101
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Early alterations in hippocampal perisomatic GABAergic synapses and network oscillations in a mouse model of Alzheimer's disease amyloidosis. PLoS One 2019; 14:e0209228. [PMID: 30645585 PMCID: PMC6333398 DOI: 10.1371/journal.pone.0209228] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/30/2018] [Indexed: 01/01/2023] Open
Abstract
Several lines of evidence imply changes in inhibitory interneuron connectivity and subsequent alterations in oscillatory network activities in the pathogenesis of Alzheimer’s Disease (AD). Recently, we provided evidence for an increased immunoreactivity of both the postsynaptic scaffold protein gephyrin and the GABAA receptor γ2-subunit in the hippocampus of young (1 and 3 months of age), APPPS1 mice. These mice represent a well-established model of cerebral amyloidosis, which is a hallmark of human AD. In this study, we demonstrate a robust increase of parvalbumin immunoreactivity and accentuated projections of parvalbumin positive (PV+) interneurons, which target perisomatic regions of pyramidal cells within the hippocampal subregions CA1 and CA3 of 3-month-old APPPS1 mice. Colocalisation studies confirmed a significant increase in the density of PV+ projections labeled with antibodies against a presynaptic (vesicular GABA transporter) and a postsynaptic marker (gephyrin) of inhibitory synapses within the pyramidal cell layer of CA1 and CA3. As perisomatic inhibition by PV+-interneurons is crucial for the generation of hippocampal network oscillations involved in spatial processing, learning and memory formation we investigated the impact of the putative enhanced perisomatic inhibition on two types of fast neuronal network oscillations in acute hippocampal slices: 1. spontaneously occurring sharp wave-ripple complexes (SPW-R), and 2. cholinergic γ-oscillations. Interestingly, both network patterns were generally preserved in APPPS1 mice similar to WT mice. However, the comparison of simultaneous CA3 and CA1 recordings revealed that the incidence and amplitude of SPW-Rs were significantly lower in CA1 vs CA3 in APPPS1 slices, whereas the power of γ-oscillations was significantly higher in CA3 vs CA1 in WT-slices indicating an impaired communication between the CA3 and CA1 network activities in APPPS1 mice. Taken together, our data demonstrate an increased GABAergic synaptic output of PV+ interneurons impinging on pyramidal cells of CA1 and CA3, which might limit the coordinated cross-talk between these two hippocampal areas in young APPPS1 mice and mediate long-term changes in synaptic inhibition during progression of amyloidosis.
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102
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Çalışkan G, Stork O. Hippocampal network oscillations at the interplay between innate anxiety and learned fear. Psychopharmacology (Berl) 2019; 236:321-338. [PMID: 30417233 DOI: 10.1007/s00213-018-5109-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 11/05/2018] [Indexed: 12/14/2022]
Abstract
The hippocampus plays a central role as a hub for episodic memory and as an integrator of multimodal sensory information in time and space. Thereby, it critically determines contextual setting and specificity of episodic memories. It is also a key site for the control of innate anxiety states and involved in psychiatric diseases with heightened anxiety and generalized fear memory such as post-traumatic stress disorder (PTSD). Expression of both innate "unlearned" anxiety and "learned" fear requires contextual processing and engagement of a brain-wide network including the hippocampus together with the amygdala and medial prefrontal cortex. Strikingly, the hippocampus is also the site of emergence of oscillatory rhythms that coordinate information processing and filtering in this network. Here, we review data on how the hippocampal network oscillations and their coordination with amygdalar and prefrontal oscillations are engaged in innate threat evaluation. We further explore how such innate oscillatory communication might have an impact on contextualization and specificity of "learned" fear. We illustrate the partial overlap of fear and anxiety networks that are built by the hippocampus in conjunction with amygdala and prefrontal cortex. We further propose that (mal)-adaptive interplay via (dis)-balanced oscillatory communication between the anxiety network and the fear network may determine the strength of fear memories and their resistance to extinction.
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Affiliation(s)
- Gürsel Çalışkan
- Department of Genetics & Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany. .,Center for Behavioral Brain Sciences, Universitätsplatz 2, 39106, Magdeburg, Germany.
| | - Oliver Stork
- Department of Genetics & Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Universitätsplatz 2, 39106, Magdeburg, Germany
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103
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Ramirez-Villegas JF, Willeke KF, Logothetis NK, Besserve M. Dissecting the Synapse- and Frequency-Dependent Network Mechanisms of In Vivo Hippocampal Sharp Wave-Ripples. Neuron 2018; 100:1224-1240.e13. [DOI: 10.1016/j.neuron.2018.09.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 06/25/2018] [Accepted: 09/24/2018] [Indexed: 01/14/2023]
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104
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Hussin AT, Leonard TK, Hoffman KL. Sharp-wave ripple features in macaques depend on behavioral state and cell-type specific firing. Hippocampus 2018; 30:50-59. [PMID: 30371963 PMCID: PMC7004038 DOI: 10.1002/hipo.23046] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/24/2018] [Accepted: 10/17/2018] [Indexed: 12/20/2022]
Abstract
Sharp-wave ripples (SWRs) are spontaneous, synchronized neural population events in the hippocampus widely thought to play a role in memory consolidation and retrieval. They occur predominantly in sleep and quiet immobility, and in primates, they also appear during active visual exploration. Typical measures of SWRs in behaving rats include changes in the rate of occurrence, or in the incidence of specific neural ensemble activity contained within the categorical SWR event. Much less is known about the relevance of spatiotemporal SWR features, though they may index underlying activity of specific cell types including ensemble-specific internally generated sequences. Furthermore, changes in SWR features during active exploratory states are unknown. In this study, we recorded hippocampal local-field potentials and single-units during periods of quiescence and as macaques performed a memory-guided visual search task. We observed that (a) ripples during quiescence have greater amplitudes and larger postripple waves (PRW) compared to those in task epochs, and (b) during "remembered" trials, ripples have larger amplitudes than during "forgotten" trials, with no change in duration or PRWs. We further found that spiking activity influences SWR features as a function of cell type and ripple timing. As expected, larger ripple amplitudes were associated with putative pyramidal or putative basket interneuron (IN) activity, even when the spikes in question exceed the duration of the ripple. In contrast, the PRW was attenuated with activity from low firing rate cells and enhanced with activity from high firing rate cells, with putative IN spikes during ripples leading to the most prominent PRW peaks. The selective changes in SWR features as a function of time window, cell type, and cognitive/vigilance states suggest that this mesoscopic field event can offer additional information about the local network and animal's state than would be appreciated from SWR event rates alone.
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Affiliation(s)
- Ahmed T Hussin
- Department of Biology, Centre for Vision Research, York University, Toronto, Ontario, Canada
| | - Timothy K Leonard
- Department of Psychology, Centre for Vision Research, York University, Toronto, Ontario, Canada
| | - Kari L Hoffman
- Department of Psychology, Centre for Vision Research, York University, Toronto, Ontario, Canada.,Department of Psychology, Center for Integrative and Cognitive Neuroscience, Vanderbilt Vision Research Center, Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee
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105
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Specificity of Primate Amygdalar Pathways to Hippocampus. J Neurosci 2018; 38:10019-10041. [PMID: 30249799 DOI: 10.1523/jneurosci.1267-18.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/16/2018] [Accepted: 09/13/2018] [Indexed: 12/30/2022] Open
Abstract
The amygdala projects to hippocampus in pathways through which affective or social stimuli may influence learning and memory. We investigated the still unknown amygdalar termination patterns and their postsynaptic targets in hippocampus from system to synapse in rhesus monkeys of both sexes. The amygdala robustly innervated the stratum lacunosum-moleculare layer of cornu ammonis fields and uncus anteriorly. Sparser terminations in posterior hippocampus innervated the radiatum and pyramidal layers at the prosubicular/CA1 juncture. The terminations, which were larger than other afferents in the surrounding neuropil, position the amygdala to influence hippocampal input anteriorly, and its output posteriorly. Most amygdalar boutons (76-80%) innervated spines of excitatory hippocampal neurons, and most of the remaining innervated presumed inhibitory neurons, identified by morphology and label with parvalbumin or calretinin, which distinguished nonoverlapping neurochemical classes of hippocampal inhibitory neurons. In CA1, amygdalar axons innervated some calretinin neurons, which disinhibit pyramidal neurons. By contrast, in CA3 the amygdala innervated both calretinin and parvalbumin neurons; the latter strongly inhibit nearby excitatory neurons. In CA3, amygdalar pathways also made closely spaced dual synapses on excitatory neurons. The strong excitatory synapses in CA3 may facilitate affective context representations and trigger sharp-wave ripples associated with memory consolidation. When the amygdala is excessively activated during traumatic events, the specialized innervation of excitatory neurons and the powerful parvalbumin inhibitory neurons in CA3 may allow the suppression of activity of nearby neurons that receive weaker nonamygdalar input, leading to biased passage of highly charged affective stimuli and generalized fear.SIGNIFICANCE STATEMENT Strong pathways from the amygdala targeted the anterior hippocampus, and more weakly its posterior sectors, positioned to influence a variety of emotional and cognitive functions. In hippocampal field CA1, the amygdala innervated some calretinin neurons, which disinhibit excitatory neurons. By contrast, in CA3 the amygdala innervated calretinin as well as some of the powerful parvalbumin inhibitory neurons and may help balance the activity of neural ensembles to allow social interactions, learning, and memory. These results suggest that when the amygdala is hyperactive during emotional upheaval, it strongly activates excitatory hippocampal neurons and parvalbumin inhibitory neurons in CA3, which can suppress nearby neurons that receive weaker input from other sources, biasing the passage of stimuli with high emotional import and leading to generalized fear.
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106
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Lupica CR, Hoffman AF. Cannabinoid disruption of learning mechanisms involved in reward processing. ACTA ACUST UNITED AC 2018; 25:435-445. [PMID: 30115765 PMCID: PMC6097761 DOI: 10.1101/lm.046748.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/06/2018] [Indexed: 02/06/2023]
Abstract
The increasing use of cannabis, its derivatives, and synthetic cannabinoids for medicinal and recreational purposes has led to burgeoning interest in understanding the addictive potential of this class of molecules. It is estimated that ∼10% of marijuana users will eventually show signs of dependence on the drug, and the diagnosis of cannabis use disorder (CUD) is increasing in the United States. The molecule that sustains the use of cannabis is Δ9-tetrahydrocannabinol (Δ9-THC), and our knowledge of its effects, and those of other cannabinoids on brain function has expanded rapidly in the past two decades. Additionally, the identification of endogenous cannabinoid (endocannabinoid) systems in brain and their roles in physiology and behavior, demonstrate extensive involvement of these lipid signaling molecules in regulating CNS function. Here, we examine roles for endogenous cannabinoids in shaping synaptic activity in cortical and subcortical brain circuits, and we discuss mechanisms in which exogenous cannabinoids, such as Δ9-THC, interact with endocannabinoid systems to disrupt neuronal network oscillations. We then explore how perturbation of the interaction of this activity within brain reward circuits may lead to impaired learning. Finally, we propose that disruption of cellular plasticity mechanisms by exogenous cannabinoids in cortical and subcortical circuits may explain the difficulty in establishing viable cannabinoid self-administration models in animals.
