2011.10.12.. 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 2011.10.12.. 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: Hippocampus 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 3 www.itk.ppke.hu HippocampusImre Kalló & Tamás FreundPázmány Péter Catholic University, Faculty of Information Technology I. Subdivisions and microcircuitry of the hippocampus. II. Interaction of excitatory and inhibitory cells. III. Septo-hippocampal pathway. IV. Theta oscillation, phase precession. V. Subcortical input of the hippocampus. VI. Gamma oscillation. Introduction to functional neurobiology: Hippocampus 10/12/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 4 062 HIPPOCAMPUSan archicortical area, which is in reciprocal connection to nearly all sensory and associative cortical areas via the entorhinal and perirhinal cortices 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 5 Introduction to functional neurobiology: Hippocampus Comparedtotheentirecerebralcortex,thesizeofthehippocampusismuchlargerinrodents,thaninhumans.Thissizedifferencesuggeststhatthememorytracesareratherstoredinthecerebralcortex. 063 Thehippocampusisessentialtoacquireandassociatedifferentsensoryinformations.Duringphilogenezis,itwashoweverunneccessaryforthehippocampustogrowparallelwiththecerebralcortextosupportthehighermemorycapacityinhumans! 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 6 Introduction to functional neurobiology: Hippocampus 066 Mostofthehippocampalneuronsexhibitaso-calledplacefield-selectivity,whichmanifestsintheirincreaseddischargerate,whentheexperimentalanimalenterstheirspecific”encodedarea”inthefield. Withtheindividualcontributionoftheplacecells,thehippocampusgeneratesacognitivemapoftheanimal’senvironment. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 7 Introduction to functional neurobiology: Hippocampus 056 Two behavior-dependent activity patterns characterize the field potential (EEG) recorded from the rodent hippocampus Theta activity (4-8 Hz oscillation) during exploration and paradox sleep Sharp waves, fast, irregular EEG in conscious, resting state, during feeding and slow-wave sleep 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 8 Introduction to functional neurobiology: Hippocampus 039 Major regions and pathways of the hippocampus The primary excitatory input derives from the entorhinal cortex through the perforant pathway. It innervates the dendrites of granule cells in the molecular layer of the dentate gyrus, and the most distal part of the dendrites of CA1-3 pyramidal cells in the lacunosum-moleculare layer. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 9 Introduction to functional neurobiology: Hippocampus 080 The trisynapticloop of the hippocampus The axons of the granule cells (mossy fibers) innervate the CA3 pyramidal cells, which in turn project (via the Schaffer collaterals in the radiatum and oriens layers) to the CA1 pyramidal cells. The latter cell population projects back to the entorhinal cortex. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 10 Introduction to functional neurobiology: Hippocampus 081 Local recurrent connections in the hippocampus 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 11 Introduction to functional neurobiology: Hippocampus Local recurrent connections in the hippocampus • Withinthehilus,axonsofthegranulecellsofthedentategyrus,themossyfibers,giveofflocalcollaterals,whichtheninnervateinterneuronsandhilarmossycells.Granulecellsdonotinnervatethemselves!!! • HilarmossycellsaretheassociationcellsoftheDG.Theiraxonsinnervatethedendritesofgranulecellsextendingquitefarlongitudinallywithintheinnerthirdofthemolecularlayer. • CA3pyramidalcellsestablishextensiveinterconnectionsthroughtheirrichrecurrentcollateral-network. • CA1pyramidalcellsdonotinnervateeachother(!),theiraxonsremainlocallyintheorienslayer,wheretheyterminateonfeed-backinterneurons. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 12 Introduction to functional neurobiology: Hippocampus Neuronal phenotypes of the hippocampus • Principalcells(excitatoryones–90% of theneurons): -Pyramidalcellsof theAmmon’shorn -Granulecellsof dentategyrus (DG) -Hilar mossycells(associationcellsof theDG) • Inhibitoryinterneurons (10% of theneurons): theirneurotransmitteris .-aminobutyricacide(GABA) 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 13 Introduction to functional neurobiology: Hippocampus CA3-piramis-rajz Principal (pyramidal and granule) cells, as major processing units of the hippocampus Theyareexcitatorycells,anduseglutamateasneurotransmitter.Theirdendritictreereceivesabout15to20thousandsexcitatorysynapse,mainlyfromotherpyramidalcells.AxonsofCA3pyramidalcellsstimulateabout40to60thousandsotherpyramidalcellsintheCA1andCA3regionsofthehippocampusformingaquasirandomlywirednetwork,whichischaracterizedwithhugedivergenceandconvergence.Incontrast,theCA1pyramidalcellsestablishlocalcollateralssparsely,whicharerestrictedtotheorienslayerandterminatemainlyoninhibitoryinterneurons. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 14 Introduction to functional neurobiology: Hippocampus 027 Principal cellsare knit in a single (pyramidal) layer (stratum) alveus str. oriens str. pyramidale str. radiatum str. lacunosum-moleculare 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 15 Introduction to functional neurobiology: Hippocampus 031 Theaxonoftheperisomaticinhibitorycells(red)ramifiesinthepyramidallayerbyestablishingmultiplecontactsonthesoma,proximaldendritesandaxoninitialsegmentofthepyramidalcells. Types:basket cells and axo-axonic (or chandalier) cells One basket cell innervate the perikaryon and proximal dendrites of more than 1000 pyramidal cells. Laminar distribution of their dendritic tree (blue) is in overlap with that of the pyramidal cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 16 Introduction to functional neurobiology: Hippocampus 088 The axo-axonic (chandalier) cells A type of perisomatic inhibitory cells, which innervatesselectively the axon initial segment (AIS) of the pyramidal cells, where action potentials are generated. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 17 Introduction to functional neurobiology: Hippocampus 085 The axon of the axo-axonic cells forms vertical ribbons of boutons, each of which establish multiple, climbing-fibre-like contacts with the AIS of the pyramidal cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 18 Introduction to functional neurobiology: Hippocampus 087 086 The axon of the axo-axonic cells forms vertical ribbons of boutons, each of which establish multiple, climbing-fibre-like contacts with the AIS of the pyramidal cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 19 Introduction to functional neurobiology: Hippocampus 032 Atypeofdendriticinhibitoryinterneuronsramifiesinthelacunosum-molecularelayerandestablishesmultiplecontactsatthedistaldendritesofthepyramidalcells. This type of interneuron is specialized for the control of entorhinal input. The axon of other dendritic inhibitory interneurons terminate in the radiatum and oriens layers, where they regulate the input provided by the Schaffer collaterals. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 20 Introduction to functional neurobiology: Hippocampus 024 The feed-forwardwayof dendritic inhibition Thedendritictree(red)aswellastheaxon(yellow)ofthedendriticinhibitorycellramifyintheoutertwo-thirdofthemolecularlayer,whichreceivestheentorhinalinput.Thistypeofinterneuron,therefore,canregulatetheeffectivenessofthepathway,whichprovidesafferentstoit,aswellastoprincipalneurons.Throughthistypeofinterneurons,theentorhinalafferentsregulatetheirowneffectivenessattheiractivity-dependentmanner. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 21 Introduction to functional neurobiology: Hippocampus 042 The feed-back way of dendritic inhibition Theaxon(yellow)ofthistypeofdendriticinhibitorycellramifiesintheoutertwo-thirdofthemolecularlayer,whichreceivestheentorhinalinput.Thedendritictree(red)isrestrictedtothehilus,whereitreceivesinputfromtheaxoncollateralsofgranulecells.Thistypeofinterneuronsregulatestheeffectivenessoftheentorhinalpathwayalsoatactivity-dependentmanner,butnotprimarilythroughtheactivityofthepathwayitself,insteadthroughthepathway-activatedgranulecellpopulation. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 22 Introduction to functional neurobiology: Hippocampus interneuron_diversity_in_hippocampus The major inhibitory interneuron-types of the hippocampalformation 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 23 Introduction to functional neurobiology: Hippocampus Big_final3cell 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 24 Introduction to functional neurobiology: Hippocampus Big_final5cell 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 25 Introduction to functional neurobiology: Hippocampus Big_final7cell 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 26 Introduction to functional neurobiology: Hippocampus 022 Neuropeptides and calcium-binding proteins are selectively present in certain inhibitory neurons Parvalbumin: perisomatic inhibitory cells 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 27 Introduction to functional neurobiology: Hippocampus 021 GABAergicterminalsarepresentinhighdensityinalllayers.Incontrast,parvalbumin-containingterminalsarealmostexclusivelyinthepyramidallayer. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 28 Introduction to functional neurobiology: Hippocampus 019 Cholecystokinin (CCK) are present also primarily in perisomatic inhibitory cells 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 29 Introduction to functional neurobiology: Hippocampus SOM.jpg Som-ires-Cre 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 30 Introduction to functional neurobiology: Hippocampus SomAxons.jpg The O-LM cell axons in the hippocampus 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 31 Introduction to functional neurobiology: Hippocampus 020 Somatostatin marksdendritic inhibitory cells, which exert inhibition in the layer of entorhinal afferents 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 32 Introduction to functional neurobiology: Hippocampus 017 Calbindin is present in those dendritic inhibitory cells, which project to the layers also innervated by the Schaffer collaterals (radiatum and oriens) . Calbindin marks also the granule cells and the CA1 pyramidal cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 33 Introduction to functional neurobiology: Hippocampus axon_arbo_vs_markers_CA1 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 34 Introduction to functional neurobiology: Hippocampus axon_arbo_vs_markers_DG 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 35 Introduction to functional neurobiology: Hippocampus 050 Interactions of excitatory and inhibitory cells can be studied with paired intracellular recordings 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 36 Introduction to functional neurobiology: Hippocampus 036# Pyramidal cells evoke large amplitude (2-3 mV) excitatory postsynaptic potentials (EPSP) in perisomaticinhibitory cells, usually through a single synapse.This is often sufficient to induce action potential in the target cell. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 37 Introduction to functional neurobiology: Hippocampus 035# Similarly, dendritic inhibitory cells receive avery potent input from the pyramidal cells, mainly through a single synapse. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 38 Introduction to functional neurobiology: Hippocampus 018 The pyramidal cell establish asymmetric synapses characteristic of the excitatory neurotransmission. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 39 Introduction to functional neurobiology: Hippocampus 050 Interactions of excitatory and inhibitory cells can be studied with paired intracellular recordings 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 40 Introduction to functional neurobiology: Hippocampus 044 Basket cells (in blue) evoke large amplitude (2-3 mV) inhibitory postsynaptic potentials (IPSP) in the target pyramidal cells (in red), through an average of 2-8 axon terminals , which synapse on the soma and the proximal dendrites. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 41 Introduction to functional neurobiology: Hippocampus 015 The basket cell establish symmetric synapses characteristic of the inhibitory neurotransmission. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 42 Introduction to functional neurobiology: Hippocampus 037 The dendritic inhibitory cells induce IPSPs (0,5-2 mV) in the pyramidal cells, through 3-18 synapses, which are located on the distal dendritic tree 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 43 Introduction to functional neurobiology: Hippocampus 041 The perisomatic inhibition inhibit the firing activity of pyramidal cells very effectivelyA single action potential of a single basket cell is capable to prevent the repetitive discharge of the pyramidal cells through 3 synaptic connection 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 44 Introduction to functional neurobiology: Hippocampus 045 The dendritic inhibition regulates the effectiveness and plasticity of excitatory inputs of pyramidal cells The dendritic inhibition prevents the opening of voltage-dependent calcium channels and the activation of NMDA receptors 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 45 Introduction to functional neurobiology: Hippocampus 079 Whytheprecisesynchronizationisimportant? Theconcurrentdischargeoftheimpulseproviderandthereceiverresultsinalastingincreaseoftheamplitudeoftheevokedexcitatorysynapticpotential. TheLongTermPotentiation(LTP)isthebasiccellularmechanismofmemory. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 46 Introduction to functional neurobiology: Hippocampus 051 The NMDA receptors are ligand as well as voltage-dependent receptors. In their open state they transmit also calcium ions. Precise synchronization of the discharge of pyramidal cells is the prerequisite for the induction of NMDA-mediated synaptic potentiation (LTP) since the synchronized retrograde propagation of action potentials tunes the release of Mg2+ blockage from the dendritic NMDA receptors (and the consequent Ca2+ influx) with the presynaptic transmitter release. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 47 Introduction to functional neurobiology: Hippocampus 028 Stimulation of the septum alone does not evoke changes in the field potential recorded in the hippocampus, but increase the excitability of the hippocampal pyramidal cells. The increased excitability is not a response to a cholinergic stimulation, instead it is the result of a reduced inhibition in the hippocampus. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 48 Introduction to functional neurobiology: Hippocampus 034 Axons from the septum provide a rich innervation of the hippocampus. Thicker fibers seem to surround perikaryons. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 49 Introduction to functional neurobiology: Hippocampus 013 Two types of septohippocampal axons terminate in the hippocampus. They can be easily distinguished according totheir thickness. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 50 Introduction to functional neurobiology: Hippocampus 012 The thick septohippocampal fibers are GABAergic, which innervate the GABAergic interneurons of the hippocampus selectively. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 51 Introduction to functional neurobiology: Hippocampus 053 The calbindin-containing dendritic inhibitory cells (marked by brown reaction product) are selectively innervated by GABAergic septal fibers (black) . 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 52 Introduction to functional neurobiology: Hippocampus 055 Dendrites of the parvalbumin-containing basket cells (brown) are also selectively innervated by the septal GABAergic fibers (black). 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 53 Introduction to functional neurobiology: Hippocampus SH_on_PV Multiple contacts are formed by septal afferents on PV-positive interneurons in a climbing fiber-like manner in the stratum oriens of the CA3 region. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 54 Introduction to functional neurobiology: Hippocampus 011 Another class of inhibitory interneurons, the somatostatin-containing dendritic inhibitory cells receive also a rich septal GABAergic innervation. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 55 Introduction to functional neurobiology: Hippocampus 082 Principal neurons of the hippocampus are synchronisedthrough GABA-GABA disinhibition 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 56 Introduction to functional neurobiology: Hippocampus 029 The septohippocampalGABA-GABA disinhibitionhas been demonstrated in vitro (a special septo-hippocampal slice was prepared for this purpose) 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 57 Introduction to functional neurobiology: Hippocampus 033 Distribution of cholinergic and GABAergic perikarya and fibers in the septo-hippocampal slices prepared for electrophysiology. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 58 Introduction to functional neurobiology: Hippocampus 030 Stimulation of the septum silences the spontaneous activity of the inhibitory cells in the hippocampus. The spontaneous IPSPs recorded from the pyramidal cells disappear during the stimulation. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 59 Introduction to functional neurobiology: Hippocampus 078 Stimulation of the septum induces (A) monosynaptic IPSPs in the hippocampal interneurons, and (B) slight depolarization of the pyramidal cells, which is a result of the disappearance of the spontaneous IPSPs. The firing interneuron is silenced by the stimulation of the septum (C). 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 60 Introduction to functional neurobiology: Hippocampus 077 During theta activity basket cells produce trains composed of 4 to 5 action potentials. Each of the action potential „packets” are in overlap with the „hyperpolarization” phase of the EEG theta. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 61 Introduction to functional neurobiology: Hippocampus Axo- axonic cell Entorhinal cortex GABAAR O-LM cell CA3 pyramids ? Dentate gyrus Subicular complex Basket cell Septum GABA PV GABAAR GABAAR GABAAR Subcortical areas Other isocortex GABAAR Bistratified cell Synaptic and temporal organisation of GABAergic interneurons and pyramidal cells in the CA1 hippocampal area of the rat Somogyi and Klausberger, J. Physiol. 2005. 562. 9-26. