989 resultados para Haller, Johannes, 1523-1575.
Resumo:
Release of endogenous dynorphin opioids within the spinal cord after partial sciatic nerve ligation (pSNL) is known to contribute to the neuropathic pain processes. Using a phosphoselective antibody [kappa opioid receptor (KOR-P)] able to detect the serine 369 phosphorylated form of the KOR, we determined possible sites of dynorphin action within the spinal cord after pSNL. KOR-P immunoreactivity (IR) was markedly increased in the L4-L5 spinal dorsal horn of wild-type C57BL/6 mice (7-21 d) after lesion, but not in mice pretreated with the KOR antagonist nor-binaltorphimine (norBNI). In addition, knock-out mice lacking prodynorphin, KOR, or G-protein receptor kinase 3 (GRK3) did not show significant increases in KOR-P IR after pSNL. KOR-P IR was colocalized in both GABAergic neurons and GFAP-positive astrocytes in both ipsilateral and contralateral spinal dorsal horn. Consistent with sustained opioid release, KOR knock-out mice developed significantly increased tactile allodynia and thermal hyperalgesia in both the early (first week) and late (third week) interval after lesion. Similarly, mice pretreated with norBNI showed enhanced hyperalgesia and allodynia during the 3 weeks after pSNL. Because sustained activation of opioid receptors might induce tolerance, we measured the antinociceptive effect of the kappa agonist U50,488 using radiant heat applied to the ipsilateral hindpaw, and we found that agonist potency was significantly decreased 7 d after pSNL. In contrast, neither prodynorphin nor GRK3 knock-out mice showed U50,488 tolerance after pSNL. These findings suggest that pSNL induced a sustained release of endogenous prodynorphin-derived opioid peptides that activated an anti-nociceptive KOR system in mouse spinal cord. Thus, endogenous dynorphin had both pronociceptive and antinociceptive actions after nerve injury and induced GRK3-mediated opioid tolerance.
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Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (a traditional ecological effect), evolution and coevolution on ecosystem processes in Trinidadian streams. We manipulated the presence and population-of-origin of two common fish species, the guppy (Poecilia reticulata) and the killifish (Rivulus hartii). We measured epilithic algal biomass and accrual, aquatic invertebrate biomass, and detrital decomposition. Our results show that, for some ecosystem responses, the effects of evolution and coevolution were larger than the effects of species invasion. Guppy evolution in response to alternative predation regimes significantly influenced algal biomass and accrual rates. Guppies from a high-predation site caused an increase in algae relative to guppies from a low-predation site; algae effects were probably shaped by observed divergence in rates of nutrient excretion and algae consumption. Rivulus-guppy coevolution significantly influenced the biomass of aquatic invertebrates. Locally coevolved populations reduced invertebrate biomass relative to non-coevolved populations. These results challenge the general assumption that intraspecific diversity is a less critical determinant of ecosystem function than is interspecific diversity. Given existing evidence for contemporary evolution in these fish species, our findings suggest considerable potential for eco-evolutionary feedbacks to operate as populations adapt to natural or anthropogenic perturbations.
Resumo:
Interactions between natural selection and environmental change are well recognized and sit at the core of ecology and evolutionary biology. Reciprocal interactions between ecology and evolution, eco-evolutionary feedbacks, are less well studied, even though they may be critical for understanding the evolution of biological diversity, the structure of communities and the function of ecosystems. Eco-evolutionary feedbacks require that populations alter their environment (niche construction) and that those changes in the environment feed back to influence the subsequent evolution of the population. There is strong evidence that organisms influence their environment through predation, nutrient excretion and habitat modification, and that populations evolve in response to changes in their environment at time-scales congruent with ecological change (contemporary evolution). Here, we outline how the niche construction and contemporary evolution interact to alter the direction of evolution and the structure and function of communities and ecosystems. We then present five empirical systems that highlight important characteristics of eco-evolutionary feedbacks: rotifer-algae chemostats; alewife-zooplankton interactions in lakes; guppy life-history evolution and nutrient cycling in streams; avian seed predators and plants; and tree leaf chemistry and soil processes. The alewife-zooplankton system provides the most complete evidence for eco-evolutionary feedbacks, but other systems highlight the potential for eco-evolutionary feedbacks in a wide variety of natural systems.
