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Fulton KA, Zimmerman D, Samuel A, Vogt K, Datta SR. Common principles for odour coding across vertebrates and invertebrates. Nat Rev Neurosci 2024; 25:453-472. [PMID: 38806946 DOI: 10.1038/s41583-024-00822-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 05/30/2024]
Abstract
The olfactory system is an ideal and tractable system for exploring how the brain transforms sensory inputs into behaviour. The basic tasks of any olfactory system include odour detection, discrimination and categorization. The challenge for the olfactory system is to transform the high-dimensional space of olfactory stimuli into the much smaller space of perceived objects and valence that endows odours with meaning. Our current understanding of how neural circuits address this challenge has come primarily from observations of the mechanisms of the brain for processing other sensory modalities, such as vision and hearing, in which optimized deep hierarchical circuits are used to extract sensory features that vary along continuous physical dimensions. The olfactory system, by contrast, contends with an ill-defined, high-dimensional stimulus space and discrete stimuli using a circuit architecture that is shallow and parallelized. Here, we present recent observations in vertebrate and invertebrate systems that relate the statistical structure and state-dependent modulation of olfactory codes to mechanisms of perception and odour-guided behaviour.
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Affiliation(s)
- Kara A Fulton
- Department of Neuroscience, Harvard Medical School, Boston, MA, USA
| | - David Zimmerman
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Aravi Samuel
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Katrin Vogt
- Department of Physics, Harvard University, Cambridge, MA, USA.
- Department of Biology, University of Konstanz, Konstanz, Germany.
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.
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2
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Gulledge AT. Cholinergic Activation of Corticofugal Circuits in the Adult Mouse Prefrontal Cortex. J Neurosci 2024; 44:e1388232023. [PMID: 38050146 PMCID: PMC10860659 DOI: 10.1523/jneurosci.1388-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/10/2023] [Accepted: 11/08/2023] [Indexed: 12/06/2023] Open
Abstract
Acetylcholine (ACh) promotes neocortical output to the thalamus and brainstem by preferentially enhancing the postsynaptic excitability of layer 5 pyramidal tract (PT) neurons relative to neighboring intratelencephalic (IT) neurons. Less is known about how ACh regulates the excitatory synaptic drive of IT and PT neurons. To address this question, spontaneous excitatory postsynaptic potentials (sEPSPs) were recorded in dual recordings of IT and PT neurons in slices of prelimbic cortex from adult female and male mice. ACh (20 µM) enhanced sEPSP amplitudes, frequencies, rise-times, and half-widths preferentially in PT neurons. These effects were blocked by the muscarinic receptor antagonist atropine (1 µM). When challenged with pirenzepine (1 µM), an antagonist selective for M1-type muscarinic receptors, ACh instead reduced sEPSP frequencies, suggesting that ACh may generally suppress synaptic transmission in the cortex via non-M1 receptors. Cholinergic enhancement of sEPSPs in PT neurons was not sensitive to antagonism of GABA receptors with gabazine (10 µM) and CGP52432 (2.5 µM) but was blocked by tetrodotoxin (1 µM), suggesting that ACh enhances action-potential-dependent excitatory synaptic transmission in PT neurons. ACh also preferentially promoted the occurrence of synchronous sEPSPs in dual recordings of PT neurons relative to IT-PT and IT-IT parings. Finally, selective chemogenetic silencing of hM4Di-expressing PT, but not commissural IT, neurons blocked cholinergic enhancement of sEPSP amplitudes and frequencies in PT neurons. These data suggest that, in addition to selectively enhancing the postsynaptic excitability of PT neurons, M1 receptor activation promotes corticofugal output by amplifying recurrent excitation within networks of PT neurons.
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Affiliation(s)
- Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover 03755, New Hampshire
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3
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Guerreiro I, Gu Z, Yakel JL, Gutkin BS. Recurring Cholinergic Inputs Induce Local Hippocampal Plasticity through Feedforward Disinhibition. eNeuro 2022; 9:ENEURO.0389-21.2022. [PMID: 36028329 PMCID: PMC9463983 DOI: 10.1523/eneuro.0389-21.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 04/22/2022] [Accepted: 05/15/2022] [Indexed: 11/30/2022] Open
Abstract
The CA1 pyramidal neurons are embedded in an intricate local circuitry that contains a variety of interneurons. The roles these interneurons play in the regulation of the excitatory synaptic plasticity remains largely understudied. Recent experiments showed that recurring cholinergic activation of α7 nACh receptors expressed in oriens-lacunosum-moleculare (OLMα2) interneurons can directly induce LTP in Schaffer collateral (SC)-CA1 synapses. Here, we pair in vitro studies with biophysically based modeling to uncover the underlying mechanisms. According to our model, α7 nAChR activation increases OLM GABAergic activity. This results in the inhibition of the fast-spiking interneurons that provide feedforward inhibition onto CA1 pyramidal neurons. This disinhibition, paired with tightly timed SC stimulation, can induce potentiation at the excitatory synapses of CA1 pyramidal neurons. Our work details the role of cholinergic modulation in disinhibition-induced hippocampal plasticity. It relates the timing of cholinergic pairing found experimentally in previous studies with the timing between disinhibition and hippocampal stimulation necessary to induce potentiation and suggests the dynamics of the involved interneurons play a crucial role in determining this timing.Significance StatementWe use a combination of experiments and mechanistic modeling to uncover the key role for cholinergic neuromodulation of feedforward disinhibitory circuits in regulating hippocampal plasticity. We found that cholinergic activation of α7 nAChR on α7 nACh receptors expressed in oriens-lacunosum-moleculare interneurons, when tightly paired with stimulation of the Schaffer collaterals, can cancel feedforward inhibition onto CA1 pyramidal cells, enabling the potentiation of the SC-CA1 synapse. Our work details how cholinergic action on GABAergic interneurons can tightly regulate the excitability and plasticity of the hippocampal network, unraveling the intricate interplay of the hierarchal inhibitory circuitry and cholinergic neuromodulation as a mechanism for hippocampal plasticity.
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Affiliation(s)
- Inês Guerreiro
- Group for Neural Theory, LNC2 INSERM U960, Département d'études cognitives, Ecole Normale Superieure, PSL Université Paris, 75005 Paris, France
| | - Zhenglin Gu
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Jerrel L Yakel
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Boris S Gutkin
- Group for Neural Theory, LNC2 INSERM U960, Département d'études cognitives, Ecole Normale Superieure, PSL Université Paris, 75005 Paris, France
- Center for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow 101000, Russia
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4
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Theta Oscillations Coincide with Sustained Hyperpolarization in CA3 Pyramidal Cells, Underlying Decreased Firing. Cell Rep 2021; 32:107868. [PMID: 32640233 DOI: 10.1016/j.celrep.2020.107868] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/22/2020] [Accepted: 06/16/2020] [Indexed: 11/20/2022] Open
Abstract
Brain states modulate the membrane potential dynamics of neurons, influencing the functional repertoire of the network. Pyramidal cells (PCs) in the hippocampal CA3 are necessary for rapid memory encoding, which preferentially occurs during exploratory behavior in the high-arousal theta state. However, the relationship between the membrane potential dynamics of CA3 PCs and theta has not been explored. Here we characterize the changes in the membrane potential of PCs in relation to theta using electrophysiological recordings in awake mice. During theta, most PCs behave in a stereotypical manner, consistently hyperpolarizing time-locked to the duration of theta. Additionally, PCs display lower membrane potential variance and a reduced firing rate. In contrast, during large irregular activity, PCs show heterogeneous changes in membrane potential. This suggests coordinated hyperpolarization of PCs during theta, possibly caused by increased inhibition. This could lead to a higher signal-to-noise ratio in the small population of PCs active during theta, as observed in ensemble recordings.
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5
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Hasselmo ME, Alexander AS, Hoyland A, Robinson JC, Bezaire MJ, Chapman GW, Saudargiene A, Carstensen LC, Dannenberg H. The Unexplored Territory of Neural Models: Potential Guides for Exploring the Function of Metabotropic Neuromodulation. Neuroscience 2020; 456:143-158. [PMID: 32278058 DOI: 10.1016/j.neuroscience.2020.03.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The space of possible neural models is enormous and under-explored. Single cell computational neuroscience models account for a range of dynamical properties of membrane potential, but typically do not address network function. In contrast, most models focused on network function address the dimensions of excitatory weight matrices and firing thresholds without addressing the complexities of metabotropic receptor effects on intrinsic properties. There are many under-explored dimensions of neural parameter space, and the field needs a framework for representing what has been explored and what has not. Possible frameworks include maps of parameter spaces, or efforts to categorize the fundamental elements and molecules of neural circuit function. Here we review dimensions that are under-explored in network models that include the metabotropic modulation of synaptic plasticity and presynaptic inhibition, spike frequency adaptation due to calcium-dependent potassium currents, and afterdepolarization due to calcium-sensitive non-specific cation currents and hyperpolarization activated cation currents. Neuroscience research should more effectively explore possible functional models incorporating under-explored dimensions of neural function.
