scholarly journals Hebbian activity-dependent plasticity in white matter

2022 ◽  
Author(s):  
Alberto Lazari ◽  
Piergiorgio Salvan ◽  
Michiel Cottaar ◽  
Daniel Papp ◽  
Matthew FS Rushworth ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
White Matter ◽  
Associative Learning ◽  
Fiber Bundle ◽  
Cortical Excitability ◽  
Brain Plasticity ◽  
Cortical Areas ◽  
Hebbian Plasticity ◽  
Synaptic Changes ◽  
Activity Dependent

Synaptic plasticity is required for learning and follows Hebb's Rule, the computational principle underpinning associative learning. In recent years, a complementary type of brain plasticity has been identified in myelinated axons, which make up the majority of brain's white matter. Like synaptic plasticity, myelin plasticity is required for learning, but it is unclear whether it is Hebbian or whether it follows different rules. Here, we provide evidence that white matter plasticity operates following Hebb's Rule in humans. Across two experiments, we find that co-stimulating cortical areas to induce Hebbian plasticity leads to relative increases in cortical excitability and associated increases in a myelin marker within the stimulated fiber bundle. We conclude that Hebbian plasticity extends beyond synaptic changes, and can be observed in human white matter fibers.

scholarly journals Strong Aversive Conditioning Triggers a Long-Lasting Generalized Aversion

2022 ◽  
Author(s):  
Raul Ramos ◽  
Chi-Hong Wu ◽  
Gina G Turrigiano
Keyword(s):  
Synaptic Plasticity ◽  
Brain Slice ◽  
Aversive Conditioning ◽  
Future Scenarios ◽  
Important Goal ◽  
Neuronal Ensemble ◽  
Deep Layers ◽  
Synaptic Changes ◽  
Activity Dependent ◽  
Hallmark Feature

Generalization is an adaptive mnemonic process in which an animal can leverage past learning experiences to navigate future scenarios, but overgeneralization is a hallmark feature of anxiety disorders. Therefore, understanding the synaptic plasticity mechanisms that govern memory generalization and its persistence is an important goal. Here, we demonstrate that strong CTA conditioning results in a long-lasting generalized aversion that persists for at least two weeks. Using brain slice electrophysiology and activity-dependent labeling of the conditioning-active neuronal ensemble within the gustatory cortex, we find that strong CTA conditioning induces a long-lasting increase in synaptic strengths that occurs uniformly across superficial and deep layers of GC. Repeated exposure to salt, the generalized tastant, causes a rapid attenuation of the generalized aversion that correlates with a reversal of the CTA-induced increases in synaptic strength. Unlike the uniform strengthening that happens across layers, reversal of the generalized aversion results in a more pronounced depression of synaptic strengths in superficial layers. Finally, the generalized aversion and its reversal do not impact the acquisition and maintenance of the aversion to the conditioned tastant (saccharin). The strong correlation between the generalized aversion and synaptic strengthening, and the reversal of both in superficial layers by repeated salt exposure, strongly suggests that the synaptic changes in superficial layers contribute to the formation and reversal of the generalized aversion. In contrast, the persistence of synaptic strengthening in deep layers correlates with the persistence of CTA. Taken together, our data suggest that layer-specific synaptic plasticity mechanisms separately govern the persistence and generalization of CTA memory.

scholarly journals NMDA Receptor Subunits Change after Synaptic Plasticity Induction and Learning and Memory Acquisition

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
María Verónica Baez ◽  
Magalí Cecilia Cercato ◽  
Diana Alicia Jerusalinsky
Keyword(s):  
Synaptic Plasticity ◽  
Learning And Memory ◽  
De Novo ◽  
Physiological Profile ◽  
Regulatory Subunits ◽  
Neuronal Soma ◽  
Synaptic Changes ◽  
Memory Acquisition ◽  
Activity Dependent ◽  
Neuron Soma

NMDA ionotropic glutamate receptors (NMDARs) are crucial in activity-dependent synaptic changes and in learning and memory. NMDARs are composed of two GluN1 essential subunits and two regulatory subunits which define their pharmacological and physiological profile. In CNS structures involved in cognitive functions as the hippocampus and prefrontal cortex, GluN2A and GluN2B are major regulatory subunits; their expression is dynamic and tightly regulated, but little is known about specific changes after plasticity induction or memory acquisition. Data strongly suggest that following appropriate stimulation, there is a rapid increase in surface GluN2A-NMDAR at the postsynapses, attributed to lateral receptor mobilization from adjacent locations. Whenever synaptic plasticity is induced or memory is consolidated, more GluN2A-NMDARs are assembled likely using GluN2A from a local translation and GluN1 from local ER. Later on, NMDARs are mobilized from other pools, and there are de novo syntheses at the neuron soma. Changes in GluN1 or NMDAR levels induced by synaptic plasticity and by spatial memory formation seem to occur in different waves of NMDAR transport/expression/degradation, with a net increase at the postsynaptic side and a rise in expression at both the spine and neuronal soma. This review aims to put together that information and the proposed hypotheses.

