Search results for "plasticity"

Distribution of PSA-NCAM expression in the amygdala of the adult rat.

2002

Synaptic plasticity in the amygdala appears to be necessary for the generation of emotional memories. However, the molecular bases of this plasticity are not fully understood. Because the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) has been implicated in memory consolidation in the hippocampus and temporal cortex, we have studied in detail the expression of this molecule in the adult rat amygdala with an antibody against PSA-NCAM. Our results demonstrate for the first time the presence of PSA-NCAM in the adult rat amygdala. Immunoreactive somata and processes are abundant in the amygdalo-hippocampal transition area, central nucleus, intra-amygdaloid bed nucleus of th…

Nonlinear finite element analysis of no-tension masonry structures

1995

A numerical approach for structural analysis of masonry walls in plane stress conditions is presented. The assumption of a perfectly no-tension material (NTM) constitutive model, whose relevant equations are in the form of classical rate-independent associated flow laws of elastoplastic material, allows one to adopt numerical procedures commonly used in computational plasticity. An accuracy analysis on the integration algorithm employed in the solution of constitutive relations has been carried out. The results obtained for some relevant case-studies and their comparison with data, available in the literature show the effectiveness of the proposed method.

Nonstationary flow surface theory for modeling the viscoplastic behaviors of soils

2016

Abstract This paper presents a three-dimensional elastic viscoplastic model that can describe the time-dependent behaviors of soft clays. The constitutive model is formulated based on the nonstationary flow surface theory and incorporates new developments, including (i) an improved definition of the nonstationary flow surface that is capable of capturing the stress–strain behaviors under different loading paths, (ii) a unique stress–strain—viscoplastic-strain-rate equation that is able to explicitly describe the nonstationary flow surface, and (iii) a final stable state concept that identifies the final equilibrium state at the end of creep and stress relaxation, which is also used to simpl…

Differential vesicular targeting and time course of synaptic secretion of the mammalian neurotrophins.

2005

Neurotrophins are a family of secreted neuronal survival and plasticity factors comprising NGF, BDNF, neurotrophin-3 (NT-3), and NT-4. Whereas synaptic secretion of BDNF has been described, the routes of intracellular targeting and secretion of NGF, NT-3, and NT-4 in neurons are poorly understood.To allow for a direct comparison of intracellular targeting and release properties, all four mammalian neurotrophins were expressed as green fluorescent protein fusion proteins in cultured rat hippocampal neurons. We show that BDNF and NT-3 are targeted more efficiently to dendritic secretory granules of the regulated pathway of secretion (BDNF, in 98% of cells; NT-3, 85%) than NGF (46%) and NT-4 (…

Spatial learning and expression patterns of PP1 mRNA in mouse hippocampus.

2009

<i>Background:</i> Synaptic plasticity is believed to be the major cellular basis for learning and memory. Protein phosphorylation is a key process involved in changes in the efficacy of neurotransmission. In long-term changes synaptic plasticity is followed by structural plasticity and protein de novo synthesis. Such mechanisms are believed to build the basis of hippocampal learning and memory investigated in the Morris water maze (MWM) task. To examine the role of dephosphorylation during that model for spatial learning, we analyzed protein phosphatase 1 (PP1) expression in the hippocampus of mice at various stages of the task and in two groups with different learning abilitie…

Non associative damage interface model for mixed mode delamination and frictional contact

2019

Abstract The present paper proposes a new interface constitutive model based on the non-associative damage mechanics and frictional plasticity. The model is developed in a thermodynamically consistent framework, with three independent damage variables. The non associative flow rules drive the concurrent evolution of the three damage variables. The interface model provides two independent values for the mode I fracture energy and the mode II fracture energy and it is able to accurately reproduce arbitrary mixed mode fracture conditions. The model can also take into account the presence of frictional effects both at the fully debonded zones and at the partially debonded ones. The experimental…

Brain stimulation in migraine

2013

Migraine is a very prevalent disease with great individual disability and socioeconomic burden. Despite intensive research effort in recent years, the etiopathogenesis of the disease remains to be elucidated. Recently, much importance has been given to mechanisms underlying the cortical excitability that has been suggested to be dysfunctional in migraine. In recent years, noninvasive brain stimulation techniques based on magnetic fields (transcranial magnetic stimulation, TMS) and on direct electrical currents (transcranial direct current stimulation, tDCS) have been shown to be safe and effective tools to explore the issue of cortical excitability, activation, and plasticity in migraine. M…

2019

Today, several pharmaceutic and non-pharmaceutic approaches exist to treat psychiatric and neurological diseases. Because of the lack of treatment procedures that are medication free and without severe side effects, transcranial direct current stimulation (tDCS) and aerobic exercise (AE) have been tested to explore the potential for initiating and modulating neuroplasticity in the human brain. Both tDCS and AE could support cognition and behavior in the clinical and non-clinical context to improve the recovery process within neurological or psychiatric conditions or to increase performance. As these techniques still lack meaningful effects, although they provide multiple beneficial opportun…

Interactions between cholinergic and fibroblast growth factor receptors in brain trophism and plasticity

2014

Acetylcholine, acting on both nicotinic receptors (nAChRs) and muscarinic receptors (mAChRs), plays a role in the regulation of synaptic plasticity, being involved in the regulation of cellular processes and cognitive functions, such as learning, memory and attention. Recently, G protein coupled receptors (GPCRs), including mAChRs, have been reported to transactivate tyrosine-kinase receptors (RTK), such as epidermal growth factor receptor (EGFR), and initiate their intracellular signaling. In this minireview we have first analysed the RTK transactivation mechanisms, involving cholinergic receptors, and thereafter the interplay between AChR and neurotrophic factor systems built up by FGF2 a…

Modeling of neuron-astrocyte interaction : application to signal and image processing

2022

The introduction of the tripartite synapse and the discovery of calcium wave propagation motivated our research to explore the potential of astrocytes as active components in brain circuits. For decades, astrocytes have been considered passive cells whose primary function is metabolic and structural support to neurons; however, recent physiological measurements suggest that astrocytes modulate neural communication, strengthen synaptic efficacy, enhance synchronization, and promote homeostasis. Inspired by these biological functions, this research aimed to implement astrocytes in artificial spiking networks for deep learning applications. First, we modeled the biological interaction between …