Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity

NMDA receptors (NMDA-R) typically contribute to excitatory synaptic transmission in the central nervous system. While calcium influx through NMDA-R plays a critical role in synaptic plasticity, experimental evidence indicates that NMDAR-mediated calcium influx also modifies neuronal excitability thr...

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Main Authors: David Gall, Geneviève Dupont
Format: Article
Language:English
Published: MDPI AG 2019-12-01
Series:International Journal of Molecular Sciences
Subjects:
Online Access:https://www.mdpi.com/1422-0067/21/1/206
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spelling doaj-027aaa7154fd4782aac140a509ec19f72020-11-25T01:15:23ZengMDPI AGInternational Journal of Molecular Sciences1422-00672019-12-0121120610.3390/ijms21010206ijms21010206Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal ActivityDavid Gall0Geneviève Dupont1Laboratoire de Physiologie et Pharmacologie (CP604), Faculté de Médecine, Université Libre de Bruxelles, Route de Lennik 808, B-1070 Bruxelles, BelgiumUnité de Chronobiologie Théorique (CP231), Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Bruxelles, BelgiumNMDA receptors (NMDA-R) typically contribute to excitatory synaptic transmission in the central nervous system. While calcium influx through NMDA-R plays a critical role in synaptic plasticity, experimental evidence indicates that NMDAR-mediated calcium influx also modifies neuronal excitability through the activation of calcium-activated potassium channels. This mechanism has not yet been studied theoretically. Our theoretical model provides a simple description of neuronal electrical activity that takes into account the tonic activity of extrasynaptic NMDA receptors and a cytosolic calcium compartment. We show that calcium influx mediated by the tonic activity of NMDA-R can be coupled directly to the activation of calcium-activated potassium channels, resulting in an overall inhibitory effect on neuronal excitability. Furthermore, the presence of tonic NMDA-R activity promotes bistability in electrical activity by dramatically increasing the stimulus interval where both a stable steady state and repetitive firing can coexist. These results could provide an intrinsic mechanism for the constitution of memory traces in neuronal circuits. They also shed light on the way by which <inline-formula> <math display="inline"> <semantics> <mi>&#946;</mi> </semantics> </math> </inline-formula>-amyloids can alter neuronal activity when interfering with NMDA-R in Alzheimer&#8217;s disease and cerebral ischemia.https://www.mdpi.com/1422-0067/21/1/206calciumneuronnmda receptorexcitabilitybistabilitymemoryalzheimer’s diseasecerebral ischemia
collection DOAJ
language English
format Article
sources DOAJ
author David Gall
Geneviève Dupont
spellingShingle David Gall
Geneviève Dupont
Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
International Journal of Molecular Sciences
calcium
neuron
nmda receptor
excitability
bistability
memory
alzheimer’s disease
cerebral ischemia
author_facet David Gall
Geneviève Dupont
author_sort David Gall
title Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
title_short Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
title_full Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
title_fullStr Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
title_full_unstemmed Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity
title_sort tonic activation of extrasynaptic nmda receptors decreases intrinsic excitability and promotes bistability in a model of neuronal activity
publisher MDPI AG
series International Journal of Molecular Sciences
issn 1422-0067
publishDate 2019-12-01
description NMDA receptors (NMDA-R) typically contribute to excitatory synaptic transmission in the central nervous system. While calcium influx through NMDA-R plays a critical role in synaptic plasticity, experimental evidence indicates that NMDAR-mediated calcium influx also modifies neuronal excitability through the activation of calcium-activated potassium channels. This mechanism has not yet been studied theoretically. Our theoretical model provides a simple description of neuronal electrical activity that takes into account the tonic activity of extrasynaptic NMDA receptors and a cytosolic calcium compartment. We show that calcium influx mediated by the tonic activity of NMDA-R can be coupled directly to the activation of calcium-activated potassium channels, resulting in an overall inhibitory effect on neuronal excitability. Furthermore, the presence of tonic NMDA-R activity promotes bistability in electrical activity by dramatically increasing the stimulus interval where both a stable steady state and repetitive firing can coexist. These results could provide an intrinsic mechanism for the constitution of memory traces in neuronal circuits. They also shed light on the way by which <inline-formula> <math display="inline"> <semantics> <mi>&#946;</mi> </semantics> </math> </inline-formula>-amyloids can alter neuronal activity when interfering with NMDA-R in Alzheimer&#8217;s disease and cerebral ischemia.
topic calcium
neuron
nmda receptor
excitability
bistability
memory
alzheimer’s disease
cerebral ischemia
url https://www.mdpi.com/1422-0067/21/1/206
work_keys_str_mv AT davidgall tonicactivationofextrasynapticnmdareceptorsdecreasesintrinsicexcitabilityandpromotesbistabilityinamodelofneuronalactivity
AT genevievedupont tonicactivationofextrasynapticnmdareceptorsdecreasesintrinsicexcitabilityandpromotesbistabilityinamodelofneuronalactivity
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