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Efeito do treinamento fisico em judocas e corredores fundistas de alto nivel na plasticidade neural; Effects of physical practice in professional judo players and long distance runners on neural plasticity

Wantuir Francisco Siqueira Jacini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/02/2007 Português
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Estudos experimentais têm sugerido que a prática de exercícios físicos associados a treinamento, planejamento e execução de movimentos complexos causam alterações estruturais no sistema nervoso. Essas podem refletir modificações benéficas à plasticidade cerebral, em resposta ao aumento da atividade imposta pela aprendizagem motora e exercícios físicos. Todavia, efeitos estruturais, com potencial implicação para o auxílio em reabilitação de problemas neurológicos, não são bem entendidos. A prática de judô demanda planejamento de atividades motoras complexas e exercícios físicos. A prática de corrida de fundo demanda pouca aprendizagem motora e contém exercícios físicos. Nosso objetivo foi Investigar variações no volume de substância cinzenta estimulada pela prática de judô e corrida de fundo através de morfometria baseada em voxels (VBM) em imagens de ressonância magnética (RM). Imagens de RM foram feitas em atletas de judô, de corrida de fundo e não atletas em um scanner de 2T (Elscint Prestige, Haifa, Israel). VBM foi feita usando os programas de analise matemática estatística de imagem (Statistical Parametric Mapping, SPM 2 e Matlab 7.0), utilizando imagens em T1 e voxels isotrópicos de 1mm. Os mapas probabilísticos com a substância cinzenta foram comparados voxel a voxel usando teste t-student para determinar diferenças significativas na CSC entre os grupos. Os resultados finais foram corrigidos por um algoritmo de correção para achados falso-positivos (False Discovery Rate - FDR) que minimiza o efeito das múltiplas comparações e eleva a sensibilidade do resultado final. Foram encontrados aumentos significativos no volume de substância cinzenta...

Phenotypic plasticity of Myzus persicae (Hemíptera: Aphididae) raised on Brassica oleracea L. var. acephala (kale) and Raphanus sativus L. (radish)

Peppe,Fernanda Borja; Lomônaco,Cecília
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 Português
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The study of variability generated by phenotypic plasticity is crucial for predicting evolutionary patterns in insect-plant systems. Given sufficient variation for plasticity, host race formation can be favored and maintained, even simpatrically. The plasticity of size and performance (assessed by the lifetime fitness index r m) of six clones of Myzus persicae was tested, with replicates allowed to develop on two hosts, kale (Brassica oleracea var. acephala) and radish (Raphanus sativus). The clones showed significant variability in their plasticity. Reaction norms varied through generations and negative genetic correlation, although not significant, tend to increase with the duration of host use. The lack of plasticity in lifetime fitness among generalist clones occurred as an after-effect of the highly plastic determinants. Significant morphological plasticity in host used was observed, but no variation in the plastic responses (GxE interaction) was detected. Strong selection for a larger size occurred among individuals reared on radish, the most unfavorable host. Morphological plasticity in general body size (in a multivariate sense) was not linear related to fitness plasticity. These observations suggest that a high potential for the evolution of host divergence favors host race formation.

Relaxed Genetic Constraint is Ancestral to the Evolution of Phenotypic Plasticity

Leichty, Aaron R.; Pfennig, David W.; Jones, Corbin D.; Pfennig, Karin S.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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Phenotypic plasticity––the capacity of a single genotype to produce different phenotypes in response to varying environmental conditions––is widespread. Yet, whether, and how, plasticity impacts evolutionary diversification is unclear. According to a widely discussed hypothesis, plasticity promotes rapid evolution because genes expressed differentially across different environments (i.e., genes with “biased” expression) experience relaxed genetic constraint and thereby accumulate variation faster than do genes with unbiased expression. Indeed, empirical studies confirm that biased genes evolve faster than unbiased genes in the same genome. An alternative hypothesis holds, however, that the relaxed constraint and faster evolutionary rates of biased genes may be a precondition for, rather than a consequence of, plasticity’s evolution. Here, we evaluated these alternative hypotheses by characterizing evolutionary rates of biased and unbiased genes in two species of frogs that exhibit a striking form of phenotypic plasticity. We also characterized orthologs of these genes in four species of frogs that had diverged from the two plastic species before the plasticity evolved. We found that the faster evolutionary rates of biased genes predated the evolution of the plasticity. Furthermore...

