2011.10.14.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 1 Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund *** **Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg. PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY sote_logo.jpg dk_fejlec.gif INFOBLOKK 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 2 Peter Pazmany Catholic University Faculty of Information Technology BEVEZETÉS A FUNKCIONÁLIS NEUROBIOLÓGIÁBA INTRODUCTION TO FUNCTIONAL NEUROBIOLOGY www.itk.ppke.hu By Imre Kalló Contributed by: Tamás Freund, Zsolt Liposits, Zoltán Nusser, László Acsády, Szabolcs Káli, József Haller, Zsófia Maglóczky, Nórbert Hájos, Emilia Madarász, György Karmos, Miklós Palkovits, Anita Kamondi, Lóránd Erőss, Róbert Gábriel, Kisvárdai Zoltán Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 3 www.itk.ppke.hu Olfaction: Determining the chemical constituents (odorants) of the environment and encoding it in the CNS Imre Kalló & Zoltán NusserPázmány Péter Catholic University, Faculty of Information Technology I. Olfactory receptors. II. Cells and synaptic connections of the olfactory bulb. III. Network activity (rhythms and oscillations) and encoding of information in the olfactory bulb. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 4 www.itk.ppke.hu CNS Sensory organs Sensory organs Sensory organs Sensory organs Sensory organs Living organism Muscles Behavior Audition Taste Olfaction Vision Environment Sensation of touch, cold, heat, pain and the position of joints Sensation of linear&angular acceleration Introduction to functional neurobiology: Olfaction OlphactoryBulb copy.jpg 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 5 www.itk.ppke.hu Location of the olfactory sensory organ in humans Olfactory bulb Granule cell Mitral cell Glomerulus Olfactoryreceptor cell Nasal cavity Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 6 www.itk.ppke.hu nose-olf-epithelium Location of the olfactory epithelium (OE; containing olfactory receptor cells) in the mouse nasal cavity Ref:Ma M, Grosmaitre X, Iwema CL, Baker H, Greer CA, Shepherd GM. Olfactory signaltransduction in the mouse septal organ. J Neurosci. 2003 Jan 1;23(1):317-24. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 7 www.itk.ppke.hu Location of the olfactory epithelium (OE; containing olfactory receptor cells) in the mouse nasal cavity Exp:Immunohistochemicalstudiesvisualisingtheolfactorymarkerproteinwereemployedtodemonstratethedistributionofreceptorcellsinthenasalmucosa,whichallowstargetingofthesecellsspecificallyinmorphologicalandfunctionalstudies.Frontalsectionsofthemousenasalcavitywerecutandinvestigatedinbrightfieldandfluorescentmicroscopes.Comparisonoftheimagesrevealedthatthereceptorcellsaredistributedonlargesurfacesofthenasalcavityinvolvingtheroof,theseptumaswellastheconchae. Ref:Ma M, Grosmaitre X, Iwema CL, Baker H, Greer CA, Shepherd GM. Olfactory signaltransduction in the mouse septal organ. J Neurosci. 2003 Jan 1;23(1):317-24. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 8 www.itk.ppke.hu Structure of the olfactory bulb and mucosa Axons (olfactory nerve) Mitral cells Olfactory bulb Axons (olfactory fila) Cribriform plate Olfactory receptor cells (about 10-20 million cells) Mucous Glomeruli Olfactory mucosa Air and odorants Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 9 www.itk.ppke.hu Structure of the olfactory mucosa Cribriform plate Basal cells (stem cells) Developing receptor cell Olfactory receptor cell Surface (supporting) epithelial cell Cilia Microvilli Mucous Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 10 www.itk.ppke.hu Location of the Jacobson’s (vomeronasal) organ Jacobson’s vomeronasal organ (VNO) is the site of sensation for pheromones. This organ is absent in humans, but has important role in animals to find mates, territorial borders and to determinesexual responsiveness etc. VNO VNO OE OE Nasal cavity Nasal cavity Mitral cells to AOT to LOT Terminal nerve Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 11 www.itk.ppke.hu The superfamily of olfactory receptor genes Ref: Buck L, Axel R (1991) A novel multigene family may encodeodorant receptors: a molecular basis for odor recognition. Cell 65:175-187.10 Olfactory genes are in large clusters at more than 25 different locations Chromosomes 5-30 genes in the clusters Coding regions (no introns present) Non-coding regions There are more than 1000 genes(gene homology is about 40-90%). 