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Affiliation(s)
- Michael E Hasselmo
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States.
| | - Andrew S Alexander
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Alec Hoyland
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Jennifer C Robinson
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Marianne J Bezaire
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - G William Chapman
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Ausra Saudargiene
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Lucas C Carstensen
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
| | - Holger Dannenberg
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Boston University, 610 Commonwealth Ave., Boston, MA 02215, United States
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6
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Richter N, Beckers N, Onur OA, Dietlein M, Tittgemeyer M, Kracht L, Neumaier B, Fink GR, Kukolja J. Effect of cholinergic treatment depends on cholinergic integrity in early Alzheimer's disease. Brain 2019; 141:903-915. [PMID: 29309600 DOI: 10.1093/brain/awx356] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/08/2017] [Indexed: 02/04/2023] Open
Abstract
In early Alzheimer's disease, which initially presents with progressive loss of short-term memory, neurodegeneration especially affects cholinergic neurons of the basal forebrain. Pharmacotherapy of Alzheimer's disease therefore often targets the cholinergic system. In contrast, cholinergic pharmacotherapy of mild cognitive impairment is debated since its efficacy to date remains controversial. We here investigated the relationship between cholinergic treatment effects and the integrity of the cholinergic system in mild cognitive impairment due to Alzheimer's disease. Fourteen patients with high likelihood of mild cognitive impairment due to Alzheimer's disease and 16 age-matched cognitively normal adults performed an episodic memory task during functional magnetic resonance imaging under three conditions: (i) without pharmacotherapy; (ii) with placebo; and (iii) with a single dose of rivastigmine (3 mg). Cortical acetylcholinesterase activity was measured using PET with the tracer 11C-N-methyl-4-piperidyl acetate (MP4A). Cortical acetylcholinesterase activity was significantly decreased in patients relative to controls, especially in the lateral temporal lobes. Without pharmacotherapy, mild cognitive impairment was associated with less memory-related neural activation in the fusiform gyrus and impaired deactivation in the posterior cingulate cortex, relative to controls. These differences were attenuated under cholinergic stimulation with rivastigmine: patients showed increased neural activation in the right fusiform gyrus but enhanced deactivation of the posterior cingulate cortex under rivastigmine, compared to placebo. Conversely, controls showed reduced activation of the fusiform gyrus and reduced deactivation of the posterior cingulate under rivastigmine, compared to placebo. In both groups, the change in neural activation in response to rivastigmine was negatively associated with local acetylcholinesterase activity. At the behavioural level, an analysis of covariance revealed a significant group × treatment interaction in episodic memory performance when accounting for hippocampal grey matter atrophy and function. Our results indicate that rivastigmine differentially affects memory-related neural activity in patients with mild cognitive impairment and cognitively normal, age-matched adults, depending on acetylcholinesterase activity as a marker for the integrity of the cortical cholinergic system. Furthermore, hippocampal integrity showed an independent association with the response of memory performance to acetylcholinesterase inhibition.
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Affiliation(s)
- Nils Richter
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Center Jülich, 52425 Jülich, Germany.,Max-Planck-Institute for Metabolism Research, 50937 Cologne, Germany
| | - Nora Beckers
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany
| | - Oezguer A Onur
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Center Jülich, 52425 Jülich, Germany
| | - Markus Dietlein
- Department of Nuclear Medicine, University Hospital Cologne, 50937 Cologne, Germany
| | - Marc Tittgemeyer
- Max-Planck-Institute for Metabolism Research, 50937 Cologne, Germany
| | - Lutz Kracht
- Max-Planck-Institute for Metabolism Research, 50937 Cologne, Germany.,Department of Nuclear Medicine, University Hospital Cologne, 50937 Cologne, Germany
| | - Bernd Neumaier
- Nuclear Chemistry, Institute of Neuroscience and Medicine (INM-5), Research Center Jülich, 52425 Jülich, Germany.,Institute for Radiochemistry and Experimental Molecular Imaging, University Hospital Cologne, 50937 Cologne, Germany
| | - Gereon R Fink
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Center Jülich, 52425 Jülich, Germany
| | - Juraj Kukolja
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany.,Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Center Jülich, 52425 Jülich, Germany
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7
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Záborszky L, Gombkoto P, Varsanyi P, Gielow MR, Poe G, Role LW, Ananth M, Rajebhosale P, Talmage DA, Hasselmo ME, Dannenberg H, Minces VH, Chiba AA. Specific Basal Forebrain-Cortical Cholinergic Circuits Coordinate Cognitive Operations. J Neurosci 2018; 38:9446-9458. [PMID: 30381436 PMCID: PMC6209837 DOI: 10.1523/jneurosci.1676-18.2018] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 11/21/2022] Open
Abstract
Based on recent molecular genetics, as well as functional and quantitative anatomical studies, the basal forebrain (BF) cholinergic projections, once viewed as a diffuse system, are emerging as being remarkably specific in connectivity. Acetylcholine (ACh) can rapidly and selectively modulate activity of specific circuits and ACh release can be coordinated in multiple areas that are related to particular aspects of cognitive processing. This review discusses how a combination of multiple new approaches with more established techniques are being used to finally reveal how cholinergic neurons, together with other BF neurons, provide temporal structure for behavior, contribute to local cortical state regulation, and coordinate activity between different functionally related cortical circuits. ACh selectively modulates dynamics for encoding and attention within individual cortical circuits, allows for important transitions during sleep, and shapes the fidelity of sensory processing by changing the correlation structure of neural firing. The importance of this system for integrated and fluid behavioral function is underscored by its disease-modifying role; the demise of BF cholinergic neurons has long been established in Alzheimer's disease and recent studies have revealed the involvement of the cholinergic system in modulation of anxiety-related circuits. Therefore, the BF cholinergic system plays a pivotal role in modulating the dynamics of the brain during sleep and behavior, as foretold by the intricacies of its anatomical map.
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Affiliation(s)
- Laszlo Záborszky
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102,
| | - Peter Gombkoto
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Peter Varsanyi
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Matthew R Gielow
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark 07102
| | - Gina Poe
- Department of Integrative Biology and Physiology, University of California, Los Angeles 90095
| | - Lorna W Role
- Department of Neurobiology and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Mala Ananth
- Program in Neuroscience and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Prithviraj Rajebhosale
- Program in Neuroscience and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - David A Talmage
- Department of Pharmacological Sciences and Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794
| | - Michael E Hasselmo
- Center for Systems Neuroscience and Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, and
| | - Holger Dannenberg
- Center for Systems Neuroscience and Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, and
| | - Victor H Minces
- Department of Cognitive Science, University of California, San Diego 92093
| | - Andrea A Chiba
- Department of Cognitive Science, University of California, San Diego 92093
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de Almeida L, Idiart M, Dean O, Devore S, Smith DM, Linster C. Internal Cholinergic Regulation of Learning and Recall in a Model of Olfactory Processing. Front Cell Neurosci 2016; 10:256. [PMID: 27877112 PMCID: PMC5099168 DOI: 10.3389/fncel.2016.00256] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/18/2016] [Indexed: 12/02/2022] Open
Abstract
In the olfactory system, cholinergic modulation has been associated with contrast modulation and changes in receptive fields in the olfactory bulb, as well the learning of odor associations in olfactory cortex. Computational modeling and behavioral studies suggest that cholinergic modulation could improve sensory processing and learning while preventing pro-active interference when task demands are high. However, how sensory inputs and/or learning regulate incoming modulation has not yet been elucidated. We here use a computational model of the olfactory bulb, piriform cortex (PC) and horizontal limb of the diagonal band of Broca (HDB) to explore how olfactory learning could regulate cholinergic inputs to the system in a closed feedback loop. In our model, the novelty of an odor is reflected in firing rates and sparseness of cortical neurons in response to that odor and these firing rates can directly regulate learning in the system by modifying cholinergic inputs to the system. In the model, cholinergic neurons reduce their firing in response to familiar odors—reducing plasticity in the PC, but increase their firing in response to novel odor—increasing PC plasticity. Recordings from HDB neurons in awake behaving rats reflect predictions from the model by showing that a subset of neurons decrease their firing as an odor becomes familiar.