Experience-dependent expression of NPAS4 regulates plasticity in adult visual cortex

Maya-Vetencourt, José Fernando; Tiraboschi, Ettore; Greco, Dario; Restani, Laura; Cerri, Chiara; Auvinen, Petri; Maffei, Lamberto; Castrén, Eero
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Português
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There is evidence that developmental-like plasticity can be reactivated in the adult visual cortex. Although activity-dependent transcription factors underlying the process of plasticity reactivation are currently unknown, recent studies point towards NPAS4 as a candidate gene for the occurrence of plasticity in the adult visual system. Here, we addressed whether NPAS4 is involved in the reinstatement of plasticity by using the monocular deprivation protocol and long-term fluoxetine treatment as a pharmacological strategy that restores plasticity in adulthood. A combination of molecular assays for gene expression and epigenetic analysis, gene delivery by lentiviral infection, shRNA interference and electrophysiology as a functional read-out, revealed a previously unknown role for the transcription factor NPAS4 in the regulation of adult visual cortical plasticity. We found that NPAS4 overexpression restores ocular dominance plasticity in adult naïve animals whereas NPAS4 down-regulation prevents the plastic outcome caused by fluoxetine in adulthood. Our findings lead the way to the identification of novel therapeutic targets for pathological conditions where reorganization of neuronal networks would be beneficial in adult life.

Generalizing (J_2) Flow Theory: Fundamental Issues in Strain Gradient Plasticity

Hutchinson, John W.
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
Português
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It has not been a simple matter to obtain a sound extension of the classical (J_2) flow theory of plasticity that incorporates a dependence on plastic strain gradients and that is capable of capturing size-dependent behaviour of metals at the micron scale. Two classes of basic extensions of classical (J_2) theory have been proposed: one with increments in higher order stresses related to increments of strain gradients and the other characterized by the higher order stresses themselves expressed in terms of increments of strain gradients. The theories proposed by Muhlhaus and Aifantis in 1991 and Fleck and Hutchinson in 2001 are in the first class, and, as formulated, these do not always satisfy thermodynamic requirements on plastic dissipation. On the other hand, theories of the second class proposed by Gudmundson in 2004 and Gurtin and Anand in 2009 have the physical deficiency that the higher order stress quantities can change discontinuously for bodies subject to arbitrarily small load changes. The present paper lays out this background to the quest for a sound phenomenological extension of the rateindependent (J_2) flow theory of plasticity to include a dependence on gradients of plastic strain. A modification of the Fleck-Hutchinson formulation that ensures its thermodynamic integrity is presented and contrasted with a comparable formulation of the second class where in the higher order stresses are expressed in terms of the plastic strain rate. Both versions are constructed to reduce to the classical (J_2) flow theory of plasticity when the gradients can be neglected and to coincide with the simpler and more readily formulated (J_2) deformation theory of gradient plasticity for deformation histories characterized by proportional straining.; Engineering and Applied Sciences

Functional Development and Plasticity of Parvalbumin Cells in Visual Cortex: Role of Thalamocortical Input

Quast, Kathleen Beth
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
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Unlike principal excitatory neurons, cortical interneurons comprise a diverse group of distinct subtypes. They can be classified by their morphology, molecular content, developmental origins, electrophysiological properties and specific connectivity patterns. The parvalbumin-positive ((PV^+)), large basket interneuron has been implicated in two cortical functions: 1) the control and shaping of the excitatory response, and 2) the initiation of critical periods for plasticity. Disruptions in both phenomena have been implicated in the etiology of cognitive developmental disorders. Careful characterization of (PV^+) cell function and plasticity in response to their primary afferent, the thalamocortical synapse, is needed to directly relate their vital contribution at a synapse-specific or network level to whole animal behavior. Here, I used electrophysiological, anatomical and molecular genetic techniques in a novel slice preparation to elucidate (PV^+) circuit development and plasticity in mouse visual cortex. I found that GFP-positive (PV^+) cells in layer 4 undergo a rapid maturation after eye opening just prior to onset of the critical period. This development occurs across a number of intrinsic physiological properties that shape their precise...

