401
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Functional roles of CREB as a positive regulator in the formation and enhancement of memory. Brain Res Bull 2014; 105:17-24. [DOI: 10.1016/j.brainresbull.2014.04.011] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/19/2014] [Accepted: 04/12/2014] [Indexed: 01/07/2023]
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402
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Park AJ, Havekes R, Choi JH, Luczak V, Nie T, Huang T, Abel T. A presynaptic role for PKA in synaptic tagging and memory. Neurobiol Learn Mem 2014; 114:101-112. [PMID: 24882624 DOI: 10.1016/j.nlm.2014.05.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 05/01/2014] [Accepted: 05/04/2014] [Indexed: 12/14/2022]
Abstract
Protein kinase A (PKA) and other signaling molecules are spatially restricted within neurons by A-kinase anchoring proteins (AKAPs). Although studies on compartmentalized PKA signaling have focused on postsynaptic mechanisms, presynaptically anchored PKA may contribute to synaptic plasticity and memory because PKA also regulates presynaptic transmitter release. Here, we examine this issue using genetic and pharmacological application of Ht31, a PKA anchoring disrupting peptide. At the hippocampal Schaffer collateral CA3-CA1 synapse, Ht31 treatment elicits a rapid decay of synaptic responses to repetitive stimuli, indicating a fast depletion of the readily releasable pool of synaptic vesicles. The interaction between PKA and proteins involved in producing this pool of synaptic vesicles is supported by biochemical assays showing that synaptic vesicle protein 2 (SV2), Rim1, and SNAP25 are components of a complex that interacts with cAMP. Moreover, acute treatment with Ht31 reduces the levels of SV2. Finally, experiments with transgenic mouse lines, which express Ht31 in excitatory neurons at the Schaffer collateral CA3-CA1 synapse, highlight a requirement for presynaptically anchored PKA in pathway-specific synaptic tagging and long-term contextual fear memory. These results suggest that a presynaptically compartmentalized PKA is critical for synaptic plasticity and memory by regulating the readily releasable pool of synaptic vesicles.
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Affiliation(s)
- Alan Jung Park
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
| | - Robbert Havekes
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
| | - Jennifer Hk Choi
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
| | - Vince Luczak
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
| | - Ting Nie
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA.,Department of Pediatrics, Emory University, VAMC, 1670 Clairmont Rd Atlanta, GA 30033, USA
| | - Ted Huang
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
| | - Ted Abel
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
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403
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Gebicke-Haerter PJ. Engram formation in psychiatric disorders. Front Neurosci 2014; 8:118. [PMID: 24904262 PMCID: PMC4036307 DOI: 10.3389/fnins.2014.00118] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 05/02/2014] [Indexed: 01/17/2023] Open
Abstract
Environmental factors substantially influence beginning and progression of mental illness, reinforcing or reducing the consequences of genetic vulnerability. Often initiated by early traumatic events, “engrams” or memories are formed that may give rise to a slow and subtle progression of psychiatric disorders. The large delay between beginning and time of onset (diagnosis) may be explained by efficient compensatory mechanisms observed in brain metabolism that use optional pathways in highly redundant molecular interactions. To this end, research has to deal with mechanisms of learning and long-term memory formation, which involves (a) epigenetic changes, (b) altered neuronal activities, and (c) changes in neuron-glia communication. On the epigenetic level, apparently DNA-methylations are more stable than histone modifications, although both closely interact. Neuronal activities basically deliver digital information, which clearly can serve as basis for memory formation (LTP). However, research in this respect has long time neglected the importance of glia. They are more actively involved in the control of neuronal activities than thought before. They can both reinforce and inhibit neuronal activities by transducing neuronal information from frequency-encoded to amplitude and frequency-modulated calcium wave patterns spreading in the glial syncytium by use of gap junctions. In this way, they serve integrative functions. In conclusion, we are dealing with two concepts of encoding information that mutually control each other and synergize: a digital (neuronal) and a wave-like (glial) computing, forming neuron-glia functional units with inbuilt feedback loops to maintain balance of excitation and inhibition. To better understand mental illness, we have to gain more insight into the dynamics of adverse environmental impact on those cellular and molecular systems. This report summarizes existing knowledge and draws some outline about further research in molecular psychiatry.
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Affiliation(s)
- Peter J Gebicke-Haerter
- Medical Faculty Mannheim, Central Institute of Mental Health, Institute of Psychopharmacology, Heidelberg University Mannheim, Germany ; Progrs. de Farmacología y Inmunología, Facultad de Medicina, Universidad de Chile Santiago, Chile
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404
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Akers KG, Martinez-Canabal A, Restivo L, Yiu AP, De Cristofaro A, Hsiang HLL, Wheeler AL, Guskjolen A, Niibori Y, Shoji H, Ohira K, Richards BA, Miyakawa T, Josselyn SA, Frankland PW. Hippocampal neurogenesis regulates forgetting during adulthood and infancy. Science 2014; 344:598-602. [PMID: 24812394 DOI: 10.1126/science.1248903] [Citation(s) in RCA: 493] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Throughout life, new neurons are continuously added to the dentate gyrus. As this continuous addition remodels hippocampal circuits, computational models predict that neurogenesis leads to degradation or forgetting of established memories. Consistent with this, increasing neurogenesis after the formation of a memory was sufficient to induce forgetting in adult mice. By contrast, during infancy, when hippocampal neurogenesis levels are high and freshly generated memories tend to be rapidly forgotten (infantile amnesia), decreasing neurogenesis after memory formation mitigated forgetting. In precocial species, including guinea pigs and degus, most granule cells are generated prenatally. Consistent with reduced levels of postnatal hippocampal neurogenesis, infant guinea pigs and degus did not exhibit forgetting. However, increasing neurogenesis after memory formation induced infantile amnesia in these species.
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Affiliation(s)
- Katherine G Akers
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, M5G 1X8, Canada
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405
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Spires-Jones TL, Hyman BT. The intersection of amyloid beta and tau at synapses in Alzheimer's disease. Neuron 2014; 82:756-71. [PMID: 24853936 PMCID: PMC4135182 DOI: 10.1016/j.neuron.2014.05.004] [Citation(s) in RCA: 748] [Impact Index Per Article: 74.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2014] [Indexed: 02/07/2023]
Abstract
The collapse of neural networks important for memory and cognition, including death of neurons and degeneration of synapses, causes the debilitating dementia associated with Alzheimer's disease (AD). We suggest that synaptic changes are central to the disease process. Amyloid beta and tau form fibrillar lesions that are the classical hallmarks of AD. Recent data indicate that both molecules may have normal roles at the synapse, and that the accumulation of soluble toxic forms of the proteins at the synapse may be on the critical path to neurodegeneration. Further, the march of neurofibrillary tangles through brain circuits appears to take advantage of recently described mechanisms of transsynaptic spread of pathological forms of tau. These two key phenomena, synapse loss and the spread of pathology through the brain via synapses, make it critical to understand the physiological and pathological roles of amyloid beta and tau at the synapse.
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Affiliation(s)
- Tara L Spires-Jones
- Centre for Cognitive and Neural Systems, The University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK; The Euan MacDonald Centre, The University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK.
| | - Bradley T Hyman
- Massachusetts General Hospital, Harvard Medical School, Neurology, 114 16(th) Street, Charlestown, MA 02129, USA.
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406
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Meyer D, Bonhoeffer T, Scheuss V. Balance and Stability of Synaptic Structures during Synaptic Plasticity. Neuron 2014; 82:430-43. [DOI: 10.1016/j.neuron.2014.02.031] [Citation(s) in RCA: 278] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2014] [Indexed: 12/27/2022]
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407
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Gershman SJ. The penumbra of learning: a statistical theory of synaptic tagging and capture. NETWORK (BRISTOL, ENGLAND) 2014; 25:97-115. [PMID: 24679103 DOI: 10.3109/0954898x.2013.862749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Learning in humans and animals is accompanied by a penumbra: Learning one task benefits from learning an unrelated task shortly before or after. At the cellular level, the penumbra of learning appears when weak potentiation of one synapse is amplified by strong potentiation of another synapse on the same neuron during a critical time window. Weak potentiation sets a molecular tag that enables the synapse to capture plasticity-related proteins synthesized in response to strong potentiation at another synapse. This paper describes a computational model which formalizes synaptic tagging and capture in terms of statistical learning mechanisms. According to this model, synaptic strength encodes a probabilistic inference about the dynamically changing association between pre- and post-synaptic firing rates. The rate of change is itself inferred, coupling together different synapses on the same neuron. When the inputs to one synapse change rapidly, the inferred rate of change increases, amplifying learning at other synapses.
