection of neural circuitry underlying Drosophila learning. The new methodologies have been used aggressively by researchers attempting to answer three critical questions about Olfactory memories formed with appetitive and aversive reinforcers: (1) Which neurons within the Olfactory nervous system mediate the acquisition of Memory? (2) What is the complete neural circuitry extending from the site(s) of acquisition to the site(s) controlling Memory expression? (3) How is information processed across this circuit to consolidate early-forming, disruptable memories to stable, late memories? Much progress has been made and a few strong conclusions have emerged: (1) Acquisition occurs at multiple sites within the Olfactory nervous system but is mediated predominantly by the γ mushroom body neurons. (2) The expression of long-term Memory is completely dependent on the synaptic output of α/β mushroom body neurons. (3) Consolidation occurs, in part, through circuit interactions between mushroom body and dorsal paired medial neurons. Despite this progress, a complete and unified model that details the pathway from acquisition to Memory expression remains elusive.
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Olfactory Memory traces in drosophila
Progress in Brain Research, 2008Co-Authors: Jacob A Berry, William C Krause, Ronald L DavisAbstract:In Drosophila, the fruit fly, coincident exposure to an odor and an aversive electric shock can produce robust behavioral Memory. This behavioral Memory is thought to be regulated by cellular Memory traces within the central nervous system of the fly. These molecular, physiological, or structural changes in neurons, induced by pairing odor and shock, regulate behavior by altering the neurons’ response to the learned environment. Recently, novel in vivo functional imaging techniques have allowed researchers to observe cellular Memory traces in intact animals. These investigations have revealed interesting temporal and spatial dynamics of cellular Memory traces. First, a short-term cellular Memory trace was discovered that exists in the antennal lobe, an early site of Olfactory processing. This trace represents the recruitment of new synaptic activity into the odor representation and forms for only a short period of time just after training. Second, an intermediate-term cellular Memory trace was found in the dorsal paired medial neuron, a neuron thought to play a role in stabilizing Olfactory memories. Finally, a long-term protein synthesis-dependent cellular Memory trace was discovered in the mushroom bodies, a structure long implicated in Olfactory learning and Memory. Therefore, it appears that aversive Olfactory associations are encoded by multiple cellular Memory traces that occur in different regions of the brain with different temporal domains.
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insect Olfactory Memory in time and space
Current Opinion in Neurobiology, 2006Co-Authors: Ronald L DavisAbstract:Recent studies using functional optical imaging have revealed that cellular Memory traces form in different areas of the insect brain after Olfactory classical conditioning. These traces are revealed as increased calcium signals or synaptic release from defined neurons, and include a short-lived trace that forms immediately after conditioning in antennal lobe projection neurons, an early trace in dopaminergic neurons, and a medium-term trace in dorsal paired medial neurons. New molecular genetic tools have revealed that for normal behavioral Memory performance, synaptic transmission from the mushroom body neurons is required only during retrieval, whereas synaptic transmission from dopaminergic neurons is required at the time of acquisition and synaptic transmission from dorsal paired medial neurons is required during the consolidation period. Such experimental results are helping to identify the types of neurons that participate in Olfactory learning and when their participation is required. Olfactory learning often occurs alongside crossmodal interactions of sensory information from other modalities. Recent studies have revealed complex interactions between the Olfactory and the visual senses that can occur during Olfactory learning, including the facilitation of learning about subthreshold Olfactory stimuli due to training with concurrent visual stimuli.
Hiromu Tanimoto - One of the best experts on this subject based on the ideXlab platform.