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 62 Introduction to functional neurobiology: Hippocampus Axo-axonic cell Basket cell O-LM cell (Bistratified) extracellular Pyramidal dendrite intracellular Theta oscillations in somata and dendrites of hippocampal pyramidal cells in vivo: activity-dependent phase-precession of action potentials Axo-axonic cell Basket cell extracellular Pyramidal soma intracellular firing Kamondi A.and Buzsáki G. Hippocampus1998;8(3):244-61 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 63 Introduction to functional neurobiology: Hippocampus 060 Membrane potential (excitability) of the hippocampal pyramidal cells oscillates at a synchronous manner, as they receive a rhythmic inhibition from the local interneurons. Activity of the local interneurons, in turn is rendered periodic by the septal GABAergic neurons. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 64 Introduction to functional neurobiology: Hippocampus So, what is the theta oscillation for? The function of the theta activity is most likely the temporal separation of the signal from the noise. The latter appear primarily at the crest phase, while the former at the trough phase of the theta. The perisomatic inhibition is increased at the trough phase, and can be overcome only by those cells, which receive an extra strong input at that moment. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 65 Introduction to functional neurobiology: Hippocampus The noise-like background discharge of the pyramidal cells is localised to the crest phase of the theta activity. Those action potentials, which transmit specific signals, are fired during the trough phase! Phase-precession 059 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 66 Introduction to functional neurobiology: Hippocampus 058 The role of the dendritic feed-back inhibitory cells is to prevent the synaptic potentiation during the noise-phase and to allow the synaptic potentiation during the signal-transmission phase. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 67 Introduction to functional neurobiology: Hippocampus The CA1-3 regions also contain dendritic feed-back inhibitory cells, the axons of which terminate in overlap with the entorhinal pathway. The marker of these neurons is somatostatin. 014 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 68 Introduction to functional neurobiology: Hippocampus 064 Feed-back inhibition is activated most likely during the pick of the crest-phase of the theta oscillation, when most pyramidal cells fire. The feed-back inhibition reachesthe distal dendritic tree concurrently with the retrograde propagating action potential and is capable to prevent potentiationby the even then arriving excitatory input! 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 69 Introduction to functional neurobiology: Hippocampus Only cells (e.g. place cells) just mediating specific signals are able to fire during the trough-phase of the theta oscillation. PHASE-PRECESSIONThese are, however not sufficient in number to activate the feed-back inhibition. If action potentials of these neurons coincide with the firing of their afferent fibers, the connection will be potentiated. There is no dendritic inhibition, which could prevent it! 065 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 70 Introduction to functional neurobiology: Hippocampus A possible mechanism of phase-precession Function of the endocannabinoid signaling in the cerebral cortex 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 71 Introduction to functional neurobiology: Hippocampus 103 102 Hájos et al., 2000, EJN Hippocampal distribution of CB1 receptors Immuno-reactivity in wild-type animals Control immuno-staining in KO animals 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 72 Introduction to functional neurobiology: Hippocampus CB1_EM.jpg CB1 receptors are located presynaptically on axon terminals 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 73 Introduction to functional neurobiology: Hippocampus 130-as 1estábla végso szoma aranyterm aranytermb Bodor et al. (2005) J.Neurosci. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 74 Introduction to functional neurobiology: Hippocampus gabas állo Bodor et al. (2005) J.Neurosci. CB1-positive axonterminalsareimmuno-reactiveforGABA, and formsymmet-ricalsynapticcontactsinthesomatosensorycortex. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 75 Introduction to functional neurobiology: Hippocampus Quantitative subcellular localization of CB1 cannabiniod receptors on GABAergic axons in the hippocampus saxon copy (Nyíri et al., 2005) Postembedding immunogold stainingof serial ultrathinsections: av.481gold/term. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 76 Introduction to functional neurobiology: Hippocampus Amplitude (pA) a a b b 1 µM WIN Time (min) a a b b 1 µM SR + 1 µM WIN 1 µM SR Time (min) Activation of CB1 cannabinoid receptors inhibits evoked IPSCs in the hippocampus Amplitude (pA) a a b b c c 1 µM SR 1 µM WIN Time (min) Hájos et al., EJN, 2000 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 77 Introduction to functional neurobiology: Hippocampus Time (min) Time (min) 1 µM WIN 1 µM WIN Mouse CB1 +/+ Mouse CB1 -/- Amplitude (pA) Control: The specific CB1-agonist is ineffective in CB1-KO animals 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 78 Introduction to functional neurobiology: Hippocampus készszinescck Large CCK-positive interneurons express CB1 receptors in the cortex and the hippocampus 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 79 Introduction to functional neurobiology: Hippocampus CB1 receptor activation diminishes the power of gamma (40 Hz) oscillations in the hippocampus Control CP 55,940 (250 nM) 200 ms 0.1mV Wash Power (mV2) 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 80 Introduction to functional neurobiology: Hippocampus 114 Wilson and Nicoll (2001) Nature 115 Role of endocannabinoids and CB1receptors in depolarization-inducedsuppression of inhibition (DSI) Wilson and Nicoll (2001) Nature 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 81 Introduction to functional neurobiology: Hippocampus Why are there two different basket cell types (PV-and CCK-containing) to generate oscillations ? One provides a rigid, non-plastic clock-work (these are the PV cells). The other’s role is fine tuning (CCK), and transmission of subcortical information related to affection and motivation 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 82 Introduction to functional neurobiology: Hippocampus basket_difference_final Freund T.F. and Katona I. (Neuron, 2007); Freund T.F. (TINS, 2003) 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 83 Introduction to functional neurobiology: Hippocampus Anxiety of animals is tested on elevated plus maze 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 84 Introduction to functional neurobiology: Hippocampus The behavior of wild type and CB1-KO mice on the elevated plus-maze 0 10 20 30 40 50 % time open arm Closed entries % open entries * * WT CB1-KO %time or entries 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 85 Introduction to functional neurobiology: Hippocampus 10 30 50 70 90 Total duration (% time) Resting Exploration 10 20 * Total duration (% time) Social interactions WT CB1-KO The behavior of wild type and CB1-KO mice in the social interaction test 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 86 Introduction to functional neurobiology: Hippocampus basket_difference_final Could individual cell types with all their complexity – rather than individual receptors or enzymes – be considered as drug targets? 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 87 Introduction to functional neurobiology: Hippocampus 056 Two different, behavior-dependent electric (EEG) activity patterns recorded from the hippocampus. Theta activity(4-8 Hz-and oscillation): during exploration and paradox sleeping Sharp-waves, fast, irregular EEG in conscious, resting state, during feeding and slow-wave sleep 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 88 Introduction to functional neurobiology: Hippocampus 083 During sharp waves large percentage of hippocampal CA3 pyramidal cells produce synchronous bursts. During population burst activity, the participating neurons start and finish their burst activity in different time points; consequently spend different time with high firing activity. The longer is the participation, the stronger will be the synaptic connection to the other members of the mini networks. Buzsáki et al., 1986 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 89 Introduction to functional neurobiology: Hippocampus 084 An electric stimulus corresponding to a sharp wave potentiate a mini network in the CA3 region. Later, spontaneous sharp waves induced field potentials turn up in similar shape suggesting that neurons involved in the generation were the same. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 90 Introduction to functional neurobiology: Hippocampus 067 The two-phase memory model of BuzsákiThe full space-information of a relatively long exploration phase (5-10 minutes) can be compressed in a single sharp wave. The serotonergic pathway originating from the raphe nuclei (dark blue reaction product) innervates selectively the hippocampal inhibitory neurons (brown). 054 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 92 Introduction to functional neurobiology: Hippocampus RH_on_CB The serotonergic pathway originating from the raphenuclei (blackreaction product, arrows) establishmultiplesynapticcontactswiththehippocampal inhibitory neurons (brown). 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 93 Introduction to functional neurobiology: Hippocampus The only ionotropicreceptor for serotonin is 5-HT3, the activation of which induces a fast excitation. These receptors are expressed exclusively by GABAergic interneurons, those which also contain CCK, VIP or calbindin. Serotonin, therefore excites interneurons responsible for perisomatic inhibition through 5-HT3 receptors. In addition, it inhibits the dendritic inhibition via presynaptic 5-HT1receptors at a non-synaptic manner. 