DOCSLIB.ORG

Perception and Representation of Temporally Patterned Odour Stimuli in the Mammalian Olfactory Bulb

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Perception and Representation of Temporally Patterned Odour Stimuli in the Mammalian Olfactory Bulb Perception and representation of temporally patterned odour stimuli in the mammalian olfactory bulb Thesis submitted for the degree of Doctor of Philosophy Andrew Erskine University College London Department of Neuroscience, Physiology and Pharmacology Supervisor Dr. Andreas T. Schaefer Examiners Dr. David Bannerman Dr. Matt Grubb Dedicated to the memories of my Grandparents, Dr. Norman Macleod (1926-2017) and Dr. Marion Macleod (1930-2017), who paved the way. I, Andrew Erskine, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Signed: 5 Contents Abstract 5 I. Introduction 9 1. Anatomy and function of early olfactory structures 13 1.1. Olfactory epithelium . 13 1.1.1. Olfactory sensory neuron physiology . 14 1.2. Olfactory bulb . 16 1.2.1. Feedforward projections to mitral and tufted cells . 16 1.2.2. Mitral and tufted cell physiology . 17 1.2.3. Glomerular layer inhibitory networks . 18 1.2.4. Glomerular layer physiology . 18 1.2.5. External plexiform layer inhibitory networks . 19 1.2.6. External plexiform layer physiology . 19 2. Computation in the early olfactory system 23 2.1. Olfactory discrimination . 23 2.1.1. Discrimination behaviour . 23 2.1.2. Circuit basis of olfactory discrimination . 24 2.1.3. Redundancy of odour coding . 26 2.2. Odour source localisation . 27 2.2.1. Odour source localisation behaviour . 28 2.2.2. Circuit basis of odour source localisation . 28 2.3. Olfactory scene segmentation . 29 2.3.1. Olfactory scene segmentation behaviour . 29 2.3.2. Circuit basis of olfactory scene segmentation . 30 i Contents Contents 3. Temporal dynamics in olfaction 31 3.1. Natural transmission of odours . 31 3.2. Perception of temporal dynamics . 33 3.2.1. Navigation behaviour . 33 3.2.2. Olfactory scene segmentation . 34 3.2.3. Detection and neuronal representation of temporal informa- tion . 35 3.2.4. The early olfactory system in the context of temporally pat- terned odour information . 37 4. Summary and aims 41 II. Methods 43 5. General 45 5.1. Animals . 45 5.2. Odours . 45 5.3. Analysis . 46 6. AutonoMouse 47 6.1. Overview . 47 6.2. Technical Development . 47 6.3. Design overview . 48 6.3.1. Terminology . 49 6.4. Construction . 50 6.4.1. Main structure . 50 6.4.2. Control modules . 50 6.5. Software and experimental control . 52 6.5.1. schedule-generator . 52 6.5.2. autonomouse-control . 53 6.6. Animal preparation . 54 6.7. RFID implant surgery . 54 6.8. Experiment initiation and maintenance . 54 ii Contents 7. Lesion study 57 7.1. Overview . 57 7.2. Task and trial structure . 57 7.2.1. General trial structure . 57 7.2.2. Task structures . 58 7.2.3. Training schedules . 60 7.3. Odour delivery . 61 7.3.1. Control stimuli . 62 7.4. Lesion induction . 63 7.5. MicroCT imaging . 65 7.5.1. MicroCT Lesion Quantification . 65 7.6. Experiment maintenance . 66 8. Odour signal recording 67 8.1. Overview . 67 8.2. Dual-energy photo-ionisation detection . 67 8.2.1. Principle . 67 8.2.2. Decomposition procedure . 68 8.3. Recording apparatus . 69 8.4. Recording conditions . 69 8.4.1. Low energy only . 69 8.4.2. Mixture . 70 8.4.3. Separated . 