3% of all human genes. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 12 www.itk.ppke.hu Structure of the olfactory-(OR) and vomeronasal (VR1 and VR2) receptors ORs_3.jpg ORs_1.jpg ORs_2.jpg V1Rs (~35) ORs (~1000) V2Rs (~150) Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 13 www.itk.ppke.hu Activation of olfactory receptors and signal transduction G AC ATP cAMP Ca++ Na+ K+ Cl- Ca++ + - gCl(Ca) gCNG K+ 2Cl- Na+ NKCCl Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 14 www.itk.ppke.hu Activation of olfactory receptors and signal transduction Olfaction2 Na+ Ca2+ Na+ Ca2+ cAMP ATP Olfactory receptor G protein G.olf Adenylatecyclase Cytoplasm membrane Cytoplasma Odorants Cyclic nucleotid-gated ion channel Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 15 www.itk.ppke.hu Cyclic AMP mediated signal transduction in the olfactory epithelial cells (AC activator) (AC inhibitor) (phosphodiesterase inhibitor) Ref:Ma M, Grosmaitre X, Iwema CL, Baker H, Greer CA, Shepherd GM. Olfactory signaltransduction in the mouse septal organ. J Neurosci. 2003 Jan 1;23(1):317-24. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 16 www.itk.ppke.hu Cyclic AMP mediated signal transduction in the olfactory epithelial cells Exp:Intactolfactoryepitheliumwaspreparedandexposedtoodorants.Perforatedpatch-clamprecordingswereperformedonthedendriticknobsofindividualolfactoryepithelialcells(OEC)tostudythecurrentsgeneratedbyodorantsandcompoundsinfluencingsignaltransduction.Odorants,andcompoundselevatingcyclicnucleotidlevelsinducedinwardcurrentsintheneuronsundervoltage-clampmode.Incontrast,ablockeroftheadenylatecyclaseinhibitedthiscurrentsupportingthecrucialroleofcAMPinthesignaltransductionofOECs. Ref:Ma M, Grosmaitre X, Iwema CL, Baker H, Greer CA, Shepherd GM. Olfactory signaltransduction in the mouse septal organ. J Neurosci. 2003 Jan 1;23(1):317-24. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 17 www.itk.ppke.hu Studies on the specificity of olfactory receptors in a gene expression model mOR912-93: -G.15, GqoG.: - mOR912-93: -G.15, GqoG.: + mOR912-93: + G.15, GqoG.: - mOR912-93: + G.15, GqoG.: + 2-heptanon Expressed genes: ORSpec1.png ORSpec2.png ORSpec4.png ORSpec3.png ATP Exp:HEK293cellsweretransfectedinvitrowithconstructsofgenesnormallynotexpressedinthiscellline,i.e.genescodingmouseolfactoryreceptors(mOR912-93)and/orGproteinsubunits(G.15,GqoG.).ChangesofintracellularCa2+concentrationwasmeasuredinresponsetoasingleodorantandtoanubiquitousactivatoroftheCNGchannelsbyusingFURA-2calciumindicator. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 18 www.itk.ppke.hu Studies on the specificity of olfactory receptors in a gene expression model : Ca responses to aliphatic ketones with slightly different carbon numbers Exp:ChangesofintracellularCa2+concentrationwasmeasuredinresponsetoslightlydifferentodorantsandtoanubiquitousactivatoroftheCNGchannelsbyusingFURA-2calciumindicator.. ORsSecK1.jpg ORsSecK2.jpg ORsSecK3.jpg 2-heptanon 2-butanon 2-dekanon ATP ATP ATP Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 19 www.itk.ppke.hu Response of a single olfactory epithelial cell to various odorants Exp:Theactivityofsingleolfactoryreceptorneuronswasrecordedinvivofromaratandexposedtovariousodorants.Singleunit(extracellular)recordingswereperformedonanolfactoryepithelialcelltostudyitsfiringactivitychangesevokedbyvariousodorants. Spontaneous actvity Metilamyl ketone Limonene Vanilla Ciklodekanon Isoamylacetate Cinammon ODOR PULSE for 2sec Ref:Duchamp-Viretet al., Odor response properties of rat olfactory receptor neurons.Science. 1999, 284:2171-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 20 www.itk.ppke.hu Response of a single olfactory epithelial cell to exposure of various concentrations of cineole Exp:Olfactoryepithelialcellswereisolatedfromafrog.Receptorcurrentsandspiketrainswererecordedbythesuction-pipetterecordingtechnique.Thecellbodywasdrawnintoasuctionpipette,leavingtheciliaexposedtothesuperfusingsolution,withintheconcentrationoftheodorantcineolewasraisedgradually. ODOR PULSE for 1 sec Ref:ReisertJ, Matthews HR. Adaptation of the odor-induced response in frogolfactory receptor cells.J Physiol(London). 