092 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 94 Introduction to functional neurobiology: Hippocampus Opticalstimulationof raphefibersexciteshippocampal interneurons invitro 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 95 Introduction to functional neurobiology: Hippocampus Electricalstimulationof rapheneuronsexciteshippocampal interneurons invivo 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 96 Introduction to functional neurobiology: Hippocampus Fastactivationis serotonin/glutamate-dependent... In vitro In vivo 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 97 Introduction to functional neurobiology: Hippocampus ...and synaptic 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 98 Introduction to functional neurobiology: Hippocampus 099 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 99 Introduction to functional neurobiology: Hippocampus 090 The m2 receptor of acetylcholine is also expressed selectivelyby interneurons. The receptor protein is present in the axon terminals of the perisomaticinhibitory neurons and in the dendritic tree of the dendritic inhibitory cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 100 Introduction to functional neurobiology: Hippocampus 091 The m2-immunoreactive axon terminals (brown) are well visible around the soma (P) and axon initial segment (arrows) of the pyramidal cells. Activation of m2 receptors in the axon terminals of basket and axo-axonic cells inhibits GABA release, consequently it reduces the perisomatic inhibition through this type of the receptor. P P P P P 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 101 Introduction to functional neurobiology: Hippocampus 093 The m2-immunoreactive terminals (b1 és b2) synapsing(arrows) onto the soma (s) and the dendrites (d) of the pyramidal cell, proved to be GABA-containing in the neighboring ultrathin sections (see the deposited gold granules). 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 102 Introduction to functional neurobiology: Hippocampus 089 Those neurons , which express m2 receptors in the soma and dendritic tree, project to the layer of the apical dendrites of the pyramidal cells and are responsible for dendritic inhibition. The activation of m2 receptors located in the soma/dendritic tree of the interneurons enhances the cell’s excitability. Acetylcholine therefore increase the dendritic inhibition through m2 receptors. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 103 Introduction to functional neurobiology: Hippocampus 097 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 104 Introduction to functional neurobiology: Hippocampus Thecerebralcortexexistsinatleasttwofunctionalstates:incholinergicactivatedstate,asasimplerelaynucleus,andinserotonergicactivatedstate,asastructureofmemory.Theswitchbetweenthetwostatesisestablishedbysubcorticalpathwaysmediatinginformationabouttheinternalmilieu(i.e.motivation,emotionandthephysiologicalstate)throughthedifferentiatedmodulationofdendriticandperisomaticinhibitions. 098 Dendritic inhibition Perisomatic inhibition DENDRITIC TREE: Plasticity of input CELL BODY: Generation of output signal AXON: SIGNAL -transmission Signals from the EXTERNAL MILIEU Effects from the INTERNAL MILIEU 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 105 Introduction to functional neurobiology: Hippocampus Gamma oscillation(40-100 Hz)It ensures synchronization with 2 to 3 msec accuracy necessary for the synaptic potentiation It is resolution for the „binding” problem 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 106 Introduction to functional neurobiology: Hippocampus 094 The binding problemThe pathways mediating various sensory modalities and submodalities do not converge in the brain, instead they diverge in the higher processing levels. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 107 Introduction to functional neurobiology: Hippocampus 077 The EEG thetais characterised by „riding” waves with a frequency of 40-100 Hz. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 108 Introduction to functional neurobiology: Hippocampus When can we record gamma oscillations in the hippocampus? Buzsáki et al., 2003 Traub et al., 1996 Theta oscillation during explorationIrregular activity during consummatorybehavior 1. Theta nested gamma2. Tail gamma followesthe sharp waves 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 109 Introduction to functional neurobiology: Hippocampus 3. Epilepticdischarges arefollowed bygammaoscillations Bragin et al., 1997 When can we record gamma oscillations in the hippocampus? 