201
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Xia S, Tully T. Segregation of odor identity and intensity during odor discrimination in Drosophila mushroom body. PLoS Biol 2008; 5:e264. [PMID: 17914903 PMCID: PMC1994992 DOI: 10.1371/journal.pbio.0050264] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 08/09/2007] [Indexed: 01/12/2023] Open
Abstract
Molecular and cellular studies have begun to unravel a neurobiological basis of olfactory processing, which appears conserved among vertebrate and invertebrate species. Studies have shown clearly that experience-dependent coding of odor identity occurs in “associative” olfactory centers (the piriform cortex in mammals and the mushroom body [MB] in insects). What remains unclear, however, is whether associative centers also mediate innate (spontaneous) odor discrimination and how ongoing experience modifies odor discrimination. Here we show in naïve flies that Gαq-mediated signaling in MB modulates spontaneous discrimination of odor identity but not odor intensity (concentration). In contrast, experience-dependent modification (conditioning) of both odor identity and intensity occurs in MB exclusively via Gαs-mediated signaling. Our data suggest that spontaneous responses to odor identity and odor intensity discrimination are segregated at the MB level, and neural activity from MB further modulates olfactory processing by experience-independent Gαq-dependent encoding of odor identity and by experience-induced Gαs-dependent encoding of odor intensity and identity. Considerable progress has been made in understanding how olfaction works as the receptor proteins, sensory neurons, and brain circuitry responsible have become increasingly well-characterized. However, olfactory processing in higher brain centers, where neuronal activity is assembled into the perception of odor quality, is poorly understood. Here, we have addressed how the mushroom body (MB)—a secondary olfactory center—is involved in olfactory discrimination. We manipulated the MB by ablation, disruption of synaptic transmission, and interruption of key cellular signaling molecules in naïve flies and in flies trained to discriminate odors. We first show that although both odor identity and intensity are encoded in the MB, only the former requires Gαq-dependent signaling and is necessary for naïve flies to spontaneously discriminate different odors. We then show that training flies to alter their olfactory response requires Gαs-mediated signaling in MB for both odor intensity and odor identity. We have thus identified (i) segregation of odor identity and odor intensity at the MB level in naïve flies and (ii) different G-protein-dependent signaling pathways for spontaneous versus experience-dependent olfactory discrimination. Experience-dependent modification of odor identity and intensity occurs in the mushroom body (MB) of flies exclusively via Gαs-mediated signaling. In contrast, Gαq-mediated signaling in MB modulates spontaneous discrimination of odor identity but not odor intensity.
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Affiliation(s)
- Shouzhen Xia
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Tim Tully
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
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202
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Smid HM, Wang G, Bukovinszky T, Steidle JLM, Bleeker MAK, van Loon JJA, Vet LEM. Species-specific acquisition and consolidation of long-term memory in parasitic wasps. Proc Biol Sci 2008; 274:1539-46. [PMID: 17439855 PMCID: PMC2176164 DOI: 10.1098/rspb.2007.0305] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Long-term memory (LTM) formation usually requires repeated, spaced learning events and is achieved by the synthesis of specific proteins. Other memory forms require a single learning experience and are independent of protein synthesis. We investigated in two closely related parasitic wasp species, Cotesia glomerata and Cotesia rubecula, whether natural differences in foraging behaviour are correlated with differences in LTM acquisition and formation. These parasitic wasp species lay their eggs in young caterpillars of pierid butterflies and can learn to associate plant odours with a successful egg laying experience on caterpillars on the odour-producing plant. We used a classical conditioning set-up, while interfering with LTM formation through translation or transcription inhibitors. We show here that C. rubecula formed LTM after three spaced learning trials, whereas C. glomerata required only a single trial for LTM formation. After three spaced learning trials, LTM formation was complete within 4 h in C. glomerata, whereas in C. rubecula, LTM formation took 3 days. Linking neurobiology with ecology, we argue that this species-specific difference in LTM acquisition and formation is adaptive given the extreme differences in both the number of foraging decisions of the two wasp species and in the spatial distributions of their respective hosts in nature.
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Affiliation(s)
- Hans M Smid
- Laboratory of Entomology, Wageningen University, 6700 EH Wageningen, The Netherlands.