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Affiliation(s)
- Samuel J Gershman
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology , Cambridge, MA , USA
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408
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Kinesin-1 regulates synaptic strength by mediating the delivery, removal, and redistribution of AMPA receptors. Neuron 2014; 80:1421-37. [PMID: 24360545 DOI: 10.1016/j.neuron.2013.10.050] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2013] [Indexed: 01/22/2023]
Abstract
A primary determinant of the strength of neurotransmission is the number of AMPA-type glutamate receptors (AMPARs) at synapses. However, we still lack a mechanistic understanding of how the number of synaptic AMPARs is regulated. Here, we show that UNC-116, the C. elegans homolog of vertebrate kinesin-1 heavy chain (KIF5), modifies synaptic strength by mediating the rapid delivery, removal, and redistribution of synaptic AMPARs. Furthermore, by studying the real-time transport of C. elegans AMPAR subunits in vivo, we demonstrate that although homomeric GLR-1 AMPARs can diffuse to and accumulate at synapses in unc-116 mutants, glutamate-gated currents are diminished because heteromeric GLR-1/GLR-2 receptors do not reach synapses in the absence of UNC-116/KIF5-mediated transport. Our data support a model in which ongoing motor-driven delivery and removal of AMPARs controls not only the number but also the composition of synaptic AMPARs, and thus the strength of synaptic transmission.
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409
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Watrous AJ, Ekstrom AD. The spectro-contextual encoding and retrieval theory of episodic memory. Front Hum Neurosci 2014; 8:75. [PMID: 24600373 PMCID: PMC3927099 DOI: 10.3389/fnhum.2014.00075] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 01/29/2014] [Indexed: 11/13/2022] Open
Abstract
The spectral fingerprint hypothesis, which posits that different frequencies of oscillations underlie different cognitive operations, provides one account for how interactions between brain regions support perceptual and attentive processes (Siegel etal., 2012). Here, we explore and extend this idea to the domain of human episodic memory encoding and retrieval. Incorporating findings from the synaptic to cognitive levels of organization, we argue that spectrally precise cross-frequency coupling and phase-synchronization promote the formation of hippocampal-neocortical cell assemblies that form the basis for episodic memory. We suggest that both cell assembly firing patterns as well as the global pattern of brain oscillatory activity within hippocampal-neocortical networks represents the contents of a particular memory. Drawing upon the ideas of context reinstatement and multiple trace theory, we argue that memory retrieval is driven by internal and/or external factors which recreate these frequency-specific oscillatory patterns which occur during episodic encoding. These ideas are synthesized into a novel model of episodic memory (the spectro-contextual encoding and retrieval theory, or "SCERT") that provides several testable predictions for future research.
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Affiliation(s)
- Andrew J Watrous
- Center for Neuroscience, University of California Davis, CA, USA ; University of Bonn, Bonn Germany
| | - Arne D Ekstrom
- Center for Neuroscience, University of California Davis, CA, USA ; Neuroscience Graduate Group, University of California Davis, CA, USA ; Department of Psychology, University of California Davis, CA, USA
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410
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Schacher S, Hu JY. The less things change, the more they are different: contributions of long-term synaptic plasticity and homeostasis to memory. Learn Mem 2014; 21:128-34. [PMID: 24532836 PMCID: PMC3929853 DOI: 10.1101/lm.027326.112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
An important cellular mechanism contributing to the strength and duration of memories is activity-dependent alterations in the strength of synaptic connections within the neural circuit encoding the memory. Reversal of the memory is typically correlated with a reversal of the cellular changes to levels expressed prior to the stimulation. Thus, for stimulus-induced changes in synapse strength and their reversals to be functionally relevant, cellular mechanisms must regulate and maintain synapse strength both prior to and after the stimuli inducing learning and memory. The strengths of synapses within a neural circuit at any given moment are determined by cellular and molecular processes initiated during development and those subsequently regulated by the history of direct activation of the neural circuit and system-wide stimuli such as stress or motivational state. The cumulative actions of stimuli and other factors on an already modified neural circuit are attenuated by homeostatic mechanisms that prevent changes in overall synaptic inputs and excitability above or below specific set points (synaptic scaling). The mechanisms mediating synaptic scaling prevent potential excitotoxic alterations in the circuit but also may attenuate additional cellular changes required for learning and memory, thereby apparently limiting information storage. What cellular and molecular processes control synaptic strengths before and after experience/activity and its reversals? In this review we will explore the synapse-, whole cell-, and circuit level-specific processes that contribute to an overall zero sum-like set of changes and long-term maintenance of synapse strengths as a consequence of the accommodative interactions between long-term synaptic plasticity and homeostasis.
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Affiliation(s)
- Samuel Schacher
- Department of Neuroscience, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, New York 10032, USA
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411
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Rogerson T, Cai DJ, Frank A, Sano Y, Shobe J, Lopez-Aranda MF, Silva AJ. Synaptic tagging during memory allocation. Nat Rev Neurosci 2014; 15:157-69. [PMID: 24496410 DOI: 10.1038/nrn3667] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There is now compelling evidence that the allocation of memory to specific neurons (neuronal allocation) and synapses (synaptic allocation) in a neurocircuit is not random and that instead specific mechanisms, such as increases in neuronal excitability and synaptic tagging and capture, determine the exact sites where memories are stored. We propose an integrated view of these processes, such that neuronal allocation, synaptic tagging and capture, spine clustering and metaplasticity reflect related aspects of memory allocation mechanisms. Importantly, the properties of these mechanisms suggest a set of rules that profoundly affect how memories are stored and recalled.
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Affiliation(s)
- Thomas Rogerson
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Denise J Cai
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Adam Frank
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Yoshitake Sano
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Justin Shobe
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Manuel F Lopez-Aranda
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
| | - Alcino J Silva
- Departments of Neurobiology, Psychiatry & Biobehavioral Sciences, and Psychology, Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
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412
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Saab BJ, Mansuy IM. Neuroepigenetics of memory formation and impairment: the role of microRNAs. Neuropharmacology 2014; 80:61-9. [PMID: 24486712 DOI: 10.1016/j.neuropharm.2014.01.026] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 01/19/2014] [Accepted: 01/20/2014] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) are a class of short non-coding RNAs that primarily regulate protein synthesis through reversible translational repression or mRNA degradation. MiRNAs can act by translational control of transcription factors or via direct action on the chromatin, and thereby contribute to the non-genetic control of gene-environment interactions. MiRNAs that regulate components of pathways required for learning and memory further modulate the influence of epigenetics on cognition in the normal and diseased brain. This review summarizes recent data exemplifying the known roles of miRNAs in memory formation in different model organisms, and describes how neuronal plasticity regulates miRNA biogenesis, activity and degradation. It also examines the relevance of miRNAs for memory impairment in human, using recent clinical observations related to neurodevelopmental and neurodegenerative diseases, and discusses the potential mechanisms by which these miRNAs may contribute to memory disorders.
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Affiliation(s)
- Bechara J Saab
- Brain Research Institute, Neuroscience Center Zürich, Faculty of Medicine of the University of Zürich and Department of Health Sciences and Technology of the Swiss Federal Institute of Technology, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Isabelle M Mansuy
- Brain Research Institute, Neuroscience Center Zürich, Faculty of Medicine of the University of Zürich and Department of Health Sciences and Technology of the Swiss Federal Institute of Technology, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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413
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Salvetti B, Morris RGM, Wang SH. The role of rewarding and novel events in facilitating memory persistence in a separate spatial memory task. Learn Mem 2014; 21:61-72. [PMID: 24429424 PMCID: PMC3895229 DOI: 10.1101/lm.032177.113] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Many insignificant events in our daily life are forgotten quickly but can be remembered for longer when other memory-modulating events occur before or after them. This phenomenon has been investigated in animal models in a protocol in which weak memories persist longer if exploration in a novel context is introduced around the time of memory encoding. This study aims to understand whether other types of rewarding or novel tasks, such as rewarded learning in a T-maze and novel object recognition, can also be effective memory-modulating events. Rats were trained in a delayed matching-to-place task to encode and retrieve food locations in an event arena. Weak encoding with only one food pellet at the sample location induced memory encoding but forgetting over 24 h. When this same weak encoding was followed by a rewarded task in a T-maze, the memory persisted for 24 h. Moreover, the same persistence of memory over 24 h could be achieved by exploration in a novel box or by a rewarded T-maze task after a “non-rewarded” weak encoding. When the one-pellet weak encoding was followed by novel object exploration, the memory did not persist at 24 h. Together, the results confirm that place encoding is possible without explicit reward, and that rewarded learning in a separate task lacking novelty can be an effective memory-modulating event. The behavioral and neurobiological implications are discussed.