70 9. Temporal olfactometer 71 9.1. Overview . 71 9.2. Construction . 71 9.3. PulseBoy . 73 10.Correlation discrimination experiment 75 10.1.Overview . 75 10.2.Odour delivery . 75 10.3.Task and trial structure . 75 10.3.1. General structure . 75 10.3.2. Stimulus structure . 76 iii Contents Contents 10.3.3. Task structure . 77 10.3.4. Group structure . 78 10.3.5. Training schedules . 80 11.2-photon imaging 83 11.1.Overview . 83 11.2.Recording procedure . 83 11.3.Stimulus protocol . 84 11.4.Analysis . 85 III. Results 87 12.Aims 89 12.1.Overview . 89 12.2.Automated behavioural training . 89 12.3.Methods for recording natural odour plume data . 90 12.4.Methods for reproducing natural odour plume statistics . 90 13.Automated behaviour as a tool for neuroscience 91 13.1.Overview . 91 13.2.AutonoMouse . 92 13.3.Consistency and reliability of training in AutonoMouse . 93 13.3.1. AutonoMouse gives high volumes of behavioural data . 93 13.3.2. Performance accuracy is stable throughout training . 95 13.3.3. Mice are motivated but not water restricted . 95 13.3.4. Mice maintain a normal level of weight increase . 96 13.4.Summary . 96 14.Investigation of olfactory bulb redundancy with AutonoMouse 105 14.1.Overview . 105 14.2.Quality of learning during olfactory discrimination . 106 14.3.Odour delivery . 107 14.4.Excitotoxic lesioning of the olfactory bulb . 109 14.5.Extreme lesions induce anosmia . 110 iv Contents 14.6.Varying lesion size results in graded performance across olfactory tasks . 111 14.7.Lesion results summary . 112 15.Physical features of temporal dynamics in olfaction 125 15.1.Overview . 125 15.2.Dual energy photo-ionisation detection . 125 15.3.Temporal correlation structure predicts odour source spatial sepa- ration . 128 16.Reproduction of naturally occurring odour signals 133 16.1.Overview . 133 16.2.Olfactometer design . 133 16.3.Olfactometer characterisation . 134 16.3.1. Signal fidelity and pulse frequency . 134 16.3.2. Control of output concentration with pulse width modulation 135 16.3.3. Generation of random concentration step changes . 135 16.3.4. Reproduction of recorded odour plumes . 137 17.Perception of temporal features 141 17.1.Overview . 141 17.2.Stimulus and experiment design . 141 17.2.1. Stimulus production . 141 17.2.2. Counterbalanced group assignment . 143 17.3.Mice learn to discriminate temporal correlations in odour signals . 144 17.3.1. Performance in correlated vs. anti-correlated experiment . 144 17.3.2. Learning occurs regardless of group assignation . 146 17.3.3. Simulated behavioural performance to extraneous sensory cues . 146 17.3.4. Reaction time increases for higher task frequencies . 148 17.3.5. Task accuracy is not based on onset detection . 149 18.Neural representation of temporal features 157 18.1.Overview . 157 18.2.2-photon imaging of projection neurons . 157 v Contents Contents 18.3.Temporally sensitive responses . 159 IV. Discussion 165 19.AutonoMouse 169 19.1.Conclusions and discussion . 169 19.2.Future work . 170 20.Lesion study 173 20.1.Conclusions and discussion . 173 20.2.Future work . 175 21.Perception and representation of odour correlation structure 177 21.1.Temporal olfactometer . 177 21.1.1. Conclusions and discussion . 177 21.2.Dual-energy photoionisation detection . 177 21.2.1. Conclusions and discussion . 177 21.2.2. Future work . ..