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Affiliation(s)
- Carl R Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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107
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Weissenberger F, Einarsson H, Matheus Gauy M, Meier F, Mujika A, Lengler J, Steger A. On the origin of lognormal network synchrony in CA1. Hippocampus 2018; 28:824-837. [PMID: 30024075 DOI: 10.1002/hipo.23004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/08/2018] [Accepted: 06/19/2018] [Indexed: 11/12/2022]
Abstract
The sharp wave ripple complex in rodent hippocampus is associated with a network burst in CA3 (NB) that triggers a synchronous event in the CA1 population (SE). The number of CA1 pyramidal cells participating in a SE has been observed to follow a lognormal distribution. However, the origin of this skewed and heavy-tailed distribution of population synchrony in CA1 remains unknown. Because the size of SEs is likely to originate from the size of the NBs and the underlying neural circuitry, we model the CA3-CA1 circuit to study the underlying mechanisms and their functional implications. We show analytically that if the size of a NB in CA3 is distributed according to a normal distribution, then the size of the resulting SE in CA1 follows a lognormal distribution. Our model predicts the distribution of the NB size in CA3, which remains to be tested experimentally. Moreover, we show that a putative lognormal NB size distribution leads to an extremely heavy-tailed SE size distribution in CA1, contradicting experimental evidence. In conclusion, our model provides general insight on the origin of lognormally distributed network synchrony as a consequence of synchronous synaptic transmission of normally distributed input events.
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Affiliation(s)
| | | | | | | | - Asier Mujika
- Department of Computer Science, Zürich, Switzerland
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108
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Takács VT, Cserép C, Schlingloff D, Pósfai B, Szőnyi A, Sos KE, Környei Z, Dénes Á, Gulyás AI, Freund TF, Nyiri G. Co-transmission of acetylcholine and GABA regulates hippocampal states. Nat Commun 2018; 9:2848. [PMID: 30030438 PMCID: PMC6054650 DOI: 10.1038/s41467-018-05136-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 06/12/2018] [Indexed: 12/13/2022] Open
Abstract
The basal forebrain cholinergic system is widely assumed to control cortical functions via non-synaptic transmission of a single neurotransmitter. Yet, we find that mouse hippocampal cholinergic terminals invariably establish GABAergic synapses, and their cholinergic vesicles dock at those synapses only. We demonstrate that these synapses do not co-release but co-transmit GABA and acetylcholine via different vesicles, whose release is triggered by distinct calcium channels. This co-transmission evokes composite postsynaptic potentials, which are mutually cross-regulated by presynaptic autoreceptors. Although postsynaptic cholinergic receptor distribution cannot be investigated, their response latencies suggest a focal, intra- and/or peri-synaptic localisation, while GABAA receptors are detected intra-synaptically. The GABAergic component alone effectively suppresses hippocampal sharp wave-ripples and epileptiform activity. Therefore, the differentially regulated GABAergic and cholinergic co-transmission suggests a hitherto unrecognised level of control over cortical states. This novel model of hippocampal cholinergic neurotransmission may lead to alternative pharmacotherapies after cholinergic deinnervation seen in neurodegenerative disorders.
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Affiliation(s)
- Virág T Takács
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Csaba Cserép
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Dániel Schlingloff
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Balázs Pósfai
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - András Szőnyi
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Katalin E Sos
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.,János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, 1085, Hungary
| | - Zsuzsanna Környei
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Ádám Dénes
- Momentum Laboratory of Neuroimmunology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Attila I Gulyás
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Tamás F Freund
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary
| | - Gábor Nyiri
- Laboratory of Cerebral Cortex Research Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u 43, Budapest, 1083, Hungary.
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109
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Bender F, Korotkova T, Ponomarenko A. Optogenetic Entrainment of Hippocampal Theta Oscillations in Behaving Mice. J Vis Exp 2018. [PMID: 30010632 DOI: 10.3791/57349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Extensive data on relationships of neural network oscillations to behavior and organization of neuronal discharge across brain regions call for new tools to selectively manipulate brain rhythms. Here we describe an approach combining projection-specific optogenetics with extracellular electrophysiology for high-fidelity control of hippocampal theta oscillations (5-10 Hz) in behaving mice. The specificity of the optogenetic entrainment is achieved by targeting channelrhodopsin-2 (ChR2) to the GABAergic population of medial septal cells, crucially involved in the generation of hippocampal theta oscillations, and a local synchronized activation of a subset of inhibitory septal afferents in the hippocampus. The efficacy of the optogenetic rhythm control is verified by a simultaneous monitoring of the local field potential (LFP) across lamina of the CA1 area and/or of neuronal discharge. Using this readily implementable preparation we show efficacy of various optogenetic stimulation protocols for induction of theta oscillations and for the manipulation of their frequency and regularity. Finally, a combination of the theta rhythm control with projection-specific inhibition addresses the readout of particular aspects of the hippocampal synchronization by efferent regions.
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Affiliation(s)
- Franziska Bender
- Systems Neurophysiology Research Group, Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf; Behavioural Neurodynamics Group, Leibniz Institute for Molecular Pharmacology (FMP)/ NeuroCure Cluster of Excellence
| | - Tatiana Korotkova
- Behavioural Neurodynamics Group, Leibniz Institute for Molecular Pharmacology (FMP)/ NeuroCure Cluster of Excellence; Neuronal Circuits and Behavior Research Group, Max Planck Institute for Metabolism Research
| | - Alexey Ponomarenko
- Systems Neurophysiology Research Group, Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf; Behavioural Neurodynamics Group, Leibniz Institute for Molecular Pharmacology (FMP)/ NeuroCure Cluster of Excellence;
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110
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Abstract
The subiculum is one of the major output areas of the hippocampus and has extensive projections to extrahippocampal targets. It is likely to play a pivotal role in the distribution of outgoing information from the hippocampus. The hippocampus, including the subiculum, is important for the formation, consolidation and retrieval of memory. These functions require a network that is flexible enough to encode incoming information and also allows for reliable distribution, storage and integration into previously encoded memories. Finally, relevant information has to be retrieved in a context-specific manner to allow for an appropriate behavioral response. The subiculum as a gateway between the hippocampus and cortex might serve to integrate and process information from the hippocampus proper and its other inputs before conveying it to more permanent storage locations. This review summarizes how the subiculum is embedded into upstream and downstream circuits, describes what is known about the local network topology and discusses cellular and functional properties of subicular cells subtypes. Lastly, it describes how these properties might help to separate information into parallel output streams and distribute it to its multiple target areas.
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111
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Malerba P, Bazhenov M. Circuit mechanisms of hippocampal reactivation during sleep. Neurobiol Learn Mem 2018; 160:98-107. [PMID: 29723670 DOI: 10.1016/j.nlm.2018.04.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/13/2018] [Accepted: 04/30/2018] [Indexed: 10/17/2022]
Abstract
The hippocampus is important for memory and learning, being a brain site where initial memories are formed and where sharp wave - ripples (SWR) are found, which are responsible for mapping recent memories to long-term storage during sleep-related memory replay. While this conceptual schema is well established, specific intrinsic and network-level mechanisms driving spatio-temporal patterns of hippocampal activity during sleep, and specifically controlling off-line memory reactivation are unknown. In this study, we discuss a model of hippocampal CA1-CA3 network generating spontaneous characteristic SWR activity. Our study predicts the properties of CA3 input which are necessary for successful CA1 ripple generation and the role of synaptic interactions and intrinsic excitability in spike sequence replay during SWRs. Specifically, we found that excitatory synaptic connections promote reactivation in both CA3 and CA1, but the different dynamics of sharp waves in CA3 and ripples in CA1 result in a differential role for synaptic inhibition in modulating replay: promoting spike sequence specificity in CA3 but not in CA1 areas. Finally, we describe how awake learning of spatial trajectories leads to synaptic changes sufficient to drive hippocampal cells' reactivation during sleep, as required for sleep-related memory consolidation.
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Affiliation(s)
- Paola Malerba
- Department of Medicine, University of California San Diego, United States
| | - Maxim Bazhenov
- Department of Medicine, University of California San Diego, United States.
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112
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Gunn BG, Cox CD, Chen Y, Frotscher M, Gall CM, Baram TZ, Lynch G. The Endogenous Stress Hormone CRH Modulates Excitatory Transmission and Network Physiology in Hippocampus. Cereb Cortex 2018; 27:4182-4198. [PMID: 28460009 PMCID: PMC6248689 DOI: 10.1093/cercor/bhx103] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Indexed: 01/06/2023] Open
Abstract
Memory is strongly influenced by stress but underlying mechanisms are unknown. Here, we
used electrophysiology, neuroanatomy, and network simulations to probe the role of the
endogenous, stress-related neuropeptide corticotropin-releasing hormone (CRH) in
modulating hippocampal function. We focused on neuronal excitability and the incidence of
sharp waves (SPWs), a form of intrinsic network activity associated with memory
consolidation. Specifically, we blocked endogenous CRH using 2 chemically distinct
antagonists of the principal hippocampal CRH receptor, CRHR1. The antagonists caused a
modest reduction of spontaneous excitatory transmission onto CA3 pyramidal cells,
mediated, in part by effects on IAHP. This was accompanied by a decrease in the
incidence but not amplitude of SPWs, indicating that the synaptic actions of CRH are
sufficient to alter the output of a complex hippocampal network. A biophysical model of
CA3 described how local actions of CRH produce macroscopic consequences including the
observed changes in SPWs. Collectively, the results provide a first demonstration of the
manner in which subtle synaptic effects of an endogenously released neuropeptide influence
hippocampal network level operations and, in the case of CRH, may contribute to the
effects of acute stress on memory.