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Affiliation(s)
- Beatrice Salvetti
- Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh EH8 9JZ, United Kingdom
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414
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Tabatadze N, McGonigal R, Neve RL, Routtenberg A. Activity-dependent Wnt 7 dendritic targeting in hippocampal neurons: plasticity- and tagging-related retrograde signaling mechanism? Hippocampus 2014; 24:455-65. [PMID: 24375790 DOI: 10.1002/hipo.22239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 11/29/2013] [Accepted: 12/16/2013] [Indexed: 01/07/2023]
Abstract
Wnt proteins have emerged as transmembrane signaling molecules that regulate learning and memory as well as synaptic plasticity at central synapses (Inestrosa and Arenas (2010) Nat Rev Neurosci 11:77-86; Maguschak and Ressler (2011) J Neurosci 31:13057-13067; Tabatadze et al. (2012) Hippocampus 22: 1228-1241; Fortress et al. (2013) J Neurosci 33:12619-12626). For example, there is both a training-selective and Wnt isoform-specific increase in Wnt 7 levels in hippocampus seven days after spatial learning in rats (Tabatadze et al. (2012) Hippocampus 22: 1228-1241). Despite growing interest in Wnt signaling pathways in the adult brain, intracellular distribution and release of Wnt molecules from synaptic compartments as well as their influence on synaptic strength and connectivity remain less well understood. As a first step in such an analysis, we show here that Wnt 7 levels in primary hippocampal cells are elevated by potassium or glutamate activation in a time-dependent manner. Subsequent Wnt 7 elevation in dendrites suggests selective somato-dendritic trafficking followed by transport from dendrites to their spines. Wnt 7 elevation is also TTX-reversible, establishing that its elevation is indeed an activity-dependent process. A second stimulation given 6 h after the first significantly reduces Wnt 7 levels in dendrites 3 h later as compared to non-stimulated controls suggesting activity-dependent Wnt 7 release from dendrites and spines. In a related experiment designed to mimic the release of Wnt 7, exogenous recombinant Wnt 7 increased the number of active zones in presynaptic terminals as indexed by bassoon. This suggests the formation of new presynaptic release sites and/or presynaptic terminals. Wnt signaling inhibitor sFRP-1 completely blocked this Wnt 7-induced elevation of bassoon cluster number and cluster area. We suggest that Wnt 7 is a plasticity-related protein involved in the regulation of presynaptic plasticity via a retrograde signaling mechanism as previously proposed (Routtenberg (1999) Trends in Neuroscience 22:255-256). These findings provide support for this proposal, which offers a new perspective on the synaptic tagging mechanism (Redondo and Morris (2011) Nat Rev Neurosci 12:17-30).
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Affiliation(s)
- Nino Tabatadze
- Department of Neurobiology, Northwestern University, Evanston, Illinois
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415
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Navakkode S, Korte M. Pharmacological activation of CB1 receptor modulates long term potentiation by interfering with protein synthesis. Neuropharmacology 2014; 79:525-33. [PMID: 24412673 DOI: 10.1016/j.neuropharm.2013.11.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 11/04/2013] [Accepted: 11/21/2013] [Indexed: 12/30/2022]
Abstract
Cognitive impairment is one of the most important side effects associated with cannabis drug abuse, as well as the serious issue concerning the therapeutic use of cannabinoids. Cognitive impairments and neuropsychiatric symptoms are caused by early synaptic dysfunctions, such as loss of synaptic connections in different brain structures including the hippocampus, a region that is believed to play an important role in certain forms of learning and memory. We report here that metaplastic priming of synapses with a cannabinoid type 1 receptor (CB1 receptor) agonist, WIN55,212-2 (WIN55), significantly impaired long-term potentiation in the apical dendrites of CA1 pyramidal neurons. Interestingly, the CB1 receptor exerts its effect by altering the balance of protein synthesis machinery towards higher protein production. Therefore the activation of CB1 receptor, prior to strong tetanization, increased the propensity to produce new proteins. In addition, WIN55 priming resulted in the expression of late-LTP in a synaptic input that would have normally expressed early-LTP, thus confirming that WIN55 priming of LTP induces new synthesis of plasticity-related proteins. Furthermore, in addition to the effects on protein translation, WIN55 also induced synaptic deficits due to the ability of CB1 receptors to inhibit the release of acetylcholine, mediated by both muscarinic and nicotinic acetylcholine receptors. Taken together this supports the notion that the modulation of cholinergic activity by CB1 receptor activation is one mechanism that regulates the synthesis of plasticity-related proteins.
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Affiliation(s)
- Sheeja Navakkode
- Zoology Institute, Division of Cellular Neurobiology, TU, Braunschweig D-38106 Germany
| | - Martin Korte
- Zoology Institute, Division of Cellular Neurobiology, TU, Braunschweig D-38106 Germany.
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416
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Affiliation(s)
- Woo-Kyoung Yoo
- Department of Physical Medicine and Rehabilitation, Hallym University College of Medicine, Korea
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417
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Abstract
Although all neurons carry the same genetic information, they vary considerably in morphology and functions and respond differently to environmental conditions. Such variability results mostly from differences in gene expression. Among the processes that regulate gene activity, epigenetic mechanisms play a key role and provide an additional layer of complexity to the genome. They allow the dynamic modulation of gene expression in a locus- and cell-specific manner. These mechanisms primarily involve DNA methylation, posttranslational modifications (PTMs) of histones and noncoding RNAs that together remodel chromatin and facilitate or suppress gene expression. Through these mechanisms, the brain gains high plasticity in response to experience and can integrate and store new information to shape future neuronal and behavioral responses. Dynamic epigenetic footprints underlying the plasticity of brain cells and circuits contribute to the persistent impact of life experiences on an individual's behavior and physiology ranging from the formation of long-term memory to the sequelae of traumatic events or of drug addiction. They also contribute to the way lifestyle, life events, or exposure to environmental toxins can predispose an individual to disease. This chapter describes the most prominent examples of epigenetic marks associated with long-lasting changes in the brain induced by experience. It discusses the role of epigenetic processes in behavioral plasticity triggered by environmental experiences. A particular focus is placed on learning and memory where the importance of epigenetic modifications in brain circuits is best understood. The relevance of epigenetics in memory disorders such as dementia and Alzheimer's disease is also addressed, and promising perspectives for potential epigenetic drug treatment discussed.
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418
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Viola H, Ballarini F, Martínez MC, Moncada D. The tagging and capture hypothesis from synapse to memory. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:391-423. [PMID: 24484708 DOI: 10.1016/b978-0-12-420170-5.00013-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The synaptic tagging and capture theory (STC) was postulated by Frey and Morris in 1997 and provided a strong framework to explain how to achieve synaptic specificity and persistence of electrophysiological-induced plasticity changes. Ten years later, the same argument was applied on learning and memory models to explain the formation of long-term memories, resulting in the behavioral tagging hypothesis (BT). These hypotheses are able to explain how a weak event that induces transient changes in the brain can establish long-lasting phenomena through a tagging and capture process. In this framework, it was postulated that the weak event sets a tag that captures plasticity-related proteins/products (PRPs) synthesized by an independent strong event. The tagging and capture processes exhibit symmetry, and therefore, PRPs can be captured if they are synthesized either before or after the setting of the tag. In summary, the hypothesis provides a wide framework that gives a solid explanation of how lasting changes occur and how the interaction between different events leads to promotion, reinforcement, or impairment of such changes. In this chapter, we will summarize the postulates of STC hypothesis, the common features between synaptic plasticity and memory, as well as a detailed compilation of the findings supporting the existence of BT process. At the end, we pose some questions related to BT mechanism and LTM formation, which probably will be answered in the near future.