Load more

Recommended publications
  • Born Granule Cells During Implicit Versus Explicit Olfactory Learning
    RESEARCH ARTICLE Opposite regulation of inhibition by adult- born granule cells during implicit versus explicit olfactory learning Nathalie Mandairon1*, Nicola Kuczewski1, Florence Kermen1, Je´ re´ my Forest1, Maellie Midroit1, Marion Richard1, Marc Thevenet1, Joelle Sacquet1, Christiane Linster2,3, Anne Didier1 1Lyon Neuroscience Research Center, Neuroplasticity and Neuropathology of Olfactory Perception Team, CNRS UMR 5292, INSERM U1028, Universite´ de Lyon, Lyon, France; 2Computational Physiology Lab, Cornell University, Ithaca, United States; 3Department of Neurobiology and Behavior, Cornell University, Ithaca, United States Abstract Both passive exposure and active learning through reinforcement enhance fine sensory discrimination abilities. In the olfactory system, this enhancement is thought to occur partially through the integration of adult-born inhibitory interneurons resulting in a refinement of the representation of overlapping odorants. Here, we identify in mice a novel and unexpected dissociation between passive and active learning at the level of adult-born granule cells. Specifically, while both passive and active learning processes augment neurogenesis, adult-born cells differ in their morphology, functional coupling and thus their impact on olfactory bulb output. Morphological analysis, optogenetic stimulation of adult-born neurons and mitral cell recordings revealed that passive learning induces increased inhibitory action by adult-born neurons, probably resulting in more sparse and thus less overlapping odor representations. Conversely, after active learning inhibitory action is found to be diminished due to reduced connectivity. In this case, strengthened odor response might underlie enhanced discriminability. *For correspondence: DOI: https://doi.org/10.7554/eLife.34976.001 [email protected] Competing interests: The authors declare that no Introduction competing interests exist. Brain representations of the environment constantly evolve through learning mediated by different Funding: See page 13 plasticity mechanisms.
    [Show full text]
  • Cell Migration in the Developing Rodent Olfactory System
    Cell. Mol. Life Sci. (2016) 73:2467–2490 DOI 10.1007/s00018-016-2172-7 Cellular and Molecular Life Sciences REVIEW Cell migration in the developing rodent olfactory system 1,2 1 Dhananjay Huilgol • Shubha Tole Received: 16 August 2015 / Revised: 8 February 2016 / Accepted: 1 March 2016 / Published online: 18 March 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract The components of the nervous system are Abbreviations assembled in development by the process of cell migration. AEP Anterior entopeduncular area Although the principles of cell migration are conserved AH Anterior hypothalamic nucleus throughout the brain, different subsystems may predomi- AOB Accessory olfactory bulb nantly utilize specific migratory mechanisms, or may aAOB Anterior division, accessory olfactory bulb display unusual features during migration. Examining these pAOB Posterior division, accessory olfactory bulb subsystems offers not only the potential for insights into AON Anterior olfactory nucleus the development of the system, but may also help in aSVZ Anterior sub-ventricular zone understanding disorders arising from aberrant cell migra- BAOT Bed nucleus of accessory olfactory tract tion. The olfactory system is an ancient sensory circuit that BST Bed nucleus of stria terminalis is essential for the survival and reproduction of a species. BSTL Bed nucleus of stria terminalis, lateral The organization of this circuit displays many evolution- division arily conserved features in vertebrates, including molecular BSTM Bed nucleus of stria terminalis, medial mechanisms and complex migratory pathways. In this division review, we describe the elaborate migrations that populate BSTMa Bed nucleus of stria terminalis, medial each component of the olfactory system in rodents and division, anterior portion compare them with those described in the well-studied BSTMpl Bed nucleus of stria terminalis, medial neocortex.
    [Show full text]
  • Chemoreception
    Senses 5 SENSES live version • discussion • edit lesson • comment • report an error enses are the physiological methods of perception. The senses and their operation, classification, Sand theory are overlapping topics studied by a variety of fields. Sense is a faculty by which outside stimuli are perceived. We experience reality through our senses. A sense is a faculty by which outside stimuli are perceived. Many neurologists disagree about how many senses there actually are due to a broad interpretation of the definition of a sense. Our senses are split into two different groups. Our Exteroceptors detect stimulation from the outsides of our body. For example smell,taste,and equilibrium. The Interoceptors receive stimulation from the inside of our bodies. For instance, blood pressure dropping, changes in the gluclose and Ph levels. Children are generally taught that there are five senses (sight, hearing, touch, smell, taste). However, it is generally agreed that there are at least seven different senses in humans, and a minimum of two more observed in other organisms. Sense can also differ from one person to the next. Take taste for an example, what may taste great to me will taste awful to someone else. This all has to do with how our brains interpret the stimuli that is given. Chemoreception The senses of Gustation (taste) and Olfaction (smell) fall under the category of Chemoreception. Specialized cells act as receptors for certain chemical compounds. As these compounds react with the receptors, an impulse is sent to the brain and is registered as a certain taste or smell. Gustation and Olfaction are chemical senses because the receptors they contain are sensitive to the molecules in the food we eat, along with the air we breath.