1999, 519:801-813. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 21 www.itk.ppke.hu Response of a single olfactory epithelial cell to exposure of various concentrations of cineole Exp:Olfactoryepithelialcellswereisolatedfromafrog.Receptorcurrentsandspiketrainswererecordedbythesuction-pipetterecordingtechnique.Thecellbodywasdrawnintoasuctionpipette,leavingtheciliaexposedtothesuperfusingsolution,withintheconcentrationoftheodorantcineolewasraisedgradually. ODOR PULSE Ref:ReisertJ, Matthews HR. Adaptation of the odor-induced response in frogolfactory receptor cells.J Physiol(London). 1999, 519:801-813. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 22 www.itk.ppke.hu Response of a single olfactory epithelial cell to exposure of various concentrations of cineole Spike frequency Number of spikes Latency or time to peak Ref:ReisertJ, Matthews HR. Adaptation of the odor-induced response in frogolfactory receptor cells.J Physiol(London). 1999, 519:801-813. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 23 www.itk.ppke.hu Activity patterns evoked by different chemical compounds in the OECs Ref:Buck, The Molecular Architecture of Odor and Pheromone Sensing in Mammals Cell, 2000, 100, 611-618 ActPat1.jpg ActPat4.jpg ActPat2.jpg ActPat5.jpg ActPat3.jpg Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 24 www.itk.ppke.hu Adaptation of receptor currents evoked by repeated exposure to odorants: effect of concentration at conditional pulse Exp:Olfactoryepithelialcellswereexposedtwicetocineole.Firsttherecordedcellwasexposedtoincreasingconcentrationofcineole(aconditionalpulse),whichwasfollowedbyasecondpulseofcineole(testpulse;usingthesameconcentrationineachtrial).Receptorcurrentsandspiketrainsgeneratedbythetestpulsewereanalysed. ODOR PULSE Ref:ReisertJ, Matthews HR. Adaptation of the odor-induced response in frogolfactory receptor cells.J Physiol(London). 1999, 519:801-813. Introduction to functional neurobiology: Olfaction www.itk.ppke.hu 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 25 Adaptation of receptor currents evoked by repeated exposure to odorants: effect of concentration at test pulse Exp:Olfactoryepithelialcellswereexposedtwicetocineole.Firsttherecordedcellwasexposedtostableconcentrationofcineole(aconditionalpulse),whichwasfollowedbyasecondpulseofcineole(testpulse;usingthistimeanincreasingconcentrationineachtrial).Receptorcurrentsandspiketrainsgeneratedbythetestpulsewereanalysed. ODOR PULSE Ref:ReisertJ, Matthews HR. Adaptation of the odor-induced response in frogolfactory receptor cells.J Physiol(London). 1999, 519:801-813. Introduction to functional neurobiology: Olfaction CondTest.png 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 26 www.itk.ppke.hu Adaptation of receptor currents evoked by repeated exposure to odorants: effect of inter-pulse time Exp:OlfactoryepithelialcellswereexposedtoodorantsorthephosphodiesteraseinhibitorIBMXwithdifferentinter-pulseintervals. CondTest2.png ODOR PULSE IBMX PULSE (phosphodiesterase inhibitor) 2 s 1 s 50 pA 50 pA Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 27 www.itk.ppke.hu Summary: OECs Theolfactorymucosaisaspecialareaofthenasalmucosa,whichisabout5cm2inhumans(150cm2indogs!),andcoversthedorsalandposteriorpartofthenasalcavity.Structurallyitcontainsolfactoryepithelialcells(OECs;10-20millioninhumans,200millionsindogs),supportingcellsandbasalcells. OECsareproducedthroughoutlife(every60daystheyarerenewed)fromthebasalprecursorcells.Theyrecogniseagreatdiversityofodorantswithspecialolfactoryreceptorproteins. Theolfactoryreceptorproteinsareseventransmembraneregion-containingreceptorscoupledtoGprotein(G.olf).Byactivatingtheadenylatecyclase,theyincreasetheintracellularlevelofcAMP,whichinturnopencyclicnucleotide-gatedionchannels,andconsequentlydepolariseOECsandcauseCa2+influx.Ca2+activatesCa2+dependentCl-channels,throughwhichtheCl-effluxresultsinfurtherdepolarization. AsingleOECexpressonlyasingleolfactoryreceptorprotein,whichsuggestitshighspecificity. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 28 www.itk.ppke.hu Summary: OECs Asinglereceptorproteinisabletobindseveralchemicalmolecules/odorantsandasinglechemicalmoleculecanbindtoseveralreceptorproteins.Differentchemicalmoleculesarecapabletoincrease(stimulatory)ordecrease(inhibitory)theactivityofOECs.Takentogether,theolfactoryreceptors,andherebytheOECsshowalowspecificityforthemolecules(severalodorantsstimulatethem). Everymoleculeinducestheirowncharacteristicactivitypattern(inspaceandtime)intheolfactoryglomeruli.Differentmoleculesinducepartiallyoverlapping,butnotidenticalactivitypatterns. TheodorantinducedelectricalresponsesofOECs(number,latencyandthefrequencyofactionpotentials)showadaptation.Theadaptationismanifestedinthesize(amplitudeandduration)ofreceptorcurrents.Aconditionalstimuluswithacertainconcentrationofodorantsreducetheextentoftheresponsetotheteststimulus.Largertheconcentrationofodorantsduringtheconditionalstimulus,thestrongertheadaptationrecordedattheteststimulus(shiftinthedose-responsecurve) Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 29 www.itk.ppke.hu Olfaction: Cellular elements and synaptic connections of the olfactory bulb Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 30 www.itk.ppke.hu Layers of the olfactory bulb OB.tif Olfactory epithelial cells Cribriform plate Layer of olfactory fibers Glomerular layer External plexiform layer Mitral cell layer Internal plexiform layer Granule cell layer Granule cells Mitral cell OEC Periglomerular cells Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 31 www.itk.ppke.hu Cells of the olfactory bulb Mitral/tufted cells Granule cell Periglomerular cells OECs -axons Granule cell Deep, short axon cells Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 32 www.itk.ppke.hu Mitral cells (excitatory, glutamatergic neurons) mitral sejtek Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 33 www.itk.ppke.hu MA137 for publication XY view 2 copy MA137 for publication YZ view sideways 3 Tufted cells (excitatory, glutamatergic neurons) Ref:Antal M, Eyre M, Finklea B, Nusser Z. External tufted cells in the main olfactory bulb form two distinct subpopulations. Eur J Neurosci. 2006 Aug;24(4):1124-36. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 34 www.itk.ppke.hu Intrabulbar, topographic projection of tufted cells Intrabulbar3.jpg Intrabulbar1.jpg Intrabulbar2.jpg Ref: Belluscioet al., Odorant receptors instruct functional circuitry in the mouse olfactory bulb, Nature, 419, 296-300. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 35 www.itk.ppke.hu Granule cells (inhibitory, GABAergic neurons) granule cells Ref: Sheperd, Synaptic Organization of the Brain, Oxford UnivPress, 2004 Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 36 www.itk.ppke.hu Deep, short-axon neurons (inhibitory, GABAergic neurons) EYRE Figure1 3D dSAC subtypes on same plot Ref:Eyre MD, Antal M, Nusser Z. Distinct deep short-axon cell subtypes of the main olfactory bulb provide novel intrabulbar and extrabulbar GABAergic connections. J Neurosci. 2008 Aug 13;28(33):8217-29. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 37 www.itk.ppke.hu Synaptic connectivity of the olfactory bulb OLFACTORY CORTEX OLFACTORY BULB basal forebrain midbrain thalamus motor output limbic system prefrontal cortex perception motor output commissural FRONTAL LOBE Introduction to functional neurobiology: Olfaction ONSyn.jpg olfactory cells axon terminals 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 38 www.itk.ppke.hu Intrabulbar synaptic connections: Glomerulus mitral/tufted cells primary dendrite PG cell dendrite PG cell axon Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 39 www.itk.ppke.hu Intrabulbar synaptic connections: External plexiform layer ONSyn2.jpg mitral/tufted cells primary dendrite granule cell dendrite 1 µm Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 40 www.itk.ppke.hu Dendro-dendritic reciprocal synapses in the external plexiform layer ONSyn3.jpg mitral/tufted cells dendrite granule cell dendrite Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 41 www.itk.ppke.hu A high density of GABAergic synapsesis present in the external plexiform layer Olf bulb gephyrin low mag Olf bulb gephyrin highmag Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 42 www.itk.ppke.hu The excitatory postsynaptic potentials (EPSPs) recorded intracellularly in granule cells are generated by the activation of AMPA and NMDA receptors EPSPgranule.png Ref: Chen et al., Analysis of relations between NMDA receptors and GABA release at olfactory bulb reciprocal synapses. 