Sex differences in brain plasticity: a new hypothesis for sex ratio bias in autism

Mottron, Laurent; Duret, Pauline; Mueller, Sophia; Moore, Robert D; Forgeot d’Arc, Baudouin; Jacquemont, Sebastien; Xiong, Lan
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
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Several observations support the hypothesis that differences in synaptic and regional cerebral plasticity between the sexes account for the high ratio of males to females in autism. First, males are more susceptible than females to perturbations in genes involved in synaptic plasticity. Second, sex-related differences in non-autistic brain structure and function are observed in highly variable regions, namely, the heteromodal associative cortices, and overlap with structural particularities and enhanced activity of perceptual associative regions in autistic individuals. Finally, functional cortical reallocations following brain lesions in non-autistic adults (for example, traumatic brain injury, multiple sclerosis) are sex-dependent. Interactions between genetic sex and hormones may therefore result in higher synaptic and consecutively regional plasticity in perceptual brain areas in males than in females. The onset of autism may largely involve mutations altering synaptic plasticity that create a plastic reaction affecting the most variable and sexually dimorphic brain regions. The sex ratio bias in autism may arise because males have a lower threshold than females for the development of this plastic reaction following a genetic or environmental event.

CORTICAL PLASTICITY INVESTIGATED WITH TRANSCRANIAL MAGNETIC STIMULATION TECHNIQUES IN PATIENTS WITH MOVEMENT DISORDERS”

KHANDKER PARVEZ, AHMAD
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
Português
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This thesis have been designed, performed or completed during the period between 2010 to 2013 in the Department of Neurology and Psychiatry, Sapienza University of Rome, Italy, (supervised by Prof. Alfredo Berardelli). The main focus of this thesis is the investigation of mechanisms of Long-Term potentiation and Long-Term depression (LTP)/(LTD)-like plasticity in primary motor cortex (M1) with repetitive transcranial magnetic stimulation (rTMS) techniques such as Theta Bursts Stimulation (TBS) in patients with different types of movement disorders including Focal Hand Dystonia (FHD) and Multiple System Atrophy (MSA). Section 1 will introduce the general knowledge and biophysical principles of Transcranial Magnetic Stimulation (TMS). Section 2 will report two studies investigating abnormalities of LTP/LTD-like plasticity in M1 in patients with FHD and MSA. The first study (Suppa A, Marsili L, Di Stasio F, Latorre A, Parvez AK, Colosimo C, Berardelli A.) is mainly focused on cortical plasticity and motor learning in patients with FHD. This study showed that patients with FHD are characterized by altered cortical plasticity in M1. In addition, in FHD patients, motor execution of simple finger movements is abnormal and characterized by reducing movement speed and altered early motor learning. The second study (Belvisi D...

A neuromorphic VLSI design for spike timing and rate based synaptic plasticity

Rahimiazghadi, S.; Al-Sarawi, S.; Abbott, D.; Iannella, N.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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Triplet-based Spike Timing Dependent Plasticity (TSTDP) is a powerful synaptic plasticity rule that acts beyond conventional pair-based STDP (PSTDP). Here, the TSTDP is capable of reproducing the outcomes from a variety of biological experiments, while the PSTDP rule fails to reproduce them. Additionally, it has been shown that the behaviour inherent to the spike rate-based Bienenstock-Cooper-Munro (BCM) synaptic plasticity rule can also emerge from the TSTDP rule. This paper proposes an analogue implementation of the TSTDP rule. The proposed VLSI circuit has been designed using the AMS 0.35 μm CMOS process and has been simulated using design kits for Synopsys and Cadence tools. Simulation results demonstrate how well the proposed circuit can alter synaptic weights according to the timing difference amongst a set of different patterns of spikes. Furthermore, the circuit is shown to give rise to a BCM-like learning rule, which is a rate-based rule. To mimic an implementation environment, a 1000 run Monte Carlo (MC) analysis was conducted on the proposed circuit. The presented MC simulation analysis and the simulation result from fine-tuned circuits show that it is possible to mitigate the effect of process variations in the proof of concept circuit; however...

