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Fletcher ML, Bendahmane M. Visualizing olfactory learning functional imaging of experience-induced olfactory bulb changes. PROGRESS IN BRAIN RESEARCH 2014; 208:89-113. [PMID: 24767480 DOI: 10.1016/b978-0-444-63350-7.00004-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The anatomical organization of sensory neuron input allows odor information to be transformed into odorant-specific spatial maps of mitral/tufted cell glomerular activity. In other sensory systems, neuronal representations of sensory stimuli can be reorganized or enhanced following learning or experience. Similarly, several studies have demonstrated both structural and physiological experience-induced changes throughout the olfactory system. As experience-induced changes within this circuit likely serve as an initial site for odor memory formation, the olfactory bulb is an ideal site for optical imaging studies of olfactory learning, as they allow for the visualization of experience-induced changes in the glomerular circuit following learning and how these changes impact of odor representations with the bulb. Presently, optical imaging techniques have been used to visualize experience-induced changes in glomerular odor representations in a variety of paradigms in short-term habituation, chronic odor exposure, and olfactory associative conditioning.
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Affiliation(s)
- Max L Fletcher
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA.
| | - Mounir Bendahmane
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA
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102
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Cleland TA. Construction of Odor Representations by Olfactory Bulb Microcircuits. PROGRESS IN BRAIN RESEARCH 2014; 208:177-203. [DOI: 10.1016/b978-0-444-63350-7.00007-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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103
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Bracey EF, Pichler B, Schaefer AT, Wallace DJ, Margrie TW. Perceptual judgements and chronic imaging of altered odour maps indicate comprehensive stimulus template matching in olfaction. Nat Commun 2013; 4:2100. [PMID: 23820818 PMCID: PMC3715885 DOI: 10.1038/ncomms3100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/03/2013] [Indexed: 11/09/2022] Open
Abstract
Lesion experiments suggest that odour input to the olfactory bulb contains significant redundant signal such that rodents can discern odours using minimal stimulus-related information. Here we investigate the dependence of odour-quality perception on the integrity of glomerular activity by comparing odour-evoked activity maps before and after epithelial lesions. Lesions prevent mice from recognizing previously experienced odours and differentially delay discrimination learning of unrecognized and novel odour pairs. Poor recognition results not from mice experiencing an altered concentration of an odour but from perception of apparent novel qualities. Consistent with this, relative intensity of glomerular activity following lesions is altered compared with maps recorded in shams and by varying odour concentration. Together, these data show that odour recognition relies on comprehensively matching input patterns to a previously generated stimulus template. When encountering novel odours, access to all glomerular activity ensures rapid generation of new templates to perform accurate perceptual judgements.
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Affiliation(s)
- Edward F Bracey
- Department of Neuroscience, Physiology and Pharmacology, University College London, University Street, London, UK
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104
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105
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Role of a ubiquitously expressed receptor in the vertebrate olfactory system. J Neurosci 2013; 33:15235-47. [PMID: 24048853 DOI: 10.1523/jneurosci.2339-13.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Odorant cues are recognized by receptors expressed on olfactory sensory neurons, the primary sensory neurons of the olfactory epithelium. Odorant receptors typically obey the "one receptor, one neuron" rule, in which the receptive field of the olfactory neuron is determined by the singular odorant receptor that it expresses. Odor-evoked receptor activity across the population of olfactory neurons is then interpreted by the brain to identify the molecular nature of the odorant stimulus. In the present study, we characterized the properties of a C family G-protein-coupled receptor that, unlike most other odorant receptors, is expressed in a large population of microvillous sensory neurons in the zebrafish olfactory epithelium and the mouse vomeronasal organ. We found that this receptor, OlfCc1 in zebrafish and its murine ortholog Vmn2r1, is a calcium-dependent, low-sensitivity receptor specific for the hydrophobic amino acids isoleucine, leucine, and valine. Loss-of-function experiments in zebrafish embryos demonstrate that OlfCc1 is required for olfactory responses to a diverse mixture of polar, nonpolar, acidic, and basic amino acids. OlfCc1 was also found to promote localization of other OlfC receptor family members to the plasma membrane in heterologous cells. Together, these results suggest that the broadly expressed OlfCc1 is required for amino acid detection by the olfactory system and suggest that it plays a role in the function and/or intracellular trafficking of other olfactory and vomeronasal receptors with which it is coexpressed.
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106
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High-affinity olfactory receptor for the death-associated odor cadaverine. Proc Natl Acad Sci U S A 2013; 110:19579-84. [PMID: 24218586 DOI: 10.1073/pnas.1318596110] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carrion smell is strongly repugnant to humans and triggers distinct innate behaviors in many other species. This smell is mainly carried by two small aliphatic diamines, putrescine and cadaverine, which are generated by bacterial decarboxylation of the basic amino acids ornithine and lysine. Depending on the species, these diamines may also serve as feeding attractants, oviposition attractants, or social cues. Behavioral responses to diamines have not been investigated in zebrafish, a powerful model system for studying vertebrate olfaction. Furthermore, olfactory receptors that detect cadaverine and putrescine have not been identified in any species so far. Here, we show robust olfactory-mediated avoidance behavior of zebrafish to cadaverine and related diamines, and concomitant activation of sparse olfactory sensory neurons by these diamines. The large majority of neurons activated by low concentrations of cadaverine expresses a particular olfactory receptor, trace amine-associated receptor 13c (TAAR13c). Structure-activity analysis indicates TAAR13c to be a general diamine sensor, with pronounced selectivity for odd chains of medium length. This receptor can also be activated by decaying fish extracts, a physiologically relevant source of diamines. The identification of a sensitive zebrafish olfactory receptor for these diamines provides a molecular basis for studying neural circuits connecting sensation, perception, and innate behavior.
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107
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Tan SJ, Kee MZL, Mathuru AS, Burkholder WF, Jesuthasan SJ. A microfluidic device to sort cells based on dynamic response to a stimulus. PLoS One 2013; 8:e78261. [PMID: 24250795 PMCID: PMC3826715 DOI: 10.1371/journal.pone.0078261] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/09/2013] [Indexed: 11/25/2022] Open
Abstract
Single cell techniques permit the analysis of cellular properties that are obscured by studying the average behavior of cell populations. One way to determine how gene expression contributes to phenotypic differences among cells is to combine functional analysis with transcriptional profiling of single cells. Here we describe a microfluidic device for monitoring the responses of single cells to a ligand and then collecting cells of interest for transcriptional profiling or other assays. As a test, cells from the olfactory epithelium of zebrafish were screened by calcium imaging to identify sensory neurons that were responsive to the odorant L-lysine. Single cells were subsequently recovered for transcriptional profiling by qRT-PCR. Responsive cells all expressed TRPC2 but not OMP, consistent with known properties of amino-acid sensitive olfactory neurons. The device can be adapted for other areas in biology where there is a need to sort and analyze cells based on their signaling responses.
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Affiliation(s)
- Swee Jin Tan
- Microfluidics Systems Biology Lab, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Michelle Z. L. Kee
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore, Singapore
| | - Ajay Sriram Mathuru
- Neural Circuitry and Behavior Lab, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - William F. Burkholder
- Microfluidics Systems Biology Lab, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Suresh J. Jesuthasan
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore, Singapore
- Neural Circuitry and Behavior Lab, Institute of Molecular and Cell Biology, Singapore, Singapore
- Department of Physiology, National University of Singapore, Singapore, Singapore
- * E-mail:
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108
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Wright NJD. Evolution of the techniques used in studying associative olfactory learning and memory in adult Drosophila in vivo: a historical and technical perspective. INVERTEBRATE NEUROSCIENCE 2013; 14:1-11. [PMID: 24149895 DOI: 10.1007/s10158-013-0163-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/08/2013] [Indexed: 11/25/2022]
Abstract
Drosophila melanogaster behavioral mutants have been isolated in which the ability to form associative olfactory memories has been disrupted primarily by altering cyclic adenosine monophosphate signal transduction. Unfortunately, the small size of the fruit fly and its neurons has made the application of neurobiological techniques typically used to investigate the physiology underlying these behaviors daunting. However, the realization that adult fruit flies could tolerate a window in the head capsule allowing access to the central structures thought to be involved plus the development of genetically expressed reporters of neuronal function has allowed a meteoric expansion of this field over the last decade. This review attempts to summarize the evolution of the techniques involved from the first use of a window to access these brain areas thought to be involved in associative olfactory learning and memory, the mushroom bodies and antennal lobes, to the current refinements which allow both high-resolution multiphoton imaging and patch clamping of identified neurons while applying the stimuli used in the behavioral protocols. This area of research now appears poised to reveal some very exciting mechanisms underlying behavior.
