scholarly journals Homeostatic Synaptic Scaling Establishes the Specificity of an Associative Memory

2020 ◽  
Author(s):  
Chi-Hong Wu ◽  
Raul Ramos ◽  
Donald B Katz ◽  
Gina G Turrigiano
Keyword(s):  
Associative Memory ◽  
Memory Formation ◽  
Homeostatic Plasticity ◽  
Synaptic Scaling ◽  
Memory Specificity ◽  
Hebbian Plasticity ◽  
Dependent Form ◽  
Subsequent Loss ◽  
Stable Memory

AbstractAccurate memory formation has been hypothesized to depend on both rapid Hebbian plasticity for initial encoding, and slower homeostatic mechanisms that prevent runaway excitation and subsequent loss of memory specificity. Here, we tested the role of synaptic scaling in shaping the specificity of conditioned taste aversion (CTA) memory, a Hebbian plasticity-dependent form of associative learning. We found that CTA memory initially generalized to non-conditioned tastants (generalized aversion), becoming specific to the conditioned tastant only over the course of many hours. Blocking synaptic scaling in the gustatory cortex (GC) prolonged the duration of the initial generalized aversion and enhanced the persistence of synaptic strength increases observed after CTA. Taken together, these findings demonstrate that synaptic scaling is important for sculpting the specificity of an associative memory and suggest that the relative strengths of Hebbian and homeostatic plasticity can modulate the balance between stable memory formation and generalization.

scholarly journals A metaplasticity view of the interaction between homeostatic and Hebbian plasticity

2017 ◽  
Vol 372 (1715) ◽  
pp. 20160155 ◽  
Author(s):  
Ada X. Yee ◽  
Yu-Tien Hsu ◽  
Lu Chen
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Associative Learning ◽  
Molecular Mechanisms ◽  
Potential Role ◽  
Homeostatic Plasticity ◽  
Network Activity ◽  
Mammalian Central Nervous System ◽  
Hebbian Plasticity

Hebbian and homeostatic plasticity are two major forms of plasticity in the nervous system: Hebbian plasticity provides a synaptic basis for associative learning, whereas homeostatic plasticity serves to stabilize network activity. While achieving seemingly very different goals, these two types of plasticity interact functionally through overlapping elements in their respective mechanisms. Here, we review studies conducted in the mammalian central nervous system, summarize known circuit and molecular mechanisms of homeostatic plasticity, and compare these mechanisms with those that mediate Hebbian plasticity. We end with a discussion of ‘local’ homeostatic plasticity and the potential role of local homeostatic plasticity as a form of metaplasticity that modulates a neuron's future capacity for Hebbian plasticity. This article is part of the themed issue ‘Integrating Hebbian and homeostatic plasticity’.

scholarly journals DNA methylation adjusts the specificity of memories depending on the learning context and promotes relearning

2016 ◽  
Author(s):  
Stephanie D Biergans ◽  
Charles Claudianos ◽  
Judith Reinhard ◽  
C Giovanni Galizia
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferases ◽  
Memory Formation ◽  
Long Term Memory ◽  
Learning Context ◽  
Memory Specificity ◽  
Learning Conditions ◽  
Reward Conditioning

AbstractThe activity of the epigenetic writers DNA methyltransferases (Dnmts) after olfactory reward conditioning is important for both stimulus-specific long-term memory (LTM) formation and extinction. It, however, remains unknown which components of memory formation Dnmts regulate (e.g. associative vs. non-associative) and in what context (e.g. varying training conditions). Here we address these aspects in order to clarify the role of Dnmt-mediated DNA methylation in memory formation. We used a pharmacological Dnmt inhibitor and classical appetitive conditioning in the honeybee Apis mellifera, a well characterized model for classical conditioning. We quantified the effect of DNA methylation on naïve odour and sugar responses, and on responses following olfactory reward conditioning. We show that (1) Dnmts do not influence naïve odour or sugar responses, (2) Dnmts do not affect the learning of new stimuli, but (3) Dnmts influence odour-coding, i.e. 'correct' (stimulus-specific) LTM formation. Particularly, Dnmts reduce memory specificity when experience is low (one-trial training), and increase memory specificity when experience is high (multiple-trial training), generating an ecologically more useful response to learning. (4) In reversal learning conditions, Dnmts are involved in regulating both excitatory (re-acquisition) and inhibitory (forgetting) processes.

scholarly journals Homeostatic structural plasticity leads to the formation of memory engrams through synaptic rewiring in recurrent networks

2020 ◽  
Author(s):  
Júlia V. Gallinaro ◽  
Nebojša Gašparović ◽  
Stefan Rotter
Keyword(s):  
Neural Networks ◽  
Synaptic Plasticity ◽  
Diffusion Process ◽  
Structural Plasticity ◽  
Memory Formation ◽  
Homeostatic Plasticity ◽  
Spiking Neural Networks ◽  
Recurrent Networks ◽  
Hebbian Plasticity ◽  
Stimulation Of

AbstractBrain networks store new memories using functional and structural synaptic plasticity. Memory formation is generally attributed to Hebbian plasticity, while homeostatic plasticity is thought to have an ancillary role in stabilizing network dynamics. Here we report that homeostatic plasticity alone can also lead to the formation of stable memories. We analyze this phenomenon using a new theory of network remodeling, combined with numerical simulations of recurrent spiking neural networks that exhibit structural plasticity based on firing rate homeostasis. These networks are able to store repeatedly presented patterns and recall them upon the presentation of incomplete cues. Storing is fast, governed by the homeostatic drift. In contrast, forgetting is slow, driven by a diffusion process. Joint stimulation of neurons induces the growth of associative connections between them, leading to the formation of memory engrams. In conclusion, homeostatic structural plasticity induces a specific type of “silent memories”, different from conventional attractor states.