An update on brain plasticity for physical therapists

Schabrun, S.; Ridding, M.; Chipchase, L.
Fonte: I O S Press Publicador: I O S Press
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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The understanding that the human brain is capable of structural and functional change throughout life has significant implications for the future of physical therapy. Cortical plasticity impacts on many areas of physical therapy including clinical practice, research and education. Although the principles of plasticity underpin developments in neurological physical therapy, relevance to musculoskeletal physical therapy is still emerging. How will key areas of musculoskeletal physical therapy change as our understanding of plasticity advances? If cortical plasticity can be harnessed, new plasticity-based therapies, that enhance performance in healthy individuals and improve pain and function in patient populations, have the potential to become the cornerstone of musculoskeletal physical therapy. In addition, common physical therapy techniques, such as electrical stimulation, require reconsideration of their clinical efficacy and application in light of new discoveries in neuroscience. The aim of this appraisal is to provide an update on brain plasticity for physical therapists in relation to clinical practice, research and education.; Siobhan M. Schabruna, Michael C. Ridding and Lucinda S. Chipchase

Neuromorphic VLSI designs for spike timing and rate-based synaptic plasticity with application in pattern classification.

Rahimi Azghadi, Seyed Mostafa
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2014 Português
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This thesis presents a versatile study on the design and Very Large Scale Integration(VLSI) implementation of various synaptic plasticity rules ranging from phenomenological rules, to biophysically realistic ones. In particular, the thesis aims at developing novel spike timing-based learning circuits that advance the current neuromorphic systems, in terms of power consumption, compactness and synaptic modification (learning) abilities. Furthermore, the thesis investigates the usefulness of the developed designs and algorithms in specific engineering tasks such as pattern classification. To follow the mentioned goals, this thesis makes several original contributions to the field of neuromorphic engineering, which are briefed in the following. First, a programmable multi-neuron neuromorphic chip is utilised to implement a number of desired rate- and timing-based synaptic plasticity rules. Specific software programs are developed to set up and program the neuromorphic chip, in a way to show the required neuronal behaviour for implementing various synaptic plasticity rules. The classical version of Spike Timing Dependent Plasticity (STDP), as well as the triplet-based STDP and the rate-based Bienenstock-Cooper-Munro (BCM) rules are implemented and successfully tested on this neuromorphic device. In addition...

Spike-based synaptic plasticity in silicon: design, implementation, application, and challenges

Rahimiazghadi, S.; Iannella, N.; Al-Sarawi, S.; Indiveri, G.; Abbott, D.
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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The ability to carry out signal processing, classification, recognition, and computation in artificial spiking neural networks (SNNs) is mediated by their synapses. In particular, through activity-dependent alteration of their efficacies, synapses play a fundamental role in learning. The mathematical prescriptions under which synapses modify their weights are termed synaptic plasticity rules. These learning rules can be based on abstract computational neuroscience models or on detailed biophysical ones. As these rules are being proposed and developed by experimental and computational neuroscientists, engineers strive to design and implement them in silicon and en masse in order to employ them in complex real-world applications. In this paper, we describe analog very large-scale integration (VLSI) circuit implementations of multiple synaptic plasticity rules, ranging from phenomenological ones (e.g., based on spike timing, mean firing rates, or both) to biophysically realistic ones (e.g., calcium-dependent models). We discuss the application domains, weaknesses, and strengths of various representative approaches proposed in the literature, and provide insight into the challenges that engineers face when designing and implementing synaptic plasticity rules in VLSI technology for utilizing them in real-world applications.; Mostafa Rahimi Azghadi...

Human motor cortex plasticity induction is influenced by multiple factors.

Cirillo, John
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012 Português
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The primary motor cortex (M1) has the essential role of controlling voluntary movement, but is also a crucial site for learning new motor skills and recovery of motor function after injury. The development of non-invasive brain stimulation techniques, particularly transcranial magnetic stimulation, has significantly contributed to our understanding of human M1 and its ability to alter in structure and function (cortical plasticity). However, large within- and between-subject differences in the capacity for cortical plasticity exist in humans. This thesis examined factors capable of influencing human M1 plasticity and motor learning, focussing on the effects of exercise, ageing, hand preference and genetics. Study 1 examined whether regular exercise influenced plasticity in human M1. Individuals with increased physical activity levels had increased M1 excitability and enhanced neuroplasticity. This was the first study to demonstrate that participation in regular physical activity offers a generalised neuroplastic enhancement within M1. Therefore, these results suggest that participation in regular physical activity may offer global benefits to human M1 function. Study 2 addressed the influence of age (young and old adults) and hand preference (dominant and non-dominant) on human M1 plasticity and motor learning for a simple motor task. In contrast to previous studies...