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Dopamine receptor Dop1R2 stabilizes appetitive Olfactory Memory through the Raf/MAPK pathway in Drosophila
The Journal of Neuroscience, 2020Co-Authors: Tomoki Nishioka, Shun Hiramatsu, Shu Kondo, Mutsuki Amano, Kozo Kaibuchi, Toshiharu Ichinose, Hiromu TanimotoAbstract:In Drosophila, dopamine signaling to the mushroom body intrinsic neurons, Kenyon cells (KCs), is critical to stabilize Olfactory Memory. Little is known about the downstream intracellular molecular signaling underlying Memory stabilization. Here we address this question in the context of sugar-rewarded Olfactory long-term Memory (LTM). We show that associative conditioning increases the phosphorylation of MAPK in KCs, via Dop1R2 signaling. Consistently, the attenuation of Dop1R2, Raf or MAPK expression in KCs selectively impairs LTM but not short-term Memory. Moreover, we show that the LTM deficit caused by the knockdown of Dop1R2 can be rescued by expressing active Raf in KCs. Thus, the Dop1R2/Raf/MAPK pathway is a pivotal downstream effector of dopamine signaling for stabilizing appetitive Olfactory Memory. SIGNIFICANCE STATEMENT Dopaminergic input to the Kenyon cells (KCs) is pivotal to stabilize Memory in Drosophila. This process is mediated by dopamine receptors like Dop1R2. Nevertheless, little is known for its underlying molecular mechanism. Here we show that the Raf/MAPK pathway is specifically engaged in appetitive long term Memory in KCs. With combined biochemical and behavioral experiments, we reveal that activation of the Raf/MAPK pathway is regulated through Dop1R2, shedding light on how dopamine modulates intracellular signaling for Memory stabilization.
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dopamine receptor dop1r2 stabilizes appetitive Olfactory Memory through the raf mapk pathway in drosophila
The Journal of Neuroscience, 2020Co-Authors: Tomoki Nishioka, Shun Hiramatsu, Shu Kondo, Mutsuki Amano, Kozo Kaibuchi, Toshiharu Ichinose, Hiromu TanimotoAbstract:In Drosophila, dopamine signaling to the mushroom body intrinsic neurons, Kenyon cells (KCs), is critical to stabilize Olfactory Memory. Little is known about the downstream intracellular molecular signaling underlying Memory stabilization. Here we address this question in the context of sugar-rewarded Olfactory long-term Memory (LTM). We show that associative conditioning increases the phosphorylation of MAPK in KCs, via Dop1R2 signaling. Consistently, the attenuation of Dop1R2, Raf or MAPK expression in KCs selectively impairs LTM but not short-term Memory. Moreover, we show that the LTM deficit caused by the knockdown of Dop1R2 can be rescued by expressing active Raf in KCs. Thus, the Dop1R2/Raf/MAPK pathway is a pivotal downstream effector of dopamine signaling for stabilizing appetitive Olfactory Memory. SIGNIFICANCE STATEMENT Dopaminergic input to the Kenyon cells (KCs) is pivotal to stabilize Memory in Drosophila. This process is mediated by dopamine receptors like Dop1R2. Nevertheless, little is known for its underlying molecular mechanism. Here we show that the Raf/MAPK pathway is specifically engaged in appetitive long term Memory in KCs. With combined biochemical and behavioral experiments, we reveal that activation of the Raf/MAPK pathway is regulated through Dop1R2, shedding light on how dopamine modulates intracellular signaling for Memory stabilization.
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short neuropeptide f acts as a functional neuromodulator for Olfactory Memory in kenyon cells of drosophila mushroom bodies
The Journal of Neuroscience, 2013Co-Authors: Stephan Knapek, Lily Kahsai, Asa M E Winther, Hiromu Tanimoto, Dick R NasselAbstract:In insects, many complex behaviors, including Olfactory Memory, are controlled by a paired brain structure, the so-called mushroom bodies (MB). In Drosophila, the development, neuroanatomy, and fun ...
Alessia Mastrodonato - One of the best experts on this subject based on the ideXlab platform.
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Olfactory Memory is enhanced in mice exposed to extremely low frequency electromagnetic fields via wnt β catenin dependent modulation of subventricular zone neurogenesis
Scientific Reports, 2018Co-Authors: Alessia Mastrodonato, Saviana Antonella Barbati, Lucia Leone, Claudia Colussi, Katia Gironi, Marco Rinaudo, Roberto Piacentini, Christine A Denny, Claudio GrassiAbstract:Exposure to extremely low-frequency electromagnetic fields (ELFEF) influences the expression of key target genes controlling adult neurogenesis and modulates hippocampus-dependent Memory. Here, we assayed whether ELFEF stimulation affects Olfactory Memory by modulating neurogenesis in the subventricular zone (SVZ) of the lateral ventricle, and investigated the underlying molecular mechanisms. We found that 30 days after the completion of an ELFEF stimulation protocol (1 mT; 50 Hz; 3.5 h/day for 12 days), mice showed enhanced Olfactory Memory and increased SVZ neurogenesis. These effects were associated with upregulated expression of mRNAs encoding for key regulators of adult neurogenesis and were mainly dependent on the activation of the Wnt pathway. Indeed, ELFEF stimulation increased Wnt3 mRNA expression and nuclear localization of its downstream target β-catenin. Conversely, inhibition of Wnt3 by Dkk-1 prevented ELFEF-induced upregulation of neurogenic genes and abolished ELFEF’s effects on Olfactory Memory. Collectively, our findings suggest that ELFEF stimulation increases Olfactory Memory via enhanced Wnt/β-catenin signaling in the SVZ and point to ELFEF as a promising tool for enhancing SVZ neurogenesis and Olfactory function.