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Affiliation(s)
- Licurgo de Almeida
- Computational Physiology Lab, Department of Neurobiology and Behavior, Cornell University Ithaca, NY, USA
| | - Marco Idiart
- Physics Institute Federal University of Rio Grande do Sul (UFRGS) Porto Alegre, Brazil
| | - Owen Dean
- Computational Physiology Lab, Department of Neurobiology and Behavior, Cornell University Ithaca, NY, USA
| | - Sasha Devore
- Computational Physiology Lab, Department of Neurobiology and Behavior, Cornell University Ithaca, NY, USA
| | - David M Smith
- Department of Psychology, Cornell University Ithaca, NY, USA
| | - Christiane Linster
- Computational Physiology Lab, Department of Neurobiology and Behavior, Cornell University Ithaca, NY, USA
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9
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Dannenberg H, Hinman JR, Hasselmo ME. Potential roles of cholinergic modulation in the neural coding of location and movement speed. ACTA ACUST UNITED AC 2016; 110:52-64. [PMID: 27677935 DOI: 10.1016/j.jphysparis.2016.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 09/06/2016] [Accepted: 09/23/2016] [Indexed: 12/26/2022]
Abstract
Behavioral data suggest that cholinergic modulation may play a role in certain aspects of spatial memory, and neurophysiological data demonstrate neurons that fire in response to spatial dimensions, including grid cells and place cells that respond on the basis of location and running speed. These neurons show firing responses that depend upon the visual configuration of the environment, due to coding in visually-responsive regions of the neocortex. This review focuses on the physiological effects of acetylcholine that may influence the sensory coding of spatial dimensions relevant to behavior. In particular, the local circuit effects of acetylcholine within the cortex regulate the influence of sensory input relative to internal memory representations via presynaptic inhibition of excitatory and inhibitory synaptic transmission, and the modulation of intrinsic currents in cortical excitatory and inhibitory neurons. In addition, circuit effects of acetylcholine regulate the dynamics of cortical circuits including oscillations at theta and gamma frequencies. These effects of acetylcholine on local circuits and network dynamics could underlie the role of acetylcholine in coding of spatial information for the performance of spatial memory tasks.
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Affiliation(s)
- Holger Dannenberg
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Center for Memory and Brain, Graduate Program for Neuroscience, Boston University, 2 Cummington Mall, Boston, MA 02215, USA.
| | - James R Hinman
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Center for Memory and Brain, Graduate Program for Neuroscience, Boston University, 2 Cummington Mall, Boston, MA 02215, USA.
| | - Michael E Hasselmo
- Center for Systems Neuroscience, Department of Psychological and Brain Sciences, Center for Memory and Brain, Graduate Program for Neuroscience, Boston University, 2 Cummington Mall, Boston, MA 02215, USA.
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10
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Formation and Dynamics of Waves in a Cortical Model of Cholinergic Modulation. PLoS Comput Biol 2015; 11:e1004449. [PMID: 26295587 PMCID: PMC4546669 DOI: 10.1371/journal.pcbi.1004449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/16/2015] [Indexed: 12/18/2022] Open
Abstract
Acetylcholine (ACh) is a regulator of neural excitability and one of the neurochemical substrates of sleep. Amongst the cellular effects induced by cholinergic modulation are a reduction in spike-frequency adaptation (SFA) and a shift in the phase response curve (PRC). We demonstrate in a biophysical model how changes in neural excitability and network structure interact to create three distinct functional regimes: localized asynchronous, traveling asynchronous, and traveling synchronous. Our results qualitatively match those observed experimentally. Cortical activity during slow wave sleep (SWS) differs from that during REM sleep or waking states. During SWS there are traveling patterns of activity in the cortex; in other states stationary patterns occur. Our model is a network composed of Hodgkin-Huxley type neurons with a M-current regulated by ACh. Regulation of ACh level can account for dynamical changes between functional regimes. Reduction of the magnitude of this current recreates the reduction in SFA the shift from a type 2 to a type 1 PRC observed in the presence of ACh. When SFA is minimal (in waking or REM sleep state, high ACh) patterns of activity are localized and easily pinned by network inhomogeneities. When SFA is present (decreasing ACh), traveling waves of activity naturally arise. A further decrease in ACh leads to a high degree of synchrony within traveling waves. We also show that the level of ACh determines how sensitive network activity is to synaptic heterogeneity. These regimes may have a profound functional significance as stationary patterns may play a role in the proper encoding of external input as memory and traveling waves could lead to synaptic regularization, giving unique insights into the role and significance of ACh in determining patterns of cortical activity and functional differences arising from the patterns.
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11
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Septo-hippocampal signal processing: breaking the code. PROGRESS IN BRAIN RESEARCH 2015; 219:103-20. [PMID: 26072236 DOI: 10.1016/bs.pbr.2015.04.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The septo-hippocampal connections appear to be a key element in the neuromodulatory cholinergic control of the hippocampal neurons. The cholinergic neuromodulation is well established in shifting behavioral states of the brain. The pacemaker role of medial septum in the limbic theta rhythm is demonstrated by lesions and pharmacological manipulations of GABAergic neurons, yet the link between the activity of different septal neuronal classes and limbic theta rhythm is not fully understood. We know even less about the information transfer between the medial septum and hippocampus--is there a particular kind of processed information that septo-hippocampal pathways transmit? This review encompasses fundamental findings together with the latest data of septo-hippocampal signal processing to tackle the frontiers of our understanding about the functional significance of medial septum to the hippocampal formation.
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12
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Abstract
Odor perception is hypothesized to be an experience-dependent process involving the encoding of odor objects by distributed olfactory cortical ensembles. Olfactory cortical neurons coactivated by a specific pattern of odorant evoked input become linked through association fiber synaptic plasticity, creating a template of the familiar odor. In this way, experience and memory play an important role in odor perception and discrimination. In other systems, memory consolidation occurs partially via slow-wave sleep (SWS)-dependent replay of activity patterns originally evoked during waking. SWS is ideal for replay given hyporesponsive sensory systems, and thus reduced interference. Here, using artificial patterns of olfactory bulb stimulation in a fear conditioning procedure in the rat, we tested the effects of imposed post-training replay during SWS and waking on strength and precision of pattern memory. The results show that imposed replay during post-training SWS enhanced the subsequent strength of memory, whereas the identical replay during waking induced extinction. The magnitude of this enhancement was dependent on the timing of imposed replay relative to cortical sharp-waves. Imposed SWS replay of stimuli, which differed from the conditioned stimulus, did not affect conditioned stimulus memory strength but induced generalization of the fear memory to novel artificial patterns. Finally, post-training disruption of piriform cortex intracortical association fiber synapses, hypothesized to be critical for experience-dependent odor coding, also impaired subsequent memory precision but not strength. These results suggest that SWS replay in the olfactory cortex enhances memory consolidation, and that memory precision is dependent on the fidelity of that replay.
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13
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Giessel AJ, Datta SR. Olfactory maps, circuits and computations. Curr Opin Neurobiol 2013; 24:120-32. [PMID: 24492088 DOI: 10.1016/j.conb.2013.09.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 09/06/2013] [Accepted: 09/20/2013] [Indexed: 11/17/2022]
Abstract
Sensory information in the visual, auditory and somatosensory systems is organized topographically, with key sensory features ordered in space across neural sheets. Despite the existence of a spatially stereotyped map of odor identity within the olfactory bulb, it is unclear whether the higher olfactory cortex uses topography to organize information about smells. Here, we review recent work on the anatomy, microcircuitry and neuromodulation of two higher-order olfactory areas: the piriform cortex and the olfactory tubercle. The piriform is an archicortical region with an extensive local associational network that constructs representations of odor identity. The olfactory tubercle is an extension of the ventral striatum that may use reward-based learning rules to encode odor valence. We argue that in contrast to brain circuits for other sensory modalities, both the piriform and the olfactory tubercle largely discard any topography present in the bulb and instead use distributive afferent connectivity, local learning rules and input from neuromodulatory centers to build behaviorally relevant representations of olfactory stimuli.
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Affiliation(s)
- Andrew J Giessel
- Harvard Medical School, Department of Neurobiology, 220 Longwood Avenue, Boston, MA 02115, United States
| | - Sandeep Robert Datta
- Harvard Medical School, Department of Neurobiology, 220 Longwood Avenue, Boston, MA 02115, United States.
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14
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Evidence for encoding versus retrieval scheduling in the hippocampus by theta phase and acetylcholine. J Neurosci 2013; 33:8689-704. [PMID: 23678113 DOI: 10.1523/jneurosci.4483-12.2013] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The formation of new memories requires new information to be encoded in the face of proactive interference from the past. Two solutions have been proposed for hippocampal region CA1: (1) acetylcholine, released in novelty, selectively suppresses excitatory projections to CA1 from CA3 (mediating the products of retrieval), while sparing entorhinal inputs (mediating novel sensory information) and (2) encoding preferentially occurs at the pyramidal-layer theta peak, coincident with input from entorhinal cortex, and retrieval occurs at the trough, coincident with input from CA3, consistent with theta phase-dependent synaptic plasticity. We examined three predictions of these models: (1) in novel environments, the preferred theta phase of CA1 place cell firing should shift closer to the CA1 pyramidal-layer theta peak, shifting the encoding-retrieval balance toward encoding; (2) the encoding-related shift in novel environments should be disrupted by cholinergic antagonism; and (3) in familiar environments, cholinergic antagonism should shift the preferred theta firing phase closer to the theta trough, shifting the encoding-retrieval balance even further toward retrieval. We tested these predictions by recording from CA1 pyramidal cells in freely moving rats as they foraged in open field environments under the influence of scopolamine (an amnestic cholinergic antagonist) or vehicle (saline). Results confirmed all three predictions, supporting both the theta phase and cholinergic models of encoding versus retrieval dynamics. Also consistent with cholinergic enhancement of encoding, scopolamine attenuated the formation of distinct spatial representations in a new environment, reducing the extent of place cell "remapping."