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Affiliation(s)
- Haydée Viola
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Fabricio Ballarini
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Cecilia Martínez
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Diego Moncada
- Instituto de Biología Celular y Neurociencias "Prof. E. De Robertis", Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Neurophysiology of Learning and Memory Research Group, Leibniz-Institut für Neurobiologie, Magdeburg, Germany
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419
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da Silva BM, Bast T, Morris RGM. Spatial memory: behavioral determinants of persistence in the watermaze delayed matching-to-place task. Learn Mem 2013; 21:28-36. [PMID: 24345637 PMCID: PMC3867716 DOI: 10.1101/lm.032169.113] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The watermaze delayed matching-to-place (DMP) task was modified to include probe trials, to quantify search preference for the correct place. Using a zone analysis of search preference, a gradual decay of one-trial memory in rats was observed over 24 h with weak memory consistently detected at a retention interval of 6 h, but unreliably at 24 h. This forgetting function in the watermaze was similar to that found using a search-preference measure in a food-reinforced dry-land DMP task in a previous study. In a search for strong and weak encoding conditions, essential for a later behavioral tagging study, three encoding trials gave strong 6-h and 24-h memory when trials were separated by 10 min (spaced training) but not 15 sec (massed training). The use of six encoding trials gave good 6-h memory with both spaced and massed training. With respect to weak encoding, placement on the escape platform, instead of the rat swimming to it, resulted in detectable memory at 30 min but this had faded to chance within 24 h. In contrast to the search-preference measure, latencies to cross the correct place revealed neither the gradual forgetting of place memory nor the benefit of spaced training.
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Affiliation(s)
- Bruno M da Silva
- Laboratory for Cognitive Neuroscience, Centre for Cognitive and Neural Systems, The University of Edinburgh, Edinburgh EH8 9JZ, United Kingdom
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420
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Müller-Dahlhaus F, Vlachos A. Unraveling the cellular and molecular mechanisms of repetitive magnetic stimulation. Front Mol Neurosci 2013; 6:50. [PMID: 24381540 PMCID: PMC3865432 DOI: 10.3389/fnmol.2013.00050] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 11/29/2013] [Indexed: 11/13/2022] Open
Abstract
Despite numerous clinical studies, which have investigated the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) in various brain diseases, our knowledge of the cellular and molecular mechanisms underlying rTMS-based therapies remains limited. Thus, a deeper understanding of rTMS-induced neural plasticity is required to optimize current treatment protocols. Studies in small animals or appropriate in vitro preparations (including models of brain diseases) provide highly useful experimental approaches in this context. State-of-the-art electrophysiological and live-cell imaging techniques that are well established in basic neuroscience can help answering some of the major questions in the field, such as (i) which neural structures are activated during TMS, (ii) how does rTMS induce Hebbian plasticity, and (iii) are other forms of plasticity (e.g., metaplasticity, structural plasticity) induced by rTMS? We argue that data gained from these studies will support the development of more effective and specific applications of rTMS in clinical practice.
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Affiliation(s)
- Florian Müller-Dahlhaus
- Department of Neurology and Stroke, Hertie Institute for Clinical Brain Research, Eberhard-Karls-University Tübingen Tübingen, Germany
| | - Andreas Vlachos
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt Frankfurt am Main, Germany
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421
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Synaptic regulation of microtubule dynamics in dendritic spines by calcium, F-actin, and drebrin. J Neurosci 2013; 33:16471-82. [PMID: 24133252 DOI: 10.1523/jneurosci.0661-13.2013] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dendritic spines are actin-rich compartments that protrude from the microtubule-rich dendritic shafts of principal neurons. Spines contain receptors and postsynaptic machinery for receiving the majority of glutamatergic inputs. Recent studies have shown that microtubules polymerize from dendritic shafts into spines and that signaling through synaptic NMDA receptors regulates this process. However, the mechanisms regulating microtubule dynamics in dendrites and spines remain unclear. Here we show that in hippocampal neurons from male and female mice, the majority of microtubules enter spines from highly localized sites at the base of spines. These entries occur in response to synapse-specific calcium transients that promote microtubule entry into active spines. We further document that spine calcium transients promote local actin polymerization, and that F-actin is both necessary and sufficient for microtubule entry. Finally, we show that drebrin, a protein known to mediate interactions between F-actin and microtubules, acts as a positive regulator of microtubule entry into spines. Together these results establish for the first time the essential mechanisms regulating microtubule entry into spines and contribute importantly to our understanding of the role of microtubules in synaptic function and plasticity.
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422
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Nonaka M, Fujii H, Kim R, Kawashima T, Okuno H, Bito H. Untangling the two-way signalling route from synapses to the nucleus, and from the nucleus back to the synapses. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130150. [PMID: 24298152 DOI: 10.1098/rstb.2013.0150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During learning and memory, it has been suggested that the coordinated electrical activity of hippocampal neurons translates information about the external environment into internal neuronal representations, which then are stored initially within the hippocampus and subsequently into other areas of the brain. A widely held hypothesis posits that synaptic plasticity is a key feature that critically modulates the triggering and the maintenance of such representations, some of which are thought to persist over time as traces or tags. However, the molecular and cell biological basis for these traces and tags has remained elusive. Here, we review recent findings that help clarify some of the molecular and cellular mechanisms critical for these events, by untangling a two-way signalling crosstalk route between the synapses and the neuronal soma. In particular, a detailed interrogation of the soma-to-synapse delivery of immediate early gene product Arc/Arg3.1, whose induction is triggered by heightened synaptic activity in many brain areas, teases apart an unsuspected 'inverse' synaptic tagging mechanism that likely contributes to maintaining the contrast of synaptic weight between strengthened and weak synapses within an active ensemble.
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Affiliation(s)
- Mio Nonaka
- Department of Neurochemistry, Graduate School of Medicine, University of Tokyo, , Bunkyo-ku, Tokyo 113-0033, Japan
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423
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Takeuchi T, Duszkiewicz AJ, Morris RGM. The synaptic plasticity and memory hypothesis: encoding, storage and persistence. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130288. [PMID: 24298167 DOI: 10.1098/rstb.2013.0288] [Citation(s) in RCA: 362] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The synaptic plasticity and memory hypothesis asserts that activity-dependent synaptic plasticity is induced at appropriate synapses during memory formation and is both necessary and sufficient for the encoding and trace storage of the type of memory mediated by the brain area in which it is observed. Criteria for establishing the necessity and sufficiency of such plasticity in mediating trace storage have been identified and are here reviewed in relation to new work using some of the diverse techniques of contemporary neuroscience. Evidence derived using optical imaging, molecular-genetic and optogenetic techniques in conjunction with appropriate behavioural analyses continues to offer support for the idea that changing the strength of connections between neurons is one of the major mechanisms by which engrams are stored in the brain.
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Affiliation(s)
- Tomonori Takeuchi
- Centre for Cognitive and Neural Systems, University of Edinburgh, , 1 George Square, Edinburgh EH8 9JZ, UK
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424
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Hardt O, Nader K, Wang YT. GluA2-dependent AMPA receptor endocytosis and the decay of early and late long-term potentiation: possible mechanisms for forgetting of short- and long-term memories. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130141. [PMID: 24298143 DOI: 10.1098/rstb.2013.0141] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The molecular processes involved in establishing long-term potentiation (LTP) have been characterized well, but the decay of early and late LTP (E-LTP and L-LTP) is poorly understood. We review recent advances in describing the mechanisms involved in maintaining LTP and homeostatic plasticity. We discuss how these phenomena could relate to processes that might underpin the loss of synaptic potentiation over time, and how they might contribute to the forgetting of short-term and long-term memories. We propose that homeostatic downscaling mediates the loss of E-LTP, and that metaplastic parameters determine the decay rate of L-LTP, while both processes require the activity-dependent removal of postsynaptic GluA2-containing AMPA receptors.
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Affiliation(s)
- Oliver Hardt
- Centre for Cognitive and Neural Systems, University of Edinburgh, , Edinburgh, UK
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425
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Fonseca R. Asymmetrical synaptic cooperation between cortical and thalamic inputs to the amygdale. Neuropsychopharmacology 2013; 38:2675-87. [PMID: 23884343 PMCID: PMC3828539 DOI: 10.1038/npp.2013.178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 07/14/2013] [Accepted: 07/17/2013] [Indexed: 02/06/2023]
Abstract
Fear conditioning, a form of associative learning is thought to involve the induction of an associative long-term potentiation of cortical and thalamic inputs to the lateral amygdala. Here, we show that stimulation of the thalamic input can reinforce a transient form of plasticity (E-LTP) induced by weak stimulation of the cortical inputs. This synaptic cooperation occurs within a time window of 30 min, suggesting that synaptic integration at amygdala synapses can occur within large time windows. Interestingly, we found that synaptic cooperation is not symmetrical. Reinforcement of a thalamic E-LTP by subsequent cortical stimulation is only observed within a shorter time window. We found that activation of endocannabinoid CB1 receptors is involved in the time restriction of thalamic and cortical synaptic cooperation in an activity-dependent manner. Our results support the hypothesis that synaptic cooperation can underlie associative learning and that synaptic tagging and capture is a general mechanism in synaptic plasticity.