Fast convergence of learning requires plasticity between inferior olive and deep cerebellar nuclei in a manipulation task: a closed-loop robotic simulation

Luque Sola, Niceto Rafael; Garrido Alc??zar, Jes??s; Carrillo S??nchez, Richard; D'Angelo, Egidio; Ros, Eduardo
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
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The cerebellum is known to play a critical role in learning relevant patterns of activity for adaptive motor control, but the underlying network mechanisms are only partly understood. The classical long-term synaptic plasticity between parallel fibers (PFs) and Purkinje cells (PCs), which is driven by the inferior olive (IO), can only account for limited aspects of learning. Recently, the role of additional forms of plasticity in the granular layer, molecular layer and deep cerebellar nuclei (DCN) has been considered. In particular, learning at DCN synapses allows for generalization, but convergence to a stable state requires hundreds of repetitions. In this paper we have explored the putative role of the IO-DCN connection by endowing it with adaptable weights and exploring its implications in a closed-loop robotic manipulation task. Our results show that IO-DCN plasticity accelerates convergence of learning by up to two orders of magnitude without conflicting with the generalization properties conferred by DCN plasticity. Thus, this model suggests that multiple distributed learning mechanisms provide a key for explaining the complex properties of procedural learning and open up new experimental questions for synaptic plasticity in the cerebellar network.

Modulation of short- and long-term plasticity in the rat auditory cortex

Rosen, Laura Gillian
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
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Plasticity of synapses is not static across the lifespan. As the brain matures and ages, the ability of neurons to undergo structural and functional change becomes more limited. Further, there are a number of modulatory factors that influence the expression of synaptic plasticity. Here, three approaches were taken to examine and manipulate plasticity in the auditory thalamocortical system of rats. Using an in vivo preparation, long-term potentiation (LTP) and paired pulse (PP) responses were used as measures of long- and short-term plasticity, respectively. First, the effect of intracortical zinc application in the primary auditory cortex (A1) on LTP was examined. Following theta burst stimulation (TBS) of the medial geniculate nucleus (MGN), juvenile and middle-age rats, but not young adults, showed greater levels of LTP with zinc application relative to age-matched control animals. Next, PP responses were examined between rats reared in unaltered acoustic conditions and those reared in continuous white noise (WN) from postnatal day (PD) 5 to PD 50-60 (i.e., subjected to patterned sound deprivation). Rats reared in WN demonstrated less PP depression relative to controls, indicating that WN rearing alters short-term thalamocortical synaptic responses. Furthermore...

Regulators of Sensory Cortical Plasticity by Neuromodulators and Sensory Experience

Kuo, Min-Ching
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
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Recent evidence indicates that the mature neocortex retains a higher degree of plasticity than traditionally assumed. Up- and down-regulation of synaptic strength, long-term potentiation (LTP) and long-term depression (LTD), is thought to be the primary mechanism mediating experience-dependent plasticity of cortical networks. The present thesis investigate factors that regulate adult cortical plasticity, focusing on the role of neuromodulators, recent sensory experience, and different anatomical divisions of the cortex in influencing synaptic strength. First, I investigated the role of the neuromodulator histamine in gating plasticity in the primary visual cortex (V1) of urethane anesthetized adult rats. Histamine applied locally in V1 produced an enhancement of LTP elicited by theta burst stimulation (TBS) of dorsal lateral geniculate nucleus (dLGN) and allowed a sub-threshold TBS to produce stable LTP. Second, the impact of visual deprivation on LTP in V1 was assessed. Animals that received 2 and 5 hr dark exposure showed greater potentiation of field potentials when stimulated though retinal light flashes or weak TBS of the dLGN, which failed to induce LTP in control animals kept in continuous light. Third, I performed a detailed characterization of LTP induced by different TBS protocols...

Plasticity of brain wave network interactions and evolution across physiologic states

Liu, Kang K. L.; Bartsch, Ronny P.; Lin, Aijing; Mantegna, Rosario N.; Ivanov, Plamen Ch.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Português
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Neural plasticity transcends a range of spatio-temporal scales and serves as the basis of various brain activities and physiologic functions. At the microscopic level, it enables the emergence of brain waves with complex temporal dynamics. At the macroscopic level, presence and dominance of specific brain waves is associated with important brain functions. The role of neural plasticity at different levels in generating distinct brain rhythms and how brain rhythms communicate with each other across brain areas to generate physiologic states and functions remains not understood. Here we perform an empirical exploration of neural plasticity at the level of brain wave network interactions representing dynamical communications within and between different brain areas in the frequency domain. We introduce the concept of time delay stability (TDS) to quantify coordinated bursts in the activity of brain waves, and we employ a system-wide Network Physiology integrative approach to probe the network of coordinated brain wave activations and its evolution across physiologic states. We find an association between network structure and physiologic states. We uncover a hierarchical reorganization in the brain wave networks in response to changes in physiologic state...