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203
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Abstract
The fruit fly Drosophila has played a central role in the development of biology during the 20th century. First chosen as a convenient organism to test evolutionary theories soon became the central element in an elaborate, fruitful, and insightful research program dealing with the nature and function of the gene. Through the activities of TH Morgan and his students, Drosophila did more than any other organism to lay down the foundations of genetics as a discipline and a tool for biology. In the last third of the century, a judicious blend of classical genetics and molecular biology focused on some mutants affecting the pattern of the Drosophila larva and the adult, and unlocked the molecular mechanisms of development. Surprisingly, many of the genes identified in this exercise turned to be conserved across organisms. This observation provided a vista of universality at a fundamental level of biological activity. At the dawn of the 21st century, Drosophila continues to be center stage in the development of biology and to open new ways of seeing cells and to understand the construction and the functioning of organisms.
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204
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Thermal disruption of mushroom body development and odor learning in Drosophila. PLoS One 2007; 2:e1125. [PMID: 17992254 PMCID: PMC2067990 DOI: 10.1371/journal.pone.0001125] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 09/25/2007] [Indexed: 11/19/2022] Open
Abstract
Environmental stress (nutritive, chemical, electromagnetic and thermal) has been shown to disrupt central nervous system (CNS) development in every model system studied to date. However, empirical linkages between stress, specific targets in the brain, and consequences for behavior have rarely been established. The present study experimentally demonstrates one such linkage by examining the effects of ecologically-relevant thermal stress on development of the Drosophila melanogaster mushroom body (MB), a conserved sensory integration and associative center in the insect brain. We show that a daily hyperthermic episode throughout larval and pupal development (1) severely disrupts MB anatomy by reducing intrinsic Kenyon cell (KC) neuron numbers but has little effect on other brain structures or general anatomy, and (2) greatly impairs associative odor learning in adults, despite having little effect on memory or sensory acuity. Hence, heat stress of ecologically relevant duration and intensity can impair brain development and learning potential.
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205
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Specific requirement of NMDA receptors for long-term memory consolidation in Drosophila ellipsoid body. Nat Neurosci 2007; 10:1578-86. [PMID: 17982450 DOI: 10.1038/nn2005] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 10/01/2007] [Indexed: 01/21/2023]
Abstract
In humans and many other animals, memory consolidation occurs through multiple temporal phases and usually involves more than one neuroanatomical brain system. Genetic dissection of Pavlovian olfactory learning in Drosophila melanogaster has revealed multiple memory phases, but the predominant view holds that all memory phases occur in mushroom body neurons. Here, we demonstrate an acute requirement for NMDA receptors (NMDARs) outside of the mushroom body during long-term memory (LTM) consolidation. Targeted dsRNA-mediated silencing of Nmdar1 and Nmdar2 (also known as dNR1 or dNR2, respectively) in cholinergic R4m-subtype large-field neurons of the ellipsoid body specifically disrupted LTM consolidation, but not retrieval. Similar silencing of functional NMDARs in the mushroom body disrupted an earlier memory phase, leaving LTM intact. Our results clearly establish an anatomical site outside of the mushroom body involved with LTM consolidation, thus revealing both a distributed brain system subserving olfactory memory formation and the existence of a system-level memory consolidation in Drosophila.
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206
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Johnson W, Bouchard TJ, McGue M, Segal NL, Tellegen A, Keyes M, Gottesman II. Genetic and environmental influences on the Verbal-Perceptual-Image Rotation (VPR) model of the structure of mental abilities in the Minnesota study of twins reared apart. INTELLIGENCE 2007. [DOI: 10.1016/j.intell.2006.10.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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207
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Valente D, Golani I, Mitra PP. Analysis of the trajectory of Drosophila melanogaster in a circular open field arena. PLoS One 2007; 2:e1083. [PMID: 17957265 PMCID: PMC2031922 DOI: 10.1371/journal.pone.0001083] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 10/02/2007] [Indexed: 11/19/2022] Open
Abstract
Background Obtaining a complete phenotypic characterization of a freely moving organism is a difficult task, yet such a description is desired in many neuroethological studies. Many metrics currently used in the literature to describe locomotor and exploratory behavior are typically based on average quantities or subjectively chosen spatial and temporal thresholds. All of these measures are relatively coarse-grained in the time domain. It is advantageous, however, to employ metrics based on the entire trajectory that an organism takes while exploring its environment. Methodology/Principal Findings To characterize the locomotor behavior of Drosophila melanogaster, we used a video tracking system to record the trajectory of a single fly walking in a circular open field arena. The fly was tracked for two hours. Here, we present techniques with which to analyze the motion of the fly in this paradigm, and we discuss the methods of calculation. The measures we introduce are based on spatial and temporal probability distributions and utilize the entire time-series trajectory of the fly, thus emphasizing the dynamic nature of locomotor behavior. Marginal and joint probability distributions of speed, position, segment duration, path curvature, and reorientation angle are examined and related to the observed behavior. Conclusions/Significance The measures discussed in this paper provide a detailed profile of the behavior of a single fly and highlight the interaction of the fly with the environment. Such measures may serve as useful tools in any behavioral study in which the movement of a fly is an important variable and can be incorporated easily into many setups, facilitating high-throughput phenotypic characterization.