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 110 Introduction to functional neurobiology: Hippocampus Two independent gamma generators in the hippocampus 1. Gamma oscillations in the dentate gyrus are dependent on extra-hippocampal input 2. Gamma oscillations in the CA3 regionare intrinsically generated and transmitted into the CA1 region Braginet al., 1995; Csicsváriet al., 2003 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 111 Introduction to functional neurobiology: Hippocampus Carbachol-induced gamma oscillations in hippocampal slices Field potential Cell-attached rec. of firing Whole-cell rec. of syn. currents 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 112 Introduction to functional neurobiology: Hippocampus BCa s.p. s.o. s.l. 1. Firing characteristics of neurons (frequency, phase, phase-coupling) 2. Properties of synaptic inputs (both excitatory and inhibitory) 3. Anatomical identification 4. Imaging techniques Recording carbachol-induced gamma oscillations in hippocampal slices 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 113 Introduction to functional neurobiology: Hippocampus Comparison of in vivo and in vitro gamma oscillations Firing of CA3 pyramidal cells is followed by the discharge of CA3 interneurons pyr int In vivo Pyramidal cells Interneurons 2kHz 15-45 Hz 2kHz In vitro Csicsvári et al., Neuron, 2003 Hájos et al., J. Neurosci. 2004 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 114 Introduction to functional neurobiology: Hippocampus Firing properties of CA3 pyramidal cells and perisomatic inhibitory neurons during cholinergically induced gamma oscillations PC1 200µV 100µV 50ms 50ms 150µV Pyramidal cell PhaseHist. degree Number of spikes PhaseHist. degree Number of spikes spike time: 0.03±0.65ms spike rate: 2.82±0.7 Hz spike time: 1.97±0.95 ms spike rate: 18.1±2.2 Hz Perisomatic inhibitory cell s.p. s.p. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 115 Introduction to functional neurobiology: Hippocampus Behavior of distinct types of neurons during gamma oscillacions Probability of Discharge ° PC IN PC IN Phase (degree) IS PC BC OLM RC field 1. Pyramidal cells fire at the negative peak of the oscillations followed by the discharge of interneurons. 2. Perisomatic inhibitory cells and IS interneurons werethe most active neuron types with strong phase coupling. 3. Dendritic-targeting interneurons fired with lowerfrequency and showed less significant phase-coupling. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 116 Introduction to functional neurobiology: Hippocampus 072 The calretinin-containing GABAergic cells are specilised for the selective innervation of other interneurons.They are interconnected abundantly via dendro-dendritic and axo-dendritic connections. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 117 Introduction to functional neurobiology: Hippocampus 075 The calretinin-containing interneuron-selective inhibitory cells exhibit rich dendro-dendritic connections 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 118 Introduction to functional neurobiology: Hippocampus 007 The calretinin-containing cells are GABAergic, and selectively innervate other GABAergic interneurons in the hippocampus 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 119 Introduction to functional neurobiology: Hippocampus 101 The calretinin-containing cells innervate each other abundantly,which facilitates their synchronization 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 120 Introduction to functional neurobiology: Hippocampus Synchronization of inhibition is facilitated by the syncytial connections of calretinin-containing cells 068 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 121 Introduction to functional neurobiology: Hippocampus There are two subpopulations of VIP-containing GABAergic cells, which are specialised for the innervation of different inhibitory cells 096 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 122 Introduction to functional neurobiology: Hippocampus 076 VIP-containimg interneurons innervate abundantly the somatostatin-containing O-LM cells. 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 123 Introduction to functional neurobiology: Hippocampus 074 Axons of VIP-containing neurons (black, arrows) innervate selectively the interneurons in the str. oriens (brown, calbindin) 2011.10.12.. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 124 Introduction to functional neurobiology: Hippocampus Hippocampal feed-back to the septumThe glutamatergiccomponent derives from the pyramidal cells, and project to the lateral septumThe GABAergic component originates from the interneurons of the str. oriens, and projects to the medial septum