Resumo:
Standing and walking generate information about friction underfoot. Five experiments examined whether walkers use such perceptual information for prospective control of locomotion. In particular, do walkers integrate information about friction underfoot with visual cues for sloping ground ahead to make adaptive locomotor decisions? Participants stood on low-, medium-, and high-friction surfaces on a flat platform and made perceptual judgments for possibilities for locomotion over upcoming slopes. Perceptual judgments did not match locomotor abilities: Participants tended to overestimate their abilities on low-friction slopes and underestimate on high-friction slopes (Experiments 1-4). Accuracy improved only for judgments made while participants were in direct contact with the slope (Experiment 5), highlighting the difficulty of incorporating information about friction underfoot into a plan for future actions.
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The dorsomedial prefrontal cortex (DMPFC) plays a central role in aspects of cognitive control and decision making. Here, we provide evidence for an anterior-to-posterior topography within the DMPFC using tasks that evoke three distinct forms of control demands--response, decision, and strategic--each of which could be mapped onto independent behavioral data. Specifically, we identify three spatially distinct regions within the DMPFC: a posterior region associated with control demands evoked by multiple incompatible responses, a middle region associated with control demands evoked by the relative desirability of decision options, and an anterior region that predicts control demands related to deviations from an individual's preferred decision-making strategy. These results provide new insight into the functional organization of DMPFC and suggest how recent controversies about its role in complex decision making and response mapping can be reconciled.
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We evaluated the intention, implementation, and impact of Costa Rica's program of payments for environmental services (PSA), which was established in the late 1990s. Payments are given to private landowners who own land in forest areas in recognition of the ecosystem services their land provides. To characterize the distribution of PSA in Costa Rica, we combined remote sensing with geographic information system databases and then used econometrics to explore the impacts of payments on deforestation. Payments were distributed broadly across ecological and socioeconomic gradients, but the 1997-2000 deforestation rate was not significantly lower in areas that received payments. Other successful Costa Rican conservation policies, including those prior to the PSA program, may explain the current reduction in deforestation rates. The PSA program is a major advance in the global institutionalization of ecosystem investments because few, if any, other countries have such a conservation history and because much can be learned from Costa Rica's experiences.
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The purpose of this study is to illustrate the development of piano variations as a genre during the Romantic era. In order to facilitate this examination of piano variations techniques, a brief look at the types of variation procedures used by composers of previous eras will assist in understanding developments that later occurred in the Romantic period. Throughout the Baroque era, composers preferred the fured-bass, fixed-melody, and harmonic forms of variation. The crowning achievement of Baroque keyboard music, Bach's Goldberg Variations (1725), contains examples of the "constantharmonic" method in its collection of 30 variations, each of which maintains both the bass and harmonic structure of the themes. While most composers of the classical period favored the "melodic-outline" form of variation, Haydn developed hybrid variation procedure that exhibits recurrence of material rather than repetition, alternating variation (ABABA), rondo variation (ABACA), and ternary variation (ABA). Haydn, Mozart and early Beethoven variations also exhibit simpler textures than do their Baroque predecessors. The nineteenth century produced numerous compositions that display variation techniques, some based on such older, classical models as melodic-outline variation and hybrid variation, others in the style of the character variation or fiee variation. At the beginning of the nineteenth century, Beethoven and Schubert used such classical variation techmques as melodic-outline variations and hybrid variations. Beethoven's late sonatas displayed such new means of expression as variation, fugue, and dramatic recitatives. The third movement of the Sonata in E major, Op. 109 (1820) has a theme and six variations of the melodic-outline type. Johannes Brahms was particularly fond of composing variations for piano. Among the best known examples of formal-outline variations are those found in the Variations and Fugue on a Theme of Handel, Op. 24 (1861). Character variations, in which styles are characterized by the retention and variability of particular elements, also flourished during the Romantic period. Cesar Franck's Variations Symphoniques (1885) are, perhaps, among the most important examples of free variations. This composition is a one-movement work consisting of three sections, Introduction, Variations, and Finale (all movements played "attaca"). This work combines two independent classical formal structures, the concerto and the variation.