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Affiliation(s)
- Dan Valente
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America.
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208
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Sugai R, Azami S, Shiga H, Watanabe T, Sadamoto H, Kobayashi S, Hatakeyama D, Fujito Y, Lukowiak K, Ito E. One-trial conditioned taste aversion in Lymnaea: good and poor performers in long-term memory acquisition. ACTA ACUST UNITED AC 2007; 210:1225-37. [PMID: 17371921 DOI: 10.1242/jeb.02735] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the majority of studies designed to elucidate the causal mechanisms of memory formation, certain members of the experimental cohort, even though subjected to exactly the same conditioning procedures, remember significantly better than others, whereas others show little or no long-term memory (LTM) formation. To begin to address the question of why this phenomenon occurs and thereby help clarify the causal mechanism of LTM formation, we used a conditioned taste aversion (CTA) procedure on individuals of the pond snail Lymnaea stagnalis and analyzed their subsequent behavior. Using sucrose as an appetitive stimulus and KCl as an aversive stimulus, we obtained a constant ratio of ;poor' to ;good' performers for CTA-LTM. We found that approximately 40% of trained snails possessed LTM following a one-trial conditioning procedure. When we examined the time-window necessary for the memory consolidation, we found that if we cooled snails to 4 degrees C for 30 min within 10 min after the one-trial conditioning, LTM was blocked. However, with delayed cooling (i.e. longer than 10 min), LTM was present. We could further interfere with LTM formation by inducing inhibitory learning (i.e. backward conditioning) after the one-trial conditioning. Finally, we examined whether we could motivate snails to acquire LTM by depriving them of food for 5 days before the one-trial conditioning. Food-deprived snails, however, failed to exhibit LTM following the one-trial conditioning. These results will help us begin to clarify why some individuals are better at learning and forming memory for specific tasks at the neuronal level.
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Affiliation(s)
- Rio Sugai
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
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209
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Asztalos Z, Baba K, Yamamoto D, Tully T. The fickle mutation of a cytoplasmic tyrosine kinase effects sensitization but not dishabituation in Drosophila melanogaster. J Neurogenet 2007; 21:59-71. [PMID: 17464798 PMCID: PMC2409174 DOI: 10.1080/01677060701249488] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
fickle is a P-element mutation identified from a screen for defects in courtship behavior and disrupts the fly homolog of Bruton's tyrosine kinase (Btk) gene (Baba et al., 1999). Here, we show that habituation of the olfactory jump reflex also is defective in fickle. Unlike, the prototypical memory mutants, rutabaga and dunce, which habituate more slowly than normal, fickle flies habituate faster than normal. fickle's faster-than-normal response decrement did not appear to be due to sensorimotor fatigue, and dishabituation of the jump response was normal. Based on a long-standing "two opponent process" theory of habituation, these data suggested that behavioral sensitization might be defective in fickle. To test this hypothesis, we designed a olfactory sensitization procedure, using the same stimuli to habituate (odor) and dishabituate (vortexing) flies. Mutant flies failed to show any sensitization with this procedure. Our study reveals a "genetic dissection" of sensitization and dishabituation and, for the first time, provides a biological confirmation of the two opponent process theory of habituation.