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15
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Tsuno Y, Mori K. Behavioral state-dependent changes in the information processing mode in the olfactory system. Commun Integr Biol 2013; 2:362-4. [PMID: 19721892 DOI: 10.4161/cib.2.4.8719] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 04/06/2009] [Indexed: 11/19/2022] Open
Abstract
Changes in behavioral state are accompanied by coordinated changes in the information processing mode in the hippocampus and neocortex of the brain. We review here the recent progress in the knowledge of behavioral state-dependent changes in the information processing mode in the central olfactory system. Olfactory cortex shows state-dependent gating of afferent sensory inputs. In the olfactory bulb, granule-to-mitral dendrodendritic synaptic inhibition is enhanced and the frequency of synchronized oscillatory activity of bulbar output neurons decreases during slow-wave sleep or deeply anesthetized state. These results suggest that the information processing mode in the whole olfactory system changes in a behavioral state-dependent manner to keep the neuronal circuits functioning optimally in each behavioral state.
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Affiliation(s)
- Yusuke Tsuno
- Department of Physiology; Graduate School of Medicine; University of Tokyo; Tokyo, Japan
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16
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Schärer YPZ, Shum J, Moressis A, Friedrich RW. Dopaminergic modulation of synaptic transmission and neuronal activity patterns in the zebrafish homolog of olfactory cortex. Front Neural Circuits 2012; 6:76. [PMID: 23109918 PMCID: PMC3478571 DOI: 10.3389/fncir.2012.00076] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 10/03/2012] [Indexed: 11/18/2022] Open
Abstract
Dopamine (DA) is an important modulator of synaptic transmission and plasticity that is causally involved in fundamental brain functions and dysfunctions. We examined the dopaminergic modulation of synaptic transmission and sensory responses in telencephalic area Dp of zebrafish, the homolog of olfactory cortex. By combining anatomical tracing and immunohistochemistry, we detected no DA neurons in Dp itself but long-range dopaminergic input from multiple other brain areas. Whole-cell recordings revealed no obvious effects of DA on membrane potential or input resistance in the majority of Dp neurons. Electrical stimulation of the olfactory tracts produced a complex sequence of synaptic currents in Dp neurons. DA selectively decreased inhibitory currents with little or no effect on excitatory components. Multiphoton calcium imaging showed that population responses of Dp neurons to olfactory tract stimulation or odor application were enhanced by DA, consistent with its effect on inhibitory synaptic transmission. These effects of DA were blocked by an antagonist of D2-like receptors. DA therefore disinhibits and reorganizes sensory responses in Dp. This modulation may affect sensory perception and could be involved in the experience-dependent modification of odor representations.
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17
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Heys JG, Schultheiss NW, Shay CF, Tsuno Y, Hasselmo ME. Effects of acetylcholine on neuronal properties in entorhinal cortex. Front Behav Neurosci 2012; 6:32. [PMID: 22837741 PMCID: PMC3402879 DOI: 10.3389/fnbeh.2012.00032] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 06/07/2012] [Indexed: 11/13/2022] Open
Abstract
The entorhinal cortex (EC) receives prominent cholinergic innervation from the medial septum and the vertical limb of the diagonal band of Broca (MSDB). To understand how cholinergic neurotransmission can modulate behavior, research has been directed toward identification of the specific cellular mechanisms in EC that can be modulated through cholinergic activity. This review focuses on intrinsic cellular properties of neurons in EC that may underlie functions such as working memory, spatial processing, and episodic memory. In particular, the study of stellate cells (SCs) in medial entorhinal has resulted in discovery of correlations between physiological properties of these neurons and properties of the unique spatial representation that is demonstrated through unit recordings of neurons in medial entorhinal cortex (mEC) from awake-behaving animals. A separate line of investigation has demonstrated persistent firing behavior among neurons in EC that is enhanced by cholinergic activity and could underlie working memory. There is also evidence that acetylcholine plays a role in modulation of synaptic transmission that could also enhance mnemonic function in EC. Finally, the local circuits of EC demonstrate a variety of interneuron physiology, which is also subject to cholinergic modulation. Together these effects alter the dynamics of EC to underlie the functional role of acetylcholine in memory.
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Affiliation(s)
- James G. Heys
- Graduate Program for Neuroscience, Center for Memory and Brain, Boston UniversityBoston, MA, USA
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18
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Nuñez A, Domínguez S, Buño W, Fernández de Sevilla D. Cholinergic-mediated response enhancement in barrel cortex layer V pyramidal neurons. J Neurophysiol 2012; 108:1656-68. [PMID: 22723675 DOI: 10.1152/jn.00156.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neocortical cholinergic activity plays a fundamental role in sensory processing and cognitive functions, but the underlying cellular mechanisms are largely unknown. We analyzed the effects of acetylcholine (ACh) on synaptic transmission and cell excitability in rat "barrel cortex" layer V (L5) pyramidal neurons in vitro. ACh through nicotinic and M1 muscarinic receptors enhanced excitatory postsynaptic currents and through nicotinic and M2 muscarinic receptors reduced inhibitory postsynaptic currents. These effects increased excitability and contributed to the generation of Ca(2+) spikes and bursts of action potentials (APs) when inputs in basal dendrites were stimulated. Ca(2+) spikes were mediated by activation of NMDA receptors (NMDARs) and L-type voltage-gated Ca(2+) channels. Additionally, we demonstrate in vivo that basal forebrain stimulation induced an atropine-sensitive increase of L5 AP responses evoked by vibrissa deflection, an effect mainly due to the enhancement of an NMDAR component. Therefore, ACh modified the excitatory/inhibitory balance and switched L5 pyramidal neurons to a bursting mode that caused a potent and sustained response enhancement with possible fundamental consequences for the function of the barrel cortex.
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Affiliation(s)
- Angel Nuñez
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo 4, 28029 Madrid, Spain
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19
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Abstract
As indicated by the profound cognitive impairments caused by cholinergic receptor antagonists, cholinergic neurotransmission has a vital role in cognitive function, specifically attention and memory encoding. Abnormally regulated cholinergic neurotransmission has been hypothesized to contribute to the cognitive symptoms of neuropsychiatric disorders. Loss of cholinergic neurons enhances the severity of the symptoms of dementia. Cholinergic receptor agonists and acetylcholinesterase inhibitors have been investigated for the treatment of cognitive dysfunction. Evidence from experiments using new techniques for measuring rapid changes in cholinergic neurotransmission provides a novel perspective on the cholinergic regulation of cognitive processes. This evidence indicates that changes in cholinergic modulation on a timescale of seconds is triggered by sensory input cues and serves to facilitate cue detection and attentional performance. Furthermore, the evidence indicates cholinergic induction of evoked intrinsic, persistent spiking mechanisms for active maintenance of sensory input, and planned responses. Models have been developed to describe the neuronal mechanisms underlying the transient modulation of cortical target circuits by cholinergic activity. These models postulate specific locations and roles of nicotinic and muscarinic acetylcholine receptors and that cholinergic neurotransmission is controlled in part by (cortical) target circuits. The available evidence and these models point to new principles governing the development of the next generation of cholinergic treatments for cognitive disorders.
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20
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Jia Y, Yamazaki Y, Nakauchi S, Sumikawa K. Alpha2 nicotine receptors function as a molecular switch to continuously excite a subset of interneurons in rat hippocampal circuits. Eur J Neurosci 2009; 29:1588-603. [PMID: 19385992 DOI: 10.1111/j.1460-9568.2009.06706.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Rapid activation of nicotinic acetylcholine receptors (nAChRs) at various anatomical and cellular locations in the hippocampus differentially modulates the operation of hippocampal circuits. However, it is largely unknown how the continued presence of nicotine affects the normal operation of hippocampal circuits. Here, we used single and dual whole-cell recordings to address this question. We found that horizontally oriented interneurons in the stratum oriens/alveus continuously discharged action potentials in the presence of nicotine. In these interneurons, bath application of nicotine produced slow inward currents that were well maintained and inhibited by the non-alpha 7 antagonist dihydro-beta-erythroidine. Single-cell reverse transcription-polymerase chain reaction analysis showed that nicotine-responding interneurons were consistently positive for the alpha2 subunit mRNA. These observations suggest that in the presence of nicotine, a subset of interneurons in the stratum oriens/alveus are continuously excited due to the sustained activation of alpha2* nAChRs. These interneurons were synaptically connected to pyramidal cells, and nicotine increased inhibitory baseline currents at the synapses and suppressed phasic inhibition at the same synapses. Nicotine-induced inhibitory activity increased background noise and masked small phasic inhibition in pyramidal cells, originating from other interneurons in the stratum radiatum. Thus, the continued presence of nicotine alters the normal operation of hippocampal circuits by gating inhibitory circuits through activating a non-desensitizing alpha2 nAChR subtype on a distinct population of interneurons.