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For my dissertation recital project, I traced the course of the violin-piano sonata in Austro- German in the 19th century, after Beethoven. My project presented works in three general categories. First, I presented works that are frequently-played standards of the violin sonata repertoire, works by Johannes Brahms, Franz Schubert, and Robert Schumann. The Second category is works by composers better known for their other compositions: Felix Mendelssohn and Richard Strauss. Finally, I choose the works seldom played these days, but worth of consideration, by Carl Maria von Weber and Max Reger. For my first recital, I performed Schubert's Violin Sonata, No. 1, Op. 137 in D major, Schumann's Violin Sonata, No. 1, Op. 105 in a minor, and Brahms' Violin Sonata, No.3, Op. 108 in d minor, with Naoko Takao as pianist. My second recital included works of Weber's Sonata, No. 1, Op. lob, in F major, Mendelssohn's Sonata, in F major (1838), and Schumann's Sonata, No.Z,Op.121 in d minor with Grace Cho. I concluded my final recital with the works of Reger's Violin Sonata, No. 1, Op. 1 in d minor and Strauss' Violin Sonata, Op. 18 in E flat major, Soo-Young Jung at the piano. All three programs are documented in a digital audio format available on compact disc, with accompanying programs also available in digital format.
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This study combines for the first time two major approaches to understanding the function and structure of neural circuits: large-scale multielectrode recordings, and confocal imaging of labeled neurons. To achieve this end, we develop a novel approach to the central problem of anatomically identifying recorded cells, based on the electrical image: the spatiotemporal pattern of voltage deflections induced by spikes on a large-scale, high-density multielectrode array. Recordings were performed from identified ganglion cell types in the macaque retina. Anatomical images of cells in the same preparation were obtained using virally transfected fluorescent labeling or by immunolabeling after fixation. The electrical image was then used to locate recorded cell somas, axon initial segments, and axon trajectories, and these signatures were used to identify recorded cells. Comparison of anatomical and physiological measurements permitted visualization and physiological characterization of numerically dominant ganglion cell types with high efficiency in a single preparation.
Resumo:
The rivalry between the men's basketball teams of Duke University and the University of North Carolina-Chapel Hill (UNC) is one of the most storied traditions in college sports. A subculture of students at each university form social bonds with fellow fans, develop expertise in college basketball rules, team statistics, and individual players, and self-identify as a member of a fan group. The present study capitalized on the high personal investment of these fans and the strong affective tenor of a Duke-UNC basketball game to examine the neural correlates of emotional memory retrieval for a complex sporting event. Male fans watched a competitive, archived game in a social setting. During a subsequent functional magnetic resonance imaging session, participants viewed video clips depicting individual plays of the game that ended with the ball being released toward the basket. For each play, participants recalled whether or not the shot went into the basket. Hemodynamic signal changes time locked to correct memory decisions were analyzed as a function of emotional intensity and valence, according to the fan's perspective. Results showed intensity-modulated retrieval activity in midline cortical structures, sensorimotor cortex, the striatum, and the medial temporal lobe, including the amygdala. Positively valent memories specifically recruited processing in dorsal frontoparietal regions, and additional activity in the insula and medial temporal lobe for positively valent shots recalled with high confidence. This novel paradigm reveals how brain regions implicated in emotion, memory retrieval, visuomotor imagery, and social cognition contribute to the recollection of specific plays in the mind of a sports fan.