    [Show full text]
  • Understanding Sensory Processing: Looking at Children's Behavior Through the Lens of Sensory Processing
    Understanding Sensory Processing: Looking at Children’s Behavior Through the Lens of Sensory Processing Communities of Practice in Autism September 24, 2009 Charlottesville, VA Dianne Koontz Lowman, Ed.D. Early Childhood Coordinator Region 5 T/TAC James Madison University MSC 9002 Harrisonburg, VA 22807 [email protected] ______________________________________________________________________________ Dianne Koontz Lowman/[email protected]/2008 Page 1 Looking at Children’s Behavior Through the Lens of Sensory Processing Do you know a child like this? Travis is constantly moving, pushing, or chewing on things. The collar of his shirt and coat are always wet from chewing. When talking to people, he tends to push up against you. Or do you know another child? Sierra does not like to be hugged or kissed by anyone. She gets upset with other children bump up against her. She doesn’t like socks with a heel or toe seam or any tags on clothes. Why is Travis always chewing? Why doesn’t Sierra liked to be touched? Why do children react differently to things around them? These children have different ways of reacting to the things around them, to sensations. Over the years, different terms (such as sensory integration) have been used to describe how children deal with the information they receive through their senses. Currently, the term being used to describe children who have difficulty dealing with input from their senses is sensory processing disorder. _____________________________________________________________________ Sensory Processing Disorder
    [Show full text]
  • Distinct Representations of Olfactory Information in Different Cortical Centres
    LETTER doi:10.1038/nature09868 Distinct representations of olfactory information in different cortical centres Dara L. Sosulski1, Maria Lissitsyna Bloom1{, Tyler Cutforth1{, Richard Axel1 & Sandeep Robert Datta1{ Sensory information is transmitted to the brain where it must be behaviours, but is unlikely to specify innate behaviours. Rather, innate processed to translate stimulus features into appropriate beha- olfactory behaviours are likely to result from the activation of genetically vioural output. In the olfactory system, distributed neural activity determined, stereotyped neural circuits. We have therefore developed a in the nose is converted into a segregated map in the olfactory strategy to trace the projections from identified glomeruli in the olfactory bulb1–3. Here we investigate how this ordered representation is bulb to higher olfactory cortical centres. transformed in higher olfactory centres in mice. We have Mitral and tufted cells that innervate a single glomerulus were developed a tracing strategy to define the neural circuits that labelled by electroporation of tetramethylrhodamine (TMR)-dextran convey information from individual glomeruli in the olfactory under the guidance of a two-photon microscope. This technique labels bulb to the piriform cortex and the cortical amygdala. The spatial mitral and tufted cells that innervate a single glomerulus and is suffi- order in the bulb is discarded in the piriform cortex; axons from ciently robust to allow the identification of axon termini within mul- individual glomeruli project diffusely to the piriform without tiple higher order olfactory centres (Figs 1a–c, 2 and Supplementary apparent spatial preference. In the cortical amygdala, we observe Figs 1–4). Labelling of glomeruli in the olfactory bulbs of mice that broad patches of projections that are spatially stereotyped for indi- express GFP under the control of specific odorant receptor promoters vidual glomeruli.