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Affiliation(s)
- Zoltan Asztalos
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
- JST, ERATO, Yamamoto Behavior Genes Project at Mitsubishi-Kasei Institute of Life Sciences, Minami-Ooya, Machida-shi, Tokyo, Japan
| | - Kotaro Baba
- JST, ERATO, Yamamoto Behavior Genes Project at Mitsubishi-Kasei Institute of Life Sciences, Minami-Ooya, Machida-shi, Tokyo, Japan
| | - Daisuke Yamamoto
- JST, ERATO, Yamamoto Behavior Genes Project at Mitsubishi-Kasei Institute of Life Sciences, Minami-Ooya, Machida-shi, Tokyo, Japan
| | - Tim Tully
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
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210
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Mery F, Pont J, Preat T, Kawecki TJ. Experimental Evolution of Olfactory Memory in Drosophila melanogaster. Physiol Biochem Zool 2007; 80:399-405. [PMID: 17508335 DOI: 10.1086/518014] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2007] [Indexed: 11/03/2022]
Abstract
In order to address the nature of genetic variation in learning performance, we investigated the response to classical olfactory conditioning in "high-learning" Drosophila melanogaster lines previously subject to selection for the ability to learn an association between the flavor of an oviposition medium and bitter taste. In a T-maze choice test, the seven high-learning lines were better at avoiding an odor previously associated with aversive mechanical shock than were five unselected "low-learning" lines originating from the same natural population. Thus, the evolved improvement in learning ability of high-learning lines generalized to another aversion learning task involving a different aversive stimulus (shock instead of bitter taste) and a different behavioral context than that used to impose selection. In this olfactory shock task, the high-learning lines showed improvements in the learning rate as well as in two forms of consolidated memory: anesthesia-resistant memory and long-term memory. Thus, genetic variation underlying the experimental evolution of learning performance in the high-learning lines affected several phases of memory formation in the course of olfactory aversive learning. However, the two forms of consolidated memory were negatively correlated among replicate high-learning lines, which is consistent with a recent hypothesis that these two forms of consolidated memory are antagonistic.
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Affiliation(s)
- Frederic Mery
- Department of Biology, University of Fribourg, Chemin du Musee 10, CH-1700 Fribourg, Switzerland
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211
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Keene AC, Waddell S. Drosophila olfactory memory: single genes to complex neural circuits. Nat Rev Neurosci 2007; 8:341-54. [PMID: 17453015 DOI: 10.1038/nrn2098] [Citation(s) in RCA: 325] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A central goal of neuroscience is to understand how neural circuits encode memory and guide behaviour. Studying simple, genetically tractable organisms, such as Drosophila melanogaster, can illuminate principles of neural circuit organization and function. Early genetic dissection of D. melanogaster olfactory memory focused on individual genes and molecules. These molecular tags subsequently revealed key neural circuits for memory. Recent advances in genetic technology have allowed us to manipulate and observe activity in these circuits, and even individual neurons, in live animals. The studies have transformed D. melanogaster from a useful organism for gene discovery to an ideal model to understand neural circuit function in memory.
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Affiliation(s)
- Alex C Keene
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, Massachusetts 01605, USA
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212
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Kaun KR, Hendel T, Gerber B, Sokolowski MB. Natural variation in Drosophila larval reward learning and memory due to a cGMP-dependent protein kinase. Learn Mem 2007; 14:342-9. [PMID: 17522025 PMCID: PMC1876758 DOI: 10.1101/lm.505807] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Animals must be able to find and evaluate food to ensure survival. The ability to associate a cue with the presence of food is advantageous because it allows an animal to quickly identify a situation associated with a good, bad, or even harmful food. Identifying genes underlying these natural learned responses is essential to understanding this ability. Here, we investigate whether natural variation in the foraging (for) gene in Drosophila melanogaster larvae is important in mediating associations between either an odor or a light stimulus and food reward. We found that for influences olfactory conditioning and that the mushroom bodies play a role in this for-mediated olfactory learning. Genotypes associated with high activity of the product of for, cGMP-dependent protein kinase (PKG), showed greater memory acquisition and retention compared with genotypes associated with low activity of PKG when trained with three conditioning trials. Interestingly, increasing the number of training trials resulted in decreased memory retention only in genotypes associated with high PKG activity. The difference in the dynamics of memory acquisition and retention between variants of for suggests that the ability to learn and retain an association may be linked to the foraging strategies of the two variants.