Activity-dependent morphological synaptic plasticity in an adult neurosecretory system: magnocellular oxytocin neurons of the hypothalamus

2000 ◽  
Vol 78 (3) ◽  
pp. 317-327 ◽  
Author(s):  
Mohammed El Majdoubi ◽  
Dominique A Poulain ◽  
Dionysia T Theodosis
Keyword(s):  
Synaptic Plasticity ◽  
General Circulation ◽  
Neurosecretory System ◽  
Cellular Mechanisms ◽  
Paraventricular Nuclei ◽  
Quantitative Analyses ◽  
Synaptic Changes ◽  
Afferent Inputs ◽  
Vasopressin Neurons ◽  
Activity Dependent

Oxytocin and vasopressin neurons, located in the supraoptic and paraventricular nuclei of the hypothalamus, send their axons to the neurohypophysis where the neurohormones are released directly into the general circulation. Hormone release depends on the electrical activity of the neurons, which in turn is regulated by different afferent inputs. During conditions that enhance oxytocin secretion (parturition, lactation, and dehydration), these afferents undergo morphological remodelling which results in an increased number of synapses contacting oxytocin neurons. The synaptic changes are reversible with cessation of stimulation. Using quantitative analyses on immunolabelled preparations, we have established that this morphological synaptic plasticity affects both inhibitory and excitatory afferent inputs to oxytocin neurons. This review describes such synaptic modifications, their functional significance, and the cellular mechanisms that may be responsible.Key words: oxytocin, vasopressin, GABA, glutamate, noradrenaline, hypothalamo-neurohypophysial system, lactation.

scholarly journals Activity-dependent synaptic plasticity in the supraoptic nucleus of the rat hypothalamus

2006 ◽  
Vol 573 (3) ◽  
pp. 711-721 ◽  
Author(s):  
Aude Panatier ◽  
Stephen J. Gentles ◽  
Charles W. Bourque ◽  
Stéphane H. R. Oliet
Keyword(s):  
Synaptic Plasticity ◽  
Supraoptic Nucleus ◽  
Rat Hypothalamus ◽  
Activity Dependent

scholarly journals Dissociation between CA3-CA1 Synaptic Plasticity and Associative Learning in TgNTRK3 Transgenic Mice

2007 ◽  
Vol 27 (9) ◽  
pp. 2253-2260 ◽  
Author(s):  
I. Sahun ◽  
J. M. Delgado-Garcia ◽  
A. Amador-Arjona ◽  
A. Giralt ◽  
J. Alberch ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Transgenic Mice ◽  
Associative Learning

scholarly journals Coupling an aVLSI Neuromorphic Vision Chip to a Neurotrophic Model of Synaptic Plasticity: The Development of Topography

2002 ◽  
Vol 14 (10) ◽  
pp. 2353-2370 ◽  
Author(s):  
Terry Elliott ◽  
Jörg Kramer
Keyword(s):  
Synaptic Plasticity ◽  
Neuronal Development ◽  
Ganglion Cells ◽  
Activity Patterns ◽  
Retinal Ganglion ◽  
Biologically Inspired ◽  
Silicon Neurons ◽  
Retina Chip ◽  
Developing System ◽  
Activity Dependent

We couple a previously studied, biologically inspired neurotrophic model of activity-dependent competitive synaptic plasticity and neuronal development to a neuromorphic retina chip. Using this system, we examine the development and refinement of a topographic mapping between an array of afferent neurons (the retinal ganglion cells) and an array of target neurons. We find that the plasticity model can indeed drive topographic refinement in the presence of afferent activity patterns generated by a real-world device. We examine the resilience of the developing system to the presence of high levels of noise by adjusting the spontaneous firing rate of the silicon neurons.

Abstract TP96: Functional Recovery and White Matter Repair After Exosomes Administration in Different Experimental Animal Models of Stroke

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Laura Otero Ortega ◽  
María Gutiérrez Fernández ◽  
Berta Rodríguez Frutos ◽  
Jaime Ramos Cejudo ◽  
Irene Lorenzo Llorente ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
White Matter ◽  
Functional Recovery ◽  
Brain Plasticity ◽  
Trophic Factors ◽  
Lesion Volume ◽  
Axonal Sprouting ◽  
Control Groups ◽  
Myelin Formation ◽  
White Matter Repair

Introduction: Extracellular vesicles such as exosomes has opened a new field of research. Exosomes are able to transfer DNAs, mRNAs, microRNAs, non-coding RNAs, proteins, trophic factors and lipids associated with brain plasticity enhancement after stroke. Aim: To investigate white matter repair after exosomes administration in two experimental models of subcortical stroke: ischemic and hemorrhage. Material/Methods: Subcortical ischemic stroke was induced by Endothelin-1 and Collagenase IV was used to induce subcortical hemorrhagic stroke into striatum. Intravenous exosomes or saline only were administrated at 24h after cerebral infarct as treatment. Exosomes were isolated from culture of adipose mesenchymal stem cell and they were characterized by Nanoshight, Electronic microscope, Western blot and Immunofluorescence. Proteins contained into exosomes were analyzed by Orbitrab. We analyzed functional recovery by Rotarod, beam walking and Rogers tests. Lesion volume and tract connectivity were studied by magnetic resonance image. Anterograde and retrograde tracers were used to analyze axonal sprouting. Myelin formation was analyzed by cryomielin. Results: Proteomics analysis of exosomes identified more than 1400 proteins, many of them involved in intercellular communication. DiI labeled-Exosomes were detected in brain and peripheral organs (liver, lung and spleen). After 28 days, treated groups showed smaller functional deficit compared to control groups in both hemorrhagic and ischemic models. Moreover, treated group showed an increase in tract connectivity at 7 and 28 days compared to control groups. Also, animals which received exosomes showed an increase axonal sprouting and myelin formation at 28 days after stroke in both hemorrhagic and ischemic stroke. The treated groups also showed higher levels of white matter-associated markers in the injured area than the control groups. Conclusion: White matter integrity in different subcortical strokes is in part restored by exosomes treatment, probably mediated by repair molecular factors implicated in axonal sprouting, remyelination and oligodendrogenesis. These findings are associated with improved functional recovery in both kinds of strokes.

Sign in / Sign up

Export Citation Format

Share Document