    [Show full text]
  • Comprehensive Connectivity of the Mouse Main Olfactory Bulb: Analysis and Online Digital Atlas
    ORIGINAL RESEARCH ARTICLE published: 07 August 2012 NEUROANATOMY doi: 10.3389/fnana.2012.00030 Comprehensive connectivity of the mouse main olfactory bulb: analysis and online digital atlas Houri Hintiryan , Lin Gou , Brian Zingg , Seita Yamashita , Hannah M. Lyden , Monica Y. Song , Arleen K. Grewal , Xinhai Zhang , Arthur W. Toga and Hong-Wei Dong* Laboratory of Neuro Imaging, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA Edited by: We introduce the first open resource for mouse olfactory connectivity data produced as Jorge A. Larriva-Sahd, Universidad part of the Mouse Connectome Project (MCP) at UCLA. The MCP aims to assemble a Nacional Autónoma de México, whole-brain connectivity atlas for the C57Bl/6J mouse using a double coinjection tracing Mexico method. Each coinjection consists of one anterograde and one retrograde tracer, which Reviewed by: Marco Aurelio M. Freire, Edmond affords the advantage of simultaneously identifying efferent and afferent pathways and and Lily Safra International Institute directly identifying reciprocal connectivity of injection sites. The systematic application for Neurosciences of Natal, Brazil of double coinjections potentially reveals interaction stations between injections and Juan Andrés De Carlos, Instituto allows for the study of connectivity at the network level. To facilitate use of the data, Cajal (Consejo Superior de Investigaciones Científicas), Spain raw images are made publicly accessible through our online interactive visualization *Correspondence: tool, the iConnectome, where users can view and annotate the high-resolution, Hong-Wei Dong, Laboratory of multi-fluorescent connectivity data (www.MouseConnectome.org). Systematic double Neuro Imaging, Department of coinjections were made into different regions of the main olfactory bulb (MOB) and data Neurology, David Geffen School of from 18 MOB cases (∼72 pathways; 36 efferent/36 afferent) currently are available to Medicine, University of California, Los Angeles, 635 Charles E.
    [Show full text]
  • Plume Dynamics Structure the Spatiotemporal Activity of Mitral/Tufted Cell Networks in the Mouse Olfactory Bulb
    ORIGINAL RESEARCH published: 30 April 2021 doi: 10.3389/fncel.2021.633757 Plume Dynamics Structure the Spatiotemporal Activity of Mitral/Tufted Cell Networks in the Mouse Olfactory Bulb Suzanne M. Lewis 1*, Lai Xu 1, Nicola Rigolli 2,3, Mohammad F. Tariq 4, Lucas M. Suarez 1, Merav Stern 5, Agnese Seminara 3 and David H. Gire 1* 1 Department of Psychology, University of Washington, Seattle, WA, United States, 2 Dipartimento di Fisica, Istituto Nazionale Fisica Nucleare (INFN) Genova, Universitá di Genova, Genova, Italy, 3 CNRS, Institut de Physique de Nice, Université Côte d’Azur, Nice, France, 4 Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States, 5 Department of Applied Mathematics, University of Washington, Seattle, WA, United States Although mice locate resources using turbulent airborne odor plumes, the stochasticity and intermittency of fluctuating plumes create challenges for interpreting odor cues in natural environments. Population activity within the olfactory bulb (OB) is thought to process this complex spatial and temporal information, but how plume dynamics Edited by: impact odor representation in this early stage of the mouse olfactory system is unknown. Shaina M. Short, The University of Utah, United States Limitations in odor detection technology have made it difficult to measure plume Reviewed by: fluctuations while simultaneously recording from the mouse’s brain. Thus, previous Andreas Schaefer, studies have measured OB activity following controlled odor pulses of varying profiles or Francis Crick Institute and University frequencies, but this approach only captures a subset of features found within olfactory College London, London, United Kingdom plumes. Adequately sampling this feature space is difficult given a lack of knowledge Shawn Denver Burton, regarding which features the brain extracts during exposure to natural olfactory scenes.