Resumo:
The cultivation of violin repertoire and its ultimate dominance of the late Nineteenth-Century orchestral library are best examined through the analysis and study of the works of Joseph Joachim (1831-1907), Johannes Brahms (1833-1897), and Robert Schumann (1810-1856). Each of these men, in their own right, made significant contributions to the development of violin repertoire during the latter half of the Nineteenth Century. Yet their achievements were also the result of a collaborative effort and shared influence, the absence of which would have yielded a diminutive musical landscape, especially in the concerti of Brahms and Joachim. This dissertation explores Joachim’s technical dexterity and its influence on Brahms and Schumann, and further studies the vital role Brahms and Schumann played in forming Joachim as both composer and editor. The pieces examined in this dissertation evidence the significant influence each of these composers shared. Three chamber compositions stand as guideposts in the analysis and establish a stylistic foundation to collaborative efforts among Joachim, Brahms, and Schumann. The preliminary recital focuses on these chamber pieces which illustrate the individual style of each composer, featuring Joachim’s Romance, Op. 2, written between 1848 and 1852, Schumann’s Second Sonata, Op. 121, written in 1851, and Brahms’ Second Sonata, Op. 100, written in 1886. A second performance includes the enigmatic F-A-E Sonata of Brahms, Schumann, and Albert Deitrich, Schumann’s pupil, as well as Joachim’s Second Concerto. A collaborative effort, the F-A-E Sonata represents Brahms’ and Schumann’s efforts to write with Joachim’s unbridled style and technique in mind. An even greater musical offering, Joachim’s Second Concerto, a gift to Brahms in 1860, has been called the “Holy Grail” of concertos, and is considered the preeminent display of Joachim’s creative genius by incorporating demanding technical challenges and Hungarian-like overtones. The third and final program features Brahms’ Concerto in D Major. A fitting response to Joachim’s gift 17 years later, Brahms’ Concerto was written for Joachim at the height of his career, bearing the performer’s stylistic elements throughout. The recital also includes various Hungarian Dances by Brahms. While the Dances were not original to Brahms, they further illustrate the underlying idiom of Hungarian folk music in both Brahms’ and Joachim’s art.
Resumo:
At the end of the sixteenth century, Germany had become one of the most active centers of early Baroque music, and therefore Austro-German music came to dominate Western music. An investigation of violin works written during this period reveals the ways in which Austro-German compositions are extraordinary contributions to the violin repertoire. This research warranted further study and performance of these works in order to determine what influence these composers had on the violin repertoire as a whole. For my dissertation recital project, I trace the history of works for violin focusing the violin concerto repertoire in particular. A genre which remained popular throughout the century, the nineteenth-century concerto served primarily as a vehicle for virtuosic display of the violin and piano as never before. For my research I studied and performed works selected from the Baroque through the Romantic period in three recorded recitals with collaborative pianists Ilya Sinaisky, Sun-ha Yun, and Seyon Lee at the Gildenhorn Recital Hall, Clarice Smith Performing Arts Center. I selected particularly prominent pieces which represent the work of significant composers from each period. The composers discussed include Johann Sebastian Bach (1685-1750), owing to the fact that his works are the culmination of the Baroque era during the first half of the eighteenth century; from the Classical period, Wolfgang Amadeus Mozart (1756-1791) all of whom emerged mixing German and Italian traditions into his own style, and Ludwig van Beethoven (1770-1827), the bridge composer between the Classical and the Romantic periods; Romantic composers, Franz Schubert (1979-1828), Johannes Brahms (1833-1897), Robert Schumann (1810-1856), Felix Mendelssohn (1809-1847), and Max Bruch (1838-1920), all who tended to mix Classic and Romantic elements. As a violinist, I learned that their own original sound, rich harmonies and unique expression made these works worthy of becoming masterpieces. I have relished the opportunity for musical and professional growth in exploring these substantial compositions.