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Affiliation(s)
- Nicholas J D Wright
- Levine College of Health Sciences, Wingate University School of Pharmacy, 515 N. Main Street, Wingate, NC, 28174, USA,
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109
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Hinz C, Namekawa I, Namekawa R, Behrmann-Godel J, Oppelt C, Jaeschke A, Müller A, Friedrich RW, Gerlach G. Olfactory imprinting is triggered by MHC peptide ligands. Sci Rep 2013; 3:2800. [PMID: 24077566 PMCID: PMC3786304 DOI: 10.1038/srep02800] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/06/2013] [Indexed: 01/28/2023] Open
Abstract
Olfactory imprinting on environmental, population- and kin-specific cues is a specific form of life-long memory promoting homing of salmon to their natal rivers and the return of coral reef fish to natal sites. Despite its ecological significance, natural chemicals for olfactory imprinting have not been identified yet. Here, we show that MHC peptides function as chemical signals for olfactory imprinting in zebrafish. We found that MHC peptides consisting of nine amino acids elicit olfactory imprinting and subsequent kin recognition depending on the MHC genotype of the fish. In vivo calcium imaging shows that some olfactory bulb neurons are highly sensitive to MHC peptides with a detection threshold at 1 pM or lower, indicating that MHC peptides are potent olfactory stimuli. Responses to MHC peptides overlapped spatially with responses to kin odour but not food odour, consistent with the hypothesis that MHC peptides are natural signals for olfactory imprinting.
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Affiliation(s)
- Cornelia Hinz
- Department of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
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110
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Zhu P, Frank T, Friedrich RW. Equalization of odor representations by a network of electrically coupled inhibitory interneurons. Nat Neurosci 2013; 16:1678-86. [PMID: 24077563 DOI: 10.1038/nn.3528] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 09/03/2013] [Indexed: 11/09/2022]
Abstract
Robustness of neuronal activity patterns against variations in input intensity is critical for neuronal computations. We found that odor representations in the olfactory bulb were stabilized by interneurons that were densely coupled to the output neurons by electrical and GABAergic synapses. This interneuron network modulated responses of output neurons as a function of stimulus intensity in two ways: it globally boosted responses to weak odors, but attenuated responses to strong odors, and it increased the sensitivity of some output neurons, but decreased the sensitivity of others. These effects are closely related to strategies used in engineering to increase dynamic range. Together, they maintained not only the mean, but also the distribution, of activity across the population of output neurons within narrow limits, which is important for pattern classification. Neuronal circuits in the olfactory bulb therefore stabilize combinatorial sensory representations against variations in stimulus intensity by generic mechanisms.
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Affiliation(s)
- Peixin Zhu
- 1] Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland. [2]
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111
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Nikaido M, Suzuki H, Toyoda A, Fujiyama A, Hagino-Yamagishi K, Kocher TD, Carleton K, Okada N. Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems. Genome Biol Evol 2013; 5:711-22. [PMID: 23501830 PMCID: PMC3641633 DOI: 10.1093/gbe/evt041] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fish use olfaction to sense a variety of nonvolatile chemical signals in water. However, the evolutionary importance of olfaction in species-rich cichlids is controversial. Here, we determined an almost complete sequence of the vomeronasal type 2 receptor-like (OlfC: putative amino acids receptor in teleosts) gene cluster using the bacterial artificial chromosome library of the Lake Victoria cichlid, Haplochromis chilotes. In the cluster region, we found 61 intact OlfC genes, which is the largest number of OlfC genes identified among the seven teleost fish investigated to date. Data mining of the Oreochromis niloticus (Nile tilapia) draft genome sequence, and genomic Southern hybridization analysis revealed that the ancestor of all modern cichlids had already developed almost the same OlfC gene repertoire, which was accomplished by lineage-specific gene expansions. Furthermore, comparison of receptor sequences showed that recently duplicated paralogs are more variable than orthologs of different species at particular sites that were predicted to be involved in amino acid selectivity. Thus, the increase of paralogs through gene expansion may lead to functional diversification in detection of amino acids. This study implies that cichlids have developed a potent capacity to detect a variety of amino acids (and their derivatives) through OlfCs, which may have contributed to the extraordinary diversity of their feeding habitats.
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Affiliation(s)
- Masato Nikaido
- Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
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112
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Arenas A, Ramírez GP, Balbuena MS, Farina WM. Behavioral and neural plasticity caused by early social experiences: the case of the honeybee. Front Physiol 2013; 4:41. [PMID: 23986708 PMCID: PMC3750948 DOI: 10.3389/fphys.2013.00041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 02/17/2013] [Indexed: 11/29/2022] Open
Abstract
Cognitive experiences during the early stages of life play an important role in shaping future behavior. Behavioral and neural long-term changes after early sensory and associative experiences have been recently reported in the honeybee. This invertebrate is an excellent model for assessing the role of precocious experiences on later behavior due to its extraordinarily tuned division of labor based on age polyethism. These studies are mainly focused on the role and importance of experiences occurred during the first days of the adult lifespan, their impact on foraging decisions, and their contribution to coordinate food gathering. Odor-rewarded experiences during the first days of honeybee adulthood alter the responsiveness to sucrose, making young hive bees more sensitive to assess gustatory features about the nectar brought back to the hive and affecting the dynamic of the food transfers and the propagation of food-related information within the colony. Early olfactory experiences lead to stable and long-term associative memories that can be successfully recalled after many days, even at foraging ages. Also they improve memorizing of new associative learning events later in life. The establishment of early memories promotes stable reorganization of the olfactory circuits inducing structural and functional changes in the antennal lobe (AL). Early rewarded experiences have relevant consequences at the social level too, biasing dance and trophallaxis partner choice and affecting recruitment. Here, we revised recent results in bees' physiology, behavior, and sociobiology to depict how the early experiences affect their cognition abilities and neural-related circuits.
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Affiliation(s)
| | | | | | - Walter M. Farina
- Grupo de Estudio de Insectos Sociales, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, IFIBYNE-CONICET, Universidad de Buenos AiresBuenos Aires, Argentina
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113
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Experience-dependent versus experience-independent postembryonic development of distinct groups of zebrafish olfactory glomeruli. J Neurosci 2013; 33:6905-16. [PMID: 23595749 DOI: 10.1523/jneurosci.5185-12.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Olfactory glomeruli are innervated with great precision by the axons of different olfactory sensory neuron types and act as functional units in odor information processing. Approximately 140 glomeruli are present in each olfactory bulb of adult zebrafish; these units consist of either highly stereotypic large glomeruli or smaller anatomically indistinguishable glomeruli. In the present study, we investigated developmental differences among these types of glomeruli. We observed that 10 large and individually identifiable glomeruli already developed before hatching, at 72 h after fertilization, in configurations that resembled their mature organization. However, the cross-sectional area of these glomeruli increased throughout larval development, and they eventually comprised the largest units in postlarval olfactory bulbs. In contrast, small and anatomically indistinguishable glomeruli formed only after hatching, apparently by segregating from five larger precursors that were identifiable during embryonic development. The differentiation of these small glomeruli proceeded with conspicuous variation in number and arrangement, both among larvae and between olfactory bulbs of the same individuals. To determine factors that might contribute to this variability, we investigated the effects of olfactory enrichment on the development of amino acid-responsive lateral glomeruli, which include both large and small units. Larvae reared in an amino acid-enriched environment had normal large lateral glomeruli, but the small lateral glomeruli were more numerous and displayed reduced cross-sectional areas compared with glomeruli in control animals. Our results suggest that large and small glomeruli mature via distinct developmental processes that may be differentially influenced by sensory experience.