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Affiliation(s)
- B. G. Gunn
- Department of Pediatrics, University of
California-Irvine, Irvine, CA, USA
| | - C. D. Cox
- Department of Anatomy/Neurobiology, University of
California-Irvine, Irvine, CA, USA
| | - Y. Chen
- Department of Pediatrics, University of
California-Irvine, Irvine, CA, USA
- Department of Anatomy/Neurobiology, University of
California-Irvine, Irvine, CA, USA
| | - M. Frotscher
- ZMNH, Institute for Structural
Neurobiology, D-20251 Hamburg,
Germany
| | - C. M. Gall
- Department of Anatomy/Neurobiology, University of
California-Irvine, Irvine, CA, USA
- Department of Neurobiology and Behavior, University of
California-Irvine, Irvine, CA, USA
| | - T. Z. Baram
- Department of Pediatrics, University of
California-Irvine, Irvine, CA, USA
- Department of Anatomy/Neurobiology, University of
California-Irvine, Irvine, CA, USA
- Department of Neurology, University of
California-Irvine, Irvine, CA, USA
- Address correspondence to Prof. T. Z. Baram, Departments of Pediatrics;
Anatomy & Neurobiology; Neurology, University of California-Irvine, Medical Sciences
I, ZOT: 4475, Irvine, CA 92697-4475, USA.
| | - G. Lynch
- Department of Anatomy/Neurobiology, University of
California-Irvine, Irvine, CA, USA
- Department of Psychiatry and Human Behavior, University
of California-Irvine, Irvine, CA, USA
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113
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Adamantidis A, Lüthi A. Optogenetic Dissection of Sleep-Wake States In Vitro and In Vivo. Handb Exp Pharmacol 2018; 253:125-151. [PMID: 29687163 DOI: 10.1007/164_2018_94] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Optogenetic tools have revolutionized insights into the fundamentals of brain function. This is particularly true for our current understanding of sleep-wake regulation and sleep rhythms. This is illustrated here through a comprehensive and step-by-step review over the major brain areas involved in transitions between sleep and wake states and in sleep rhythmogenesis.
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Affiliation(s)
- Antoine Adamantidis
- Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland. .,Department of Clinical Research (DKF), University of Bern, Bern, Switzerland.
| | - Anita Lüthi
- Department of Fundamental Neurosciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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114
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Jiang H, Liu S, Geng X, Caccavano A, Conant K, Vicini S, Wu J. Pacing Hippocampal Sharp-Wave Ripples With Weak Electric Stimulation. Front Neurosci 2018; 12:164. [PMID: 29599704 PMCID: PMC5862867 DOI: 10.3389/fnins.2018.00164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/28/2018] [Indexed: 11/13/2022] Open
Abstract
Sharp-wave ripples (SWRs) are spontaneous neuronal population events that occur in the hippocampus during sleep and quiet restfulness, and are thought to play a critical role in the consolidation of episodic memory. SWRs occur at a rate of 30-200 events per minute. Their overall abundance may, however, be reduced with aging and neurodegenerative disease. Here we report that the abundance of SWR within murine hippocampal slices can be increased by paced administration of a weak electrical stimulus, especially when the spontaneously occurring rate is low or compromised. Resultant SWRs have large variations in amplitude and ripple patterns, which are morphologically indistinguishable from those of spontaneous SWRs, despite identical stimulus parameters which presumably activate the same CA3 neurons surrounding the electrode. The stimulus intensity for reliably pacing SWRs is weaker than that required for inducing detectable evoked field potentials in CA1. Moreover, repetitive ~1 Hz stimuli with low intensity can reliably evoke thousands of SWRs without detectable LTD or "habituation." Our results suggest that weak stimuli may facilitate the spontaneous emergence of SWRs without significantly altering their characteristics. Pacing SWRs with weak electric stimuli could potentially be useful for restoring their abundance in the damaged hippocampus.
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Affiliation(s)
- Huiyi Jiang
- Department of Pediatrics, The First Hospital of Jilin University, Chang Chun, China
- Department of Neuroscience, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
| | - Shicheng Liu
- Department of Pediatrics, The First Hospital of Jilin University, Chang Chun, China
- Department of Neuroscience, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
| | - Xinling Geng
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Adam Caccavano
- Department of Pharmacology, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
| | - Katherine Conant
- Department of Neuroscience, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
| | - Stefano Vicini
- Department of Pharmacology, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
| | - Jianyoung Wu
- Department of Neuroscience, Georgetown University Medical Center, Georgetown University, Washington, DC, United States
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115
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Raveau M, Polygalov D, Boehringer R, Amano K, Yamakawa K, McHugh TJ. Alterations of in vivo CA1 network activity in Dp(16)1Yey Down syndrome model mice. eLife 2018; 7:31543. [PMID: 29485402 PMCID: PMC5841929 DOI: 10.7554/elife.31543] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 02/25/2018] [Indexed: 12/14/2022] Open
Abstract
Down syndrome, the leading genetic cause of intellectual disability, results from an extra-copy of chromosome 21. Mice engineered to model this aneuploidy exhibit Down syndrome-like memory deficits in spatial and contextual tasks. While abnormal neuronal function has been identified in these models, most studies have relied on in vitro measures. Here, using in vivo recording in the Dp(16)1Yey model, we find alterations in the organization of spiking of hippocampal CA1 pyramidal neurons, including deficits in the generation of complex spikes. These changes lead to poorer spatial coding during exploration and less coordinated activity during sharp-wave ripples, events involved in memory consolidation. Further, the density of CA1 inhibitory neurons expressing neuropeptide Y, a population key for the generation of pyramidal cell bursts, were significantly increased in Dp(16)1Yey mice. Our data refine the ‘over-suppression’ theory of Down syndrome pathophysiology and suggest specific neuronal subtypes involved in hippocampal dysfunction in these model mice.
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Affiliation(s)
- Matthieu Raveau
- Laboratory for Neurogenetics, RIKEN, Brain Science Institute, Saitama, Japan
| | - Denis Polygalov
- Laboratory for Circuit and Behavioral Physiology, RIKEN, Brain Science Institute, Saitama, Japan
| | - Roman Boehringer
- Laboratory for Circuit and Behavioral Physiology, RIKEN, Brain Science Institute, Saitama, Japan
| | - Kenji Amano
- Laboratory for Neurogenetics, RIKEN, Brain Science Institute, Saitama, Japan
| | - Kazuhiro Yamakawa
- Laboratory for Neurogenetics, RIKEN, Brain Science Institute, Saitama, Japan
| | - Thomas J McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN, Brain Science Institute, Saitama, Japan
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116
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Çalışkan G, Stork O. Hippocampal network oscillations as mediators of behavioural metaplasticity: Insights from emotional learning. Neurobiol Learn Mem 2018; 154:37-53. [PMID: 29476822 DOI: 10.1016/j.nlm.2018.02.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 01/15/2023]
Abstract
Behavioural metaplasticity is evident in experience-dependent changes of network activity patterns in neuronal circuits that connect the hippocampus, amygdala and medial prefrontal cortex. These limbic regions are key structures of a brain-wide neural network that translates emotionally salient events into persistent and vivid memories. Communication in this network by-and-large depends on behavioural state-dependent rhythmic network activity patterns that are typically generated and/or relayed via the hippocampus. In fact, specific hippocampal network oscillations have been implicated to the acquisition, consolidation and retrieval, as well as the reconsolidation and extinction of emotional memories. The hippocampal circuits that contribute to these network activities, at the same time, are subject to both Hebbian and non-Hebbian forms of plasticity during memory formation. Further, it has become evident that adaptive changes in the hippocampus-dependent network activity patterns provide an important means of adjusting synaptic plasticity. We here summarise our current knowledge on how these processes in the hippocampus in interaction with amygdala and medial prefrontal cortex mediate the formation and persistence of emotional memories.
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Affiliation(s)
- Gürsel Çalışkan
- Department of Genetics & Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany.
| | - Oliver Stork
- Department of Genetics & Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany; Center for Behavioral Brain Sciences, Universitätsplatz 2, 39106 Magdeburg, Germany
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117
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Hippocampal Ripple Oscillations and Inhibition-First Network Models: Frequency Dynamics and Response to GABA Modulators. J Neurosci 2018; 38:3124-3146. [PMID: 29453207 DOI: 10.1523/jneurosci.0188-17.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 01/25/2018] [Accepted: 02/05/2018] [Indexed: 11/21/2022] Open
Abstract
Hippocampal ripples are involved in memory consolidation, but the mechanisms underlying their generation remain unclear. Models relying on interneuron networks in the CA1 region disagree on the predominant source of excitation to interneurons: either "direct," via the Schaffer collaterals that provide feedforward input from CA3 to CA1, or "indirect," via the local pyramidal cells in CA1, which are embedded in a recurrent excitatory-inhibitory network. Here, we used physiologically constrained computational models of basket-cell networks to investigate how they respond to different conditions of transient, noisy excitation. We found that direct excitation of interneurons could evoke ripples (140-220 Hz) that exhibited intraripple frequency accommodation and were frequency-insensitive to GABA modulators, as previously shown in in vitro experiments. In addition, the indirect excitation of the basket-cell network enabled the expression of intraripple frequency accommodation in the fast-gamma range (90-140 Hz), as in vivo In our model, intraripple frequency accommodation results from a hysteresis phenomenon in which the frequency responds differentially to the rising and descending phases of the transient excitation. Such a phenomenon predicts a maximum oscillation frequency occurring several milliseconds before the peak of excitation. We confirmed this prediction for ripples in brain slices from male mice. These results suggest that ripple and fast-gamma episodes are produced by the same interneuron network that is recruited via different excitatory input pathways, which could be supported by the previously reported intralaminar connectivity bias between basket cells and functionally distinct subpopulations of pyramidal cells in CA1. Together, our findings unify competing inhibition-first models of rhythm generation in the hippocampus.SIGNIFICANCE STATEMENT The hippocampus is a part of the brain of humans and other mammals that is critical for the acquisition and consolidation of memories. During deep sleep and resting periods, the hippocampus generates high-frequency (∼200 Hz) oscillations called ripples, which are important for memory consolidation. The mechanisms underlying ripple generation are not well understood. A prominent hypothesis holds that the ripples are generated by local recurrent networks of inhibitory neurons. Using computational models and experiments in brain slices from rodents, we show that the dynamics of interneuron networks clarify several previously unexplained characteristics of ripple oscillations, which advances our understanding of hippocampus-dependent memory consolidation.