Spatiotemporal Dynamics of Calcium/calmodulin-dependent Kinase II in Single Dendritic Spines During Synaptic Plasticity

Lee, Seok-Jin
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011 Português
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Synaptic plasticity is the leading candidate for the cellular/molecular basis of learning and memory. One of the key molecules involved in synaptic plasticity is Calcium/calmodulin-dependent Kinase II (CaMKII). Synaptic plasticity can be expressed at a single dendritic spine independent of its neighboring dendritic spines. Here, we investigated how long the activity of CaMKII lasts during synaptic plasticity of single dendritic spines. We found that CaMKII activity lasted ~2 minutes during synaptic plasticity and was restricted to the dendritic spines undergoing synaptic plasticity while nearby dendritic spines did not show any change in the level of CaMKII activity. Our experimental data argue against the persistent activation of CaMKII in dendritic spines undergoing synaptic plasticity and suggest that the activity of CaMKII is a spine-specific biochemical signal necessary for synapse-specificity of synaptic plasticity. We provide a biophysical explanation of how spine-specific CaMKII activation can be achieved during synaptic plasticity. We also found that CaMKII is activated by highly localized calcium influx in the proximity of Voltage-dependent Calcium Channels (VDCCs) and a different set of VDCCs and their respective Ca2+ nanodomains are responsible for the differential activation of CaMKII between dendritic spines and dendritic shafts.

; Dissertation

Independent genetic control of maize (Zea mays L.) kernel weight determination and its phenotypic plasticity

Prado, S.A.; Sadras, V.O.; Borrás, L.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Maize kernel weight (KW) is associated with the duration of the grain-filling period (GFD) and the rate of kernel biomass accumulation (KGR). It is also related to the dynamics of water and hence is physiologically linked to the maximum kernel water content (MWC), kernel desiccation rate (KDR), and moisture concentration at physiological maturity (MCPM). This work proposed that principles of phenotypic plasticity can help to consolidated the understanding of the environmental modulation and genetic control of these traits. For that purpose, a maize population of 245 recombinant inbred lines (RILs) was grown under different environmental conditions. Trait plasticity was calculated as the ratio of the variance of each RIL to the overall phenotypic variance of the population of RILs. This work found a hierarchy of plasticities: KDR ≈ GFD > MCPM > KGR > KW > MWC. There was no phenotypic and genetic correlation between traits per se and trait plasticities. MWC, the trait with the lowest plasticity, was the exception because common quantitative trait loci were found for the trait and its plasticity. Independent genetic control of a trait per se and genetic control of its plasticity is a condition for the independent evolution of traits and their plasticities. This allows breeders potentially to select for high or low plasticity in combination with high or low values of economically relevant traits.; Santiago Alvarez Prado...

Geographic range size, seedling ecophysiology and phenotypic plasticity in Australian Acacia species

Pohlman, Catherine; Nicotra, Adrienne; Murray, Brad
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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Aim: The degree to which eco-physiological traits critical to seedling establishment are related to differences in geographic range size among species is not well understood. Here, we first tested the idea that seedling ecophysiological attributes associated with establishment differ between narrowly distributed and geographically widespread plant species. Secondly, we tested the notion that species occupying wide geographic ranges have greater phenotypic plasticity in response to the environment than contrasted species with more restricted distributions. Location: Eastern Australia. Methods: We compared five pairs of geographically restricted and widespread Acacia species grown under glasshouse conditions for differences in seedling relative growth rate and associated allocational, morphological and physiological traits. We then examined whether widespread species displayed greater phenotypic plasticity in these traits than narrowly distributed species in response to changes in soil water availability. Results: Neither relative growth rate nor any measure of biomass accumulation or allocation differed significantly between seedlings of narrowly distributed and widespread species. In addition, the plasticity of biomass allocation was not greater in widespread species. However...