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Affiliation(s)
- Yousheng Jia
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550, USA
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21
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Graupner M, Gutkin B. Modeling nicotinic neuromodulation from global functional and network levels to nAChR based mechanisms. Acta Pharmacol Sin 2009; 30:681-93. [PMID: 19498415 PMCID: PMC4002372 DOI: 10.1038/aps.2009.87] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Accepted: 05/05/2009] [Indexed: 01/04/2023] Open
Abstract
Neuromodulator action has received increasing attention in theoretical neuroscience. Yet models involving both neuronal populations dynamics at the circuit level and detailed receptor properties are only now being developed. Here we review recent computational approaches to neuromodulation, focusing specifically on acetylcholine (ACh) and nicotine. We discuss illustrative examples of models ranging from functional top-down to neurodynamical bottom-up. In the top-down approach, a computational theory views ACh as encoding the uncertainty expected in an environment. A different line of models accounts for neural population dynamics treating ACh as toggling neuronal networks between read-in of information and recall of memory. Building on the neurodynamics idea we discuss two models of nicotine's action with increasing degree of biological realism. Both consider explicitly receptor-level mechanisms but with different scales of detail. The first is a large-scale model of nicotine-dependent modulation of dopaminergic signaling that is capable of simulating nicotine self-administration. The second is a novel approach where circuit-level neurodynamics of the ventral tegmental area (VTA) are combined with explicit models of the dynamics of specific nicotinic ACh receptor subtypes. We show how the model is constructed based on local anatomy, electrophysiology and receptor properties and provide an illustration of its potential. In particular, we show how the model can shed light on the specific mechanisms by which nicotine controls dopaminergic neurotransmission in the VTA. This model serves us to conclude that detailed accounts for neuromodulator action at the basis of behavioral and cognitive models are crucial to understand how neuromodulators mediate their functional properties.
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Affiliation(s)
- Michael Graupner
- Group for Neural Theory, Laboratoire de Neurosciences Cognitives, INSERM Unité 960, Départment d'Etudes Cognitives, École Normale Supérieure, 29, rue d'Ulm, 75005 Paris, France
| | - Boris Gutkin
- Group for Neural Theory, Laboratoire de Neurosciences Cognitives, INSERM Unité 960, Départment d'Etudes Cognitives, École Normale Supérieure, 29, rue d'Ulm, 75005 Paris, France
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22
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Takahashi H, Magee JC. Pathway interactions and synaptic plasticity in the dendritic tuft regions of CA1 pyramidal neurons. Neuron 2009; 62:102-11. [PMID: 19376070 DOI: 10.1016/j.neuron.2009.03.007] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 11/11/2008] [Accepted: 03/04/2009] [Indexed: 10/20/2022]
Abstract
Input comparison is thought to occur in many neuronal circuits, including the hippocampus, where functionally important interactions between the Schaffer collateral and perforant pathways have been hypothesized. We investigated this idea using multisite, whole-cell recordings and Ca2+ imaging and found that properly timed, repetitive stimulation of both pathways results in the generation of large plateau potentials in distal dendrites of CA1 pyramidal neurons. These dendritic plateau potentials produce widespread Ca2+ influx, large after-depolarizations, burst firing output, and long-term potentiation of perforant path synapses. Plateau duration is directly related to the strength and temporal overlap of pathway activation and involves back-propagating action potentials and both NMDA receptors and voltage-gated Ca2+ channels. Thus, the occurrence of highly correlated SC and PP input to CA1 is signaled by a dramatic change in output mode and an increase in input efficacy, all induced by a large plateau potential in the distal dendrites of CA1 pyramidal neurons.
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Affiliation(s)
- Hiroto Takahashi
- Howard Hughes Medical Institute, Janelia Farm Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
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23
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Lucas-Meunier E, Monier C, Amar M, Baux G, Frégnac Y, Fossier P. Involvement of nicotinic and muscarinic receptors in the endogenous cholinergic modulation of the balance between excitation and inhibition in the young rat visual cortex. Cereb Cortex 2009; 19:2411-27. [PMID: 19176636 DOI: 10.1093/cercor/bhn258] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study aims to clarify how endogenous release of cortical acetylcholine (ACh) modulates the balance between excitation and inhibition evoked in visual cortex. We show that electrical stimulation in layer 1 produced a significant release of ACh measured intracortically by chemoluminescence and evoked a composite synaptic response recorded intracellularly in layer 5 pyramidal neurons of rat visual cortex. The pharmacological specificity of the ACh neuromodulation was determined from the continuous whole-cell voltage clamp measurement of stimulation-locked changes of the input conductance during the application of cholinergic agonists and antagonists. Blockade of glutamatergic and gamma-aminobutyric acid (GABAergic) receptors suppressed the evoked response, indicating that stimulation-induced release of ACh does not directly activate a cholinergic synaptic conductance in recorded neurons. Comparison of cytisine and mecamylamine effects on nicotinic receptors showed that excitation is enhanced by endogenous evoked release of ACh through the presynaptic activation of alpha(*)beta4 receptors located on glutamatergic fibers. DHbetaE, the selective alpha4beta2 nicotinic receptor antagonist, induced a depression of inhibition. Endogenous ACh could also enhance inhibition by acting directly on GABAergic interneurons, presynaptic to the recorded cell. We conclude that endogenous-released ACh amplifies the dominance of the inhibitory drive and thus decreases the excitability and sensory responsiveness of layer 5 pyramidal neurons.
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Affiliation(s)
- Estelle Lucas-Meunier
- Laboratoire de neurobiologie cellulaire et moléculaire, UPR CNRS 9040, Gif-sur-Yvette, France
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24
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Cholinergic control of GABA release: emerging parallels between neocortex and hippocampus. Trends Neurosci 2008; 31:317-27. [DOI: 10.1016/j.tins.2008.03.008] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 03/24/2008] [Accepted: 03/25/2008] [Indexed: 01/26/2023]
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25
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Abstract
1. The piriform cortex (PC) is the largest subdivision of the olfactory cortex and the first cortical destination of olfactory information. Despite the relatively simple anatomy of the PC and its obvious appeal as a model system for the study of cortical sensory processing, there are many outstanding questions about its basic cell physiology. In the present article, we review what is known about GABAergic inhibitory interneurons in the PC. 2. The GABA-containing neurons in the PC are morphologically diverse, ranging from small neurogliaform cells to large multipolar forms. Some of these classes are distributed across all three main layers of the PC, whereas others have a more restricted laminar expression. 3. Distinct and overlapping populations of GABAergic basket cells in Layers II and III of the PC express different combinations of calcium-binding proteins and neuropeptides. Few Layer I interneurons express any of the molecular markers so far examined. 4. The intrinsic firing properties of one or two types of putative PC interneurons have been measured and inhibitory post-synaptic responses have been recorded in PC pyramidal cells following extracellular stimulation. However, little is known about the physiology of the subtypes of interneurons identified. 5. In view of the likely importance of PC interneurons in olfactory learning, olfactory coding and epileptogenesis, further investigation of their properties is likely to be highly informative.
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Affiliation(s)
- Norimitsu Suzuki
- Division of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
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26
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Neuromodulation by glutamate and acetylcholine can change circuit dynamics by regulating the relative influence of afferent input and excitatory feedback. Mol Neurobiol 2007; 36:184-200. [PMID: 17952661 DOI: 10.1007/s12035-007-0032-z] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Accepted: 02/02/2007] [Indexed: 10/23/2022]
Abstract
Substances such as acetylcholine and glutamate act as both neurotransmitters and neuromodulators. As neuromodulators, they change neural information processing by regulating synaptic transmitter release, altering baseline membrane potential and spiking activity, and modifying long-term synaptic plasticity. Slice physiology research has demonstrated that many neuromodulators differentially modulate afferent, incoming information compared to intrinsic and recurrent processing in cortical structures such as piriform cortex, neocortex, and the hippocampus. The enhancement of afferent (external) pathways versus the suppression at recurrent (internal) pathways could cause cortical dynamics to switch between a predominant influence of external stimulation to a predominant influence of internal recall. Modulation of afferent versus intrinsic processing could contribute to the role of neuromodulators in regulating attention, learning, and memory effects in behavior.
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27
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Kremin T, Hasselmo ME. Cholinergic suppression of glutamatergic synaptic transmission in hippocampal region CA3 exhibits laminar selectivity: Implication for hippocampal network dynamics. Neuroscience 2007; 149:760-7. [PMID: 17964734 DOI: 10.1016/j.neuroscience.2007.07.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 06/28/2007] [Accepted: 07/11/2007] [Indexed: 11/24/2022]
Abstract
Acetylcholine may help set the dynamics within neural systems to facilitate the learning of new information. Neural models have shown that if new information is encoded at the same time as retrieval of existing information that is already stored, the memories will interfere with each other. Structures such as the hippocampus have a distinct laminar organization of inputs that allows this hypothesis to be tested. In region CA1 of the rat (Sprague Dawley) hippocampus, the cholinergic agonist carbachol (CCh) suppresses transmission in stratum radiatum (SR), at synapses of the Schaffer collateral projection from CA3, while having lesser effects in stratum lacunosum-moleculare (SLM), the perforant path projection from entorhinal cortex (Hasselmo and Schnell, 1994). The current research extends support of this selectivity by demonstrating laminar effects in region CA3. CCh caused significantly greater suppression in SR than in SLM at low concentrations, while the difference in suppression was not significant at higher concentrations. Differences in paired-pulse facilitation suggest presynaptic inhibition substantially contributes to the suppression and is highly concentration and stratum dependent. This selective suppression of the recurrent excitation would be appropriate to set CA3 dynamics to prevent runaway modification of the synapses of excitatory recurrent collaterals by reducing the influence of previously stored associations and allowing incoming information from the perforant path to have a predominant influence on neural activity.