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114
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Renninger SL, Orger MB. Two-photon imaging of neural population activity in zebrafish. Methods 2013; 62:255-67. [PMID: 23727462 DOI: 10.1016/j.ymeth.2013.05.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 05/21/2013] [Accepted: 05/22/2013] [Indexed: 02/08/2023] Open
Abstract
Rapidly developing imaging technologies including two-photon microscopy and genetically encoded calcium indicators have opened up new possibilities for recording neural population activity in awake, behaving animals. In the small, transparent zebrafish, it is even becoming possible to image the entire brain of a behaving animal with single-cell resolution, creating brain-wide functional maps. In this chapter, we comprehensively review past functional imaging studies in zebrafish, and the insights that they provide into the functional organization of neural circuits. We further offer a basic primer on state-of-the-art methods for in vivo calcium imaging in the zebrafish, including building a low-cost two-photon microscope and highlight possible challenges and technical considerations.
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Affiliation(s)
- Sabine L Renninger
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Avenida Brasília, Doca de Pedrouços, Lisbon, Portugal
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115
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Abstract
The main olfactory system encodes information about molecules in a combinatorial fashion by distributed spatiotemporal activity patterns. As activity propagates from sensory neurons to the olfactory bulb and to higher brain areas, odor information is processed by multiple transformations of these activity patterns. This review discusses neuronal computations associated with such transformations in the olfactory system of zebrafish, a small vertebrate that offers advantages for the quantitative analysis and manipulation of neuronal activity in the intact brain. The review focuses on pattern decorrelation in the olfactory bulb and on the readout of multiplexed sensory representations in the telencephalic area Dp, the homolog of the olfactory cortex. These computations are difficult to study in larger species and may provide insights into general information-processing strategies in the brain.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
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116
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Arrenberg AB, Driever W. Integrating anatomy and function for zebrafish circuit analysis. Front Neural Circuits 2013; 7:74. [PMID: 23630469 PMCID: PMC3632786 DOI: 10.3389/fncir.2013.00074] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/03/2013] [Indexed: 01/31/2023] Open
Abstract
Due to its transparency, virtually every brain structure of the larval zebrafish is accessible to light-based interrogation of circuit function. Advanced stimulation techniques allow the activation of optogenetic actuators at different resolution levels, and genetically encoded calcium indicators report the activity of a large proportion of neurons in the CNS. Large datasets result and need to be analyzed to identify cells that have specific properties—e.g., activity correlation to sensory stimulation or behavior. Advances in three-dimensional (3D) functional mapping in zebrafish are promising; however, the mere coordinates of implicated neurons are not sufficient. To comprehensively understand circuit function, these functional maps need to be placed into the proper context of morphological features and projection patterns, neurotransmitter phenotypes, and key anatomical landmarks. We discuss the prospect of merging functional and anatomical data in an integrated atlas from the perspective of our work on long-range dopaminergic neuromodulation and the oculomotor system. We propose that such a resource would help researchers to surpass current hurdles in circuit analysis to achieve an integrated understanding of anatomy and function.
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Affiliation(s)
- Aristides B Arrenberg
- Developmental Biology, Institute of Biology I, Faculty of Biology, BIOSS - Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg Freiburg, Germany
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117
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Friedrich RW, Genoud C, Wanner AA. Analyzing the structure and function of neuronal circuits in zebrafish. Front Neural Circuits 2013; 7:71. [PMID: 23630467 PMCID: PMC3632777 DOI: 10.3389/fncir.2013.00071] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/03/2013] [Indexed: 11/13/2022] Open
Abstract
The clever choice of animal models has been instrumental for many breakthrough discoveries in life sciences. One of the outstanding challenges in neuroscience is the in-depth analysis of neuronal circuits to understand how interactions between large numbers of neurons give rise to the computational power of the brain. A promising model organism to address this challenge is the zebrafish, not only because it is cheap, transparent and accessible to sophisticated genetic manipulations but also because it offers unique advantages for quantitative analyses of circuit structure and function. One of the most important advantages of zebrafish is its small brain size, both at larval and adult stages. Small brains enable exhaustive measurements of neuronal activity patterns by optical imaging and facilitate large-scale reconstructions of wiring diagrams by electron microscopic approaches. Such information is important, and probably essential, to obtain mechanistic insights into neuronal computations underlying higher brain functions and dysfunctions. This review provides a brief overview over current methods and motivations for dense reconstructions of neuronal activity and connectivity patterns. It then discusses selective advantages of zebrafish and provides examples how these advantages are exploited to study neuronal computations in the olfactory bulb.
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118
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Kermen F, Franco LM, Wyatt C, Yaksi E. Neural circuits mediating olfactory-driven behavior in fish. Front Neural Circuits 2013; 7:62. [PMID: 23596397 PMCID: PMC3622886 DOI: 10.3389/fncir.2013.00062] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/18/2013] [Indexed: 11/13/2022] Open
Abstract
The fish olfactory system processes odor signals and mediates behaviors that are crucial for survival such as foraging, courtship, and alarm response. Although the upstream olfactory brain areas (olfactory epithelium and olfactory bulb) are well-studied, less is known about their target brain areas and the role they play in generating odor-driven behaviors. Here we review a broad range of literature on the anatomy, physiology, and behavioral output of the olfactory system and its target areas in a wide range of teleost fish. Additionally, we discuss how applying recent technological advancements to the zebrafish (Danio rerio) could help in understanding the function of these target areas. We hope to provide a framework for elucidating the neural circuit computations underlying the odor-driven behaviors in this small, transparent, and genetically amenable vertebrate.
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Affiliation(s)
- Florence Kermen
- Neuroelectronics Research Flanders Leuven, Belgium ; Vlaams Instituut voor Biotechnologie Leuven, Belgium
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119
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Furudono Y, Cruz G, Lowe G. Glomerular input patterns in the mouse olfactory bulb evoked by retronasal odor stimuli. BMC Neurosci 2013; 14:45. [PMID: 23565900 PMCID: PMC3626767 DOI: 10.1186/1471-2202-14-45] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 04/03/2013] [Indexed: 12/05/2022] Open
Abstract
Background Odorant stimuli can access the olfactory epithelium either orthonasally, by inhalation through the external nares, or retronasally by reverse airflow from the oral cavity. There is evidence that odors perceived through these two routes can differ in quality and intensity. We were curious whether such differences might potentially have a neural basis in the peripheral mechanisms of odor coding. To explore this possibility, we compared olfactory receptor input to glomeruli in the dorsal olfactory bulb evoked by orthonasal and retronasal stimulation. Maps of glomerular response were acquired by optical imaging of transgenic mice expressing synaptopHluorin (spH), a fluorescent reporter of presynaptic activity, in olfactory nerve terminals. Results We found that retronasally delivered odorants were able to activate inputs to multiple glomeruli in the dorsal olfactory bulb. The retronasal responses were smaller than orthonasal responses to odorants delivered at comparable concentrations and flow rates, and they displayed higher thresholds and right-shifted dose–response curves. Glomerular maps of orthonasal and retronasal responses were usually well overlapped, with fewer total numbers of glomeruli in retronasal maps. However, maps at threshold could be quite distinct with little overlap. Retronasal responses were also more narrowly tuned to homologous series of aliphatic odorants of varying carbon chain length, with longer chain, more hydrophobic compounds evoking little or no response at comparable vapor levels. Conclusions Several features of retronasal olfaction are possibly referable to the observed properties of glomerular odorant responses. The finding that retronasal responses are weaker and sparser than orthonasal responses is consistent with psychophysical studies showing lower sensitivity for retronasal olfaction in threshold and suprathreshold tests. The similarity and overlap of orthonasal and retronasal odor maps at suprathreshold concentrations agrees with generally similar perceived qualities for the same odorant stimuli administered by the two routes. However, divergence of maps near threshold is a potential factor in perceptual differences between orthonasal and retronasal olfaction. Narrower tuning of retronasal responses suggests that they may be less influenced by chromatographic adsorption effects.