    [Show full text]
  • The Olfactory Bulb Theta Rhythm Follows All Frequencies of Diaphragmatic Respiration in the Freely Behaving Rat
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Frontiers - Publisher Connector ORIGINAL RESEARCH ARTICLE published: 11 June 2014 BEHAVIORAL NEUROSCIENCE doi: 10.3389/fnbeh.2014.00214 The olfactory bulb theta rhythm follows all frequencies of diaphragmatic respiration in the freely behaving rat Daniel Rojas-Líbano 1,2†, Donald E. Frederick 2,3, José I. Egaña 4 and Leslie M. Kay 1,2,3* 1 Committee on Neurobiology, The University of Chicago, Chicago, IL, USA 2 Institute for Mind and Biology, The University of Chicago, Chicago, IL, USA 3 Department of Psychology, The University of Chicago, Chicago, IL, USA 4 Departamento de Anestesiología y Reanimación, Facultad de Medicina, Universidad de Chile, Santiago, Chile Edited by: Sensory-motor relationships are part of the normal operation of sensory systems. Sensing Donald A. Wilson, New York occurs in the context of active sensor movement, which in turn influences sensory University School of Medicine, USA processing. We address such a process in the rat olfactory system. Through recordings of Reviewed by: the diaphragm electromyogram (EMG), we monitored the motor output of the respiratory Thomas A. Cleland, Cornell University, USA circuit involved in sniffing behavior, simultaneously with the local field potential (LFP) of Emmanuelle Courtiol, New York the olfactory bulb (OB) in rats moving freely in a familiar environment, where they display University Langone Medical Center, a wide range of respiratory frequencies. We show that the OB LFP represents the sniff USA cycle with high reliability at every sniff frequency and can therefore be used to study the *Correspondence: neural representation of motor drive in a sensory cortex.
    [Show full text]
  • Special Issue “Olfaction: from Genes to Behavior”
    G C A T T A C G G C A T genes Editorial Special Issue “Olfaction: From Genes to Behavior” Edgar Soria-Gómez 1,2,3 1 Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain; [email protected] or [email protected] 2 Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, 48940 Leioa, Spain 3 IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain Received: 12 June 2020; Accepted: 15 June 2020; Published: 15 June 2020 The senses dictate how the brain represents the environment, and this representation is the basis of how we act in the world. Among the five senses, olfaction is maybe the most mysterious and underestimated one, probably because a large part of the olfactory information is processed at the unconscious level in humans [1–4]. However, it is undeniable the influence of olfaction in the control of behavior and cognitive processes. Indeed, many studies demonstrate a tight relationship between olfactory perception and behavior [5]. For example, olfactory cues are determinant for partner selection [6,7], parental care [8,9], and feeding behavior [10–13], and the sense of smell can even contribute to emotional responses, cognition and mood regulation [14,15]. Accordingly, it has been shown that a malfunctioning of the olfactory system could be causally associated with the occurrence of important diseases, such as neuropsychiatric depression or feeding-related disorders [16,17]. Thus, a clear identification of the biological mechanisms involved in olfaction is key in the understanding of animal behavior in physiological and pathological conditions.
    [Show full text]
  • Smell & Taste.Pdf
    Smell and Taste 428 Special senses 1. SMELL (OLFACTION) 1.1 Overview Smell is the least Understood sense. It is mainly subjective. In dogs and other animals, it is more developed than humans. - There are dfferent stimuli that can be smelled such as: camphoraceous, musky, flora (flower), pepperminty, ethereal, pungent, putrid 1.2 Structure of Olfactory epithelium and bulb See the figure on the next page! 1.2.1 Olfactory mucous membrane It is the upper lining of the nasal cavity (near the septum), containing olfactory (odorant) receptors that are responsible for smelling. o Olfactory receptors are bipolar neurons which receive stimuli in the nasal cavity (through cilia) and transmits them through axons, leave the olfactory epithelium and travel into CNS (olfactory bulb). o Although they are nerve cells, olfactory receptor cells are replaced every 60 days or so, and they grow their axon into the correct place in CNS. Olfactory epithelium contains three types of cells (the olfactory receptors cells discussed) as well as two other types of cells: o Olfactory (Bowman’s) glands: produce mucus that dissolves odorants o Supporting cell o Basal cells: regenerate olfactory receptor cells. 1 Smell and Taste 428 1.2.2 Olfactory bulb The olfactory bulb is made up of nerves that receive olfactory signals from axons of olfactory receptor cells. These nerves are of two cell types: o Mitral cells (most important) (M) o Tufted cells (smaller than mitral cells) (T) Mitral and tufted cells release glutamate The synapse between the axons of olfactory receptor cells and dendrites of mitral cells occur in clusters called olphactory glomeruli (OG) In a glomerulus, about 1000 olfactory receptor axons converge onto 1 mitral cell.
