Search results for "plasticity"
showing 10 items of 765 documents
Shakedown Analysis Within the Framework of Strain Gradient Plasticity
2015
A class of rate-independent material models is addressed within the framework of isotropic strain gradient plasticity. These models exhibit a size dependence through the strengthening effects (Hall–Petch effects), whereby the yield stress is related to the effective plastic strain by a suitable second-order partial differential equation with related boundary conditions. For a perfectly plastic material with strengthening effects, the classical concepts of plastic and shakedown limit analysis do hold, which lead to size dependent plastic and shakedown limit loads according to the dictum: smaller is stronger. In the perspective of a development of direct methods for applications to small-scal…
Synaptopodin regulates denervation-induced homeostatic synaptic plasticity
2013
Synaptopodin (SP) is a marker and essential component of the spine apparatus (SA), an enigmatic cellular organelle composed of stacked smooth endoplasmic reticulum that has been linked to synaptic plasticity. However, SP/SA-mediated synaptic plasticity remains incompletely understood. To study the role of SP/SA in homeostatic synaptic plasticity we here used denervation-induced synaptic scaling of mouse dentate granule cells as a model system. This form of plasticity is of considerable interest in the context of neurological diseases that are associated with the loss of neurons and subsequent denervation of connected brain regions. In entorhino-hippocampal slice cultures prepared from SP-de…
Prenatal Music Exposure Induces Long-Term Neural Effects
2013
We investigated the neural correlates induced by prenatal exposure to melodies using brains' event-related potentials (ERPs). During the last trimester of pregnancy, the mothers in the learning group played the ‘Twinkle twinkle little star’ -melody 5 times per week. After birth and again at the age of 4 months, we played the infants a modified melody in which some of the notes were changed while ERPs to unchanged and changed notes were recorded. The ERPs were also recorded from a control group, who received no prenatal stimulation. Both at birth and at the age of 4 months, infants in the learning group had stronger ERPs to the unchanged notes than the control group. Furthermore, the ERP amp…
Noninvasive monitoring of polymer curing reactions by dielectrometry
2011
A microwave sensor system for the noninvasive monitoring of the curing process of a thermoset material placed inside a metallic mold is described. The microwave sensor is designed as an open-ended coaxial resonator with a curved surface adapted to the mold inner shape. The analysis of the microwave resonator comprises a recently developed method for deembedding the effect of coupling network in overcoupled resonators, so the range of permitted measurements encompass both low and high dielectric losses of polymeric materials. Results show that noninvasive, continuous monitoring of the microwave dielectric properties of the thermoset material can be performed in real time, allowing one to che…
A common thread for pain and memory synapses? Brain-derived neurotrophic factor and trkB receptors.
2003
Recent evidence indicates that trophic factors can exert fast effects on neurones and so alter synaptic plasticity. Here, we focus on brain-derived neurotrophic factor (BDNF), which exerts a modulatory action at hippocampal synapses that are involved in learning and memory, and at the first pain synapse between primary sensory neurones and dorsal horn neurones. Hippocampal and sensory neurones share some properties for the release of endogenous BDNF. In the Schaffer collateral pathway of the hippocampus, binding of BDNF to high-affinity trkB receptors is essential for the induction of long-term potentiation, a specific type of synaptic plasticity. However, the consequences of BDNF binding t…
Endocannabinoid signals in the control of emotion.
2008
The appropriate control of emotional responses evoked by environmental stimuli is an important innate mechanism for ensuring quality of life and even for survival. Inappropriate responses and decreased abilities to adjust to changed environmental situations can lead to psychiatric disorders, such as posttraumatic stress disorders, phobia and depression. Endocannabinoid signalling has emerged as one of the regulatory systems of the brain supporting appropriate emotional responses. As various components of the endocannabinoid system have become therapeutic targets, understanding the endocannabinoids’ mechanism of action is an important research topic for a rationalized drug design and optimal…
DOES ENVIRONMENTAL ROBUSTNESS PLAY A ROLE IN FLUCTUATING ENVIRONMENTS?
2013
Fluctuating environments are expected to select for individuals that have highest geometric fitness over the experienced environments. This leads to the prediction that genetically determined environmental robustness in fitness, and average fitness across environments should be positively genetically correlated to fitness in fluctuating environments. Because quantitative genetic experiments resolving these predictions are missing, we used a full-sib, half-sib breeding design to estimate genetic variance for egg-to-adult viability in Drosophila melanogaster exposed to two constant or fluctuating temperatures that were above the species' optimum temperature, during development. Viability in t…
Bet-hedging in diapausing egg hatching of temporary rotifer populations - A review of models and new insights
2014
Habitat unpredictability is a local adaptation factor shaping life-history traits in rotifer populations. It may select for the evolution of bet-hedging through risk-spreading strategies in diapausing egg hatching. This means that a fraction of diapausing eggs in wild populations do not hatch even when the conditions are favorable for population growth. Thus, there is a remaining fraction of viable diapausing eggs standing in the sediments for longer periods. According to theory, it is expected that the incidence of bet-hedging strategies for diapausing egg hatching will be higher in more uncertain habitats. Here, we review the major predictions derived from theoretical models applied to th…
From foes to friends: Viral infections expand the limits of host phenotypic plasticity
2020
Phenotypic plasticity enables organisms to survive in the face of unpredictable environmental stress. Intimately related to the notion of phenotypic plasticity is the concept of the reaction norm that places phenotypic plasticity in the context of a genotype-specific response to environmental gradients. Whether reaction norms themselves evolve and which factors might affect their shape has been the object of intense debates among evolutionary biologists along the years. Since their discovery, viruses have been considered as pathogens. However, new viromic techniques and a shift in conceptual paradigms are showing that viruses are mostly non-pathogenic ubiquitous entities. Recent studies hav…
Profiling the diversity of innate lymphoid cells
2015
Genome-wide transcriptional profiling of tissue-resident innate lymphoid cells (ILCs) has provided important insight not only into their developmental relationships and phenotypic plasticity but also into previously unknown functions.