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118
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Shishkina TV, Mishchenko TA, Mitroshina EV, Shirokova OM, Pimashkin AS, Kastalskiy IA, Mukhina IV, Kazantsev VB, Vedunova MV. Glial cell line-derived neurotrophic factor (GDNF) counteracts hypoxic damage to hippocampal neural network function in vitro. Brain Res 2018; 1678:310-321. [DOI: 10.1016/j.brainres.2017.10.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 12/14/2022]
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119
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Gönner L, Vitay J, Hamker FH. Predictive Place-Cell Sequences for Goal-Finding Emerge from Goal Memory and the Cognitive Map: A Computational Model. Front Comput Neurosci 2017; 11:84. [PMID: 29075187 PMCID: PMC5643423 DOI: 10.3389/fncom.2017.00084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/01/2017] [Indexed: 01/19/2023] Open
Abstract
Hippocampal place-cell sequences observed during awake immobility often represent previous experience, suggesting a role in memory processes. However, recent reports of goals being overrepresented in sequential activity suggest a role in short-term planning, although a detailed understanding of the origins of hippocampal sequential activity and of its functional role is still lacking. In particular, it is unknown which mechanism could support efficient planning by generating place-cell sequences biased toward known goal locations, in an adaptive and constructive fashion. To address these questions, we propose a model of spatial learning and sequence generation as interdependent processes, integrating cortical contextual coding, synaptic plasticity and neuromodulatory mechanisms into a map-based approach. Following goal learning, sequential activity emerges from continuous attractor network dynamics biased by goal memory inputs. We apply Bayesian decoding on the resulting spike trains, allowing a direct comparison with experimental data. Simulations show that this model (1) explains the generation of never-experienced sequence trajectories in familiar environments, without requiring virtual self-motion signals, (2) accounts for the bias in place-cell sequences toward goal locations, (3) highlights their utility in flexible route planning, and (4) provides specific testable predictions.
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Affiliation(s)
- Lorenz Gönner
- Artificial Intelligence, Department of Computer Science, Technische Universität Chemnitz, Chemnitz, Germany
| | - Julien Vitay
- Artificial Intelligence, Department of Computer Science, Technische Universität Chemnitz, Chemnitz, Germany
| | - Fred H Hamker
- Artificial Intelligence, Department of Computer Science, Technische Universität Chemnitz, Chemnitz, Germany.,Bernstein Center Computational Neuroscience, Humboldt-Universität Berlin, Berlin, Germany
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120
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Xia F, Richards BA, Tran MM, Josselyn SA, Takehara-Nishiuchi K, Frankland PW. Parvalbumin-positive interneurons mediate neocortical-hippocampal interactions that are necessary for memory consolidation. eLife 2017; 6:27868. [PMID: 28960176 PMCID: PMC5655147 DOI: 10.7554/elife.27868] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 09/28/2017] [Indexed: 12/13/2022] Open
Abstract
Following learning, increased coupling between spindle oscillations in the medial prefrontal cortex (mPFC) and ripple oscillations in the hippocampus is thought to underlie memory consolidation. However, whether learning-induced increases in ripple-spindle coupling are necessary for successful memory consolidation has not been tested directly. In order to decouple ripple-spindle oscillations, here we chemogenetically inhibited parvalbumin-positive (PV+) interneurons, since their activity is important for regulating the timing of spiking activity during oscillations. We found that contextual fear conditioning increased ripple-spindle coupling in mice. However, inhibition of PV+ cells in either CA1 or mPFC eliminated this learning-induced increase in ripple-spindle coupling without affecting ripple or spindle incidence. Consistent with the hypothesized importance of ripple-spindle coupling in memory consolidation, post-training inhibition of PV+ cells disrupted contextual fear memory consolidation. These results indicate that successful memory consolidation requires coherent hippocampal-neocortical communication mediated by PV+ cells.
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Affiliation(s)
- Frances Xia
- Department of Physiology, University of Toronto, Toronto, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children, University Avenue, Toronto, Canada
| | - Blake A Richards
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Matthew M Tran
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Sheena A Josselyn
- Department of Physiology, University of Toronto, Toronto, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children, University Avenue, Toronto, Canada.,Department of Psychology, University of Toronto, Toronto, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Canada
| | - Kaori Takehara-Nishiuchi
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.,Department of Psychology, University of Toronto, Toronto, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Canada
| | - Paul W Frankland
- Department of Physiology, University of Toronto, Toronto, Canada.,Program in Neurosciences and Mental Health, Hospital for Sick Children, University Avenue, Toronto, Canada.,Department of Psychology, University of Toronto, Toronto, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Canada
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121
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Sun ZY, Bozzelli PL, Caccavano A, Allen M, Balmuth J, Vicini S, Wu JY, Conant K. Disruption of perineuronal nets increases the frequency of sharp wave ripple events. Hippocampus 2017; 28:42-52. [PMID: 28921856 DOI: 10.1002/hipo.22804] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/22/2017] [Accepted: 09/13/2017] [Indexed: 12/30/2022]
Abstract
Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells (PCs) and require initial excitation of CA1 PCs as well as participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons. These interneurons are relatively unique in that they represent the major neuronal cell type known to be surrounded by perineuronal nets (PNNs), lattice like structures composed of a hyaluronin backbone that surround the cell soma and proximal dendrites. Though the function of the PNN is not completely understood, previous studies suggest it may serve to localize glutamatergic input to synaptic contacts and thus influence the activity of ensheathed cells. Noting that FS PV interneurons impact the activity of PCs thought to initiate SWRs, and that their activity is critical to ripple expression, we examine the effects of PNN integrity on SWR activity in the hippocampus. Extracellular recordings from the stratum radiatum of horizontal murine hippocampal hemisections demonstrate SWRs that occur spontaneously in CA1. As compared with vehicle, pre-treatment (120 min) of paired hemislices with hyaluronidase, which cleaves the hyaluronin backbone of the PNN, decreases PNN integrity and increases SWR frequency. Pre-treatment with chondroitinase, which cleaves PNN side chains, also increases SWR frequency. Together, these data contribute to an emerging appreciation of extracellular matrix as a regulator of neuronal plasticity and suggest that one function of mature perineuronal nets could be to modulate the frequency of SWR events.
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Affiliation(s)
- Zhi Yong Sun
- Jilin Women and Children's Health Hospital, Changchun, Jilin, China
| | - P Lorenzo Bozzelli
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia
| | - Adam Caccavano
- Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Department of Pharmacology, Georgetown University School of Medicine, Washington, District of Columbia
| | - Megan Allen
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia
| | - Jason Balmuth
- Applied Physics Laboratory, Johns Hopkins University, Baltimore, Maryland
| | - Stefano Vicini
- Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Department of Pharmacology, Georgetown University School of Medicine, Washington, District of Columbia
| | - Jian-Young Wu
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia
| | - Katherine Conant
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia
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122
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Canakci S, Toy MF, Inci AF, Liu X, Kuzum D. Computational analysis of network activity and spatial reach of sharp wave-ripples. PLoS One 2017; 12:e0184542. [PMID: 28915251 PMCID: PMC5600383 DOI: 10.1371/journal.pone.0184542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 08/25/2017] [Indexed: 11/19/2022] Open
Abstract
Network oscillations of different frequencies, durations and amplitudes are hypothesized to coordinate information processing and transfer across brain areas. Among these oscillations, hippocampal sharp wave-ripple complexes (SPW-Rs) are one of the most prominent. SPW-Rs occurring in the hippocampus are suggested to play essential roles in memory consolidation as well as information transfer to the neocortex. To-date, most of the knowledge about SPW-Rs comes from experimental studies averaging responses from neuronal populations monitored by conventional microelectrodes. In this work, we investigate spatiotemporal characteristics of SPW-Rs and how microelectrode size and distance influence SPW-R recordings using a biophysical model of hippocampus. We also explore contributions from neuronal spikes and synaptic potentials to SPW-Rs based on two different types of network activity. Our study suggests that neuronal spikes from pyramidal cells contribute significantly to ripples while high amplitude sharp waves mainly arise from synaptic activity. Our simulations on spatial reach of SPW-Rs show that the amplitudes of sharp waves and ripples exhibit a steep decrease with distance from the network and this effect is more prominent for smaller area electrodes. Furthermore, the amplitude of the signal decreases strongly with increasing electrode surface area as a result of averaging. The relative decrease is more pronounced when the recording electrode is closer to the source of the activity. Through simulations of field potentials across a high-density microelectrode array, we demonstrate the importance of finding the ideal spatial resolution for capturing SPW-Rs with great sensitivity. Our work provides insights on contributions from spikes and synaptic potentials to SPW-Rs and describes the effect of measurement configuration on LFPs to guide experimental studies towards improved SPW-R recordings.
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Affiliation(s)
- Sadullah Canakci
- Electrical and Computer Engineering Department, Boston University, Boston, Massachusetts, United States of America
| | - Muhammed Faruk Toy
- Electrical and Computer Engineering Department, University of California San Diego, La Jolla, California, United States of America
- Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey
| | - Ahmet Fatih Inci
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Xin Liu
- Electrical and Computer Engineering Department, University of California San Diego, La Jolla, California, United States of America
| | - Duygu Kuzum
- Electrical and Computer Engineering Department, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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123
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Liu Y, McAfee SS, Heck DH. Hippocampal sharp-wave ripples in awake mice are entrained by respiration. Sci Rep 2017; 7:8950. [PMID: 28827599 PMCID: PMC5566471 DOI: 10.1038/s41598-017-09511-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/26/2017] [Indexed: 12/31/2022] Open
Abstract
Several recent studies have shown that respiration modulates oscillatory neuronal activity in the neocortex and hippocampus on a cycle-by-cycle basis. It was suggested that this respiratory influence on neuronal activity affects cognitive functions, including memory. Sharp-wave ripples (SWRs) are high-frequency local field potential activity patterns characteristic for the hippocampus and implicated in memory consolidation and recall. Here we show that the timing of SWR events is modulated by the respiratory cycle, with a significantly increased probability of SWRs during the early expiration phase. This influence of respiration on SWR occurrence was eliminated when olfactory bulb activity was inhibited. Our findings represent a possible neuronal mechanism for a direct influence of the respiratory cycle on memory function.
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Affiliation(s)
- Yu Liu
- Department of Anatomy and Neurobiology, University of Tennessee HSC, Memphis, TN, 38163, USA
| | - Samuel S McAfee
- Department of Anatomy and Neurobiology, University of Tennessee HSC, Memphis, TN, 38163, USA
| | - Detlef H Heck
- Department of Anatomy and Neurobiology, University of Tennessee HSC, Memphis, TN, 38163, USA.