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Affiliation(s)
- T Kremin
- Ernest Gallo Clinic & Research Center, University of California at San Francisco, 5858 Horton Street, Suite 200, Emeryville, CA 94680, USA.
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28
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Raghanti MA, Stimpson CD, Marcinkiewicz JL, Erwin JM, Hof PR, Sherwood CC. Cholinergic innervation of the frontal cortex: Differences among humans, chimpanzees, and macaque monkeys. J Comp Neurol 2007; 506:409-24. [DOI: 10.1002/cne.21546] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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29
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Hasselmo ME. The role of acetylcholine in learning and memory. Curr Opin Neurobiol 2006; 16:710-5. [PMID: 17011181 PMCID: PMC2659740 DOI: 10.1016/j.conb.2006.09.002] [Citation(s) in RCA: 1021] [Impact Index Per Article: 56.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 08/31/2006] [Accepted: 09/18/2006] [Indexed: 11/27/2022]
Abstract
Pharmacological data clearly indicate that both muscarinic and nicotinic acetylcholine receptors have a role in the encoding of new memories. Localized lesions and antagonist infusions demonstrate the anatomical locus of these cholinergic effects, and computational modeling links the function of cholinergic modulation to specific cellular effects within these regions. Acetylcholine has been shown to increase the strength of afferent input relative to feedback, to contribute to theta rhythm oscillations, activate intrinsic mechanisms for persistent spiking, and increase the modification of synapses. These effects might enhance different types of encoding in different cortical structures. In particular, the effects in entorhinal and perirhinal cortex and hippocampus might be important for encoding new episodic memories.
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Affiliation(s)
- Michael E Hasselmo
- Center for Memory and Brain, Boston University, 2 Cummington Street, Boston, MA 02215, USA.
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30
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Soto G, Kopell N, Sen K. Network architecture, receptive fields, and neuromodulation: computational and functional implications of cholinergic modulation in primary auditory cortex. J Neurophysiol 2006; 96:2972-83. [PMID: 16899641 DOI: 10.1152/jn.00459.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Two fundamental issues in auditory cortical processing are the relative importance of thalamocortical versus intracortical circuits in shaping response properties in primary auditory cortex (ACx), and how the effects of neuromodulators on these circuits affect dynamic changes in network and receptive field properties that enhance signal processing and adaptive behavior. To investigate these issues, we developed a computational model of layers III and IV (LIII/IV) of AI, constrained by anatomical and physiological data. We focus on how the local and global cortical architecture shape receptive fields (RFs) of cortical cells and on how different well-established cholinergic effects on the cortical network reshape frequency-tuning properties of cells in ACx. We identify key thalamocortical and intracortical circuits that strongly affect tuning curves of model cortical neurons and are also sensitive to cholinergic modulation. We then study how differential cholinergic modulation of network parameters change the tuning properties of our model cells and propose two different mechanisms: one intracortical (involving muscarinic receptors) and one thalamocortical (involving nicotinic receptors), which may be involved in rapid plasticity in ACx, as recently reported in a study by Fritz and coworkers.
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Affiliation(s)
- Gabriel Soto
- Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02215, USA
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31
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Whalley BJ, Constanti A. Developmental changes in presynaptic muscarinic modulation of excitatory and inhibitory neurotransmission in rat piriform cortex in vitro: relevance to epileptiform bursting susceptibility. Neuroscience 2006; 140:939-56. [PMID: 16616427 DOI: 10.1016/j.neuroscience.2006.02.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 02/22/2006] [Accepted: 02/22/2006] [Indexed: 10/24/2022]
Abstract
Suppression of depolarizing postsynaptic potentials and isolated GABA-A receptor-mediated fast inhibitory postsynaptic potentials by the muscarinic acetylcholine receptor agonist, oxotremorine-M (10 microM), was investigated in adult and immature (P14-P30) rat piriform cortical (PC) slices using intracellular recording. Depolarizing postsynaptic potentials evoked by layers II-III stimulation underwent concentration-dependent inhibition in oxotremorine-M that was most likely presynaptic and M2 muscarinic acetylcholine receptor-mediated in immature, but M1-mediated in adult (P40-P80) slices; percentage inhibition was smaller in immature than in adult piriform cortex. In contrast, compared with adults, layer Ia-evoked depolarizing postsynaptic potentials in immature piriform cortex slices in oxotremorine-M, showed a prolonged multiphasic depolarization with superimposed fast transients and spikes, and an increased 'all-or-nothing' character. Isolated N-methyl-d-aspartate receptor-mediated layer Ia depolarizing postsynaptic potentials (although significantly larger in immature slices) were however, unaffected by oxotremorine-M, but blocked by dl-2-amino-5-phosphonovaleric acid. Fast inhibitory postsynaptic potentials evoked by layer Ib or layers II-III-fiber stimulation in immature slices were significantly smaller than in adults, despite similar estimated mean reversal potentials ( approximately -69 and -70 mV respectively). In oxotremorine-M, only layer Ib-fast inhibitory postsynaptic potentials were suppressed; suppression was again most likely presynaptic M2-mediated in immature slices, but M1-mediated in adults. The degree of fast inhibitory postsynaptic potential suppression was however, greater in immature than in adult piriform cortex. Our results demonstrate some important physiological and pharmacological differences between excitatory and inhibitory synaptic systems in adult and immature piriform cortex that could contribute toward the increased susceptibility of this region to muscarinic agonist-induced epileptiform activity in immature brain slices.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/physiology
- Aging/physiology
- Animals
- Animals, Newborn
- Causality
- Epilepsy/physiopathology
- Excitatory Postsynaptic Potentials/drug effects
- Excitatory Postsynaptic Potentials/physiology
- Female
- Male
- Muscarinic Agonists/pharmacology
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Olfactory Pathways/cytology
- Olfactory Pathways/growth & development
- Organ Culture Techniques
- Oxotremorine/pharmacology
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Rats
- Rats, Sprague-Dawley
- Reaction Time/drug effects
- Reaction Time/physiology
- Receptor, Muscarinic M1/agonists
- Receptor, Muscarinic M1/metabolism
- Receptor, Muscarinic M2/agonists
- Receptor, Muscarinic M2/metabolism
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/metabolism
- Receptors, Muscarinic/drug effects
- Receptors, Muscarinic/physiology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- B J Whalley
- Department of Pharmacology, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, UK.
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32
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Abstract
Computational models are increasingly essential to systems neuroscience. Models serve as proofs of concept, tests of sufficiency, and as quantitative embodiments of working hypotheses and are important tools for understanding and interpreting complex data sets. In the olfactory system, models have played a particularly prominent role in framing contemporary theories and presenting novel hypotheses, a role that will only grow as the complexity and intricacy of experimental data continue to increase. This review will attempt to provide a comprehensive, functional overview of computational ideas in olfaction and outline a computational framework for olfactory processing based on the insights provided by these diverse models and their supporting data.
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Affiliation(s)
- Thomas A Cleland
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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Tateno T, Jimbo Y, Robinson HPC. Spatio-temporal cholinergic modulation in cultured networks of rat cortical neurons: Evoked activity. Neuroscience 2005; 134:439-48. [PMID: 15979809 DOI: 10.1016/j.neuroscience.2005.04.055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 04/01/2005] [Accepted: 04/27/2005] [Indexed: 11/30/2022]
Abstract
We studied the effects of carbachol, a cholinergic agonist, on extracellularly evoked firing of networks in mature cultures of rat cortical neurons, using multi-electrode arrays to monitor the activity of large numbers of neurons simultaneously. These cultures show evoked burst firing which propagates through dense synaptic connections. When a brief voltage pulse was applied to one extracellular electrode, spiking electrical responses were evoked in neurons throughout the network. The response had two components: an early phase, terminating within 30-80 ms, and a late phase which could last several hundreds of milliseconds. Action potentials evoked during the early phase were precisely timed, with only small jitter. In contrast, the late phase characteristically showed clusters of electrical activity with significant spatio-temporal fluctuations. The late phase was suppressed by applying a relatively small amount of carbachol (5 microM) in the external solution, even though the spontaneous firing rate was not significantly changed. Carbachol increased both the spike-timing precision and the speed of propagation of population spikes, and selectively increased the firing coincidence in a subset of neuron pairs in the network, while suppressing late variable firing in responses. Hence, the results give quantitative support for the idea that cholinergic activation in the cortex has a general role of focusing or enhancing significant associative firing of neurons.