    [Show full text]
  • Arc-Expressing Neuronal Ensembles
    14070 • The Journal of Neuroscience, October 14, 2015 • 35(41):14070–14075 Brief Communications Arc-Expressing Neuronal Ensembles Supporting Pattern Separation Require Adrenergic Activity in Anterior Piriform Cortex: An Exploration of Neural Constraints on Learning X Amin MD. Shakhawat,1 XAli Gheidi,1 X Iain T. MacIntyre,1 Melissa L. Walsh,1 XCarolyn W. Harley,2 and XQi Yuan1 1Division of Biomedical Sciences, Faculty of Medicine, and 2Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John’s, Newfoundland A1B 3V6, Canada Arc ensembles in adult rat olfactory bulb (OB) and anterior piriform cortex (PC) were assessed after discrimination training on highly similar odor pairs. Nonselective ␣- and ␤-adrenergic antagonists or saline were infused in the OB or anterior PC during training. OB adrenergic blockade slowed, but did not prevent, odor discrimination learning. After criterion performance, Arc ensembles in anterior piriform showed enhanced stability for the rewarded odor and pattern separation for the discriminated odors as described previously. Anterior piriform adrenergic blockade prevented acquisition of similar odor discrimination and of OB ensemble changes, even with extended overtraining. Mitral and granule cell Arc ensembles in OB showed enhanced stability for rewarded odor only in the saline group. Pattern separation was not seen in the OB. Similar odor discrimination co-occurs with increased stability in rewarded odor representa- tions and pattern separation to reduce encoding overlap. The difficulty of similar discriminations may relate to the necessity to both strengthen rewarded representations and weaken overlap across similar representations. Key words: Arc; norepinephrine; odor discrimination; olfactory bulb; pattern separation; piriform cortex Significance Statement We show for the first time that adrenoceptors in anterior piriform cortex (aPC) must be engaged for adult rats to learn to discriminate highly similar odors.
    [Show full text]
  • Clusters of Secretagogin-Expressing Neurons in the Aged Human Olfactory Tract Lack Terminal Differentiation
    Clusters of secretagogin-expressing neurons in the aged human olfactory tract lack terminal differentiation Johannes Attemsa,1, Alan Alparb,c,1, Lauren Spenceb, Shane McParlanda, Mathias Heikenwalderd, Mathias Uhléne, Heikki Tanilaf, Tomas G. M. Hökfeltg,2, and Tibor Harkanyb,c,2 aInstitute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE4 5PL, United Kingdom; bEuropean Neuroscience Institute at Aberdeen, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; cDivision of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, and gDepartment of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden; dInstitute of Virology, Technische Universität/Helmholtz Zentrum München, D-81675 Munich, Germany; eScience for Life Laboratory, Royal Institute of Technology, SE-17121 Stockholm, Sweden; and fDepartment of Neurology, Kuopio University Hospital and A. I. Virtanen Institute, University of Eastern Finland, FI-70211, Kuopio, Finland Contributed by Tomas G. M. Hökfelt, March 6, 2012 (sent for review November 10, 2011) Expanding the repertoire of molecularly diverse neurons in the olfactory system, we found secretagogin-positive (secretagogin+) human nervous system is paramount to characterizing the neuro- neurons in the RMS and olfactory bulb (16). Therefore, we hy- nal networks that underpin sensory processing. Defining neuronal pothesized that secretagogin may reveal previously undescribed identities is particularly timely in the human olfactory system, cellular identities and cytoarchitectural
    [Show full text]