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120
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Muto A, Ohkura M, Abe G, Nakai J, Kawakami K. Real-time visualization of neuronal activity during perception. Curr Biol 2013; 23:307-11. [PMID: 23375894 DOI: 10.1016/j.cub.2012.12.040] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 12/23/2012] [Accepted: 12/24/2012] [Indexed: 10/27/2022]
Abstract
To understand how the brain perceives the external world, it is desirable to observe neuronal activity in the brain in real time during perception. The zebrafish is a suitable model animal for fluorescence imaging studies to visualize neuronal activity because its body is transparent through the embryonic and larval stages. Imaging studies have been carried out to monitor neuronal activity in the larval spinal cord and brain using Ca(2+) indicator dyes and DNA-encoded Ca(2+) indicators, such as Cameleon, GFP-aequorin, and GCaMPs. However, temporal and spatial resolution and sensitivity of these tools are still limited, and imaging of brain activity during perception of a natural object has not yet been demonstrated. Here we demonstrate visualization of neuronal activity in the optic tectum of larval zebrafish by genetically expressing the new version of GCaMP. First, we demonstrate Ca(2+) transients in the tectum evoked by a moving spot on a display and identify direction-selective neurons. Second, we show tectal activity during perception of a natural object, a swimming paramecium, revealing a functional visuotopic map. Finally, we image the tectal responses of a free-swimming larval fish to a paramecium and thereby correlate neuronal activity in the brain with prey capture behavior.
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Affiliation(s)
- Akira Muto
- Division of Molecular and Developmental Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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Abstract
The olfactory system encodes information about molecules by spatiotemporal patterns of activity across distributed populations of neurons and extracts information from these patterns to control specific behaviors. Recent studies used in vivo recordings, optogenetics, and other methods to analyze the mechanisms by which odor information is encoded and processed in the olfactory system, the functional connectivity within and between olfactory brain areas, and the impact of spatiotemporal patterning of neuronal activity on higher-order neurons and behavioral outputs. The results give rise to a faceted picture of olfactory processing and provide insights into fundamental mechanisms underlying neuronal computations. This review focuses on some of this work presented in a Mini-Symposium at the Annual Meeting of the Society for Neuroscience in 2012.
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122
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Wang L, Gallagher EP. Role of Nrf2 antioxidant defense in mitigating cadmium-induced oxidative stress in the olfactory system of zebrafish. Toxicol Appl Pharmacol 2013; 266:177-86. [DOI: 10.1016/j.taap.2012.11.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/27/2012] [Accepted: 11/08/2012] [Indexed: 12/17/2022]
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123
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Hassenklöver T, Pallesen LP, Schild D, Manzini I. Amino acid- vs. peptide-odorants: responses of individual olfactory receptor neurons in an aquatic species. PLoS One 2012; 7:e53097. [PMID: 23300867 PMCID: PMC3531423 DOI: 10.1371/journal.pone.0053097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/23/2012] [Indexed: 12/17/2022] Open
Abstract
Amino acids are widely used waterborne olfactory stimuli proposed to serve as cues in the search for food. In natural waters the main source of amino acids is the decomposition of proteins. But this process also produces a variety of small peptides as intermediate cleavage products. In the present study we tested whether amino acids actually are the natural and adequate stimuli for the olfactory receptors they bind to. Alternatively, these olfactory receptors could be peptide receptors which also bind amino acids though at lower affinity. Employing calcium imaging in acute slices of the main olfactory epithelium of the fully aquatic larvae of Xenopus laevis we show that amino acids, and not peptides, are more effective waterborne odorants.
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Affiliation(s)
- Thomas Hassenklöver
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Lars P. Pallesen
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
| | - Detlev Schild
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Ivan Manzini
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
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124
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Gliem S, Syed AS, Sansone A, Kludt E, Tantalaki E, Hassenklöver T, Korsching SI, Manzini I. Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream. Cell Mol Life Sci 2012; 70:1965-84. [PMID: 23269434 PMCID: PMC3656224 DOI: 10.1007/s00018-012-1226-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 11/30/2022]
Abstract
In contrast to the single sensory surface present in teleost fishes, several spatially segregated subsystems with distinct molecular and functional characteristics define the mammalian olfactory system. However, the evolutionary steps of that transition remain unknown. Here we analyzed the olfactory system of an early diverging tetrapod, the amphibian Xenopus laevis, and report for the first time the existence of two odor-processing streams, sharply segregated in the main olfactory bulb and partially segregated in the olfactory epithelium of pre-metamorphic larvae. A lateral odor-processing stream is formed by microvillous receptor neurons and is characterized by amino acid responses and Gαo/Gαi as probable signal transducers, whereas a medial stream formed by ciliated receptor neurons is characterized by responses to alcohols, aldehydes, and ketones, and Gαolf/cAMP as probable signal transducers. To reveal candidates for the olfactory receptors underlying these two streams, the spatial distribution of 12 genes from four olfactory receptor gene families was determined. Several class II and some class I odorant receptors (ORs) mimic the spatial distribution observed for the medial stream, whereas a trace amine-associated receptor closely parallels the spatial pattern of the lateral odor-processing stream. Other olfactory receptors (some class I odorant receptors and vomeronasal type 1 receptors) and odor responses (to bile acids, amines) were not lateralized, the latter not even in the olfactory bulb, suggesting an incomplete segregation. Thus, the olfactory system of X. laevis exhibits an intermediate stage of segregation and as such appears well suited to investigate the molecular driving forces behind olfactory regionalization.
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Affiliation(s)
- Sebastian Gliem
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
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125
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Kress S, Wullimann MF. Correlated basal expression of immediate early gene egr1 and tyrosine hydroxylase in zebrafish brain and downregulation in olfactory bulb after transitory olfactory deprivation. J Chem Neuroanat 2012; 46:51-66. [DOI: 10.1016/j.jchemneu.2012.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/10/2012] [Accepted: 09/11/2012] [Indexed: 02/02/2023]
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126
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Schärer YPZ, Shum J, Moressis A, Friedrich RW. Dopaminergic modulation of synaptic transmission and neuronal activity patterns in the zebrafish homolog of olfactory cortex. Front Neural Circuits 2012; 6:76. [PMID: 23109918 PMCID: PMC3478571 DOI: 10.3389/fncir.2012.00076] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 10/03/2012] [Indexed: 11/18/2022] Open
Abstract
Dopamine (DA) is an important modulator of synaptic transmission and plasticity that is causally involved in fundamental brain functions and dysfunctions. We examined the dopaminergic modulation of synaptic transmission and sensory responses in telencephalic area Dp of zebrafish, the homolog of olfactory cortex. By combining anatomical tracing and immunohistochemistry, we detected no DA neurons in Dp itself but long-range dopaminergic input from multiple other brain areas. Whole-cell recordings revealed no obvious effects of DA on membrane potential or input resistance in the majority of Dp neurons. Electrical stimulation of the olfactory tracts produced a complex sequence of synaptic currents in Dp neurons. DA selectively decreased inhibitory currents with little or no effect on excitatory components. Multiphoton calcium imaging showed that population responses of Dp neurons to olfactory tract stimulation or odor application were enhanced by DA, consistent with its effect on inhibitory synaptic transmission. These effects of DA were blocked by an antagonist of D2-like receptors. DA therefore disinhibits and reorganizes sensory responses in Dp. This modulation may affect sensory perception and could be involved in the experience-dependent modification of odor representations.
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127
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Strauch M, Ditzen M, Galizia CG. Keeping their distance? Odor response patterns along the concentration range. Front Syst Neurosci 2012; 6:71. [PMID: 23087621 PMCID: PMC3474990 DOI: 10.3389/fnsys.2012.00071] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 09/28/2012] [Indexed: 11/30/2022] Open
Abstract
We investigate the interplay of odor identity and concentration coding in the antennal lobe (AL) of the honeybee Apis mellifera. In this primary olfactory center of the honeybee brain, odors are encoded by the spatio-temporal response patterns of olfactory glomeruli. With rising odor concentration, further glomerular responses are recruited into the patterns, which affects distances between the patterns. Based on calcium-imaging recordings, we found that such pattern broadening renders distances between glomerular response patterns closer to chemical distances between the corresponding odor molecules. Our results offer an explanation for the honeybee's improved odor discrimination performance at higher odor concentrations.