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Affiliation(s)
- T Tateno
- Department of Physiology, Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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Otmakhova NA, Lisman JE. Contribution of Ih and GABAB to Synaptically Induced Afterhyperpolarizations in CA1: A Brake on the NMDA Response. J Neurophysiol 2004; 92:2027-39. [PMID: 15163674 DOI: 10.1152/jn.00427.2004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
CA1 pyramidal cells receive two major excitatory inputs: the perforant path (PP) terminates in the most distal dendrites, whereas the Schaffer collaterals (SC) terminate more proximally. We have examined the mechanism of the afterhyperpolarization (AHP) that follows single subthreshold excitatory postsynaptic potentials (EPSPs) in these inputs. The AHPs were not reduced by a GABAA antagonist or by agents that block Ca2+ entry. Application of the Ih blocker, ZD7288, partially blocked the AHP in the PP; the substantial remaining component was blocked by 2-hydroxysaclofen, a GABAB antagonist. In contrast, the AHP in the SC depends nearly completely on Ih, with almost no GABAB component. Thus postsynaptic GABAB receptors appear to be preferentially involved at distal synapses, consistent with the spatial distribution of GABAB receptors and g protein-coupled inward rectifying potassium (GIRK) channels. GABAB does, however, play a role at proximal synapses through presynaptic suppression of glutamate release, a mechanism that is much weaker at distal synapses. Experiments were conducted to explore the functional role of the AHP in the PP, which has a higher N-methyl-d-aspartate (NMDA)/AMPA ratio than the SC. Blockade of the AHP converted a response that had a small NMDA component to one that had a large component. These results indicate that the Ih and postsynaptic GABAB conductances act as a brake on distally generated NMDA responses.
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Affiliation(s)
- Nonna A Otmakhova
- Department of Biology, Brandeis Univ., 415 South St., Waltham, MA 02454, USA
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35
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Hasselmo ME, McGaughy J. High acetylcholine levels set circuit dynamics for attention and encoding and low acetylcholine levels set dynamics for consolidation. PROGRESS IN BRAIN RESEARCH 2004; 145:207-31. [PMID: 14650918 DOI: 10.1016/s0079-6123(03)45015-2] [Citation(s) in RCA: 369] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Michael E Hasselmo
- Department of Psychology, Center for Memory and Brain, Program in Neuroscience, Boston University, 2 Cummington St., Boston, MA 02215, USA.
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36
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Linster C, Maloney M, Patil M, Hasselmo ME. Enhanced cholinergic suppression of previously strengthened synapses enables the formation of self-organized representations in olfactory cortex. Neurobiol Learn Mem 2003; 80:302-14. [PMID: 14521872 DOI: 10.1016/s1074-7427(03)00078-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computational modeling assists in analyzing the specific functional role of the cellular effects of acetylcholine within cortical structures. In particular, acetylcholine may regulate the dynamics of encoding and retrieval of information by regulating the magnitude of synaptic transmission at excitatory recurrent connections. Many abstract models of associative memory function ignore the influence of changes in synaptic strength during the storage process and apply the effect of these changes only during a so-called recall-phase. Efforts to ensure stable activity with more realistic, continuous updating of the synaptic strength during the storage process have shown that the memory capacity of a realistic cortical network can be greatly enhanced if cholinergic modulation blocks transmission at synaptic connections of the association fibers during the learning process. We here present experimental data from an olfactory cortex brain slice preparation showing that previously potentiated fibers show significantly greater suppression (presynaptic inhibition) by the cholinergic agonist carbachol than unpotentiated fibers. We conclude that low suppression of non-potentiated fibers during the learning process ensures the formation of self-organized representations in the neural network while the higher suppression of previously potentiated fibers minimizes interference between overlapping patterns. We show in a computational model of olfactory cortex, that, together, these two phenomena reduce the overlap between patterns that are stored within the same neural network structure. These results further demonstrate the contribution of acetylcholine to mechanisms of cortical plasticity. The results are consistent with the extensive evidence supporting a role for acetylcholine in encoding of new memories and enhancement of response to salient sensory stimuli.
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Affiliation(s)
- Christiane Linster
- Department of Psychology Center for Memory and Brain and Program in Neuroscience, Boston University, 2 Cummington Street, Boston, MA 02215, USA.
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37
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Lucas-Meunier E, Fossier P, Baux G, Amar M. Cholinergic modulation of the cortical neuronal network. Pflugers Arch 2003; 446:17-29. [PMID: 12690458 DOI: 10.1007/s00424-002-0999-2] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2002] [Indexed: 01/15/2023]
Abstract
Acetylcholine (ACh) is an important neurotransmitter of the CNS that binds both nicotinic and muscarinic receptors to exert its action. However, the mechanisms underlying the effects of cholinergic receptors have still not been completely elucidated. Central cholinergic neurons, mainly located in basal forebrain, send their projections to different structures including the cortex. The cortical innervation is diffuse and roughly topographic, which has prompted some authors to suspect a modulating role of ACh on the activity of the cortical network rather than a direct synaptic role. The cholinergic system is implicated in functional, behavioural and pathological states including cognitive function, nicotine addiction, Alzheimer's disease, Tourette's syndrome, epilepsies and schizophrenia. As these processes depend on the activation of glutamatergic and GABAergic systems, the cholinergic terminals must exert their effects via the modulation of excitatory and/or inhibitory neurotransmission. However, the understanding of cholinergic modulation is complex because it is the result of a mixture of positive and negative modulation, implying that there are various types, or even subtypes, of cholinergic receptors. In this review, we summarize the current knowledge on central cholinergic systems (projections and receptors) and then aim to focus on the implications for ACh in the modulation of cortical neuronal activity.
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Affiliation(s)
- E Lucas-Meunier
- Laboratoire de Neurobiologie Cellulaire et Moléculaire, INAF-CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette cedex, France.
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38
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Abstract
Cholinergic and GABAergic innervation of the hippocampus plays an important role in human memory function and rat spatial navigation. Drugs which block acetylcholine receptors or enhance GABA receptor activation cause striking impairments in the encoding of new information. Lesions of the cholinergic innervation of the hippocampus reduce the amplitude of hippocampal theta rhythm and cause impairments in spatial navigation tasks, including the Morris water maze, eight-arm radial maze, spatial reversal and delayed alternation. Here, we review previous work on the role of cholinergic modulation in memory function, and we present a new model of the hippocampus and entorhinal cortex describing the interaction of these regions for goal-directed spatial navigation in behavioral tasks. These mechanisms require separate functional phases for: (1) encoding of pathways without interference from retrieval, and (2) retrieval of pathways for guiding selection of the next movement. We present analysis exploring how phasic changes in physiological variables during hippocampal theta rhythm could provide these different phases and enhance spatial navigation function.
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Affiliation(s)
- Michael E Hasselmo
- Department of Psychology, Center for BioDynamics, Boston University, MA 02215, USA.
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Tiesinga PH, Fellous JM, José JV, Sejnowski TJ. Computational model of carbachol-induced delta, theta, and gamma oscillations in the hippocampus. Hippocampus 2002; 11:251-74. [PMID: 11769308 DOI: 10.1002/hipo.1041] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Field potential recordings from the rat hippocampus in vivo contain distinct frequency bands of activity, including delta (0.5-2 Hz), theta (4-12 Hz), and gamma (30-80 Hz), that are correlated with the behavioral state of the animal. The cholinergic agonist carbachol (CCH) induces oscillations in the delta (CCH-delta), theta (CCH-theta), and gamma (CCH-gamma) frequency ranges in the hippocampal slice preparation, eliciting asynchronous CCH-theta, synchronous CCH-delta, and synchronous CCH-theta with increasing CCH concentration (Fellous and Seinowski, Hippocampus 2000;1 0:187-197). In a network model of area CA3, the time scale for CCH-delta corresponded to the decay constant of the gating variable of the calcium-dependent potassium (K-AHP) current, that of CCH-theta to an intrinsic subthreshold membrane potential oscillation of the pyramidal cells, and that of CCH-gamma to the decay constant of GABAergic inhibitory synaptic potentials onto the pyramidal cells. In model simulations, the known physiological effects of carbachol on the muscarinic and K-AHP currents, and on the strengths of excitatory postsynaptic potentials, reproduced transitions from asynchronous CCH-theta to CCH-delta and from CCH-delta to synchronous CCH-theta. The simulations also exhibited the interspersed CCH-gamma/CCH-delta and CCH-gamma/CCH-theta that were observed in experiments. The model, in addition, predicted an oscillatory state with all three frequency bands present, which has not yet been observed experimentally.
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Affiliation(s)
- P H Tiesinga
- Sloan Center for Theoretical Neurobiology, Salk Institute, La Jolla, California 92037, USA.