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Affiliation(s)
- Rosalina Fonseca
- Champalimaud Neuroscience Program at Gulbenkian Institute of Science, Oeiras, Portugal,Cellular and Systems Neuroscience, Gulbenkian Institute of Science, Rua da Quinta Grande, 6, Oeiras 2850 Portugal, Tel: +351 214 404 664, Fax: +351 214 407 970, E-mail:
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426
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Moskal JR, Burch R, Burgdorf JS, Kroes RA, Stanton PK, Disterhoft JF, Leander JD. GLYX-13, an NMDA receptor glycine site functional partial agonist enhances cognition and produces antidepressant effects without the psychotomimetic side effects of NMDA receptor antagonists. Expert Opin Investig Drugs 2013; 23:243-54. [PMID: 24251380 DOI: 10.1517/13543784.2014.852536] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The N-methyl-d-aspartate receptor-ionophore complex plays a key role in learning and memory and has efficacy in animals and humans with affective disorders. GLYX-13 is an N-methyl-d-aspartate receptor (NMDAR) glycine-site functional partial agonist and cognitive enhancer that also shows rapid antidepressant activity without psychotomimetic side effects. AREAS COVERED The authors review the mechanism of action of GLYX-13 that was investigated in preclinical studies and evaluated in clinical studies. Specifically, the authors review its pharmacology, pharmacokinetics, and drug safety that were demonstrated in clinical studies. EXPERT OPINION NMDAR full antagonists can produce rapid antidepressant effects in treatment-resistant subjects; however, they are often accompanied by psychotomimetic effects that make chronic use outside of a clinical trial inpatient setting problematic. GLYX-13 appears to exert its antidepressant effects in the frontal cortex via NMDAR-triggered synaptic plasticity. Understanding the mechanistic underpinning of GLYX-13's antidepressant action should provide both novel insights into the role of the glutamatergic system in depression and identify new targets for therapeutic development.
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Affiliation(s)
- Joseph R Moskal
- Northwestern University, McCormick School of Engineering and Applied Science, Falk Center for Molecular Therapeutics, Department of Biomedical Engineering , 1801 Maple Avenue, Suite 4300, Evanston IL 60201 , USA
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427
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Blackwell KT, Jedrzejewska-Szmek J. Molecular mechanisms underlying neuronal synaptic plasticity: systems biology meets computational neuroscience in the wilds of synaptic plasticity. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2013; 5:717-31. [PMID: 24019266 PMCID: PMC3947422 DOI: 10.1002/wsbm.1240] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 12/29/2022]
Abstract
Interactions among signaling pathways that are activated by transmembrane receptors produce complex networks and emergent dynamical behaviors that are implicated in synaptic plasticity. Temporal dynamics and spatial aspects are critical determinants of cell responses such as synaptic plasticity, although the mapping between spatiotemporal activity pattern and direction of synaptic plasticity is not completely understood. Computational modeling of neuronal signaling pathways has significantly contributed to understanding signaling pathways underlying synaptic plasticity. Spatial models of signaling pathways in hippocampal neurons have revealed mechanisms underlying the spatial distribution of extracellular signal-related kinase (ERK) activation in hippocampal neurons. Other spatial models have demonstrated that the major role of anchoring proteins in striatal and hippocampal synaptic plasticity is to place molecules near their activators. Simulations of yet other models have revealed that the spatial distribution of synaptic plasticity may differ for potentiation versus depression. In general, the most significant advances have been made by interactive modeling and experiments; thus, an interdisciplinary approach should be applied to investigate critical issues in neuronal signaling pathways. These issues include identifying which transmembrane receptors are key for activating ERK in neurons, and the crucial targets of kinases that produce long-lasting synaptic plasticity. Although the number of computer programs for computationally efficient simulation of large reaction-diffusion networks is increasing, parameter estimation and sensitivity analysis in these spatial models remain more difficult than in single compartment models. Advances in live cell imaging coupled with further software development will continue to accelerate the development of spatial models of synaptic plasticity.
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Affiliation(s)
- KT Blackwell
- Molecular Neuroscience Department, The Krasnow Institute for Advanced Studies George Mason University, Fairfax, VA 22030-444, USA
| | - J Jedrzejewska-Szmek
- Molecular Neuroscience Department, The Krasnow Institute for Advanced Studies George Mason University, Fairfax, VA 22030-444, USA
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428
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de Berker AO, Bikson M, Bestmann S. Predicting the behavioral impact of transcranial direct current stimulation: issues and limitations. Front Hum Neurosci 2013; 7:613. [PMID: 24109445 PMCID: PMC3790257 DOI: 10.3389/fnhum.2013.00613] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/12/2013] [Indexed: 11/13/2022] Open
Abstract
The transcranial application of weak currents to the human brain has enjoyed a decade of widespread use, providing a simple and powerful tool for non-invasively altering human brain function. However, our understanding of current delivery and its impact upon neural circuitry leaves much to be desired. We argue that the credibility of conclusions drawn with transcranial direct current stimulation (tDCS) is contingent upon realistic explanations of how tDCS works, and that our present understanding of tDCS limits the technique's use to localize function in the human brain. We outline two central issues where progress is required: the localization of currents, and predicting their functional consequence. We encourage experimenters to eschew simplistic explanations of mechanisms of transcranial current stimulation. We suggest the use of individualized current modeling, together with computational neurostimulation to inform mechanistic frameworks in which to interpret the physiological impact of tDCS. We hope that through mechanistically richer descriptions of current flow and action, insight into the biological processes by which transcranial currents influence behavior can be gained, leading to more effective stimulation protocols and empowering conclusions drawn with tDCS.
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Affiliation(s)
- Archy O de Berker
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London London, UK
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429
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The role of γ-secretase in hippocampal synaptic transmission and activity-dependent synaptic plasticity. Neurosci Lett 2013; 554:16-21. [DOI: 10.1016/j.neulet.2013.08.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/08/2013] [Accepted: 08/27/2013] [Indexed: 11/23/2022]
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430
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Kelley P, Whatson T. Making long-term memories in minutes: a spaced learning pattern from memory research in education. Front Hum Neurosci 2013; 7:589. [PMID: 24093012 PMCID: PMC3782739 DOI: 10.3389/fnhum.2013.00589] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 09/01/2013] [Indexed: 12/23/2022] Open
Abstract
Memory systems select from environmental stimuli those to encode permanently. Repeated stimuli separated by timed spaces without stimuli can initiate Long-Term Potentiation (LTP) and long-term memory (LTM) encoding. These processes occur in time scales of minutes, and have been demonstrated in many species. This study reports on using a specific timed pattern of three repeated stimuli separated by 10 min spaces drawn from both behavioral and laboratory studies of LTP and LTM encoding. A technique was developed based on this pattern to test whether encoding complex information into LTM in students was possible using the pattern within a very short time scale. In an educational context, stimuli were periods of highly compressed instruction, and spaces were created through 10 min distractor activities. Spaced Learning in this form was used as the only means of instruction for a national curriculum Biology course, and led to very rapid LTM encoding as measured by the high-stakes test for the course. Remarkably, learning at a greatly increased speed and in a pattern that included deliberate distraction produced significantly higher scores than random answers (p < 0.00001) and scores were not significantly different for experimental groups (one hour spaced learning) and control groups (four months teaching). Thus learning per hour of instruction, as measured by the test, was significantly higher for the spaced learning groups (p < 0.00001). In a third condition, spaced learning was used to replace the end of course review for one of two examinations. Results showed significantly higher outcomes for the course using spaced learning (p < 0.0005). The implications of these findings and further areas for research are briefly considered.
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Affiliation(s)
- Paul Kelley
- Science + Technology in LearningWhitley Bay, UK
| | - Terry Whatson
- Life, Health and Chemical Sciences, The Open UniversityMilton Keynes, UK
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431
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Frankland PW, Köhler S, Josselyn SA. Hippocampal neurogenesis and forgetting. Trends Neurosci 2013; 36:497-503. [DOI: 10.1016/j.tins.2013.05.002] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/06/2013] [Accepted: 05/09/2013] [Indexed: 10/26/2022]
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432
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Abstract
Although memory can be hazy at times, it is often assumed that memories of violent or otherwise stressful events are so well encoded that they are effectively indelible and that confidently retrieved memories are almost certainly accurate. However, findings from basic psychological research and neuroscience studies indicate that memory is a reconstructive process that is susceptible to distortion. In the courtroom, even minor memory distortions can have severe consequences that are partly driven by common misunderstandings about memory--for example, that memory is more veridical than it may actually be.