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Affiliation(s)
- Martin Strauch
- Department of Neurobiology, University of Konstanz Konstanz, Germany ; Bioinformatics and Information Mining, University of Konstanz Konstanz, Germany
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128
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Nikolaou N, Lowe AS, Walker AS, Abbas F, Hunter PR, Thompson ID, Meyer MP. Parametric functional maps of visual inputs to the tectum. Neuron 2012; 76:317-324. [PMID: 23083735 DOI: 10.1016/j.neuron.2012.08.040] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2012] [Indexed: 11/17/2022]
Abstract
How features of the visual scene are encoded in the population activity of retinal ganglion cells (RGCs) targeting specific regions of the brain is not well understood. To address this, we have used a genetically encoded reporter of presynaptic function (SyGCaMP3) to record visually evoked activity in the population of RGC axons innervating the zebrafish tectum. Using unbiased voxel-wise analysis of SyGCaMP3 signals, we identify three subtypes of direction-selective and two subtypes of orientation-selective retinal input. Composite parametric functional maps generated across many larvae show laminar segregation of direction- and orientation-selective responses and unexpected retinotopic biases in the distribution of functional subtypes. These findings provide a systematic description of the form, organization, and dimensionality of visual inputs to the brain and will serve as a platform for understanding emergent properties in tectal circuits associated with visually driven behavior.
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Affiliation(s)
- Nikolas Nikolaou
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Andrew S Lowe
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Alison S Walker
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Fatima Abbas
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Paul R Hunter
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Ian D Thompson
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
| | - Martin P Meyer
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
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129
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Braubach OR, Fine A, Croll RP. Distribution and functional organization of glomeruli in the olfactory bulbs of zebrafish (Danio rerio). J Comp Neurol 2012; 520:2317-39, Spc1. [PMID: 22581687 DOI: 10.1002/cne.23075] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Odor molecules are transduced by thousands of olfactory sensory neurons (OSNs) located in the nasal cavity. Each OSN expresses a single functional odorant receptor protein and projects an axon from the sensory epithelia to an olfactory bulb glomerulus, which is selectively innervated by only one or a few OSN types. We used whole-mount immunocytochemistry to study the neurochemistry and anatomical organization of glomeruli in the zebrafish olfactory system. By employing combinations of antibodies against G-protein α subunits, calcium-binding proteins, and general neuronal markers, we selectively labeled various OSN types, their axonal projections to glomeruli, and the detailed anatomical distributions of individual glomeruli in different regions of the olfactory bulb. In this way we identified ≈140 glomeruli in each olfactory bulb of mature zebrafish. A small subset (27) of these glomeruli was unambiguously identifiable in nearly all animals examined. These units were large and, located mainly in the medial olfactory bulbs. Most glomeruli, however, were comparatively small, anatomically indistinguishable, and located in coarsely circumscribed regions; almost all of these latter glomeruli were innervated by OSNs that were labeled with anti-G(α s/olf) and/or anti-calretinin antibodies. Collectively, our results provide a uniquely detailed description of a vertebrate olfactory system and highlight anatomically distinct parallel neural pathways that mediate early aspects of olfactory processing in the zebrafish.
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Affiliation(s)
- Oliver R Braubach
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
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130
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Miyasaka N, Wanner AA, Li J, Mack-Bucher J, Genoud C, Yoshihara Y, Friedrich RW. Functional development of the olfactory system in zebrafish. Mech Dev 2012; 130:336-46. [PMID: 23010553 DOI: 10.1016/j.mod.2012.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 09/05/2012] [Accepted: 09/06/2012] [Indexed: 11/29/2022]
Abstract
The olfactory system has become a popular model to study the function of neuronal circuits and the molecular and cellular mechanisms underlying the development of neurons and their connections. An excellent model to combine studies of function and development is the zebrafish because it not only permits sophisticated molecular and genetic analyses of development, but also functional measurements of neuronal activity patterns in the intact brain. This article reviews insights into the functional development of the olfactory system that have been obtained in zebrafish. The focus is on the specification of olfactory sensory neurons (OSNs), the mechanisms controlling odorant receptor expression and OSN identity, the pathfinding of OSN axons towards target glomeruli in the olfactory bulb (OB), the development of glomeruli and functional topographic maps in the OB, and the development of inhibitory interneurons in the OB.
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Affiliation(s)
- Nobuhiko Miyasaka
- Laboratory for Neurobiology of Synapse, RIKEN Brain Science Institute, Saitama 351-0198, Japan
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131
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Fu Y, Yu S, Ma Y, Wang Y, Zhou Y. Functional degradation of the primary visual cortex during early senescence in rhesus monkeys. Cereb Cortex 2012; 23:2923-31. [PMID: 22941715 DOI: 10.1093/cercor/bhs282] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Visual function in humans degrades during the early stage of senescence beginning from middle 50s to 60s. To identify its underlying neural mechanisms, we investigated the aging effects on the primary visual cortex (V1) cells in early senescent (ES) monkeys (Macaca mulatta). Under anesthesia, receptive field properties of V1 cells were examined by extracellular single-unit recordings in the young adult (YA; 5-6 years old), ES (19-24 years old), and late senescent (LS; 28-32 years old) monkeys. We found clear indications of functional degradation in early senescence, including impaired stimulus selectivities, increased level of spontaneous activity and declined signal-to-noise ratio, and dynamic range of V1 cell responses. Importantly, the functional degradation in early senescence exhibited unique features that were different from the results for the LS animals, such as remarkable individual variability in orientation selectivity and unchanged peak response elicited by visual stimulation. Our results demonstrate that the function of V1 degrades during the early stage of aging in nonhuman primate, suggesting potential neural correlates for functional deficits observed in early senescence in human subjects. Moreover, these results provide new insight into the dynamics of the aging-related functional deterioration, revealing a more complex and heterogeneous picture of this process.
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Affiliation(s)
- Yu Fu
- Biomedical Engineering laboratory, Information School, Yunnan University, Kunming, Yunnan 650091, PR China
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132
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Rangan AV. Functional roles for synaptic-depression within a model of the fly antennal lobe. PLoS Comput Biol 2012; 8:e1002622. [PMID: 22927802 PMCID: PMC3426607 DOI: 10.1371/journal.pcbi.1002622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 06/11/2012] [Indexed: 11/18/2022] Open
Abstract
Several experiments indicate that there exists substantial synaptic-depression at the synapses between olfactory receptor neurons (ORNs) and neurons within the drosophila antenna lobe (AL). This synaptic-depression may be partly caused by vesicle-depletion, and partly caused by presynaptic-inhibition due to the activity of inhibitory local neurons within the AL. While it has been proposed that this synaptic-depression contributes to the nonlinear relationship between ORN and projection neuron (PN) firing-rates, the precise functional role of synaptic-depression at the ORN synapses is not yet fully understood. In this paper we propose two hypotheses linking the information-coding properties of the fly AL with the network mechanisms responsible for ORNAL synaptic-depression. Our first hypothesis is related to variance coding of ORN firing-rate information — once stimulation to the ORNs is sufficiently high to saturate glomerular responses, further stimulation of the ORNs increases the regularity of PN spiking activity while maintaining PN firing-rates. The second hypothesis proposes a tradeoff between spike-time reliability and coding-capacity governed by the relative contribution of vesicle-depletion and presynaptic-inhibition to ORNAL synaptic-depression. Synaptic-depression caused primarily by vesicle-depletion will give rise to a very reliable system, whereas an equivalent amount of synaptic-depression caused primarily by presynaptic-inhibition will give rise to a less reliable system that is more sensitive to small shifts in odor stimulation. These two hypotheses are substantiated by several small analyzable toy models of the fly AL, as well as a more physiologically realistic large-scale computational model of the fly AL involving glomerular channels. Understanding the intricacies of sensory processing is a major scientific challenge. In this paper we examine the early stages of the olfactory system of the fruit-fly. Many experiments have revealed a great deal regarding the architecture of this system, including the types of neurons within it, as well as the connections those neurons make amongst one another. In this paper we examine the potential dynamics produced by this neuronal network. Specifically, we construct a computational model of this early olfactory system and study the effects of synaptic-depression within this system. We find that the dynamics and coding properties of this system depend strongly on the strength, and sources of, synaptic-depression. This work has ramifications for understanding the coding properties of other insect olfactory systems, and perhaps even other sensory modalities in other animals.
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Affiliation(s)
- Aaditya V Rangan
- Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America.