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Olfactory Memory is enhanced in mice exposed to extremely low-frequency electromagnetic fields via Wnt/β-catenin dependent modulation of subventricular zone neurogenesis.
Scientific Reports, 2018Co-Authors: Alessia Mastrodonato, Saviana Antonella Barbati, Lucia Leone, Claudia Colussi, Katia Gironi, Marco Rinaudo, Roberto Piacentini, Christine A Denny, Claudio GrassiAbstract:Exposure to extremely low-frequency electromagnetic fields (ELFEF) influences the expression of key target genes controlling adult neurogenesis and modulates hippocampus-dependent Memory. Here, we assayed whether ELFEF stimulation affects Olfactory Memory by modulating neurogenesis in the subventricular zone (SVZ) of the lateral ventricle, and investigated the underlying molecular mechanisms. We found that 30 days after the completion of an ELFEF stimulation protocol (1 mT; 50 Hz; 3.5 h/day for 12 days), mice showed enhanced Olfactory Memory and increased SVZ neurogenesis. These effects were associated with upregulated expression of mRNAs encoding for key regulators of adult neurogenesis and were mainly dependent on the activation of the Wnt pathway. Indeed, ELFEF stimulation increased Wnt3 mRNA expression and nuclear localization of its downstream target β-catenin. Conversely, inhibition of Wnt3 by Dkk-1 prevented ELFEF-induced upregulation of neurogenic genes and abolished ELFEF’s effects on Olfactory Memory. Collectively, our findings suggest that ELFEF stimulation increases Olfactory Memory via enhanced Wnt/β-catenin signaling in the SVZ and point to ELFEF as a promising tool for enhancing SVZ neurogenesis and Olfactory function.
F. Roces - One of the best experts on this subject based on the ideXlab platform.
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Foraging leafcutter ants: Olfactory Memory underlies delayed avoidance of plants unsuitable for the symbiotic fungus
Animal Behaviour, 2011Co-Authors: N. Saverschek, F. RocesAbstract:Leafcutter ants are known to reject previously accepted plants if they prove to be unsuitable for their symbiotic fungus: a phenomenon that involves avoidance learning. Workers need to associate the detrimental effects of the incorporated plant with its characteristics, chemical and/or physical features, thus allowing plant recognition at the foraging site on subsequent days, and its avoidance. We addressed the question of to what extent Olfactory Memory underlies delayed avoidance of plants unsuitable for the symbiotic fungus. Odour is an important plant characteristic used as a recognition cue outside the nest during foraging. Acromyrmex ambiguus foragers were able to learn about a plant’s unsuitability for their symbiotic fungus, rejecting this substrate in a binary choice experiment in the laboratory. Presented with leaf discs of two plant species simultaneously, one known to be unsuitable and one suitable, individual foragers significantly preferred the suitable plant species. When presented only with the plant odour, foragers steered away from the odour of the known unsuitable plant species, moving towards the simultaneously presented odour of a suitable plant species. Foragers were therefore able to identify plant species and recall information about substrate suitability for the fungus through the plant’s odour alone. None the less, foragers showed a significantly stronger avoidance of known unsuitable substrate when they could make contact with the leaf discs, suggesting the use of additional cues for plant identification. It is argued that not only appetitive, but also aversive learned responses are involved in the process of plant recognition by foraging leafcutter ants.