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Affiliation(s)
- Karla R. Kaun
- Department of Biology, University of Toronto, Mississauga, Ontario L5L-1C6, Canada
| | - Thomas Hendel
- Department of Genetics and Neurobiology, University of Wuerzburg, Biozentrum am Hubland, 97074 Wuerzburg, Germany
| | - Bertram Gerber
- Department of Genetics and Neurobiology, University of Wuerzburg, Biozentrum am Hubland, 97074 Wuerzburg, Germany
| | - Marla B. Sokolowski
- Department of Biology, University of Toronto, Mississauga, Ontario L5L-1C6, Canada
- Corresponding author.E-mail ; fax (905) 828-3792
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213
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Abstract
Negatively reinforced olfactory conditioning has been widely employed to identify learning and memory genes, signal transduction pathways and neural circuitry in Drosophila. To delineate the molecular and cellular processes underlying reward-mediated learning and memory, we developed a novel assay system for positively reinforced olfactory conditioning. In this assay, flies were involuntarily exposed to the appetitive unconditioned stimulus sucrose along with a conditioned stimulus odour during training and their preference for the odour previously associated with sucrose was measured to assess learning and memory capacities. After one training session, wild-type Canton S flies displayed reliable performance, which was enhanced after two training cycles with 1-min or 15-min inter-training intervals. Higher performance scores were also obtained with increasing sucrose concentration. Memory in Canton S flies decayed slowly when measured at 30 min, 1 h and 3 h after training; whereas, it had declined significantly at 6 h and 12 h post-training. When learning mutant t beta h flies, which are deficient in octopamine, were challenged, they exhibited poor performance, validating the utility of this assay. As the Drosophila model offers vast genetic and transgenic resources, the new appetitive conditioning described here provides a useful tool with which to elucidate the molecular and cellular underpinnings of reward learning and memory. Similar to negatively reinforced conditioning, this reward conditioning represents classical olfactory conditioning. Thus, comparative analyses of learning and memory mutants in two assays may help identify the molecular and cellular components that are specific to the unconditioned stimulus information used in conditioning.
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Affiliation(s)
- Y-C Kim
- Neuroscience, The Huck Institute, Pennsylvania State University, University Park, PA, USA
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214
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Lin HH, Lin CY, Chiang AS. Internal representations of smell in the Drosophila brain. J Biomed Sci 2007; 14:453-9. [PMID: 17440836 DOI: 10.1007/s11373-007-9168-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Accepted: 03/14/2007] [Indexed: 01/26/2023] Open
Abstract
Recent advances in sensory neuroscience using Drosophila olfaction as a model system have revealed brain maps representing the external world. Once we understand how the brain's built-in capability generates the internal olfactory maps, we can then elaborate how the brain computes and makes decision to elicit complex behaviors. Here, we review current progress in mapping Drosophila olfactory circuits and discuss their relationships with innate olfactory behaviors.
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Affiliation(s)
- Hui-Hao Lin
- Institute of Biotechnology and Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan, ROC
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215
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Schwaerzel M, Jaeckel A, Mueller U. Signaling at A-kinase anchoring proteins organizes anesthesia-sensitive memory in Drosophila. J Neurosci 2007; 27:1229-33. [PMID: 17267579 PMCID: PMC6673183 DOI: 10.1523/jneurosci.4622-06.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ubiquitous cAMP-protein kinase A (PKA) signaling pathway exhibits complex temporal requirements during the time course of associative memory processing. This directly raises questions about the molecular mechanisms that provide signaling specificity to this pathway. Here, we use Drosophila olfactory conditioning to show that divergent cAMP signaling is mediated by functionally distinct pools of PKA. One particular pool is organized via the PKA regulatory type II subunit at the level of A-kinase anchoring proteins (AKAPs), a family of scaffolding proteins that provides focal points of spatiotemporal signal integration. This AKAP-bound pool of PKA is acting within neurons of the mushroom bodies to support a late phase of aversive memory. The requirement for AKAP-bound PKA signaling is limited to aversive memory, but dispensable during appetitive memory. This finding suggests the existence of additional mechanisms to support divergence within the cAMP-PKA signaling pathway during memory processing. Together, our results show that subcellular organization of signaling components plays a key role in memory processing.
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Affiliation(s)
- Martin Schwaerzel
- Saarland University, Faculty 8.3 Life Science, Department of Zoology and Physiology, 66041 Saarbrucken, Germany.