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133
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Dopaminergic modulation of mitral cells and odor responses in the zebrafish olfactory bulb. J Neurosci 2012; 32:6830-40. [PMID: 22593052 DOI: 10.1523/jneurosci.6026-11.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In the olfactory bulb, the modulatory neurotransmitter dopamine (DA) is coexpressed with GABA by local interneurons, but its role in odor processing remains obscure. We examined functions of DA mediated by D₂-like receptors in the olfactory bulb of adult zebrafish by pharmacology, whole-cell recordings, calcium imaging, and optogenetics. Bath application of DA had no detectable effect on odorant-evoked sensory input. DA directly hyperpolarized mitral cells (MCs) via D₂-like receptors and slightly increased their response gain. Consistent with this effect on input-output functions of MCs, small odorant responses were suppressed, whereas strong responses were enhanced in the presence of DA. These effects increased the root-mean-square contrast of population activity patterns but did not reduce their correlations. Optical stimulation of interneurons expressing channelrhodopsin-2 evoked fast GABAergic inhibitory currents in mitral cells but failed to activate D₂ receptor-mediated currents when stimuli were short. Prolonged stimulus trains, however, activated a slow hyperpolarizing current that was blocked by an antagonist of D₂-like receptors. GABA and DA are therefore both released from interneurons by electrical activity and hyperpolarize MCs, but D₂-dependent dopaminergic effects occur on slower timescales. Additional effects of DA may be mediated by D₁-like receptors. These results indicate that DA acts on D₂-like receptors via asynchronous release and/or volume transmission and implicate DA in the slow adaptation of circuit function. The shift of the membrane potential away from spike threshold could adapt mitral cells to background input without compromising their sensitivity.
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134
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Netrin/DCC signaling guides olfactory sensory axons to their correct location in the olfactory bulb. J Neurosci 2012; 32:4440-56. [PMID: 22457493 DOI: 10.1523/jneurosci.4442-11.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Olfactory sensory neurons expressing particular olfactory receptors project to specific reproducible locations within the bulb. The axonal guidance cues that organize this precise projection pattern are only beginning to be identified. To aid in their identification and characterization, we generated a transgenic zebrafish line, OR111-7:IRES:Gal4, in which a small subset of olfactory sensory neurons is labeled. Most sensory neurons expressing the OR111-7 transgene project to a specific location within the bulb, the central zone protoglomerulus, while a smaller number project to the lateral glomerulus 1 protoglomerulus. Inhibiting Netrin/DCC (deleted in colorectal cancer) signaling perturbs the ability of OR111-7-expressing axons to enter the olfactory bulb and alters their patterns of termination within the bulb. The Netrin receptor DCC is expressed in olfactory sensory neurons around the time that they elaborate their axons, netrin1a is expressed near the medial-most margin of the olfactory bulb, and netrin1b is expressed within the ventral region of the bulb. Loss of Netrin/DCC signaling components causes some OR111-7-expressing sensory axons to wander posteriorly after exiting the olfactory pit, away from netrin-expressing areas in the bulb. OR111-7-expressing axons that enter the bulb target the central zone less precisely than normal, spreading away from netrin-expressing regions. These pathfinding errors can be corrected by the reexpression of DCC within OR111-7 transgene-expressing neurons in DCC morphant embryos. These findings implicate Netrins as the only known attractants for olfactory sensory neurons, first drawing OR111-7-expressing axons into the bulb and then into the ventromedially positioned central zone protoglomerulus.
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135
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Carcaud J, Hill T, Giurfa M, Sandoz JC. Differential coding by two olfactory subsystems in the honeybee brain. J Neurophysiol 2012; 108:1106-21. [PMID: 22572948 DOI: 10.1152/jn.01034.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sensory systems use parallel processing to extract and process different features of environmental stimuli. Parallel processing has been studied in the auditory, visual, and somatosensory systems, but equivalent research in the olfactory modality is scarce. The honeybee Apis mellifera is an interesting model for such research as its relatively simple brain contains a dual olfactory system, with a clear neural dichotomy from the periphery to higher-order centers, based on two main neuronal tracts [medial (m) and lateral (l) antenno-protocerebral tract (APT)]. The function of this dual system is as yet unknown, and attributes like odor quality and odor quantity might be separately encoded in these subsystems. We have thus studied olfactory coding at the input of both subsystems, using in vivo calcium imaging. As one of the subsystems (m-APT) has never been imaged before, a novel imaging preparation was developed to this end, and responses to a panel of aliphatic odorants at different concentrations were compared in both subsystems. Our data show a global redundancy of olfactory coding at the input of both subsystems but unravel some specificities for encoding chemical group and carbon chain length of odor molecules.
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Affiliation(s)
- Julie Carcaud
- Université de Toulouse (UPS), Centre de Recherches sur la Cognition Animale, Toulouse Cedex, France
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136
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Galizia CG, Franke T, Menzel R, Sandoz JC. Optical imaging of concealed brain activity using a gold mirror in honeybees. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:743-749. [PMID: 22414536 DOI: 10.1016/j.jinsphys.2012.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 02/24/2012] [Accepted: 02/27/2012] [Indexed: 05/31/2023]
Abstract
Brain activity is inherently combinatorial and three-dimensional. Optical imaging techniques offer a suitable opportunity to record many activity foci simultaneously, but under conventional microscopy conditions, optical access is generally limited to the frontal part of the brain. Thus, even for cases in which optical recordings have delivered substantial data, our knowledge of deeper layers is deficient. Using the honeybee olfactory system as a test system, we report that by using a gold-sputtered cover slip as a minute mirror, it is possible to optically access and record from otherwise inaccessible brain areas. In insects, the first brain area to code for odors is the antennal lobe (comparable to the vertebrate olfactory bulb). Several previous studies have characterized glomerular odor response patterns of the frontal view, readily accessible when the head capsule of the bee is opened. However, until now, the back and the sides of the antennal lobe have remained utterly unexplored. This is particularly relevant because in the honeybee these two views coincide with two separate olfactory subsystems, related to two axonal tracts of second-order neurons: the lAPT and the mAPT. Combining wide-field microscopy, calcium imaging, and a minute mirror, we report the first glomerular odor responses from the side of the honeybee antennal lobe.
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137
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Gollo LL, Mirasso C, Eguíluz VM. Signal integration enhances the dynamic range in neuronal systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:040902. [PMID: 22680413 DOI: 10.1103/physreve.85.040902] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/09/2011] [Indexed: 06/01/2023]
Abstract
The dynamic range measures the capacity of a system to discriminate the intensity of an external stimulus. Such an ability is fundamental for living beings to survive: to leverage resources and to avoid danger. Consequently, the larger is the dynamic range, the greater is the probability of survival. We investigate how the integration of different input signals affects the dynamic range, and in general the collective behavior of a network of excitable units. By means of numerical simulations and a mean-field approach, we explore the nonequilibrium phase transition in the presence of integration. We show that the firing rate in random and scale-free networks undergoes a discontinuous phase transition depending on both the integration time and the density of integrator units. Moreover, in the presence of external stimuli, we find that a system of excitable integrator units operating in a bistable regime largely enhances its dynamic range.
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Affiliation(s)
- Leonardo L Gollo
- IFISC (CSIC-UIB), Instituto de Física Interdisciplinar y Sistemas Complejos, E-07122 Palma de Mallorca, Spain.
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138
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Kawai T, Abe H, Oka Y. Dopaminergic neuromodulation of synaptic transmission between mitral and granule cells in the teleost olfactory bulb. J Neurophysiol 2012; 107:1313-24. [DOI: 10.1152/jn.00536.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A growing body of evidence suggests that teleosts are important models for the study of neural processing of olfactory information, and the functional role of dopamine (DA), which is a potent neuromodulator endogenous to the mammalian olfactory bulb, has been one of the strongest focuses in this field. However, the cellular mechanisms of dopaminergic neuromodulation in olfactory bulbar neural circuits have not been fully understood. We investigated such mechanisms by using the goldfish, which offers several advantages for analyzing olfactory information processing by electrophysiological methods. First, we found in the olfactory bulb that numerous cell bodies of the dopaminergic neurons are mainly distributed in the mitral cell layer and extend fine processes to the glomerular layer. Next, we made in vitro field potential recordings and showed that synaptic transmissions from mitral to granule cells were suppressed by DA application. DA also increased the paired-pulse ratio, suggesting that the suppression of synaptic transmission is caused by a decrease in presynaptic glutamate release from the mitral cells. Furthermore, DA significantly suppressed the oscillatory activity of the olfactory bulb in response to olfactory stimuli. Although DA suppresses the synaptic inputs from the olfactory nerve to the olfactory bulbar neurons in mammals, this phenomenon was not observed in the goldfish. These findings indicate that suppression of the mitral to granule cell synaptic transmission in the reciprocal synapses plays an important role in the negative regulation of olfactory responsiveness in the goldfish olfactory bulb.