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Foraging leafcutter ants: Olfactory Memory underlies delayed avoidance of plants unsuitable for the symbiotic fungus
Animal Behaviour, 2011Co-Authors: N. Saverschek, F. RocesAbstract:Leafcutter ants are known to reject previously accepted plants if they prove to be unsuitable for their symbiotic fungus: a phenomenon that involves avoidance learning. Workers need to associate the detrimental effects of the incorporated plant with its characteristics, chemical and/or physical features, thus allowing plant recognition at the foraging site on subsequent days, and its avoidance. We addressed the question of to what extent Olfactory Memory underlies delayed avoidance of plants unsuitable for the symbiotic fungus. Odour is an important plant characteristic used as a recognition cue outside the nest during foraging. Acromyrmex ambiguus foragers were able to learn about a plant's unsuitability for their symbiotic fungus, rejecting this substrate in a binary choice experiment in the laboratory. Presented with leaf discs of two plant species simultaneously, one known to be unsuitable and one suitable, individual foragers significantly preferred the suitable plant species. When presented only with the plant odour, foragers steered away from the odour of the known unsuitable plant species, moving towards the simultaneously presented odour of a suitable plant species. Foragers were therefore able to identify plant species and recall information about substrate suitability for the fungus through the plant's odour alone. None the less, foragers showed a significantly stronger avoidance of known unsuitable substrate when they could make contact with the leaf discs, suggesting the use of additional cues for plant identification. It is argued that not only appetitive, but also aversive learned responses are involved in the process of plant recognition by foraging leafcutter ants. © 2011 The Association for the Study of Animal Behaviour.
Catherine Armengaud - One of the best experts on this subject based on the ideXlab platform.
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Effect of a thymol application on Olfactory Memory and gene expression levels in the brain of the honeybee Apis mellifera
Environmental Science and Pollution Research, 2015Co-Authors: Elsa Bonnafé, Florian Drouard, Lucie Hotier, Jean-luc Carayon, Pierre Marty, Michel Treilhou, Catherine ArmengaudAbstract:Essential oils are used by beekeepers to control the Varroa mites that infest honeybee colonies. So, bees can be exposed to thymol formulations in the hive. The effects of the monoterpenoid thymol were explored on Olfactory Memory and gene expression in the brain of the honeybee. In bees previously exposed to thymol (10 or 100 ng/bee), the specificity of the response to the conditioned stimulus (CS) was lost 24 h after learning. Besides, the octopamine receptor OA1 gene Amoa1 showed a significant decrease of expression 3 h after exposure with 10 or 100 ng/bee of thymol. With the same doses, expression of Rdl gene, coding for a GABA receptor subunit, was not significantly modified but the trpl gene was upregulated 1 and 24 h after exposure to thymol. These data indicated that the genes coding for the cellular targets of thymol could be rapidly regulated after exposure to this molecule. Memory and sensory processes should be investigated in bees after chronic exposure in the hive to thymol-based preparations.
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Differential involvement of glutamate-gated chloride channel splice variants in the Olfactory Memory processes of the honeybee Apis mellifera
Pharmacology Biochemistry and Behavior, 2014Co-Authors: Fabien Démares, Florian Drouard, Isabelle Massou, Cindy Crattelet, Aurore Lœuillet, Célia Bettiol, Valérie Raymond, Catherine ArmengaudAbstract:Abstract Glutamate-gated chloride channels (GluCl) belong to the cys-loop ligand-gated ion channel superfamily and their expression had been described in several invertebrate nervous systems. In the honeybee, a unique gene amel_glucl encodes two alternatively spliced subunits, Amel_GluCl A and Amel_GluCl B. The expression and differential localization of those variants in the honeybee brain had been previously reported. Here we characterized the involvement of each variant in Olfactory learning and Memory processes, using specific small-interfering RNA (siRNA) targeting each variant. Firstly, the efficacy of the two siRNAs to decrease their targets' expression was tested, both at mRNA and protein levels. The two proteins showed a decrease of their respective expression 24 h after injection. Secondly, each siRNA was injected into the brain to test whether or not it affected Olfactory Memory by using a classical paradigm of conditioning the proboscis extension reflex (PER). Amel_GluCl A was found to be involved only in retrieval of 1-nonanol, whereas Amel_GluCl B was involved in the PER response to 2-hexanol used as a conditioned stimulus or as new odorant. Here for the first time, a differential behavioral involvement of two highly similar GluCl subunits has been characterized in an invertebrate species.