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124
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Abnormalities in Dynamic Brain Activity Caused by Mild Traumatic Brain Injury Are Partially Rescued by the Cannabinoid Type-2 Receptor Inverse Agonist SMM-189. eNeuro 2017; 4:eN-NWR-0387-16. [PMID: 28828401 PMCID: PMC5562300 DOI: 10.1523/eneuro.0387-16.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 06/26/2017] [Accepted: 07/03/2017] [Indexed: 12/23/2022] Open
Abstract
Mild traumatic brain injury (mTBI) can cause severe long-term cognitive and emotional deficits, including impaired memory, depression, and persevering fear, but the neuropathological basis of these deficits is uncertain. As medial prefrontal cortex (mPFC) and hippocampus play important roles in memory and emotion, we used multi-site, multi-electrode recordings of oscillatory neuronal activity in local field potentials (LFPs) in awake, head-fixed mice to determine if the functioning of these regions was abnormal after mTBI, using a closed-skull focal cranial blast model. We evaluated mPFC, hippocampus CA1, and primary somatosensory/visual cortical areas (S1/V1). Although mTBI did not alter the power of oscillations, it did cause increased coherence of θ (4-10 Hz) and β (10-30 Hz) oscillations within mPFC and S1/V1, reduced CA1 sharp-wave ripple (SWR)-evoked LFP activity in mPFC, downshifted SWR frequencies in CA1, and enhanced θ-γ phase-amplitude coupling (PAC) within mPFC. These abnormalities might be linked to the impaired memory, depression, and persevering fear seen after mTBI. Treatment with the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189 has been shown to mitigate functional deficits and neuronal injury after mTBI in mice. We found that SMM-189 also reversed most of the observed neurophysiological abnormalities. This neurophysiological rescue is likely to stem from the previously reported reduction in neuron loss and/or the preservation of neuronal function and connectivity resulting from SMM-189 treatment, which appears to stem from the biasing of microglia from the proinflammatory M1 state to the prohealing M2 state by SMM-189.
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125
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Mechanisms for Selective Single-Cell Reactivation during Offline Sharp-Wave Ripples and Their Distortion by Fast Ripples. Neuron 2017. [PMID: 28641116 DOI: 10.1016/j.neuron.2017.05.032] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Memory traces are reactivated selectively during sharp-wave ripples. The mechanisms of selective reactivation, and how degraded reactivation affects memory, are poorly understood. We evaluated hippocampal single-cell activity during physiological and pathological sharp-wave ripples using juxtacellular and intracellular recordings in normal and epileptic rats with different memory abilities. CA1 pyramidal cells participate selectively during physiological events but fired together during epileptic fast ripples. We found that firing selectivity was dominated by an event- and cell-specific synaptic drive, modulated in single cells by changes in the excitatory/inhibitory ratio measured intracellularly. This mechanism collapses during pathological fast ripples to exacerbate and randomize neuronal firing. Acute administration of a use- and cell-type-dependent sodium channel blocker reduced neuronal collapse and randomness and improved recall in epileptic rats. We propose that cell-specific synaptic inputs govern firing selectivity of CA1 pyramidal cells during sharp-wave ripples.
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126
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An Optogenetic Approach for Investigation of Excitatory and Inhibitory Network GABA Actions in Mice Expressing Channelrhodopsin-2 in GABAergic Neurons. J Neurosci 2017; 36:5961-73. [PMID: 27251618 DOI: 10.1523/jneurosci.3482-15.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 04/12/2016] [Indexed: 01/16/2023] Open
Abstract
UNLABELLED To investigate excitatory and inhibitory GABA actions in cortical neuronal networks, we present a novel optogenetic approach using a mouse knock-in line with conditional expression of channelrhodopsin-2 (ChR2) in GABAergic interneurons. During whole-cell recordings from hippocampal and neocortical slices from postnatal day (P) 2-P15 mice, photostimulation caused depolarization and excitation of interneurons and evoked barrages of postsynaptic GABAergic currents. Excitatory/inhibitory GABA actions on pyramidal cells were assessed by monitoring the alteration in the frequency of EPSCs during photostimulation of interneurons. We found that in slices from P2-P8 mice, photostimulation evoked an increase in EPSC frequency, whereas in P9-P15 mice the response switched to a reduction in EPSC frequency, indicating a developmental excitatory-to-inhibitory switch in GABA actions on glutamatergic neurons. Using a similar approach in urethane-anesthetized animals in vivo, we found that photostimulation of interneurons reduces EPSC frequency at ages P3-P9. Thus, expression of ChR2 in GABAergic interneurons of mice enables selective photostimulation of interneurons during the early postnatal period, and these mice display a developmental excitatory-to-inhibitory switch in GABA action in cortical slices in vitro, but so far show mainly inhibitory GABA actions on spontaneous EPSCs in the immature hippocampus and neocortex in vivo SIGNIFICANCE STATEMENT We report a novel optogenetic approach for investigating excitatory and inhibitory GABA actions in mice with conditional expression of channelrhodopsin-2 in GABAergic interneurons. This approach shows a developmental excitatory-to-inhibitory switch in the actions of GABA on glutamatergic neurons in neocortical and hippocampal slices from neonatal mouse pups in vitro, but also reveals inhibitory GABA actions in the neonatal mouse neocortex and hippocampus in vivo.
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127
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Lapato AS, Tiwari-Woodruff SK. Connexins and pannexins: At the junction of neuro-glial homeostasis & disease. J Neurosci Res 2017; 96:31-44. [PMID: 28580666 DOI: 10.1002/jnr.24088] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 04/08/2017] [Accepted: 05/01/2017] [Indexed: 12/15/2022]
Abstract
In the central nervous system (CNS), connexin (Cx)s and pannexin (Panx)s are an integral component of homeostatic neuronal excitability and synaptic plasticity. Neuronal Cx gap junctions form electrical synapses across biochemically similar GABAergic networks, allowing rapid and extensive inhibition in response to principle neuron excitation. Glial Cx gap junctions link astrocytes and oligodendrocytes in the pan-glial network that is responsible for removing excitotoxic ions and metabolites. In addition, glial gap junctions help constrain excessive excitatory activity in neurons and facilitate astrocyte Ca2+ slow wave propagation. Panxs do not form gap junctions in vivo, but Panx hemichannels participate in autocrine and paracrine gliotransmission, alongside Cx hemichannels. ATP and other gliotransmitters released by Cx and Panx hemichannels maintain physiologic glutamatergic tone by strengthening synapses and mitigating aberrant high frequency bursting. Under pathological depolarizing and inflammatory conditions, gap junctions and hemichannels become dysregulated, resulting in excessive neuronal firing and seizure. In this review, we present known contributions of Cxs and Panxs to physiologic neuronal excitation and explore how the disruption of gap junctions and hemichannels lead to abnormal glutamatergic transmission, purinergic signaling, and seizures.
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Affiliation(s)
- Andrew S Lapato
- Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA, 92521.,Center for Glial-Neuronal Interactions, University of California Riverside, Riverside, CA, 92521
| | - Seema K Tiwari-Woodruff
- Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA, 92521.,Center for Glial-Neuronal Interactions, University of California Riverside, Riverside, CA, 92521.,Neuroscience Graduate Program, University of California Riverside, Riverside, CA, 92521
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128
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Prominent differences in sharp waves, ripples and complex spike bursts between the dorsal and the ventral rat hippocampus. Neuroscience 2017; 352:131-143. [DOI: 10.1016/j.neuroscience.2017.03.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 12/17/2022]
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129
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Differential excitatory control of 2 parallel basket cell networks in amygdala microcircuits. PLoS Biol 2017; 15:e2001421. [PMID: 28542195 PMCID: PMC5443504 DOI: 10.1371/journal.pbio.2001421] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 04/28/2017] [Indexed: 12/29/2022] Open
Abstract
Information processing in neural networks depends on the connectivity among excitatory and inhibitory neurons. The presence of parallel, distinctly controlled local circuits within a cortical network may ensure an effective and dynamic regulation of microcircuit function. By applying a combination of optogenetics, electrophysiological recordings, and high resolution microscopic techniques, we uncovered the organizing principles of synaptic communication between principal neurons and basket cells in the basal nucleus of the amygdala. In this cortical structure, known to be critical for emotional memory formation, we revealed the presence of 2 parallel basket cell networks expressing either parvalbumin or cholecystokinin. While the 2 basket cell types are mutually interconnected within their own category via synapses and gap junctions, they avoid innervating each other, but form synaptic contacts with axo-axonic cells. Importantly, both basket cell types have the similar potency to control principal neuron spiking, but they receive excitatory input from principal neurons with entirely diverse features. This distinct feedback synaptic excitation enables a markedly different recruitment of the 2 basket cell types upon the activation of local principal neurons. Our data suggest fundamentally different functions for the 2 parallel basket cell networks in circuit operations in the amygdala. The perisomatic region of neurons refers collectively to the membrane surface of the cell body or soma, proximal dendrites, and axon initial segment. This is a unique functional domain in which the activity of a neuron can be controlled in the most effective manner. In the cerebral cortex, the perisomatic region of excitatory principal cells is solely innervated by inhibitory interneurons, which can be divided into 3 functional groups: axo-axonic cells and 2 types of basket cells. The reason why 3 distinct types of inhibitory cells are specialized to control principal cell firing is still unknown. To reveal the possible differences in the role of the 3 interneuron types played in cortical operation, we have investigated the organizing principles of synaptic communication between principal cells and inhibitory cell types in the basal nucleus of the amygdala. In this cortical structure, known to be critical for affective behavior, we revealed that the 2 basket cell types avoid innervating each other but contact axo-axonic cells. Both basket cell types have a similar potency to control principal cell firing, but they receive excitatory input from principal cells with entirely distinct features. Our data suggest fundamentally different functions for the 2 parallel basket cell networks in amygdala operation.
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130
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Parvalbumin-expressing interneurons coordinate hippocampal network dynamics required for memory consolidation. Nat Commun 2017; 8:15039. [PMID: 28382952 PMCID: PMC5384212 DOI: 10.1038/ncomms15039] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 02/21/2017] [Indexed: 12/19/2022] Open
Abstract
Activity in hippocampal area CA1 is essential for consolidating episodic memories, but it is unclear how CA1 activity patterns drive memory formation. We find that in the hours following single-trial contextual fear conditioning (CFC), fast-spiking interneurons (which typically express parvalbumin (PV)) show greater firing coherence with CA1 network oscillations. Post-CFC inhibition of PV+ interneurons blocks fear memory consolidation. This effect is associated with loss of two network changes associated with normal consolidation: (1) augmented sleep-associated delta (0.5-4 Hz), theta (4-12 Hz) and ripple (150-250 Hz) oscillations; and (2) stabilization of CA1 neurons' functional connectivity patterns. Rhythmic activation of PV+ interneurons increases CA1 network coherence and leads to a sustained increase in the strength and stability of functional connections between neurons. Our results suggest that immediately following learning, PV+ interneurons drive CA1 oscillations and reactivation of CA1 ensembles, which directly promotes network plasticity and long-term memory formation.