2000, 25, 625-33. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 43 www.itk.ppke.hu The inhibitory postsynaptic potentials (IPSPs) recorded intracellularly in mitral cells are generated by the activation of GABAAreceptors Ref: Chen et al., Analysis of relations between NMDA receptors and GABA release at olfactory bulb reciprocal synapses. 2000, 25, 625-33. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 44 www.itk.ppke.hu Synchronous activation of mitral cells projecting to the same glomerulus Ref:SchoppaNE, Westbrook GL. AMPA autoreceptorsdrive correlated spiking inolfactory bulb glomeruli. Nat Neurosci. 2000, 5:1194-202. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 45 www.itk.ppke.hu Synchronous activation of mitral cells projecting to the same glomerulus Ref:SchoppaNE, Westbrook GL. AMPA autoreceptorsdrive correlated spiking inolfactory bulb glomeruli. NatNeurosci. 2002 Nov;5(11):1194-202. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 46 www.itk.ppke.hu Dendritic electric synapses (gap junctions) are responsible for the synchronous activation of mitral cells projecting to the same glomerulus Ref:SchoppaNE, Westbrook GL. AMPA autoreceptorsdrive correlated spiking inolfactory bulb glomeruli. NatNeurosci. 2002 Nov;5(11):1194-202. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 47 www.itk.ppke.hu Distribution of connexin36 proteins establishing gap junctions in the olfactory bulb Olf bulb cx36 highmag Olf bulb cx36 low mag Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 48 www.itk.ppke.hu Electron microscopic localization of connexin36 Olf bulb cx36 EM Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 49 www.itk.ppke.hu Summary: layers and cells Layersoftheolfactorybulb:Layerofolfactoryfila,glomerularlayer,externalplexiformlayer,layerofmitralcells,internalplexiformlayer,layerofgranule Cellularelementsoftheolfactorybulb:Juxtaglomerularcells(externaltuftedandperiglomerularcells),middleandinternaltuftedcells,mitralcells,granulecellsandshort-axoncells Mitralcells:Theyaretheprincipalcellsoftheolfactorybulbprovidingexcitatoryprojectionstootherpartsofthebrain.Theircellbodiesare15-30µmwithoneprimarydendriteramifyinginasingleglomerulus,wheretheyreceivetheirmainexcitatoryinputfromtheaxonsofOECs.Theyhaveseveralsecundaryorlateraldendrites,whichareseveralmillimeterslongandestablishreciprocaldendro-dendriticconnections. Tuftedcells:Theyarealsoprincipalcellsoftheolfactorybulb.Excitatory,glutamtergiccellswithsynapticconnectionsverysimilartothoseestablishedbymitralcells.Theyhave,however,moreextensive,wide-spredlocalcollateralsintheinternalplexiformlayer. Granulecells:GABAergic,inhibitoryinterneurons,withnoaxons!Theircellbodiesare6-8µm,andthedendritesare200-400µm.Thedendritesreceivetheinput(mainlyexcitatoryfrommitralcells),aswellasprovidetheoutput(inhibitory,ontothelateraldendritesofmitralcells). Periglomerularcells:GABAergicinhibitoryinterneurons.Someofthosearedopaminergic.Theyhavesmallcellbodies,andasingle,shortdendriteramifyingintheglomerulus.TheyreceiveexcitatoryinputfromtheaxonsofOECsandthedendritesofmitral/tuftedcells.TheyprovideaGABAergicoutputtothedendritesofmitral/tuftedcellsandtootherperiglomerularcells. Short-axoncells:GABAergicinhibitoryinterneurons,whichcanbefoundinalmostalllayers. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 50 www.itk.ppke.hu Summary: synaptic connections Sensory input: Excitatory, glutamatergic input from the OECs in the glomeruli. Central (centrifugal) inputs: From the pyramidal cells of the olfactory cortex (glutamatergic), from the anterior olfactory nucleus (glutamatergic), the DBB (cholinergic), the locus coeruleus (noradrenergic) and the raphe nuclei (serotonergic). Most of the centrifugal fibers terminate in the granule cell layer. Central (centripetal) outputs : Mitral-and tufted cells project to the primary olfactory cortex, the anterior olfactory nucleus, the taenia tectae, the dorsal peduncular nucleus, the anterior cortical amygdaloid nucleus and the lateral olfactory tract nucleus. The olfactory