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Affiliation(s)
- Joyce W Lacy
- Department of Psychology Azusa Pacific University Azusa, CA 91702
| | - Craig E L Stark
- Center for the Neurobiology of Learning and Memory and Department of Neurobiology and Behavior University of California, Irvine Irvine, CA 92697-3800
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433
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Yamaguchi M, Manabe H, Murata K, Mori K. Reorganization of neuronal circuits of the central olfactory system during postprandial sleep. Front Neural Circuits 2013; 7:132. [PMID: 23966911 PMCID: PMC3743305 DOI: 10.3389/fncir.2013.00132] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 07/26/2013] [Indexed: 11/30/2022] Open
Abstract
Plastic changes in neuronal circuits often occur in association with specific behavioral states. In this review, we focus on an emerging view that neuronal circuits in the olfactory system are reorganized along the wake-sleep cycle. Olfaction is crucial to sustaining the animals' life, and odor-guided behaviors have to be newly acquired or updated to successfully cope with a changing odor world. It is therefore likely that neuronal circuits in the olfactory system are highly plastic and undergo repeated reorganization in daily life. A remarkably plastic feature of the olfactory system is that newly generated neurons are continually integrated into neuronal circuits of the olfactory bulb (OB) throughout life. New neurons in the OB undergo an extensive selection process, during which many are eliminated by apoptosis for the fine tuning of neuronal circuits. The life and death decision of new neurons occurs extensively during a short time window of sleep after food consumption (postprandial sleep), a typical daily olfactory behavior. We review recent studies that explain how olfactory information is transferred between the OB and the olfactory cortex (OC) along the course of the wake-sleep cycle. Olfactory sensory input is effectively transferred from the OB to the OC during waking, while synchronized top-down inputs from the OC to the OB are promoted during the slow-wave sleep. We discuss possible neuronal circuit mechanisms for the selection of new neurons in the OB, which involves the encoding of olfactory sensory inputs and memory trace formation during waking and internally generated activities in the OC and OB during subsequent sleep. The plastic changes in the OB and OC are well coordinated along the course of olfactory behavior during wakefulness and postbehavioral rest and sleep. We therefore propose that the olfactory system provides an excellent model in which to understand behavioral state-dependent plastic mechanisms of the neuronal circuits in the brain.
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Affiliation(s)
- Masahiro Yamaguchi
- Department of Physiology, Graduate School of Medicine, The University of Tokyo Tokyo, Japan ; Japan Science and Technology Agency, CREST Tokyo, Japan
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434
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"Master" neurons induced by operant conditioning in rat motor cortex during a brain-machine interface task. J Neurosci 2013; 33:8308-20. [PMID: 23658171 DOI: 10.1523/jneurosci.2744-12.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Operant control of a prosthesis by neuronal cortical activity is one of the successful strategies for implementing brain-machine interfaces (BMI), by which the subject learns to exert a volitional control of goal-directed movements. However, it remains unknown if the induced brain circuit reorganization affects preferentially the conditioned neurons whose activity controlled the BMI actuator during training. Here, multiple extracellular single-units were recorded simultaneously in the motor cortex of head-fixed behaving rats. The firing rate of a single neuron was used to control the position of a one-dimensional actuator. Each time the firing rate crossed a predefined threshold, a water bottle moved toward the rat, until the cumulative displacement of the bottle allowed the animal to drink. After a learning period, most (88%) conditioned neurons raised their activity during the trials, such that the time to reward decreased across sessions: the conditioned neuron fired strongly, reliably and swiftly after trial onset, although no explicit instruction in the learning rule imposed a fast neuronal response. Moreover, the conditioned neuron fired significantly earlier and more strongly than nonconditioned neighboring neurons. During the first training sessions, an increase in firing rate variability was seen only for the highly conditionable neurons. This variability then decreased while the conditioning effect increased. These findings suggest that modifications during training target preferentially the neuron chosen to control the BMI, which acts then as a "master" neuron, leading in time the reconfiguration of activity in the local cortical network.
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435
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Morris GP, Clark IA, Zinn R, Vissel B. Microglia: a new frontier for synaptic plasticity, learning and memory, and neurodegenerative disease research. Neurobiol Learn Mem 2013; 105:40-53. [PMID: 23850597 DOI: 10.1016/j.nlm.2013.07.002] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 07/03/2013] [Indexed: 12/25/2022]
Abstract
We focus on emerging roles for microglia in synaptic plasticity, cognition and disease. We outline evidence that ramified microglia, traditionally thought to be functionally "resting" (i.e. quiescent) in the normal brain, in fact are highly dynamic and plastic. Ramified microglia continually and rapidly extend processes, contact synapses in an activity and experience dependent manner, and play a functionally dynamic role in synaptic plasticity, possibly through release of cytokines and growth factors. Ramified microglial also contribute to structural plasticity through the elimination of synapses via phagocytic mechanisms, which is necessary for normal cognition. Microglia have numerous mechanisms to monitor neuronal activity and numerous mechanisms also exist to prevent them transitioning to an activated state, which involves retraction of their surveying processes. Based on the evidence, we suggest that maintaining the ramified state of microglia is essential for normal synaptic and structural plasticity that supports cognition. Further, we propose that change of their ramified morphology and function, as occurs in inflammation associated with numerous neurological disorders such as Alzheimer's and Parkinson's disease, disrupts their intricate and essential synaptic functions. In turn altered microglia function could cause synaptic dysfunction and excess synapse loss early in disease, initiating a range of pathologies that follow. We conclude that the future of learning and memory research depends on an understanding of the role of non-neuronal cells and that this should include using sophisticated molecular, cellular, physiological and behavioural approaches combined with imaging to causally link the role of microglia to brain function and disease including Alzheimer's and Parkinson's disease and other neuropsychiatric disorders.
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Affiliation(s)
- Gary P Morris
- Neurodegenerative Disorders, Garvan Institute of Medical Research, Neuroscience Department, Sydney, Australia; Faculty of Medicine, University of New South Wales, Sydney, Australia.
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436
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Cassini LF, Sierra RO, Haubrich J, Crestani AP, Santana F, de Oliveira Alvares L, Quillfeldt JA. Memory reconsolidation allows the consolidation of a concomitant weak learning through a synaptic tagging and capture mechanism. Hippocampus 2013; 23:931-41. [PMID: 23733489 DOI: 10.1002/hipo.22149] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 05/20/2013] [Accepted: 05/20/2013] [Indexed: 12/21/2022]
Abstract
Motivated by the synaptic tagging and capture (STC) hypothesis, it was recently shown that a weak learning, only able to produce short-term memory (STM), can succeed in establishing long-term memory (LTM) with a concomitant, stronger experience. This is consistent with the capture, by the first-tagged event, of the so-called plasticity-related proteins (PRPs) provided by the second one. Here, we describe how a concomitant session of reactivation/reconsolidation of a stronger, contextual fear conditioning (CFC) memory, allowed LTM to result from a weak spatial object recognition (wSOR) training. Consistent with an STC process, the effect was observed only during a critical time window and was dependent on the CFC reconsolidation-related protein synthesis. Retrieval by itself (without reconsolidation) did not have the same promoting effect. We also found that the inactivation of the NMDA receptor by AP5 prevented wSOR training to receive this support of CFC reconsolidation (supposedly through the production of PRPs), which may be the equivalent of blocking the setting of a learning tag in the dorsal CA1 region for that task. Furthermore, either a Water Maze reconsolidation, or a CFC extinction session, allowed the formation of wSOR-LTM. These results suggest for the first time that a reconsolidation session can promote the consolidation of a concomitant weak learning through a probable STC mechanism. These findings allow new insights concerning the influence of reconsolidation in the acquisition of memories of otherwise unrelated events during daily life situations.