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131
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Rebola N, Carta M, Mulle C. Operation and plasticity of hippocampal CA3 circuits: implications for memory encoding. Nat Rev Neurosci 2017; 18:208-220. [DOI: 10.1038/nrn.2017.10] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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132
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Memory replay in balanced recurrent networks. PLoS Comput Biol 2017; 13:e1005359. [PMID: 28135266 PMCID: PMC5305273 DOI: 10.1371/journal.pcbi.1005359] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 02/13/2017] [Accepted: 01/09/2017] [Indexed: 11/19/2022] Open
Abstract
Complex patterns of neural activity appear during up-states in the neocortex and sharp waves in the hippocampus, including sequences that resemble those during prior behavioral experience. The mechanisms underlying this replay are not well understood. How can small synaptic footprints engraved by experience control large-scale network activity during memory retrieval and consolidation? We hypothesize that sparse and weak synaptic connectivity between Hebbian assemblies are boosted by pre-existing recurrent connectivity within them. To investigate this idea, we connect sequences of assemblies in randomly connected spiking neuronal networks with a balance of excitation and inhibition. Simulations and analytical calculations show that recurrent connections within assemblies allow for a fast amplification of signals that indeed reduces the required number of inter-assembly connections. Replay can be evoked by small sensory-like cues or emerge spontaneously by activity fluctuations. Global-potentially neuromodulatory-alterations of neuronal excitability can switch between network states that favor retrieval and consolidation.
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133
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Lévesque M, Shiri Z, Chen LY, Avoli M. High-frequency oscillations and mesial temporal lobe epilepsy. Neurosci Lett 2017; 667:66-74. [PMID: 28115239 DOI: 10.1016/j.neulet.2017.01.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 01/18/2017] [Accepted: 01/19/2017] [Indexed: 01/25/2023]
Abstract
The interest of epileptologists has recently shifted from the macroscopic analysis of interictal spikes and seizures to the microscopic analysis of short events in the EEG that are not visible to the naked eye but are observed once the signal has been filtered in specific frequency bands. With the use of new technologies that allow multichannel recordings at high sampling rates and the development of computer algorithms that permit the automated analysis of extensive amounts of data, it is now possible to extract high-frequency oscillations (HFOs) between 80 and 500Hz from the EEG; HFOs have been further categorised as ripples (80-200Hz) and fast ripples (250-500Hz). Within the context of epileptic disorders, HFOs should reflect the pathological activity of neural networks that sustain seizure generation, and could serve as biomarkers of epileptogenesis and ictogenesis. We review here the presumptive cellular mechanisms of ripples and fast ripples in mesial temporal lobe epilepsy. We also focus on recent findings regarding the occurrence of HFOs during epileptiform activity observed in in vitro models of epileptiform synchronization, in in vivo models of mesial temporal lobe epilepsy and in epileptic patients. Finally, we address the effects of anti-epileptic drugs on HFOs and raise some questions and issues related to the definition of HFOs.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, H3A 2B4, Canada
| | - Zahra Shiri
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, H3A 2B4, Canada
| | - Li-Yuan Chen
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, H3A 2B4, Canada.
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134
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Li Y, Chen X, Dzakpasu R, Conant K. Dopamine-dependent effects on basal and glutamate stimulated network dynamics in cultured hippocampal neurons. J Neurochem 2017; 140:550-560. [PMID: 27925199 DOI: 10.1111/jnc.13915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 11/23/2016] [Accepted: 11/28/2016] [Indexed: 01/15/2023]
Abstract
Oscillatory activity occurs in cortical and hippocampal networks with specific frequency ranges thought to be critical to working memory, attention, differentiation of neuronal precursors, and memory trace replay. Synchronized activity within relatively large neuronal populations is influenced by firing and bursting frequency within individual cells, and the latter is modulated by changes in intrinsic membrane excitability and synaptic transmission. Published work suggests that dopamine, a potent modulator of learning and memory, acts on dopamine receptor 1-like dopamine receptors to influence the phosphorylation and trafficking of glutamate receptor subunits, along with long-term potentiation of excitatory synaptic transmission in striatum and prefrontal cortex. Prior studies also suggest that dopamine can influence voltage gated ion channel function and membrane excitability in these regions. Fewer studies have examined dopamine's effect on related endpoints in hippocampus, or potential consequences in terms of network burst dynamics. In this study, we record action potential activity using a microelectrode array system to examine the ability of dopamine to modulate baseline and glutamate-stimulated bursting activity in an in vitro network of cultured murine hippocampal neurons. We show that dopamine stimulates a dopamine type-1 receptor-dependent increase in number of overall bursts within minutes of its application. Notably, however, at the concentration used herein, dopamine did not increase the overall synchrony of bursts between electrodes. Although the number of bursts normalizes by 40 min, bursting in response to a subsequent glutamate challenge is enhanced by dopamine pretreatment. Dopamine-dependent potentiation of glutamate-stimulated bursting was not observed when the two modulators were administered concurrently. In parallel, pretreatment of murine hippocampal cultures with dopamine stimulated lasting increases in the phosphorylation of the glutamate receptor subunit GluA1 at serine 845. This effect is consistent with the possibility that enhanced membrane insertion of GluAs may contribute to a more slowly evolving dopamine-dependent potentiation of glutamate-stimulated bursting. Together, these results are consistent with the possibility that dopamine can influence hippocampal bursting by at least two temporally distinct mechanisms, contributing to an emerging appreciation of dopamine-dependent effects on network activity in the hippocampus.
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Affiliation(s)
- Yan Li
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia, USA
| | - Xin Chen
- Department of Physics, Georgetown University, Washington, District of Columbia, USA
| | - Rhonda Dzakpasu
- Department of Physics, Georgetown University, Washington, District of Columbia, USA.,Department of Pharmacology, Georgetown University School of Medicine, Washington, District of Columbia, USA.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia, USA
| | - Katherine Conant
- Department of Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia, USA.,Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, District of Columbia, USA
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135
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Polepalli JS, Wu H, Goswami D, Halpern CH, Südhof TC, Malenka RC. Modulation of excitation on parvalbumin interneurons by neuroligin-3 regulates the hippocampal network. Nat Neurosci 2017; 20:219-229. [PMID: 28067903 PMCID: PMC5272845 DOI: 10.1038/nn.4471] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/23/2016] [Indexed: 02/07/2023]
Abstract
Hippocampal network activity is generated by a complex interplay between excitatory pyramidal cells and inhibitory interneurons. Although much is known about the molecular properties of excitatory synapses on pyramidal cells, comparatively little is known about excitatory synapses on interneurons. Here we show that conditional deletion of the postsynaptic cell adhesion molecule neuroligin-3 in parvalbumin interneurons causes a decrease in NMDA-receptor-mediated postsynaptic currents and an increase in presynaptic glutamate release probability by selectively impairing the inhibition of glutamate release by presynaptic Group III metabotropic glutamate receptors. As a result, the neuroligin-3 deletion altered network activity by reducing gamma oscillations and sharp wave ripples, changes associated with a decrease in extinction of contextual fear memories. These results demonstrate that neuroligin-3 specifies the properties of excitatory synapses on parvalbumin-containing interneurons by a retrograde trans-synaptic mechanism and suggest a molecular pathway whereby neuroligin-3 mutations contribute to neuropsychiatric disorders.
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Affiliation(s)
- Jai S Polepalli
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Hemmings Wu
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
| | - Debanjan Goswami
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Casey H Halpern
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA
| | - Robert C Malenka
- Nancy Pritzker Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California, USA
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136
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Veres JM, Nagy GA, Hájos N. Perisomatic GABAergic synapses of basket cells effectively control principal neuron activity in amygdala networks. eLife 2017; 6. [PMID: 28060701 PMCID: PMC5218536 DOI: 10.7554/elife.20721] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/16/2016] [Indexed: 12/17/2022] Open
Abstract
Efficient control of principal neuron firing by basket cells is critical for information processing in cortical microcircuits, however, the relative contribution of their perisomatic and dendritic synapses to spike inhibition is still unknown. Using in vitro electrophysiological paired recordings we reveal that in the mouse basal amygdala cholecystokinin- and parvalbumin-containing basket cells provide equally potent control of principal neuron spiking. We performed pharmacological manipulations, light and electron microscopic investigations to show that, although basket cells innervate the entire somato-denditic membrane surface of principal neurons, the spike controlling effect is achieved primarily via the minority of synapses targeting the perisomatic region. As the innervation patterns of individual basket cells on their different postsynaptic partners show high variability, the impact of inhibitory control accomplished by single basket cells is also variable. Our results show that both basket cell types can powerfully regulate the activity in amygdala networks predominantly via their perisomatic synapses. DOI:http://dx.doi.org/10.7554/eLife.20721.001
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Affiliation(s)
- Judit M Veres
- 'Lendület' Laboratory of Network Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Gergő A Nagy
- 'Lendület' Laboratory of Network Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Norbert Hájos
- 'Lendület' Laboratory of Network Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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137
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Gan J, Weng SM, Pernía-Andrade AJ, Csicsvari J, Jonas P. Phase-Locked Inhibition, but Not Excitation, Underlies Hippocampal Ripple Oscillations in Awake Mice In Vivo. Neuron 2016; 93:308-314. [PMID: 28041883 PMCID: PMC5263253 DOI: 10.1016/j.neuron.2016.12.018] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 08/08/2016] [Accepted: 12/06/2016] [Indexed: 11/27/2022]
Abstract
Sharp wave-ripple (SWR) oscillations play a key role in memory consolidation during non-rapid eye movement sleep, immobility, and consummatory behavior. However, whether temporally modulated synaptic excitation or inhibition underlies the ripples is controversial. To address this question, we performed simultaneous recordings of excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) and local field potentials (LFPs) in the CA1 region of awake mice in vivo. During SWRs, inhibition dominated over excitation, with a peak conductance ratio of 4.1 ± 0.5. Furthermore, the amplitude of SWR-associated IPSCs was positively correlated with SWR magnitude, whereas that of EPSCs was not. Finally, phase analysis indicated that IPSCs were phase-locked to individual ripple cycles, whereas EPSCs were uniformly distributed in phase space. Optogenetic inhibition indicated that PV+ interneurons provided a major contribution to SWR-associated IPSCs. Thus, phasic inhibition, but not excitation, shapes SWR oscillations in the hippocampal CA1 region in vivo. High-resolution synaptic current recording during sharp wave-ripples (SWRs) in vivo Inhibition dominates over excitation during SWRs in the hippocampal CA1 region Phasic inhibition, but not excitation, is phase-locked to individual ripple cycles PV+ interneurons substantially contribute to SWR-associated inhibitory conductance
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Affiliation(s)
- Jian Gan
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria
| | - Shih-Ming Weng
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria
| | | | - Jozsef Csicsvari
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria
| | - Peter Jonas
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
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138
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Halász P. The relationship of medial temporal lobe epilepsy with the declarative memory system. JOURNAL OF EPILEPTOLOGY 2016. [DOI: 10.1515/joepi-2016-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
SummaryIntroduction.Medial temporal lobe of epilepsy (MTLE) is considered as local/regional epilepsy. However, as was discussed in Part I of this review (Halász, 2016a) there is more evidence regarding the involvement of both temporal lobes so as to consider MTLE as one of the typical bilateral system epilepsies.Aim.To provide contemporary review of MTLE in relation to the declarative memory system and the newly recognized hippocampo-frontal memory consolidation during slow wave sleep.Methods.A review of the available literature on experimental and clinical data and also the authors own studies in MTLE patients.Review, discussion and results.New experimental and clinical neurophysiological data have shown that MTLE is closely linked to the hippocampal memory system. It is likely that hippocampal spiking is the epileptic variations of the normal sharp wave ripple events mediating the encoding and consolidation of memory engrams by a hippocampo-frontal dialogue during slow wave sleep.Conclusions.The source of memory impairment in MTLE patients is not merely the cell loss and synaptic transformation of the hippocampal structure, but the every night interference with memory consolidation due to interictal spiking.