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Affiliation(s)
- Takafumi Kawai
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hideki Abe
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yoshitaka Oka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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139
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Russell JT. Imaging calcium signals in vivo: a powerful tool in physiology and pharmacology. Br J Pharmacol 2012; 163:1605-25. [PMID: 20718728 DOI: 10.1111/j.1476-5381.2010.00988.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The design and engineering of organic fluorescent Ca(2+) indicators approximately 30 years ago opened the door for imaging cellular Ca(2+) signals with a high degree of temporal and spatial resolution. Over this time, Ca(2+) imaging has revolutionized our approaches for tissue-level spatiotemporal analysis of functional organization and has matured into a powerful tool for in situ imaging of cellular activity in the living animal. In vivo Ca(2+) imaging with temporal resolution at the millisecond range and spatial resolution at micrometer range has been achieved through novel designs of Ca(2+) sensors, development of modern microscopes and powerful imaging techniques such as two-photon microscopy. Imaging Ca(2+) signals in ensembles of cells within tissue in 3D allows for analysis of integrated cellular function, which, in the case of the brain, enables recording activity patterns in local circuits. The recent development of miniaturized compact, fibre-optic-based, mechanically flexible microendoscopes capable of two-photon microscopy opens the door for imaging activity in awake, behaving animals. This development is poised to open a new chapter in physiological experiments and for pharmacological approaches in the development of novel therapies.
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Affiliation(s)
- James T Russell
- Section on Cell Biology and Signal Transduction, Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development/NIH, 49 Convent Drive, Bethesda, MD 20892-4480, USA.
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140
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Cleland TA, Chen SYT, Hozer KW, Ukatu HN, Wong KJ, Zheng F. Sequential mechanisms underlying concentration invariance in biological olfaction. FRONTIERS IN NEUROENGINEERING 2012; 4:21. [PMID: 22287949 PMCID: PMC3251820 DOI: 10.3389/fneng.2011.00021] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/19/2011] [Indexed: 11/13/2022]
Abstract
Concentration invariance-the capacity to recognize a given odorant (analyte) across a range of concentrations-is an unusually difficult problem in the olfactory modality. Nevertheless, humans and other animals are able to recognize known odors across substantial concentration ranges, and this concentration invariance is a highly desirable property for artificial systems as well. Several properties of olfactory systems have been proposed to contribute to concentration invariance, but none of these alone can plausibly achieve full concentration invariance. We here propose that the mammalian olfactory system uses at least six computational mechanisms in series to reduce the concentration-dependent variance in odor representations to a level at which different concentrations of odors evoke reasonably similar representations, while preserving variance arising from differences in odor quality. We suggest that the residual variance then is treated like any other source of stimulus variance, and categorized appropriately into "odors" via perceptual learning. We further show that naïve mice respond to different concentrations of an odorant just as if they were differences in quality, suggesting that, prior to odor categorization, the learning-independent compensatory mechanisms are limited in their capacity to achieve concentration invariance.
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Affiliation(s)
- Thomas A Cleland
- Computational Physiology Laboratory, Department of Psychology, Cornell University, Ithaca NY, USA
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141
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Kettunen P. Calcium imaging in the zebrafish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1039-71. [PMID: 22453983 DOI: 10.1007/978-94-007-2888-2_48] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The zebrafish (Danio rerio) has emerged as a new model system during the last three decades. The fact that the zebrafish larva is transparent enables sophisticated in vivo imaging. While being the vertebrate, the reduced complexity of its nervous system and small size make it possible to follow large-scale activity in the whole brain. Its genome is sequenced and many genetic and molecular tools have been developed that simplify the study of gene function. Since the mid 1990s, the embryonic development and neuronal function of the larval, and later, adult zebrafish have been studied using calcium imaging methods. The choice of calcium indicator depends on the desired number of cells to study and cell accessibility. Dextran indicators have been used to label cells in the developing embryo from dye injection into the one-cell stage. Dextrans have also been useful for retrograde labeling of spinal cord neurons and cells in the olfactory system. Acetoxymethyl (AM) esters permit labeling of larger areas of tissue such as the tectum, a region responsible for visual processing. Genetically encoded calcium indicators have been expressed in various tissues by the use of cell-specific promoters. These studies have contributed greatly to our understanding of basic biological principles during development and adulthood, and of the function of disease-related genes in a vertebrate system.
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Affiliation(s)
- Petronella Kettunen
- Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Sweden.
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142
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Gayoso J, Castro A, Anadón R, Manso MJ. Crypt cells of the zebrafish Danio rerio mainly project to the dorsomedial glomerular field of the olfactory bulb. Chem Senses 2011; 37:357-69. [PMID: 22167271 DOI: 10.1093/chemse/bjr109] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The olfactory mucosa of the zebrafish consists of 3 morphological types of olfactory receptor neurons (ORNs): ciliated, microvillous, and crypt cells. Previous studies in the zebrafish have revealed differential projections of ciliated and microvillous ORNs, which project to different glomerular fields. However, the bulbar targets of zebrafish crypt cells were not identified. Here, we analyze the relationship between crypt cells of the olfactory epithelium and dorsal glomerular fields of the zebrafish olfactory bulbs, as wells as the connections between these bulbar regions and forebrain regions. For this purpose, a lipophilic carbocyanine tracer (DiI) was used in fixed tissue. Application of DiI to the dorsomedial glomerular field mainly labeled crypt cells in the zebrafish olfactory epithelium. By contrast, application of DiI to the dorsolateral glomerular fields mainly labeled bipolar ORNs and only occasionally crypt cells. Bulbar efferent cells (mitral cells) contacting these dorsal glomerular fields project to different telencephalic areas, with the posterior zone of the dorsal telencephalic area (Dp) as the common target. However, dorsomedial and dorsolateral glomerular fields projected differentially to the ventral telencephalon, the former projecting to the ventrolateral supracommissural region. Retrograde labeling from the ventrolateral supracommissural region revealed mitral cells associated with 2 large glomeruli in the bulbar dorsomedial region, which putatively receives inputs from the crypt cells, indicating the existence of a crypt cell olfactory subsystem with separate projections, in the zebrafish. The comparative significance of the secondary olfactory pathways of zebrafish that convey information from crypt cells is discussed.
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Affiliation(s)
- José Gayoso
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, A Coruña, Spain
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143
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Neuronal filtering of multiplexed odour representations. Nature 2011; 479:493-8. [PMID: 22080956 DOI: 10.1038/nature10633] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 10/13/2011] [Indexed: 01/13/2023]
Abstract
Neuronal activity patterns contain information in their temporal structure, indicating that information transfer between neurons may be optimized by temporal filtering. In the zebrafish olfactory bulb, subsets of output neurons (mitral cells) engage in synchronized oscillations during odour responses, but information about odour identity is contained mostly in non-oscillatory firing rate patterns. Using optogenetic manipulations and odour stimulation, we found that firing rate responses of neurons in the posterior zone of the dorsal telencephalon (Dp), a target area homologous to olfactory cortex, were largely insensitive to oscillatory synchrony of mitral cells because passive membrane properties and synaptic currents act as low-pass filters. Nevertheless, synchrony influenced spike timing. Moreover, Dp neurons responded primarily during the decorrelated steady state of mitral cell activity patterns. Temporal filtering therefore tunes Dp neurons to components of mitral cell activity patterns that are particularly informative about precise odour identity. These results demonstrate how temporal filtering can extract specific information from multiplexed neuronal codes.
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144
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Abstract
A central goal of modern neuroscience is to obtain a mechanistic understanding of higher brain functions under healthy and diseased conditions. Addressing this challenge requires rigorous experimental and theoretical analysis of neuronal circuits. Recent advances in optogenetics, high-resolution in vivo imaging, and reconstructions of synaptic wiring diagrams have created new opportunities to achieve this goal. To fully harness these methods, model organisms should allow for a combination of genetic and neurophysiological approaches in vivo. Moreover, the brain should be small in terms of neuron numbers and physical size. A promising vertebrate organism is the zebrafish because it is small, it is transparent at larval stages and it offers a wide range of genetic tools and advantages for neurophysiological approaches. Recent studies have highlighted the potential of zebrafish for exhaustive measurements of neuronal activity patterns, for manipulations of defined cell types in vivo and for studies of causal relationships between circuit function and behavior. In this article, we summarize background information on the zebrafish as a model in modern systems neuroscience and discuss recent results.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland.
