1
|
Squadrani L, Wert-Carvajal C, Müller-Komorowska D, Bohmbach K, Henneberger C, Verzelli P, Tchumatchenko T. Astrocytes enhance plasticity response during reversal learning. Commun Biol 2024; 7:852. [PMID: 38997325 PMCID: PMC11245475 DOI: 10.1038/s42003-024-06540-8] [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: 08/26/2023] [Accepted: 07/03/2024] [Indexed: 07/14/2024] Open
Abstract
Astrocytes play a key role in the regulation of synaptic strength and are thought to orchestrate synaptic plasticity and memory. Yet, how specifically astrocytes and their neuroactive transmitters control learning and memory is currently an open question. Recent experiments have uncovered an astrocyte-mediated feedback loop in CA1 pyramidal neurons which is started by the release of endocannabinoids by active neurons and closed by astrocytic regulation of the D-serine levels at the dendrites. D-serine is a co-agonist for the NMDA receptor regulating the strength and direction of synaptic plasticity. Activity-dependent D-serine release mediated by astrocytes is therefore a candidate for mediating between long-term synaptic depression (LTD) and potentiation (LTP) during learning. Here, we show that the mathematical description of this mechanism leads to a biophysical model of synaptic plasticity consistent with the phenomenological model known as the BCM model. The resulting mathematical framework can explain the learning deficit observed in mice upon disruption of the D-serine regulatory mechanism. It shows that D-serine enhances plasticity during reversal learning, ensuring fast responses to changes in the external environment. The model provides new testable predictions about the learning process, driving our understanding of the functional role of neuron-glia interaction in learning.
Collapse
Affiliation(s)
- Lorenzo Squadrani
- Institute of Experimental Epileptology and Cognition Research, Medical Faculty, University of Bonn, Bonn, Germany
| | - Carlos Wert-Carvajal
- Institute of Experimental Epileptology and Cognition Research, Medical Faculty, University of Bonn, Bonn, Germany
| | | | - Kirsten Bohmbach
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Pietro Verzelli
- Institute of Experimental Epileptology and Cognition Research, Medical Faculty, University of Bonn, Bonn, Germany.
| | - Tatjana Tchumatchenko
- Institute of Experimental Epileptology and Cognition Research, Medical Faculty, University of Bonn, Bonn, Germany.
| |
Collapse
|
2
|
Litif CG, Flom LT, Sandum KL, Hodgins SL, Vaccaro L, Stitzel JA, Blouin NA, Mannino MC, Gigley JP, Schoborg TA, Bobadilla AC. Differential genetic expression within reward-specific ensembles in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.02.565378. [PMID: 37961222 PMCID: PMC10635086 DOI: 10.1101/2023.11.02.565378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Maladaptive reward seeking is a hallmark of cocaine use disorder. To develop therapeutic targets, it is critical to understand the neurobiological changes specific to cocaine-seeking without altering the seeking of natural rewards, e.g., sucrose. The prefrontal cortex (PFC) and the nucleus accumbens core (NAcore) are known regions associated with cocaine- and sucrose-seeking ensembles, i.e., a sparse population of co-activated neurons. Within ensembles, transcriptomic alterations in the PFC and NAcore underlie the learning and persistence of cocaine- and sucrose-seeking behavior. However, transcriptomes exclusively driving cocaine seeking independent from sucrose seeking have not yet been defined using a within-subject approach. Using Ai14:cFos-TRAP2 transgenic mice in a dual cocaine and sucrose self-administration model, we fluorescently sorted (FACS) and characterized (RNAseq) the transcriptomes defining cocaine- and sucrose-seeking ensembles. We found reward- and region-specific transcriptomic changes that will help develop clinically relevant genetic approaches to decrease cocaine-seeking behavior without altering non-drug reward-based positive reinforcement.
Collapse
Affiliation(s)
- Carl G. Litif
- School of Pharmacy, University of Wyoming, Laramie, Wyoming, USA
| | - Levi T. Flom
- School of Pharmacy, University of Wyoming, Laramie, Wyoming, USA
| | | | | | - Lucio Vaccaro
- School of Pharmacy, University of Wyoming, Laramie, Wyoming, USA
| | - Jerry A. Stitzel
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
- Institute for Behavioral Genetics, University of Colorado Boulder, Boulder, Colorado, USA
| | - Nicolas A. Blouin
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | | | - Jason P. Gigley
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | - Todd A. Schoborg
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | - Ana-Clara Bobadilla
- School of Pharmacy, University of Wyoming, Laramie, Wyoming, USA
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| |
Collapse
|
3
|
Grella SL, Donaldson TN. Contextual memory engrams, and the neuromodulatory influence of the locus coeruleus. Front Mol Neurosci 2024; 17:1342622. [PMID: 38375501 PMCID: PMC10875109 DOI: 10.3389/fnmol.2024.1342622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/19/2024] [Indexed: 02/21/2024] Open
Abstract
Here, we review the basis of contextual memory at a conceptual and cellular level. We begin with an overview of the philosophical foundations of traversing space, followed by theories covering the material bases of contextual representations in the hippocampus (engrams), exploring functional characteristics of the cells and subfields within. Next, we explore various methodological approaches for investigating contextual memory engrams, emphasizing plasticity mechanisms. This leads us to discuss the role of neuromodulatory inputs in governing these dynamic changes. We then outline a recent hypothesis involving noradrenergic and dopaminergic projections from the locus coeruleus (LC) to different subregions of the hippocampus, in sculpting contextual representations, giving a brief description of the neuroanatomical and physiological properties of the LC. Finally, we examine how activity in the LC influences contextual memory processes through synaptic plasticity mechanisms to alter hippocampal engrams. Overall, we find that phasic activation of the LC plays an important role in promoting new learning and altering mnemonic processes at the behavioral and cellular level through the neuromodulatory influence of NE/DA in the hippocampus. These findings may provide insight into mechanisms of hippocampal remapping and memory updating, memory processes that are potentially dysregulated in certain psychiatric and neurodegenerative disorders.