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40
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Abstract
This review examines the role of acetylcholine in synaptic plasticity in archi-, paleo- and neocortex. Studies using microiontophoretic application of acetylcholine in vivo and in vitro and electrical stimulation of the basal forebrain have demonstrated that ACh can produce long-lasting increases in neural responsiveness. This evidence comes mainly from models of heterosynaptic facilitation in which acetylcholine produces a strengthening of a second, noncholinergic synaptic input onto the same neuron. The argument that the basal forebrain cholinergic system is essential in some models of plasticity is supported by studies that have selectively lesioned the cholinergic basal forebrain. This review will examine the mechanisms whereby acetylcholine might induce synaptic plasticity. It will also consider the neural circuitry implicated in these studies, namely the pathways that are susceptible to cholinergic plasticity and the neural regulation of the cholinergic system.
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Affiliation(s)
- D D Rasmusson
- Department of Physiology and Biophysics, Dalhousie University, NS, B3H 4H7, Halifax, Canada.
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Hsieh CY, Cruikshank SJ, Metherate R. Differential modulation of auditory thalamocortical and intracortical synaptic transmission by cholinergic agonist. Brain Res 2000; 880:51-64. [PMID: 11032989 DOI: 10.1016/s0006-8993(00)02766-9] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To investigate synaptic mechanisms underlying information processing in auditory cortex, we examined cholinergic modulation of synaptic transmission in a novel slice preparation containing thalamocortical and intracortical inputs to mouse auditory cortex. Extracellular and intracellular recordings were made in cortical layer IV while alternately stimulating thalamocortical afferents (via medial geniculate or downstream subcortical stimulation) and intracortical afferents. Either subcortical or intracortical stimulation elicited a fast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-sensitive, monosynaptic EPSP followed by long-duration, polysynaptic activity. The cholinergic agonist carbachol suppressed each of the synaptic potentials to different degrees. At low concentrations (5 microM) carbachol strongly reduced (>60%) the polysynaptic slow potentials for both pathways but did not affect the monosynaptic fast potentials. At higher doses (10-50 microM), carbachol also reduced the fast potentials, but reduced the intracortically-elicited fast potential significantly more than the thalamocortically-elicited fast potential, which at times was actually enhanced. Atropine (0.5 microM) blocked the effects of carbachol, indicating muscarinic receptor involvement. We conclude that muscarinic modulation can strongly suppress intracortical synaptic activity while exerting less suppression, or actually enhancing, thalamocortical inputs. Such differential actions imply that auditory information processing may favor sensory information relayed through the thalamus over ongoing cortical activity during periods of increased acetylcholine (ACh) release.
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Affiliation(s)
- C Y Hsieh
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92697-4550, USA
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42
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Kimura F. Cholinergic modulation of cortical function: a hypothetical role in shifting the dynamics in cortical network. Neurosci Res 2000; 38:19-26. [PMID: 10997574 DOI: 10.1016/s0168-0102(00)00151-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Wide innervation of cholinergic projections throughout the cortex implies that acetylcholine (ACh) plays an essential role in information processing, but how it works is still enigmatic. Experimental as well as theoretical work in the olfactory cortex and hippocampus suggests that ACh, via the muscarinic receptors, serves to shift the dynamics of the cortical networks into a state where afferent influence predominates over intracortical influence. Recent experiments in the visual and somatosensory cortex suggested that this hypothesis could be extended to neocortex. In addition, participation of the nicotinic receptors in regulating the synaptic response in the somatosensory cortex further substantiates this hypothesis. This hypothesis, derived mainly from in vitro work, also seemed to account for results from in vivo experiments without any obvious inconsistencies.
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Affiliation(s)
- F Kimura
- Department of Neuroscience, Biomedical Research Center, Osaka University Graduate School of Medicine, Suita, Japan
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43
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Fellous JM, Sejnowski TJ. Cholinergic induction of oscillations in the hippocampal slice in the slow (0.5-2 Hz), theta (5-12 Hz), and gamma (35-70 Hz) bands. Hippocampus 2000; 10:187-97. [PMID: 10791841 DOI: 10.1002/(sici)1098-1063(2000)10:2<187::aid-hipo8>3.0.co;2-m] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Carbachol, a muscarinic receptor agonist, produced three distinct spontaneous oscillations in the CA3 region of rat hippocampal slices. Carbachol concentrations in the 4-13 microM range produced regular synchronized CA3 discharges at 0.5-2 Hz (carbachol-delta). Higher concentrations (13-60 microM) produced short episodes of 5-10 Hz (carbachol-theta) oscillations separated by nonsynchronous activity. Concentrations of carbachol ranging from 8-25 microM also produced irregular episodes of high-frequency discharges (carbachol-gamma, 35-70 Hz), in isolation or mixed with carbachol-theta and carbachol-delta. At carbachol concentrations sufficient to induce carbachol-theta, low concentrations of APV reversibly transformed carbachol-theta into carbachol-delta. Higher concentrations of D,L-2-amino-5-phosphonopentanoic acid (APV) reversibly and completely blocked carbachol-theta. A systematic study of the effects of carbachol shows that the frequency of spontaneous oscillations depended nonlinearly on the level of muscarinic activation. Field and intracellular recordings from CA1 and CA3 pyramidal cells and interneurons during carbachol-induced rhythms revealed that the hippocampal circuitry preserved in the slice was capable of spontaneous activity over the range of frequencies observed in vivo and suggests that the presence of these rhythms could be under neuromodulatory control.
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Affiliation(s)
- J M Fellous
- Computational Neurobiology Laboratory, Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA.
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44
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Abstract
Computational modeling provides a means for linking the physiological and anatomical characteristics of entorhinal cortex at a cellular level to the functional role of this region in behavior. We have developed detailed simulations of entorhinal cortical neurons and networks, with an emphasis on the role of acetylcholine in entorhinal cortical function. Computational modeling suggests that when acetylcholine levels are high, this sets appropriate dynamics for the storage of stimuli during performance of delayed matching tasks. In particular, acetylcholine activates a calcium-sensitive nonspecific cation current which provides an intrinsic cellular mechanism which could maintain neuronal activity across a delay period. Simulations demonstrate how this phenomena could underlie entorhinal cortex delay activity as described in previous unit recordings. Acetylcholine also induces theta rhythm oscillations which may be appropriate for timing of afferent input to be encoded in hippocampus and for extraction of individual stored sequences from multiple stored sequences. Lower levels of acetylcholine may allow sharp wave dynamics which can reactivate associations encoded in hippocampus and drive the formation of additional traces in hippocampus and entorhinal cortex during consolidation.
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Affiliation(s)
- M E Hasselmo
- Department of Psychology, Boston University, Massachusetts 02215, USA.
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45
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Princivalle A, Spreafico R, Bowery N, De Curtis M. Layer-specific immunocytochemical localization of GABA(B)R1a and GABA(B)R1b receptors in the rat piriform cortex. Eur J Neurosci 2000; 12:1516-20. [PMID: 10762380 DOI: 10.1046/j.1460-9568.2000.01060.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A peculiar, layer-segregated immunoreactive distribution of GABABR1a and GABABR1b receptor antibodies is present in the piriform cortex of adult rats. The GABABR1a antibody selectively marked the neuropile in layer Ia, where afferent olfactory fibres and intrinsic GABAergic (gamma-aminobutyric acid) axons terminate on the distal apical dendrites of pyramidal neurons. The GABABR1b antibody was detected in the soma and the large basal dendrites of layer II and III neurons. The pattern of distribution observed supports the hypothesis that (presynaptic) GABABR1a receptors in the superficial molecular layer modulate neurotransmitter release in a feedforward synaptic circuit, whereas GABABR1b (postsynaptic) receptors mediate feedback inhibitory potentials on principal cells.
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Affiliation(s)
- A Princivalle
- Department of Pharmacology, University of Birmingham, UK
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46
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Fellous JM, Sejnowski TJ. Cholinergic induction of oscillations in the hippocampal slice in the slow (0.5-2 Hz), theta (5-12 Hz), and gamma (35-70 Hz) bands. Hippocampus 2000. [DOI: 10.1002/(sici)1098-1063(2000)10:2%3c187::aid-hipo8%3e3.0.co;2-m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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47
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Abstract
Clinical and experimental evidence suggests that hippocampal damage causes more severe disruption of episodic memories if those memories were encoded in the recent rather than the more distant past. This decrease in sensitivity to damage over time might reflect the formation of multiple traces within the hippocampus itself, or the formation of additional associative links in entorhinal and association cortices. Physiological evidence also supports a two-stage model of the encoding process in which the initial encoding occurs during active waking and deeper consolidation occurs via the formation of additional memory traces during quiet waking or slow-wave sleep. In this article I will describe the changes in cholinergic tone within the hippocampus in different stages of the sleep-wake cycle and will propose that these changes modulate different stages of memory formation. In particular, I will suggest that the high levels of acetylcholine that are present during active waking might set the appropriate dynamics for encoding new information in the hippocampus, by partially suppressing excitatory feedback connections and so facilitating encoding without interference from previously stored information. By contrast, the lower levels of acetylcholine that are present during quiet waking and slow-wave sleep might release this suppression and thereby allow a stronger spread of activity within the hippocampus itself and from the hippocampus to the entorhinal cortex, thus facilitating the process of consolidation of separate memory traces.
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