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145
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Abstract
High-resolution tracing of projections from the olfactory bulb to its cortical targets revealed coarse topography and stereotopy in some areas but highly distributed, combinatorial connectivity in others. These results provide a basis for understanding innate and associative olfactory processing and perception.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research and University of Basel, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
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146
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Carlsson MA, Bisch-Knaden S, Schäpers A, Mozuraitis R, Hansson BS, Janz N. Odour maps in the brain of butterflies with divergent host-plant preferences. PLoS One 2011; 6:e24025. [PMID: 21901154 PMCID: PMC3162027 DOI: 10.1371/journal.pone.0024025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/04/2011] [Indexed: 11/18/2022] Open
Abstract
Butterflies are believed to use mainly visual cues when searching for food and oviposition sites despite that their olfactory system is morphologically similar to their nocturnal relatives, the moths. The olfactory ability in butterflies has, however, not been thoroughly investigated. Therefore, we performed the first study of odour representation in the primary olfactory centre, the antennal lobes, of butterflies. Host plant range is highly variable within the butterfly family Nymphalidae, with extreme specialists and wide generalists found even among closely related species. Here we measured odour evoked Ca2+ activity in the antennal lobes of two nymphalid species with diverging host plant preferences, the specialist Aglais urticae and the generalist Polygonia c-album. The butterflies responded with stimulus-specific combinations of activated glomeruli to single plant-related compounds and to extracts of host and non-host plants. In general, responses were similar between the species. However, the specialist A. urticae responded more specifically to its preferred host plant, stinging nettle, than P. c-album. In addition, we found a species-specific difference both in correlation between responses to two common green leaf volatiles and the sensitivity to these compounds. Our results indicate that these butterflies have the ability to detect and to discriminate between different plant-related odorants.
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147
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Pain F, L'heureux B, Gurden H. Visualizing odor representation in the brain: a review of imaging techniques for the mapping of sensory activity in the olfactory glomeruli. Cell Mol Life Sci 2011; 68:2689-709. [PMID: 21584811 PMCID: PMC11114686 DOI: 10.1007/s00018-011-0708-4] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Revised: 03/30/2011] [Accepted: 04/21/2011] [Indexed: 01/15/2023]
Abstract
The brain transforms clues from the external world, the sensory stimuli, into activities in neuroglial networks. These circuits are activated in specialized sensory cortices where specific functional modules are responsible for the spatiotemporal coding of the stimulus. A major challenge in the neuroscience field has been to image the spatial distribution and follow the temporal dynamics of the activation of such large populations in vivo. Functional imaging techniques developed in the last 30 years have enabled researchers to solve this critical issue, and are reviewed here. These techniques utilize sources of contrast of radioisotopic, magnetic and optical origins and exploit two major families of signals to image sensory activity: the first class uses sources linked to cellular energy metabolism and hemodynamics, while the second involves exogenous indicators of neuronal activity. The whole panel of imaging techniques has fostered the functional exploration of the olfactory bulb which is one of the most studied sensory structures. We summarize the major results obtained using these techniques that describe the spatial and temporal activity patterns in the olfactory glomeruli, the first relay of olfactory information processing in the main olfactory bulb. We conclude this review by describing promising technical developments in optical imaging and future directions in the study of olfactory spatiotemporal coding.
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Affiliation(s)
- F Pain
- Laboratoire Imagerie et Modélisation en Neurobiologie et Cancérologie, UMR Université Paris Sud, CNRS, Campus d'Orsay Bat, France.
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148
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Wyart C, Del Bene F. Let there be light: zebrafish neurobiology and the optogenetic revolution. Rev Neurosci 2011; 22:121-30. [PMID: 21615266 DOI: 10.1515/rns.2011.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Optogenetics has revolutionized the toolbox arsenal that neuroscientists now possess to investigate neuronal circuit function in intact and living animals. With a combination of light emitting 'sensors' and light activated 'actuators', we can monitor and control neuronal activity with minimal perturbation and unprecedented spatiotemporal resolution. Zebrafish neuronal circuits represent an ideal system to apply an optogenetic based analysis owing to its transparency, relatively small size and amenability to genetic manipulation. In this review, we describe some of the most recent advances in the development and applications of optogenetic sensors (i.e., genetically encoded calcium indicators and voltage sensors) and actuators (i.e., light activated ion channels and ion pumps). We focus mostly on the tools that have already been successfully applied in zebrafish and on those that show the greatest potential for the future. We also describe crucial technical aspects to implement optogenetics in zebrafish including strategies to drive a high level of transgene expression in defined neuronal populations, and recent optical advances that allow the precise spatiotemporal control of sample illumination.
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Affiliation(s)
- Claire Wyart
- Institut du Cerveau et de la Moelle epiniere, Centre de Recherche, CHU Pitié-Salpétrière, Paris, France.
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149
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Valentincic T, Miklavc P, Kralj S, Zgonik V. Olfactory discrimination of complex mixtures of amino acids by the black bullhead Ameiurus melas. JOURNAL OF FISH BIOLOGY 2011; 79:33-52. [PMID: 21722109 DOI: 10.1111/j.1095-8649.2011.02976.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
On the basis of previous findings of behavioural discrimination of amino acids and on the knowledge of electrophysiology of the catfish (genera Ictalurus and Ameiurus) olfactory organs, behavioural experiments that investigated olfactory discrimination of amino acid mixtures were carried out on the black bullhead Ameiurus melas. Repeated presentations of food-rewarded mixtures released increased swimming activity measured by counting the number of turns >90° within 90 s of stimulus addition. Non-rewarded amino acids and their mixtures released little swimming activity, indicating that A. melas discriminated between the conditioned and the non-conditioned stimuli. Two questions of mixture discrimination were addressed: (1) Are A. melas able to detect components within simple and complex amino acid mixtures? (2) What are the smallest differences between two complex mixtures that A. melas can detect? Three and 13 component mixtures tested were composed primarily of equipotent amino acids [determined by equal electroolfactogram (EOG) amplitude] that contained L-Cys at ×100 the equipotent concentration. Ameiurus melas initially perceived the ternary amino acid mixture as its more stimulatory component alone [i.e. cysteine (Cys)], whereas the conditioned 13 component mixture containing the more stimulatory L-Cys was perceived immediately as different from L-Cys alone. The results indicate that components of ternary mixtures are detectable by A. melas but not those of more complex mixtures. To test for the smallest detectable differences in composition between similar multimixtures, all mixture components were equipotent. Initially, A. melas were unable to discriminate the mixtures of six amino acids from the conditioned mixtures of seven amino acids, whereas they discriminated immediately the mixtures of four and five amino acids from the conditioned mixture. Experience with dissimilar mixtures enabled the A. melas to start discriminating the seven-component conditioned mixture from its six-component counterparts. After fewer than five training trials, A. melas discriminated the mixtures of nine and 10 amino acids from a conditioned mixture of 12 equipotent amino acids; however, irrespective of the number of training trials, A. melas were unable to discriminate the 12 component mixture from its 11 component counterparts.
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Affiliation(s)
- T Valentincic
- Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana, Slovenia.
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150
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Raman B, Stopfer M, Semancik S. Mimicking biological design and computing principles in artificial olfaction. ACS Chem Neurosci 2011; 2:487-499. [PMID: 22081790 DOI: 10.1021/cn200027r] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Biology has inspired solutions to many engineering problems, including chemical sensing. Modern approaches to chemical sensing have been based on the biological principle of combining cross-selective chemical sensors with a pattern recognition engine to identify odors. Here, we review some recent advances made in mimicking biological design and computing principles to develop an electronic nose. The resulting technology will have important applications in fundamental biological research, as well as in industrial, security, and medical domains.
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Affiliation(s)
- Baranidharan Raman
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, United States
| | - Mark Stopfer
- National Institute of Child Health & Development, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Steve Semancik
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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