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Affiliation(s)
- Lindsey F Cassini
- Psychobiology and Neurocomputation Laboratory, Biophysics Department, Institute of Biosciences, 91.501-970; Graduate Program in Neuroscience, Institute of Health Sciences, 90.046-900, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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437
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Ballarini F, Martínez MC, Díaz Perez M, Moncada D, Viola H. Memory in Elementary School Children Is Improved by an Unrelated Novel Experience. PLoS One 2013; 8:e66875. [PMID: 23840541 PMCID: PMC3686730 DOI: 10.1371/journal.pone.0066875] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 05/10/2013] [Indexed: 01/15/2023] Open
Abstract
Education is the most traditional means with formative effect on the human mind, learning and memory being its fundamental support. For this reason, it is essential to find different strategies to improve the studentś performance. Based on previous work, we hypothesized that a novel experience could exert an enhancing effect on learning and memory within the school environment. Here we show that novel experience improved the memory of literary or graphical activities when it is close to these learning sessions. We found memory improvements in groups of students who had experienced a novel science lesson 1 hour before or after the reading of a story, but not when these events were 4 hours apart. Such promoting effect on long-term memory (LTM) was also reproduced with another type of novelty (a music lesson) and also after another type of learning task (a visual memory). Interestingly, when the lesson was familiar, it failed to enhance the memory of the other task. Our results show that educationally relevant novel events experienced during normal school hours can improve LTM for tasks/activities learned during regular school lessons. This effect is restricted to a critical time window around learning and is particularly dependent on the novel nature of the associated experience. These findings provide a tool that could be easily transferred to the classroom by the incorporation of educationally novel events in the school schedule as an extrinsic adjuvant of other information acquired some time before or after it. This approach could be a helpful tool for the consolidation of certain types of topics that generally demand a great effort from the children.
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Affiliation(s)
- Fabricio Ballarini
- Instituto de Biología Celular y Neurociencias Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Cecilia Martínez
- Instituto de Biología Celular y Neurociencias Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Magdalena Díaz Perez
- Instituto de Biología Celular y Neurociencias Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Diego Moncada
- Instituto de Biología Celular y Neurociencias Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Haydée Viola
- Instituto de Biología Celular y Neurociencias Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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438
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McReynolds JR, McIntyre CK. Emotional modulation of the synapse. Rev Neurosci 2013; 23:449-61. [PMID: 23096101 DOI: 10.1515/revneuro-2012-0047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 07/05/2012] [Indexed: 11/15/2022]
Abstract
Acute stress and emotional arousal can enhance the consolidation of long-term memories in a manner that is dependent on β -adrenoceptor activation in the basolateral complex of the amygdala (BLA). The BLA interacts with multiple memory systems in the brain to modulate a variety of classes of memory. However, the synaptic mechanisms of this interaction remain unresolved. This review describes the evidence of modulation of memory and synaptic plasticity produced by emotional arousal,stress hormones, and pharmacological or electrophysiological stimulation of the amygdala. The amygdala modulation of local translation and/or degradation of the synaptic plasticity-related proteins, activity-regulated cytoskeletal-associated protein and calcium/calmodulin dependent protein kinase II α , is offered as a potential mechanism for the rapid memory consolidation that is associated with emotionally arousing events. This model shares features with synaptic tagging and the emotional tagging hypotheses.
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Affiliation(s)
- Jayme R McReynolds
- Department of Behavioral and BrainSciences, The University of Texas at Dallas, Richardson, TX 75080, USA
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439
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Pre- and postsynaptic twists in BDNF secretion and action in synaptic plasticity. Neuropharmacology 2013; 76 Pt C:610-27. [PMID: 23791959 DOI: 10.1016/j.neuropharm.2013.05.043] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/12/2013] [Accepted: 05/14/2013] [Indexed: 12/30/2022]
Abstract
Overwhelming evidence collected since the early 1990's strongly supports the notion that BDNF is among the key regulators of synaptic plasticity in many areas of the mammalian central nervous system. Still, due to the extremely low expression levels of endogenous BDNF in most brain areas, surprisingly little data i) pinpointing pre- and postsynaptic release sites, ii) unraveling the time course of release, and iii) elucidating the physiological levels of synaptic activity driving this secretion are available. Likewise, our knowledge regarding pre- and postsynaptic effects of endogenous BDNF at the single cell level in mediating long-term potentiation still is sparse. Thus, our review will discuss the data currently available regarding synaptic BDNF secretion in response to physiologically relevant levels of activity, and will discuss how endogenously secreted BDNF affects synaptic plasticity, giving a special focus on spike timing-dependent types of LTP and on mossy fiber LTP. We will attempt to open up perspectives how the remaining challenging questions regarding synaptic BDNF release and action might be addressed by future experiments. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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440
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Bock J, Poeggel G, Gruss M, Wingenfeld K, Braun K. Infant Cognitive Training Preshapes Learning-Relevant Prefrontal Circuits for Adult Learning: Learning-Induced Tagging of Dendritic Spines. Cereb Cortex 2013; 24:2920-30. [DOI: 10.1093/cercor/bht148] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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441
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Abstract
In isolated hippocampal slices, decaying long-term potentiation (LTP) can be stabilized, and converted to late-LTP lasting many hours, by prior or subsequent strong high-frequency tetanization of an independent input to a common population of neurons—a phenomenon known as ‘synaptic tagging and capture’. Here we show that the same phenomenon occurs in the intact rat. Late-LTP can be induced in CA1 during the inhibition of protein synthesis if an independent input is strongly tetanized beforehand. Conversely, declining early-LTP induced by weak tetanization can be converted into lasting late-LTP by subsequent strong tetanization of a separate input. These findings indicate that synaptic tagging and capture is not limited to in vitro preparations; the past and future activity of neurons plays a critical role in determining the persistence of synaptic changes in the living animal, thus providing a bridge between cellular studies of protein-synthesis-dependent synaptic potentiation and behavioural studies of memory persistence.
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442
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Matched pre- and post-synaptic changes underlie synaptic plasticity over long time scales. J Neurosci 2013; 33:6257-66. [PMID: 23575825 DOI: 10.1523/jneurosci.3740-12.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Modifications of synaptic efficacies are considered essential for learning and memory. However, it is not known how the underlying functional components of synaptic transmission change over long time scales. To address this question, we studied cortical synapses from young Wistar rats before and after 12 h intervals of spontaneous or glutamate-induced spiking activity. We found that, under these conditions, synaptic efficacies can increase or decrease by up to 10-fold. Statistical analyses reveal that these changes reflect modifications in the number of presynaptic release sites, together with postsynaptic changes that maintain the quantal size per release site. The quantitative relation between the presynaptic and postsynaptic transmission components was not affected when synaptic plasticity was enhanced or reduced using a broad range of pharmacological agents. These findings suggest that ongoing synaptic plasticity results in matched presynaptic and postsynaptic modifications, in which elementary modules that span the synaptic cleft are added or removed as a function of experience.
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443
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Papoutsi A, Kastellakis G, Psarrou M, Anastasakis S, Poirazi P. Coding and decoding with dendrites. ACTA ACUST UNITED AC 2013; 108:18-27. [PMID: 23727338 DOI: 10.1016/j.jphysparis.2013.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 03/26/2013] [Accepted: 05/21/2013] [Indexed: 01/19/2023]
Abstract
Since the discovery of complex, voltage dependent mechanisms in the dendrites of multiple neuron types, great effort has been devoted in search of a direct link between dendritic properties and specific neuronal functions. Over the last few years, new experimental techniques have allowed the visualization and probing of dendritic anatomy, plasticity and integrative schemes with unprecedented detail. This vast amount of information has caused a paradigm shift in the study of memory, one of the most important pursuits in Neuroscience, and calls for the development of novel theories and models that will unify the available data according to some basic principles. Traditional models of memory considered neural cells as the fundamental processing units in the brain. Recent studies however are proposing new theories in which memory is not only formed by modifying the synaptic connections between neurons, but also by modifications of intrinsic and anatomical dendritic properties as well as fine tuning of the wiring diagram. In this review paper we present previous studies along with recent findings from our group that support a key role of dendrites in information processing, including the encoding and decoding of new memories, both at the single cell and the network level.
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Affiliation(s)
- Athanasia Papoutsi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece; Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - George Kastellakis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece; Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Maria Psarrou
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece
| | - Stelios Anastasakis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece.
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444
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Maney DL. The incentive salience of courtship vocalizations: hormone-mediated 'wanting' in the auditory system. Hear Res 2013; 305:19-30. [PMID: 23665125 DOI: 10.1016/j.heares.2013.04.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 04/12/2013] [Accepted: 04/19/2013] [Indexed: 12/27/2022]
Abstract
Conspecific vocalizations differ from many other sounds in that they have natural incentive salience. Our thinking about auditory responses to vocalizations may therefore benefit from models originally developed to understand reward. According to those models, the brain attributes incentive salience to rewarding stimuli via the activity of monoaminergic neuromodulators. These neuromodulators, in turn, mediate the effects of experience and internal state. Songbirds lend themselves well to this discussion because the natural incentive salience of song is clearly modulated by both factors. Their auditory responses have been well-studied, particularly the song-induced expression of plasticity-associated genes such as ZENK. Here I review evidence that ZENK responses to song are regulated by monoamine neuromodulators, and I interpret this evidence in the context of incentive salience. First, hearing conspecific song engages monoaminergic activity in the auditory system and elsewhere. Second, in females this activity may be regulated by the same hormones that regulate behavioral preferences for song. Finally, much of the evidence thought to implicate neuromodulators in song discrimination and memory suggests that they may affect incentive salience. Expanding the study of incentive salience beyond the mesolimbic reward system may reveal some new ways of thinking about its underlying neural basis. This article is part of a Special Issue entitled "Communication Sounds and the Brain: New Directions and Perspectives".