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216
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Vergoz V, Roussel E, Sandoz JC, Giurfa M. Aversive learning in honeybees revealed by the olfactory conditioning of the sting extension reflex. PLoS One 2007; 2:e288. [PMID: 17372627 PMCID: PMC1810431 DOI: 10.1371/journal.pone.0000288] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 02/20/2007] [Indexed: 11/18/2022] Open
Abstract
Invertebrates have contributed greatly to our understanding of associative learning because they allow learning protocols to be combined with experimental access to the nervous system. The honeybee Apis mellifera constitutes a standard model for the study of appetitive learning and memory since it was shown, almost a century ago, that bees learn to associate different sensory cues with a reward of sugar solution. However, up to now, no study has explored aversive learning in bees in such a way that simultaneous access to its neural bases is granted. Using odorants paired with electric shocks, we conditioned the sting extension reflex, which is exhibited by harnessed bees when subjected to a noxious stimulation. We show that this response can be conditioned so that bees learn to extend their sting in response to the odorant previously punished. Bees also learn to extend the proboscis to one odorant paired with sugar solution and the sting to a different odorant paired with electric shock, thus showing that they can master both appetitive and aversive associations simultaneously. Responding to the appropriate odorant with the appropriate response is possible because two different biogenic amines, octopamine and dopamine subserve appetitive and aversive reinforcement, respectively. While octopamine has been previously shown to substitute for appetitive reinforcement, we demonstrate that blocking of dopaminergic, but not octopaminergic, receptors suppresses aversive learning. Therefore, aversive learning in honeybees can now be accessed both at the behavioral and neural levels, thus opening new research avenues for understanding basic mechanisms of learning and memory.
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Affiliation(s)
- Vanina Vergoz
- Research Centre on Animal Cognition, Centre National de la Recherche Scientifique (CNRS)-University Paul-Sabatier, Toulouse, France
| | - Edith Roussel
- Research Centre on Animal Cognition, Centre National de la Recherche Scientifique (CNRS)-University Paul-Sabatier, Toulouse, France
| | - Jean-Christophe Sandoz
- Research Centre on Animal Cognition, Centre National de la Recherche Scientifique (CNRS)-University Paul-Sabatier, Toulouse, France
| | - Martin Giurfa
- Research Centre on Animal Cognition, Centre National de la Recherche Scientifique (CNRS)-University Paul-Sabatier, Toulouse, France
- * To whom correspondence should be addressed. E-mail:
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217
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Nichols CD. Drosophila melanogaster neurobiology, neuropharmacology, and how the fly can inform central nervous system drug discovery. Pharmacol Ther 2006; 112:677-700. [PMID: 16935347 DOI: 10.1016/j.pharmthera.2006.05.012] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 05/24/2006] [Indexed: 01/25/2023]
Abstract
Central nervous system (CNS) drug discovery in the post-genomic era is rapidly evolving. Older empirical methods are giving way to newer technologies that include bioinformatics, structural biology, genetics, and modern computational approaches. In the search for new medical therapies, and in particular treatments for disorders of the central nervous system, there has been increasing recognition that identification of a single biological target is unlikely to be a recipe for success; a broad perspective is required. Systems biology is one such approach, and has been increasingly recognized as a very important area of research, as it places specific molecular targets within a context of overall biochemical action. Understanding the complex interactions between the components within a given biological system that lead to modifications in output, such as changes in behavior or development, may be important avenues of discovery to identify new therapies. One avenue to drug discovery that holds tremendous potential is the use of model genetic organisms such as the fruit fly, Drosophila melanogaster. The similarity between mode of drug action, behavior, and gene response in D. melanogaster and mammalian systems, combined with the power of genetics, have recently made the fly a very attractive system to study fundamental neuropharmacological processes relevant to human diseases. The promise that the use of model organisms such as the fly offers is speed, high throughput, and dramatically reduced overall costs that together should result in an enhanced rate of discovery.
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Affiliation(s)
- Charles D Nichols
- Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112, USA.