scholarly journals A Bidirectional Switch in the Shank3 Phosphorylation State Biases Synapses toward Up or Down Scaling

2021 ◽  
Author(s):  
Gina G Turrigiano ◽  
Chi-Hong Wu ◽  
Vedakumar Tatavarty ◽  
Pierre M Jean-Beltran ◽  
Andrea Guerrero ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Scaling Up ◽  
Homeostatic Plasticity ◽  
Synaptic Scaling ◽  
Synaptic Localization ◽  
Neocortical Neurons ◽  
Associated Proteins ◽  
Scaling Down ◽  
Activity Dependent

Homeostatic synaptic plasticity requires widespread remodeling of synaptic signaling and scaffolding networks, but the role of posttranslational modifications in this process has not been systematically studied. Using deepscale, quantitative analysis of the phosphoproteome in mouse neocortical neurons, we found wide-spread and temporally complex changes during synaptic scaling up and down. We observed 424 bidirectionally modulated phosphosites that were strongly enriched for synapse-associated proteins, including S1539 in the ASD-associated synaptic scaffold protein Shank3. Using a parallel proteomic analysis performed on Shank3 isolated from rat neocortical neurons by immunoaffinity, we identified two sites that were hypo-phosphorylated during scaling up and hyper-phosphorylated during scaling down: one (rat S1615) that corresponded to S1539 in mouse, and a second highly conserved site, rat S1586. The phosphorylation status of these sites modified the synaptic localization of Shank3 during scaling protocols, and dephosphorylation of these sites via PP2A activity was essential for the maintenance of synaptic scaling up. Finally, phosphomimetic mutations at these sites prevented scaling up but not down, while phosphodeficient mutations prevented scaling down but not up. Thus, an activity-dependent switch between hypo- and hyperphosphorylation at S1586/ S1615 of Shank3 enables scaling up or down, respectively. Collectively our data show that activity-dependent phosphoproteome dynamics are important for the functional reconfiguration of synaptic scaffolds, and can bias synapses toward upward or downward homeostatic plasticity.

scholarly journals Percolation in networks with local homeostatic plasticity

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Giacomo Rapisardi ◽  
Ivan Kryven ◽  
Alex Arenas
Keyword(s):  
Biological Networks ◽  
Transportation Systems ◽  
Active Networks ◽  
Homeostatic Plasticity ◽  
Neural Cells ◽  
Epidemic Spreading ◽  
Synaptic Scaling ◽  
Critical Transitions ◽  
Network Connectedness

AbstractPercolation is a process that impairs network connectedness by deactivating links or nodes. This process features a phase transition that resembles paradigmatic critical transitions in epidemic spreading, biological networks, traffic and transportation systems. Some biological systems, such as networks of neural cells, actively respond to percolation-like damage, which enables these structures to maintain their function after degradation and aging. Here we study percolation in networks that actively respond to link damage by adopting a mechanism resembling synaptic scaling in neurons. We explain critical transitions in such active networks and show that these structures are more resilient to damage as they are able to maintain a stronger connectedness and ability to spread information. Moreover, we uncover the role of local rescaling strategies in biological networks and indicate a possibility of designing smart infrastructures with improved robustness to perturbations.

Role of MicroRNA Genes miR-1000 and miR-375 in Forming Olfactory Conditional Memory in Drosophila melanogaster

MicroRNA ◽  
2020 ◽  
Vol 09 ◽  
Author(s):  
Sadniman Rahman ◽  
Chaity Modak ◽  
Mousumi Akter ◽  
Mohammad Shamimul Alam
Keyword(s):  
Learning And Memory ◽  
Short Term Memory ◽  
Memory Loss ◽  
Memory Formation ◽  
Neural Integration ◽  
Significant Difference ◽  
Locomotion Speed ◽  
Microrna Genes ◽  
With Memory

Background: Learning and memory is basic aspects in neurogenetics as most of the neurological disorders start with dementia or memory loss. Several genes associated with memory formation have been discovered. MicroRNA genes miR-1000 and miR-375 were reported to be associated with neural integration and glucose homeostasis in some insects and vertebrates. However, neuronal function of these genes is yet to be established in D. melanogaster. Objective: Possible role of miR-1000 and miR-375 in learning and memory formation in this fly has been explored in the present study. Methods: Both appetitive and aversive olfactory conditional learning were tested in the miR-1000 and miR-375 knockout (KO) strains and compared with wild one. Five days old third instar larvae were trained by allowing them to be associated with an odor with reward (fructose) or punishment (salt). Then, the larvae were tested to calculate their preferences to the odor trained with. Learning index (LI) values and larval locomotion speed were calculated for all strains. Results: No significant difference was observed for larval locomotion speed in mutant strains. Knockout strain of miR-1000 showed significant deficiency in both appetitive and aversive memory formation whereas miR-375 KO strain showed a significantly lower response only in appetitive one. Conclusion: The results of the present study indicate important role played by these two genes in forming short-term memory in D. melanogaster.

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