cortex projects also to several other brain regions including the thalamus, limbic system, prefrontal cortex etc. Intrabulbar synaptic connections: In the glomeruli: Axon terminals of the OECs provide excitatory (glutamatergic) input to the primary dendrites of mitral/tufted cells and to the dendrites of certain periglomerular cells. The periglomerular cells establish dendro-dendritic synapses with the primary dendrites of mitral/tufted cells , and vica versa receive excitatory dendro-dendritic inputs. The periglomerular cells establish inhibitory dendro-dendritic synapses and axo-dendritic synapses with each others’ dendrites.Dendritic gap junctions are responsible for the synchronous activity of mitral cells projecting to the same glomeruli. External plexiform layer: Lateral dendrites of mitral/tufted cells establish dendro-dendritic reciprocal synapses with the dendrites of granule cells. The mitral/tufted cells provides excitatory (via glutamatergic synapses) input to the dendrites of granule cells, and vica versa receive inhibitory, GABAergic input. Internal plexiform layer: Local collaterals of mitral/tufted cells establish excitatory axo-dendritic synapses with the dendrites of granule cells and deep, short-axon cells. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 51 www.itk.ppke.hu Olfaction: Network phenomena (rhythmic phenomena, oscillations) and encoding the information Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 52 www.itk.ppke.hu V Measuring field potentials From the surface of the skull (EEG) From the surface of the brain From the brain (a certain brain region) The field potential is the summation of spatial and temporal alterations of synaptic and voltage-dependent currents in a defined region of the brain. Consequently, it refers to and characterizes the activity of a certain cell or afferent population. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 53 www.itk.ppke.hu Oscillation: rhythmic change in the field potential The prerequisite of development of oscillation is the periodic and synchronous activity of a certain cell population. Periodic, but asynchronous activity of cells Cell1:I IIIIIII Cell 2:I IIIIIII Cell 3:I IIIIIII Cell 4: I IIIIIII All:IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Synchronous, but non-periodic activity of cells Cell1:II IIII I IIIIIII IIIIII Cell2:II IIII I IIIIIII IIIIII Cell3:II IIII I IIIIIII IIIIII Cell4: II IIII I IIIIIII IIIIII All:II IIII I IIIIIII IIIIII Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 54 www.itk.ppke.hu Oscillation: rhythmic change in the field potential The prerequisite of development of oscillation is the periodic and synchronous activity of a certain cell population. Cell1:I IIIIIIIIIIIIIIIIIIII Cell2: Cell3:I IIIIIIIIII Cell4: I IIIII Cell5: I IIIIIII Cell6: I IIIIIII Cell7: I IIIIIII All:I IIIIIIIIIIIIIIIIIIII Synchronous and periodic activity of cells Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 55 www.itk.ppke.hu Field potential recorded from behaving mice Resting stateExploration, sniffing Ref: Nusser Z, Kay LM, Laurent G, HomanicsGE, ModyI. Disruption of GABA(A)receptors on GABAergic interneurons leads to increased oscillatory power in theolfactory bulb network. J Neurophysiol. 2001 Dec;86(6):2823-33. Am PhysiolSoc, used with permission Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 56 www.itk.ppke.hu No information is carried solely by the oscillation of field potential; it marks simply, that a population of cells exhibits synchronous and periodic activity in a defined brain region. An examiner, however, can use the field potential as a timekeeper (time reference frame), i.e. can compare the activity of a single cell to it (to the activity of the rest of cells). Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 57 www.itk.ppke.hu Brain map or encoding information in the brain Brain map: It is part of the nervous system, where the distribution of neurons represents a sort of physico-chemical parameter of the environment (e.g. olfactory bulb). Topographic brain map: It is a sort of brain map, where the spatial distribution of neurons represents a defined parameter (neighborship) in the environment (e.g. in the visual field –retina). Code: Signs, symbols, system of rules, through which information can be transferred and regained into its original form. If brain map is part of the neuronal code, it means, that encoding and decoding of the information take by necessity in consideration the spatial distribution of the neurons. If the identity of the neurons (their own characteristic electric properties) counts, and not their regional distribution, then we talk about the identity coding. (An example, by which the physical arrangment is part of the code, is the genetic code, the DNA. Another example, by which the physical arrangement is surely not part of the code, is the encoding of the momentary location of the animal by the hippocampal place-cells.) Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 58 www.itk.ppke.hu Dynamically developing activity pattern in a population of cells Cell1:I IIIIIII Cell2: I III Cell3:I III Cell4:I III Cell5: I IIII Cell6: I III Cell7: All:I IIIIIII Odorant“A” Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 59 www.itk.ppke.hu Information coding with a dynamically developing activity pattern in a population of cells ‘population’, ’temporal’ and ’identity’ code (theory) Cell1:IIII I Cell2:III I Cell3:III Cell4: Cycle:1 2 3 4 Cell1:IIII I Cell2:III I Cell3: Cell4: IIIIIIIIII Cycle:1 2 3 4 Cell1:IIII Cell2:IIIIIII I Cell3:III Cell4:IIIIIIIII Cycle: 1 2 3 4 Cell1:III Cell2:III I Cell3:IIII I I Cell4:II III Cycle:1 2 3 4 Odorant “A” Odorant “C” Odorant “B” Odorant “D” Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 60 www.itk.ppke.hu Information coding with a dynamically developing activity pattern in a population of cells ‘population’, ’temporal’ and ’identity’ code (theory) Cell1: Cell2: Parallel recording of two ‘projection’ cells (corresponding to mitral cells) responding to 6 different odorant mixture in locust Ref: Stopferet al., Impaired odourdiscrimination on desynchronizationof odour-encoding neural assemblies. Nature, 1997, 390, 70-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 61 www.itk.ppke.hu Odorant evoked 30 Hz oscillation of field potential in the „mushroom body” Ref:Stopfer M, Bhagavan S, Smith BH, Laurent G. Impaired odour discrimination on desynchronization of odour-encoding neural assemblies. Nature. 1997 Nov 6;390(6655):70-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 62 www.itk.ppke.hu The GABAA receptor blocker picrotoxin removes the odorant-evoked oscillation of field potential in the „mushroom body” Ref:Stopfer M, Bhagavan S, Smith BH, Laurent G. Impaired odour discrimination on desynchronization of odour-encoding neural assemblies. Nature. 1997 Nov 6;390(6655):70-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 63 www.itk.ppke.hu The GABAA receptor blocker picrotoxin does not influence the specificity and the strength of the cellular response evoked by the odorants Ref:Stopfer M, Bhagavan S, Smith BH, Laurent G. Impaired odour discrimination on desynchronization of odour-encoding neural assemblies. Nature. 1997 Nov 6;390(6655):70-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 64 www.itk.ppke.hu The temporal synchronization of the firing of “projection” cells is necessary to distinguish molecules with similar chemical structure Ref:Stopfer M, Bhagavan S, Smith BH, Laurent G. Impaired odour discrimination on desynchronization of odour-encoding neural assemblies. Nature. 1997 Nov 6;390(6655):70-4. Introduction to functional neurobiology: Olfaction 2011.10.14. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 65 www.itk.ppke.hu Summary: information coding Anodorstimulusevokesatemporallychanging,complex,odor-specificresponse.Theresponsepatternissimilarfromtesttotest.Adifferentodorstimulusevokesadifferentresponsepatterninthesameneuron,andthesameodorstimulusgeneratesdifferentresponsepatternsinothercells.Takentogether,theodorevokedactivitypatternisspecificforthestimulusandalsoforthecells,whereitisgenerated. Tounderstandinformation-codingintheolfactorysystemitisnecessarytolearnabouttheidentityofcells,thetemporalpatternoftheiractivityandtheirsynchronityrelatedtoeachother.Itissuggestedthatintheolfactorysysteminformationisencodedbyadynamicallydevelopingactivitypattern(withtemporalandidentitycode)inapopulationofcells(inaneuronalensemble).