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218
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Stough S, Shobe JL, Carew TJ. Intermediate-term processes in memory formation. Curr Opin Neurobiol 2006; 16:672-8. [PMID: 17097872 DOI: 10.1016/j.conb.2006.10.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 10/27/2006] [Indexed: 01/08/2023]
Abstract
Neuroscientists have invested considerable effort in attempting to elucidate the molecular mechanisms that mediate short-term and long-term forms of learning and memory. For instance, the discovery of long-term potentiation inspired a field that has produced hundreds of studies examining both early and late forms of long-term potentiation. And at the behavioral level, most neuroscientists investigate either short- or long-term forms of memory or some combination of the two. The general belief that plasticity was restricted to short- and long-term temporal domains lasted for many years because of the apparent continuity of memory and its molecular characterization from one domain to the other. In cellular studies of plasticity, the short-term stage typically lasts in the range of minutes, and requires modification of pre-existing proteins, whereas long-term changes, such as synaptic growth, last for hours to days and require transcription and translation. As both behavioral and cellular studies covered a wider range of temporal domains, from the initiation of brief memory to the expression of long-lasting memory, it was at least tacitly assumed that these studies also captured any intervening domains as well. However, between these two temporal extremes lies a unique form of intermediate-term synaptic plasticity and memory, which mechanistically is a blend of the early and late forms.
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Affiliation(s)
- Shara Stough
- Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
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219
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Abstract
The honey bee Apis mellifera displays the most complex behavior of any insect. This, and its utility to humans, makes it a fascinating object of study for biologists. Such studies are now further enabled by the release of the honey-bee genome sequence.
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Affiliation(s)
- Michael Ashburner
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK.
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220
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Abstract
Considerable evidence suggests that the formation of long-term memories requires a critical period of new protein synthesis. Recently, the notion that some of these newly synthesized proteins originate through local translation in neuronal dendrites has gained some traction. Here, we review the experimental support for this idea and highlight some of the key questions outstanding in this area.
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Affiliation(s)
- Michael A Sutton
- Division of Biology 114-96, California Institute of Technology, Howard Hughes Medical Institute, Pasadena, CA 91125, USA
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221
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Kobayashi M, Michaut L, Ino A, Honjo K, Nakajima T, Maruyama Y, Mochizuki H, Ando M, Ghangrekar I, Takahashi K, Saigo K, Ueda R, Gehring WJ, Furukubo-Tokunaga K. Differential microarray analysis of Drosophila mushroom body transcripts using chemical ablation. Proc Natl Acad Sci U S A 2006; 103:14417-22. [PMID: 16971484 PMCID: PMC1599978 DOI: 10.1073/pnas.0606571103] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mushroom bodies (MBs) are the centers for olfactory associative learning and elementary cognitive functions in the Drosophila brain. As a way to systematically elucidate genes preferentially expressed in MBs, we have analyzed genome-wide alterations in transcript profiles associated with MB ablation by hydroxyurea. We selected 100 genes based on microarray data and examined their expression patterns in the brain by in situ hybridization. Seventy genes were found to be expressed in the posterodorsal cortex, which harbors the MB cell bodies. These genes encode proteins of diverse functions, including transcription, signaling, cell adhesion, channels, and transporters. Moreover, we have examined developmental functions of 40 of the microarray-identified genes by transgenic RNA interference; 8 genes were found to cause mild-to-strong MB defects when suppressed with a MB-Gal4 driver. These results provide important information not only on the repertoire of genes that control MB development but also on the repertoire of neural factors that may have important physiological functions in MB plasticity.
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Affiliation(s)
- Masatomo Kobayashi
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Lydia Michaut
- Department of Cell Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Ayako Ino
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Ken Honjo
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Taiki Nakajima
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Yasushi Maruyama
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Hiroaki Mochizuki
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Mai Ando
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Indrayani Ghangrekar
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Kuniaki Takahashi
- Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan; and
| | - Kaoru Saigo
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo 113-0032, Japan
| | - Ryu Ueda
- Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan; and
| | - Walter J. Gehring
- Department of Cell Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
- To whom correspondence may be addressed. E-mail:
or
| | - Katsuo Furukubo-Tokunaga
- *Graduate School of Life and Environmental Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8572, Japan
- To whom correspondence may be addressed. E-mail:
or
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222
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Abstract
Local protein synthesis in the synapse is required for synaptic plasticity and has been implicated in learning and memory. However, direct evidence that behavioral training induces local protein synthesis has been lacking. In this issue of Cell, Ashraf et al. (2006) observe persistent local protein synthesis in the antennal lobe synapses of the fruit fly following olfactory-avoidance learning. This protein synthesis is regulated by the RNA-induced silencing complex (RISC).
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