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139
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Gulyás AI, Freund TF, Káli S. The Effects of Realistic Synaptic Distribution and 3D Geometry on Signal Integration and Extracellular Field Generation of Hippocampal Pyramidal Cells and Inhibitory Neurons. Front Neural Circuits 2016; 10:88. [PMID: 27877113 PMCID: PMC5099150 DOI: 10.3389/fncir.2016.00088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 10/17/2016] [Indexed: 12/02/2022] Open
Abstract
In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells (PCs) and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree. We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that PCs and inhibitory neurons probably use different input integration strategies. In PCs, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies of active dendritic integration. In the electrotonically compact parvalbumin- and cholecystokinincontaining interneurons, synaptic events are visible in the whole dendritic arbor, and thus the entire dendritic tree may form a single integrative element. Calretinin-containing interneurons were found to be electrotonically extended, which suggests the possibility of complex dendritic processing in this cell type. Our results also highlight the need for the integration of methods that allow the measurement of dendritic processes into studies of synaptic interactions and dynamics in neural networks.
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Affiliation(s)
- Attila I Gulyás
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Tamás F Freund
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Szabolcs Káli
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
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140
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Talakoub O, Gomez Palacio Schjetnan A, Valiante TA, Popovic MR, Hoffman KL. Closed-Loop Interruption of Hippocampal Ripples through Fornix Stimulation in the Non-Human Primate. Brain Stimul 2016; 9:911-918. [DOI: 10.1016/j.brs.2016.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/13/2016] [Accepted: 07/27/2016] [Indexed: 12/23/2022] Open
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141
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Calcium sensor regulation of the CaV2.1 Ca2+ channel contributes to long-term potentiation and spatial learning. Proc Natl Acad Sci U S A 2016; 113:13209-13214. [PMID: 27799552 DOI: 10.1073/pnas.1616206113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Many forms of short-term synaptic plasticity rely on regulation of presynaptic voltage-gated Ca2+ type 2.1 (CaV2.1) channels. However, the contribution of regulation of CaV2.1 channels to other forms of neuroplasticity and to learning and memory are not known. Here we have studied mice with a mutation (IM-AA) that disrupts regulation of CaV2.1 channels by calmodulin and related calcium sensor proteins. Surprisingly, we find that long-term potentiation (LTP) of synaptic transmission at the Schaffer collateral-CA1 synapse in the hippocampus is substantially weakened, even though this form of synaptic plasticity is thought to be primarily generated postsynaptically. LTP in response to θ-burst stimulation and to 100-Hz tetanic stimulation is much reduced. However, a normal level of LTP can be generated by repetitive 100-Hz stimulation or by depolarization of the postsynaptic cell to prevent block of NMDA-specific glutamate receptors by Mg2+ The ratio of postsynaptic responses of NMDA-specific glutamate receptors to those of AMPA-specific glutamate receptors is decreased, but the postsynaptic current from activation of NMDA-specific glutamate receptors is progressively increased during trains of stimuli and exceeds WT by the end of 1-s trains. Strikingly, these impairments in long-term synaptic plasticity and the previously documented impairments in short-term synaptic plasticity in IM-AA mice are associated with pronounced deficits in spatial learning and memory in context-dependent fear conditioning and in the Barnes circular maze. Thus, regulation of CaV2.1 channels by calcium sensor proteins is required for normal short-term synaptic plasticity, LTP, and spatial learning and memory in mice.
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142
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Maier P, Kaiser ME, Grinevich V, Draguhn A, Both M. Differential effects of oxytocin on mouse hippocampal oscillationsin vitro. Eur J Neurosci 2016; 44:2885-2898. [DOI: 10.1111/ejn.13412] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 09/09/2016] [Accepted: 09/20/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Pia Maier
- Institute of Physiology and Pathophysiology; University of Heidelberg; Im Neuenheimer Feld 326 69120 Heidelberg Germany
| | - Martin E. Kaiser
- Institute of Physiology and Pathophysiology; University of Heidelberg; Im Neuenheimer Feld 326 69120 Heidelberg Germany
| | - Valery Grinevich
- Schaller Research Group on Neuropeptides; German Cancer Research Center (DKFZ) and Network Cluster of Excellence; University of Heidelberg; Heidelberg Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology; University of Heidelberg; Im Neuenheimer Feld 326 69120 Heidelberg Germany
| | - Martin Both
- Institute of Physiology and Pathophysiology; University of Heidelberg; Im Neuenheimer Feld 326 69120 Heidelberg Germany
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143
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Oliva A, Fernández-Ruiz A, Buzsáki G, Berényi A. Role of Hippocampal CA2 Region in Triggering Sharp-Wave Ripples. Neuron 2016; 91:1342-1355. [PMID: 27593179 DOI: 10.1016/j.neuron.2016.08.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/17/2016] [Accepted: 07/29/2016] [Indexed: 12/20/2022]
Abstract
Sharp-wave ripples (SPW-Rs) in the hippocampus are implied in memory consolidation, as shown by observational and interventional experiments. However, the mechanism of their generation remains unclear. Using two-dimensional silicon probe arrays, we investigated the propagation of SPW-Rs across the hippocampal CA1, CA2, and CA3 subregions. Synchronous activation of CA2 ensembles preceded SPW-R-related population activity in CA3 and CA1 regions. Deep CA2 neurons gradually increased their activity prior to ripples and were suppressed during the population bursts of CA3-CA1 neurons (ramping cells). Activity of superficial CA2 cells preceded the activity surge in CA3-CA1 (phasic cells). The trigger role of the CA2 region in SPW-R was more pronounced during waking than sleeping. These results point to the CA2 region as an initiation zone for SPW-Rs.
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Affiliation(s)
- Azahara Oliva
- MTA-SZTE "Momentum" Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged 6720, Hungary
| | - Antonio Fernández-Ruiz
- MTA-SZTE "Momentum" Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged 6720, Hungary; School of Physics, Complutense University, 28040 Madrid, Spain
| | - György Buzsáki
- New York University Neuroscience Institute and Center for Neural Science, New York University, New York, NY 10016, USA.
| | - Antal Berényi
- MTA-SZTE "Momentum" Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, Szeged 6720, Hungary; New York University Neuroscience Institute and Center for Neural Science, New York University, New York, NY 10016, USA.
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144
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Microcircuits in respiratory rhythm generation: commonalities with other rhythm generating networks and evolutionary perspectives. Curr Opin Neurobiol 2016; 41:53-61. [PMID: 27589601 DOI: 10.1016/j.conb.2016.08.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
Abstract
Rhythmicity is critical for the generation of rhythmic behaviors and higher brain functions. This review discusses common mechanisms of rhythm generation, including the role of synaptic inhibition and excitation, with a focus on the mammalian respiratory network. This network generates three phases of breathing and is highly integrated with brain regions associated with numerous non-ventilatory behaviors. We hypothesize that during evolution multiple rhythmogenic microcircuits were recruited to accommodate the generation of each breathing phase. While these microcircuits relied primarily on excitatory mechanisms, synaptic inhibition became increasingly important to coordinate the different microcircuits and to integrate breathing into a rich behavioral repertoire that links breathing to sensory processing, arousal, and emotions as well as learning and memory.
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145
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Assessment of Methods for the Intracellular Blockade of GABAA Receptors. PLoS One 2016; 11:e0160900. [PMID: 27501143 PMCID: PMC4976935 DOI: 10.1371/journal.pone.0160900] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/26/2016] [Indexed: 12/11/2022] Open
Abstract
Selective blockade of inhibitory synaptic transmission onto specific neurons is a useful tool for dissecting the excitatory and inhibitory synaptic components of ongoing network activity. To achieve this, intracellular recording with a patch solution capable of blocking GABAA receptors has advantages over other manipulations, such as pharmacological application of GABAergic antagonists or optogenetic inhibition of populations of interneurones, in that the majority of inhibitory transmission is unaffected and hence the remaining network activity preserved. Here, we assess three previously described methods to block inhibition: intracellular application of the molecules picrotoxin, 4,4’-dinitro-stilbene-2,2’-disulphonic acid (DNDS) and 4,4’-diisothiocyanostilbene-2,2’-disulphonic acid (DIDS). DNDS and picrotoxin were both found to be ineffective at blocking evoked, monosynaptic inhibitory postsynaptic currents (IPSCs) onto mouse CA1 pyramidal cells. An intracellular solution containing DIDS and caesium fluoride, but lacking nucleotides ATP and GTP, was effective at decreasing the amplitude of IPSCs. However, this effect was found to be independent of DIDS, and the absence of intracellular nucleotides, and was instead due to the presence of fluoride ions in this intracellular solution, which also blocked spontaneously occurring IPSCs during hippocampal sharp waves. Critically, intracellular fluoride ions also caused a decrease in both spontaneous and evoked excitatory synaptic currents and precluded the inclusion of nucleotides in the intracellular solution. Therefore, of the methods tested, only fluoride ions were effective for intracellular blockade of IPSCs but this approach has additional cellular effects reducing its selectivity and utility.