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Evidence for a role of GABA- and glutamate-gated chloride channels in Olfactory Memory.
Pharmacology Biochemistry and Behavior, 2012Co-Authors: Katia Boumghar, Thomas Couret-fauvel, Mikael Garcia, Catherine ArmengaudAbstract:Abstract In the honeybee, we investigated the role of transmissions mediated by GABA-gated chloride channels and glutamate-gated chloride channels (GluCls) of the mushroom bodies (MBs) on Olfactory learning using a single-trial Olfactory conditioning paradigm. The GABAergic antagonist picrotoxin (PTX) or the GluCl antagonist l -trans-pyrrolidine-2,4-dicarboxylic acid ( l -trans-PDC) was injected alone or in combination into the α-lobes of MBs. PTX impaired early long-term Olfactory Memory when injected before conditioning or before testing. l -trans-PDC alone induced no significant effect on learning and Memory but induced a less specific response to the conditioned odor. When injected before PTX, l -trans-PDC was able to modulate PTX effects. These results emphasize the role of MB GABA-gated chloride channels in consolidation processes and strongly support that GluCls are involved in the perception of the conditioned stimulus.
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Glutamatergic and GABAergic effects of fipronil on Olfactory learning and Memory in the honeybee
Invertebrate Neuroscience, 2009Co-Authors: Abdessalam Kacimi El Hassani, Julien Pierre Dupuis, Monique Gauthier, Catherine ArmengaudAbstract:We investigated here the role of transmissions mediated by GABA and glutamate-gated chloride channels (GluCls) in Olfactory learning and Memory in honeybees, both of these channels being a target for fipronil. To do so, we combined Olfactory conditioning with injections of either the GABA- and glutamate-interfering fipronil alone, or in combination with the blocker of glutamate transporter l-trans-Pyrrolidine-2,4-Dicarboxylicacid (l-trans-PDC), or the GABA analog Trans-4-Aminocrotonic Acid (TACA). Our results show that a low dose of fipronil (0.1 ng/bee) impaired Olfactory Memory, while a higher dose (0.5 ng/bee) had no effect. The detrimental effect induced by the low dose of fipronil was rescued by the coinjection of l-trans-PDC but was rather increased by the coinjection of TACA. Moreover, using whole-cell patch-clamp recordings, we observed that l-trans-PDC reduced glutamate-induced chloride currents in antennal lobe cells. We interpret these results as reflecting the involvement of both GluCl and GABA receptors in the impairment of Olfactory Memory induced by fipronil.
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Inhibitory neurotransmission and Olfactory Memory in honeybees
Neurobiology of Learning and Memory, 2008Co-Authors: Abdessalam Kacimi El Hassani, Monique Gauthier, Martin Giurfa, Catherine ArmengaudAbstract:Abstract In insects, γ-aminobutyric acid (GABA) and glutamate mediate fast inhibitory neurotransmission through ligand-gated chloride channel receptors. Both GABA and glutamate have been identified in the Olfactory circuit of the honeybee. Here we investigated the role of inhibitory transmission mediated by GABA and glutamate-gated chloride channels (GluCls) in Olfactory learning and Memory in honeybees. We combined Olfactory conditioning with injection of ivermectin, an agonist of GluCl receptors. We also injected a blocker of glutamate transporters ( l - trans -PDC) or a GABA analog (TACA). We measured acquisition and retention 1, 24 and 48 h after the last acquisition trial. A low dose of ivermectin (0.01 ng/bee) impaired long-term Olfactory Memory (48 h) while a higher dose (0.05 ng/bee) had no effect. Double injections of ivermectin and l - trans -PDC or TACA had different effects on Memory retention, depending on the doses and agents combined. When the low dose of ivermectin was injected after Ringer, long-term Memory was again impaired (48 h). Such an effect was rescued by injection of both TACA and l - trans -PDC. A combination of the higher dose of ivermectin and TACA decreased retention at 48 h. We interpret these results as reflecting the involvement of both GluCl and GABA receptors in the impairment of Olfactory long-term Memory induced by ivermectin. These results illustrate the diversity of inhibitory transmission and its implication in long-term Olfactory Memory in honeybees.