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Affiliation(s)
- Donna L Maney
- Department of Psychology, 36 Eagle Row, Emory University, Atlanta, GA 30322, USA.
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445
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Hulme SR, Jones OD, Abraham WC. Emerging roles of metaplasticity in behaviour and disease. Trends Neurosci 2013; 36:353-62. [PMID: 23602195 DOI: 10.1016/j.tins.2013.03.007] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/19/2013] [Accepted: 03/19/2013] [Indexed: 12/01/2022]
Abstract
Since its initial conceptualisation, metaplasticity has come to encompass a wide variety of phenomena and mechanisms, creating the important challenge of understanding how they contribute to network function and behaviour. Here, we present a framework for considering potential roles of metaplasticity across three domains of function. First, metaplasticity appears ideally placed to prepare for subsequent learning by either enhancing learning ability generally or by preparing neuronal networks to encode specific content. Second, metaplasticity can homeostatically regulate synaptic plasticity, and this likely has important behavioural consequences by stabilising synaptic weights while ensuring the ongoing availability of synaptic plasticity. Finally, we discuss emerging evidence that metaplasticity mechanisms may play a role in disease causally and may serve as a potential therapeutic target.
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Affiliation(s)
- Sarah R Hulme
- Department of Psychology and Brain Health Research Centre, Box 56, University of Otago, Dunedin, 9054, New Zealand
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446
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Leal G, Comprido D, Duarte CB. BDNF-induced local protein synthesis and synaptic plasticity. Neuropharmacology 2013; 76 Pt C:639-56. [PMID: 23602987 DOI: 10.1016/j.neuropharm.2013.04.005] [Citation(s) in RCA: 442] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 03/25/2013] [Accepted: 04/03/2013] [Indexed: 12/16/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is an important regulator of synaptic transmission and long-term potentiation (LTP) in the hippocampus and in other brain regions, playing a role in the formation of certain forms of memory. The effects of BDNF in LTP are mediated by TrkB (tropomyosin-related kinase B) receptors, which are known to be coupled to the activation of the Ras/ERK, phosphatidylinositol 3-kinase/Akt and phospholipase C-γ (PLC-γ) pathways. The role of BDNF in LTP is best studied in the hippocampus, where the neurotrophin acts at pre- and post-synaptic levels. Recent studies have shown that BDNF regulates the transport of mRNAs along dendrites and their translation at the synapse, by modulating the initiation and elongation phases of protein synthesis, and by acting on specific miRNAs. Furthermore, the effect of BDNF on transcription regulation may further contribute to long-term changes in the synaptic proteome. In this review we discuss the recent progress in understanding the mechanisms contributing to the short- and long-term regulation of the synaptic proteome by BDNF, and the role in synaptic plasticity, which is likely to influence learning and memory formation. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Graciano Leal
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
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447
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Soltoggio A, Lemme A, Reinhart F, Steil JJ. Rare neural correlations implement robotic conditioning with delayed rewards and disturbances. Front Neurorobot 2013; 7:6. [PMID: 23565092 PMCID: PMC3613617 DOI: 10.3389/fnbot.2013.00006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 03/06/2013] [Indexed: 11/13/2022] Open
Abstract
Neural conditioning associates cues and actions with following rewards. The environments in which robots operate, however, are pervaded by a variety of disturbing stimuli and uncertain timing. In particular, variable reward delays make it difficult to reconstruct which previous actions are responsible for following rewards. Such an uncertainty is handled by biological neural networks, but represents a challenge for computational models, suggesting the lack of a satisfactory theory for robotic neural conditioning. The present study demonstrates the use of rare neural correlations in making correct associations between rewards and previous cues or actions. Rare correlations are functional in selecting sparse synapses to be eligible for later weight updates if a reward occurs. The repetition of this process singles out the associating and reward-triggering pathways, and thereby copes with distal rewards. The neural network displays macro-level classical and operant conditioning, which is demonstrated in an interactive real-life human-robot interaction. The proposed mechanism models realistic conditioning in humans and animals and implements similar behaviors in neuro-robotic platforms.
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Affiliation(s)
- Andrea Soltoggio
- Faculty of Technology, Research Institute for Cognition and Robotics (CoR-Lab), Bielefeld University Bielefeld, Germany
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448
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Abstract
In the course of trial-and-error learning, the results of actions, manifested as rewards or punishments, occur often seconds after the actions that caused them. How can a reward be associated with an earlier action when the neural activity that caused that action is no longer present in the network? This problem is referred to as the distal reward problem. A recent computational study proposes a solution using modulated plasticity with spiking neurons and argues that precise firing patterns in the millisecond range are essential for such a solution. In contrast, the study reported in this letter shows that it is the rarity of correlating neural activity, and not the spike timing, that allows the network to solve the distal reward problem. In this study, rare correlations are detected in a standard rate-based computational model by means of a threshold-augmented Hebbian rule. The novel modulated plasticity rule allows a randomly connected network to learn in classical and instrumental conditioning scenarios with delayed rewards. The rarity of correlations is shown to be a pivotal factor in the learning and in handling various delays of the reward. This study additionally suggests the hypothesis that short-term synaptic plasticity may implement eligibility traces and thereby serve as a selection mechanism in promoting candidate synapses for long-term storage.
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Affiliation(s)
- Andrea Soltoggio
- Research Institute for Cognition and Robotics and Faculty of Technology, Bielefeld University, Bielefeld 33615, Germany
| | - Jochen J. Steil
- Research Institute for Cognition and Robotics and Faculty of Technology, Bielefeld University, Bielefeld 33615, Germany
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449
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Abstract
Over more than a century of research has established the fact that sleep benefits the retention of memory. In this review we aim to comprehensively cover the field of "sleep and memory" research by providing a historical perspective on concepts and a discussion of more recent key findings. Whereas initial theories posed a passive role for sleep enhancing memories by protecting them from interfering stimuli, current theories highlight an active role for sleep in which memories undergo a process of system consolidation during sleep. Whereas older research concentrated on the role of rapid-eye-movement (REM) sleep, recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation and also enlightened some of the underlying electrophysiological, neurochemical, and genetic mechanisms, as well as developmental aspects in these processes. Specifically, newer findings characterize sleep as a brain state optimizing memory consolidation, in opposition to the waking brain being optimized for encoding of memories. Consolidation originates from reactivation of recently encoded neuronal memory representations, which occur during SWS and transform respective representations for integration into long-term memory. Ensuing REM sleep may stabilize transformed memories. While elaborated with respect to hippocampus-dependent memories, the concept of an active redistribution of memory representations from networks serving as temporary store into long-term stores might hold also for non-hippocampus-dependent memory, and even for nonneuronal, i.e., immunological memories, giving rise to the idea that the offline consolidation of memory during sleep represents a principle of long-term memory formation established in quite different physiological systems.
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Affiliation(s)
- Björn Rasch
- Division of Biopsychology, Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland.
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450
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Consolidation differentially modulates schema effects on memory for items and associations. PLoS One 2013; 8:e56155. [PMID: 23409144 PMCID: PMC3567062 DOI: 10.1371/journal.pone.0056155] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 01/07/2013] [Indexed: 12/22/2022] Open
Abstract
Newly learned information that is congruent with a preexisting schema is often better remembered than information that is incongruent. This schema effect on memory has previously been associated to more efficient encoding and consolidation mechanisms. However, this effect is not always consistently supported in the literature, with differential schema effects reported for different types of memory, different retrieval cues, and the possibility of time-dependent effects related to consolidation processes. To examine these effects more directly, we tested participants on two different types of memory (item recognition and associative memory) for newly encoded visuo-tactile associations at different study-test intervals, thus probing memory retrieval accuracy for schema-congruent and schema-incongruent items and associations at different time points (t = 0, t = 20, and t = 48 hours) after encoding. Results show that the schema effect on visual item recognition only arises after consolidation, while the schema effect on associative memory is already apparent immediately after encoding, persisting, but getting smaller over time. These findings give further insight into different factors influencing the schema effect on memory, and can inform future schema experiments by illustrating the value of considering effects of memory type and consolidation on schema-modulated retrieval.
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