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146
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Kohus Z, Káli S, Rovira‐Esteban L, Schlingloff D, Papp O, Freund TF, Hájos N, Gulyás AI. Properties and dynamics of inhibitory synaptic communication within the CA3 microcircuits of pyramidal cells and interneurons expressing parvalbumin or cholecystokinin. J Physiol 2016; 594:3745-74. [PMID: 27038232 PMCID: PMC4929320 DOI: 10.1113/jp272231] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/21/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS To understand how a network operates, its elements must be identified and characterized, and the interactions of the elements need to be studied in detail. In the present study, we describe quantitatively the connectivity of two classes of inhibitory neurons in the hippocampal CA3 area (parvalbumin-positive and cholecystokinin-positive interneurons), a key region for the generation of behaviourally relevant synchronous activity patterns. We describe how interactions among these inhibitory cells and their local excitatory target neurons evolve over the course of physiological and pathological activity patterns. The results of the present study enable the construction of precise neuronal network models that may help us understand how network dynamics is generated and how it can underlie information processing and pathological conditions in the brain. We show how inhibitory dynamics between parvalbumin-positive basket cells and pyramidal cells could contribute to sharp wave-ripple generation. ABSTRACT Different hippocampal activity patterns are determined primarily by the interaction of excitatory cells and different types of interneurons. To understand the mechanisms underlying the generation of different network dynamics, the properties of synaptic transmission need to be uncovered. Perisomatic inhibition is critical for the generation of sharp wave-ripples, gamma oscillations and pathological epileptic activities. Therefore, we aimed to quantitatively and systematically characterize the temporal properties of the synaptic transmission between perisomatic inhibitory neurons and pyramidal cells in the CA3 area of mouse hippocampal slices, using action potential patterns recorded during physiological and pathological network states. Parvalbumin-positive (PV+) and cholecystokinin-positive (CCK+) interneurons showed distinct intrinsic physiological features. Interneurons of the same type formed reciprocally connected subnetworks, whereas the connectivity between interneuron classes was sparse. The characteristics of unitary interactions depended on the identity of both synaptic partners, whereas the short-term plasticity of synaptic transmission depended mainly on the presynaptic cell type. PV+ interneurons showed frequency-dependent depression, whereas more complex dynamics characterized the output of CCK+ interneurons. We quantitatively captured the dynamics of transmission at these different types of connection with simple mathematical models, and describe in detail the response to physiological and pathological discharge patterns. Our data suggest that the temporal propeties of PV+ interneuron transmission may contribute to sharp wave-ripple generation. These findings support the view that intrinsic and synaptic features of PV+ cells make them ideally suited for the generation of physiological network oscillations, whereas CCK+ cells implement a more subtle, graded control in the hippocampus.
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Affiliation(s)
- Z. Kohus
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- János Szentágothai, PhD Program of Semmelweis UniversityBudapestHungary
| | - S. Káli
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- Péter Pázmány Catholic UniversityFaculty of Information TechnologyBudapestHungary
| | - L. Rovira‐Esteban
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - D. Schlingloff
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- János Szentágothai, PhD Program of Semmelweis UniversityBudapestHungary
| | - O. Papp
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - T. F. Freund
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
- Péter Pázmány Catholic UniversityFaculty of Information TechnologyBudapestHungary
| | - N. Hájos
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
| | - A. I. Gulyás
- Institute of Experimental MedicineHungarian Academy of SciencesBudapestHungary
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147
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Wester JC. Reverse engineering inhibitory circuits in hippocampal CA3. J Physiol 2016; 594:3485-6. [DOI: 10.1113/jp272620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jason C. Wester
- Program in Developmental Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development; National Institutes of Health; Bethesda MD 20892 USA
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148
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Vedunova MV, Shishkina TV, Mishchenko TA, Mitroshina EV, Astrakhanova TA, Pimashkin AS, Mukhina IV. Antihypoxic and Neuroprotective Effects of Glial Cell-Derived Neurotrophic Factor (GDNF) in Cultures of Dissociated Hippocampal Cells under Conditions of Experimental Hypoxia. Bull Exp Biol Med 2016; 161:168-74. [PMID: 27259499 DOI: 10.1007/s10517-016-3369-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 11/26/2022]
Abstract
We analyzed the effect of glial cell derived neurotrophic factor (GDNF) on changes in functional bioelectric and calcium activity in dissociated hippocampal cell cultures under conditions of modeled acute normobaric hypoxia in vitro. GDNF (1 ng/ml) partially neutralized the negative effects of hypoxia on cell survival and parameters of functional network activity. GDNF exhibited a pronounced anti-hypoxic effect.
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Affiliation(s)
- M V Vedunova
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia.
- Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation, Nizhny Novgorod, Russia.
| | - T V Shishkina
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
- Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation, Nizhny Novgorod, Russia
| | - T A Mishchenko
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
- Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation, Nizhny Novgorod, Russia
| | - E V Mitroshina
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
- Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation, Nizhny Novgorod, Russia
| | - T A Astrakhanova
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
| | - A S Pimashkin
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
| | - I V Mukhina
- N. I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russia
- Nizhny Novgorod State Medical Academy, Ministry of Health of the Russian Federation, Nizhny Novgorod, Russia
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149
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Zarnadze S, Bäuerle P, Santos-Torres J, Böhm C, Schmitz D, Geiger JR, Dugladze T, Gloveli T. Cell-specific synaptic plasticity induced by network oscillations. eLife 2016; 5. [PMID: 27218453 PMCID: PMC4929000 DOI: 10.7554/elife.14912] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/23/2016] [Indexed: 12/28/2022] Open
Abstract
Gamma rhythms are known to contribute to the process of memory encoding. However, little is known about the underlying mechanisms at the molecular, cellular and network levels. Using local field potential recording in awake behaving mice and concomitant field potential and whole-cell recordings in slice preparations we found that gamma rhythms lead to activity-dependent modification of hippocampal networks, including alterations in sharp wave-ripple complexes. Network plasticity, expressed as long-lasting increases in sharp wave-associated synaptic currents, exhibits enhanced excitatory synaptic strength in pyramidal cells that is induced postsynaptically and depends on metabotropic glutamate receptor-5 activation. In sharp contrast, alteration of inhibitory synaptic strength is independent of postsynaptic activation and less pronounced. Further, we found a cell type-specific, directionally biased synaptic plasticity of two major types of GABAergic cells, parvalbumin- and cholecystokinin-expressing interneurons. Thus, we propose that gamma frequency oscillations represent a network state that introduces long-lasting synaptic plasticity in a cell-specific manner. DOI:http://dx.doi.org/10.7554/eLife.14912.001 Changes in the strength of synapses – the connections between neurons – form the basis of learning and memory. This process, which is known as synaptic plasticity, incorporates transient experiences into persistent memory traces. However, a single synapse should not be viewed in isolation. Neurons typically belong to extensive networks made up of large numbers of cells, which show coordinated patterns of activity. The synchronized firing of the neurons in such a network is referred to as a network oscillation. The frequency of an oscillation – that is, the number of times per second that its component cells are active at the same time – reflects distinct physiological functions. For example, high frequency oscillations called gamma waves help new memories to form, but it is not clear exactly how they do this. By studying gamma oscillations in a brain region called the hippocampus, Zarnadze, Bäuerle et al. provide insights into the underlying mechanisms. Signals from “excitatory” neurons make the neuron on the other side of the synapse more likely to fire in response, and signals for “inhibitory” neurons make it less likely to fire. By recording the activity of excitatory neurons in mouse brain slices, Zarnadze, Bäuerle et al. show that gamma oscillations increase the strength of excitatory synapses in the hippocampus, allowing neurons to signal more easily across these connections. Blocking the activity of a protein called metabotropic glutamate receptor 5 prevents this increase in excitatory synaptic strength, suggesting that these receptors play an important role in memory processing. In contrast to excitatory neurons, gamma oscillations have different effects on two types of inhibitory neurons within the hippocampus. The oscillations increase the excitability of gamma-supporting inhibitory neurons, but at the same time reduce that of gamma-disturbing inhibitory neurons. These opposing changes in turn support synaptic plasticity. By showing that gamma oscillations contribute to changes in synaptic strength within the hippocampus, Zarnadze, Bäuerle et al. help to explain the importance of these rhythms for memory processing. Further research is now needed to fully decipher the roles of different cell types, and the synaptic connections between them, in the formation of new memories. DOI:http://dx.doi.org/10.7554/eLife.14912.002
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Affiliation(s)
- Shota Zarnadze
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany
| | - Peter Bäuerle
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany
| | - Julio Santos-Torres
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany
| | - Claudia Böhm
- Neuroscience Research Center, Charité -Universitätsmedizin Berlin, Berlin, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité -Universitätsmedizin Berlin, Berlin, Germany.,The NeuroCure Cluster of Excellence, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Jörg Rp Geiger
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany.,The NeuroCure Cluster of Excellence, Berlin, Germany
| | - Tamar Dugladze
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany.,The NeuroCure Cluster of Excellence, Berlin, Germany
| | - Tengis Gloveli
- Institute of Neurophysiology, Charité -Universitätsmedizin Berlin, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
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150
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Malerba P, Krishnan GP, Fellous JM, Bazhenov M. Hippocampal CA1 Ripples as Inhibitory Transients. PLoS Comput Biol 2016; 12:e1004880. [PMID: 27093059 PMCID: PMC4836732 DOI: 10.1371/journal.pcbi.1004880] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 03/23/2016] [Indexed: 11/18/2022] Open
Abstract
Memories are stored and consolidated as a result of a dialogue between the hippocampus and cortex during sleep. Neurons active during behavior reactivate in both structures during sleep, in conjunction with characteristic brain oscillations that may form the neural substrate of memory consolidation. In the hippocampus, replay occurs within sharp wave-ripples: short bouts of high-frequency activity in area CA1 caused by excitatory activation from area CA3. In this work, we develop a computational model of ripple generation, motivated by in vivo rat data showing that ripples have a broad frequency distribution, exponential inter-arrival times and yet highly non-variable durations. Our study predicts that ripples are not persistent oscillations but result from a transient network behavior, induced by input from CA3, in which the high frequency synchronous firing of perisomatic interneurons does not depend on the time scale of synaptic inhibition. We found that noise-induced loss of synchrony among CA1 interneurons dynamically constrains individual ripple duration. Our study proposes a novel mechanism of hippocampal ripple generation consistent with a broad range of experimental data, and highlights the role of noise in regulating the duration of input-driven oscillatory spiking in an inhibitory network. Our memories are consolidated while we sleep through a bidirectional exchange of information between two brain areas called cortex and hippocampus. Neurons that were active in behavioral tasks reactivate again in both structures during sleep in a process of linking and modifying memories from the short term storage of the hippocampus to permanent storage in the neocortex. This process occurs mainly during short oscillatory hippocampal electrical events called sharp wave-ripples. We propose a novel mechanism of ripple generation consistent with a wide range of experimental data, to explain how hippocampal network properties shape ripple frequency and duration. Understanding the neuronal mechanism underlying ripples is crucial to explaining how the interaction between hippocampus and cortex during sleep enables memory consolidation.
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Affiliation(s)
- Paola Malerba
- Department of Cell Biology and Neuroscience, University of California Riverside, Riverside, California, United States of America
| | - Giri P Krishnan
- Department of Cell Biology and Neuroscience, University of California Riverside, Riverside, California, United States of America
| | - Jean-Marc Fellous
- Department of Psychology, University of Arizona, Tucson, Arizona, United States of America
| | - Maxim Bazhenov
- Department of Cell Biology and Neuroscience, University of California Riverside, Riverside, California, United States of America
- * E-mail:
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