Collapse
Affiliation(s)
- Stephanie L. Grella
- MNEME Lab, Department of Psychology, Program in Neuroscience, Loyola University Chicago, Chicago, IL, United States
| | - Tia N. Donaldson
- Systems Neuroscience and Behavior Lab, Department of Psychology, The University of New Mexico, Albuquerque, NM, United States
| |
Collapse
|
4
|
Brazhe A, Verisokin A, Verveyko D, Postnov D. Astrocytes: new evidence, new models, new roles. Biophys Rev 2023; 15:1303-1333. [PMID: 37975000 PMCID: PMC10643736 DOI: 10.1007/s12551-023-01145-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/08/2023] [Indexed: 11/19/2023] Open
Abstract
Astrocytes have been in the limelight of active research for about 3 decades now. Over this period, ideas about their function and role in the nervous system have evolved from simple assistance in energy supply and homeostasis maintenance to a complex informational and metabolic hub that integrates data on local neuronal activity, sensory and arousal context, and orchestrates many crucial processes in the brain. Rapid progress in experimental techniques and data analysis produces a growing body of data, which can be used as a foundation for formulation of new hypotheses, building new refined mathematical models, and ultimately should lead to a new level of understanding of the contribution of astrocytes to the cognitive tasks performed by the brain. Here, we highlight recent progress in astrocyte research, which we believe expands our understanding of how low-level signaling at a cellular level builds up to processes at the level of the whole brain and animal behavior. We start our review with revisiting data on the role of noradrenaline-mediated astrocytic signaling in locomotion, arousal, sensory integration, memory, and sleep. We then briefly review astrocyte contribution to the regulation of cerebral blood flow regulation, which is followed by a discussion of biophysical mechanisms underlying astrocyte effects on different brain processes. The experimental section is closed by an overview of recent experimental techniques available for modulation and visualization of astrocyte dynamics. We then evaluate how the new data can be potentially incorporated into the new mathematical models or where and how it already has been done. Finally, we discuss an interesting prospect that astrocytes may be key players in important processes such as the switching between sleep and wakefulness and the removal of toxic metabolites from the brain milieu.
Collapse
Affiliation(s)
- Alexey Brazhe
- Department of Biophysics, Biological Faculty, Lomonosov Moscow State University, Leninskie Gory, 1/24, Moscow, 119234 Russia
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry RAS, GSP-7, Miklukho-Maklay Str., 16/10, Moscow, 117997 Russia
| | - Andrey Verisokin
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Darya Verveyko
- Department of Theoretical Physics, Kursk State University, Radishcheva st., 33, Kursk, 305000 Russia
| | - Dmitry Postnov
- Department of Optics and Biophotonics, Saratov State University, Astrakhanskaya st., 83, Saratov, 410012 Russia
| |
Collapse
|
5
|
Purushotham SS, Buskila Y. Astrocytic modulation of neuronal signalling. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1205544. [PMID: 37332623 PMCID: PMC10269688 DOI: 10.3389/fnetp.2023.1205544] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023]
Abstract
Neuronal signalling is a key element in neuronal communication and is essential for the proper functioning of the CNS. Astrocytes, the most prominent glia in the brain play a key role in modulating neuronal signalling at the molecular, synaptic, cellular, and network levels. Over the past few decades, our knowledge about astrocytes and their functioning has evolved from considering them as merely a brain glue that provides structural support to neurons, to key communication elements. Astrocytes can regulate the activity of neurons by controlling the concentrations of ions and neurotransmitters in the extracellular milieu, as well as releasing chemicals and gliotransmitters that modulate neuronal activity. The aim of this review is to summarise the main processes through which astrocytes are modulating brain function. We will systematically distinguish between direct and indirect pathways in which astrocytes affect neuronal signalling at all levels. Lastly, we will summarize pathological conditions that arise once these signalling pathways are impaired focusing on neurodegeneration.
Collapse
Affiliation(s)
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- The MARCS Institute, Western Sydney University, Campbelltown, NSW, Australia
| |
Collapse
|