Resumo:
A relatively unexplored area of the harpsichord repertoire is the group of transcriptions made by J.S. Bach (1685-1750), Jean Henry d'Anglebert (1629-1691), and Jean-Baptiste Forqueray (1699-1782). These transcriptions are valuable and worth exploring and performing. Studying them provides unique insights into their composer‘s musical thinking. By comparing transcriptions with their original sources, the transcriber's decisions and priorities can be observed. The performance component of this dissertation comprises three recitals. The first features works of Johann Sebastian Bach: two transcriptions of violin concerti by Antonio Vivaldi (1678-1741), and two transcriptions of trio sonatas by Johann Adam Reinken (1643-1722). The most salient feature of Bach‘s transcriptions is his addition of musical material: ornamenting slow movements, adding diminutions and idiomatic keyboard figurations throughout, and recomposing and expanding fugal movements. The second recital features works of Jean Henry d'Anglebert and Jean-Baptiste Forqueray, two French composer/performers. From d'Anglebert‘s many transcriptions, I assembled two key-related suites: the first comprised of lute pieces by Ennemond Gaultier (c. 1575-1651), and the second comprised of movements from operas by Jean-Baptiste Lully (1632-1687). Forqueray's transcriptions are of suites for viola da gamba and continuo, composed by his father, Antoine Forqueray (1671-1745). Creative and varied ornamentation, along with the style brisé of arpeggiated chords, are the most important features of d‘Anglebert‘s transcriptions. Forqueray‘s transcriptions are highly virtuosic and often feature the tenor and bass range of the harpsichord. The third recital features my own transcriptions: the first suite for solo cello by J.S. Bach, excerpts from the opera La Descente d’Orphée aux Enfers by Marc-Antoine Charpentier (1643-1704), and two violin pieces by Nicola Matteis (fl. c. 1670-c. 1698). In these transcriptions, I demonstrate what I have learned from studying and performing the works in the first two recitals. These recitals were performed in the Leah Smith Hall at the University of Maryland on May 4, 2010; May 11, 2010; and October 7, 2010. They were recorded on compact discs and are archived within the Digital Repository at the University of Maryland (DRUM).
Resumo:
The main impetus for a mini-symposium on corticothalamic interrelationships was the recent number of studies highlighting the role of the thalamus in aspects of cognition beyond sensory processing. The thalamus contributes to a range of basic cognitive behaviors that include learning and memory, inhibitory control, decision-making, and the control of visual orienting responses. Its functions are deeply intertwined with those of the better studied cortex, although the principles governing its coordination with the cortex remain opaque, particularly in higher-level aspects of cognition. How should the thalamus be viewed in the context of the rest of the brain? Although its role extends well beyond relaying of sensory information from the periphery, the main function of many of its subdivisions does appear to be that of a relay station, transmitting neural signals primarily to the cerebral cortex from a number of brain areas. In cognition, its main contribution may thus be to coordinate signals between diverse regions of the telencephalon, including the neocortex, hippocampus, amygdala, and striatum. This central coordination is further subject to considerable extrinsic control, for example, inhibition from the basal ganglia, zona incerta, and pretectal regions, and chemical modulation from ascending neurotransmitter systems. What follows is a brief review on the role of the thalamus in aspects of cognition and behavior, focusing on a summary of the topics covered in a mini-symposium held at the Society for Neuroscience meeting, 2014.
Resumo:
Huntington's disease (HD) is a neurodegenerative disease caused by the expansion of a poly-glutamine (poly-Q) stretch in the huntingtin (Htt) protein. Gain-of-function effects of mutant Htt have been extensively investigated as the major driver of neurodegeneration in HD. However, loss-of-function effects of poly-Q mutations recently emerged as potential drivers of disease pathophysiology. Early synaptic problems in the excitatory cortical and striatal connections have been reported in HD, but the role of Htt protein in synaptic connectivity was unknown. Therefore, we investigated the role of Htt in synaptic connectivity in vivo by conditionally silencing Htt in the developing mouse cortex. When cortical Htt function was silenced, cortical and striatal excitatory synapses formed and matured at an accelerated pace through postnatal day 21 (P21). This exuberant synaptic connectivity was lost over time in the cortex, resulting in the deterioration of synapses by 5 weeks. Synaptic decline in the cortex was accompanied with layer- and region-specific reactive gliosis without cell loss. To determine whether the disease-causing poly-Q mutation in Htt affects synapse development, we next investigated the synaptic connectivity in a full-length knock-in mouse model of HD, the zQ175 mouse. Similar to the cortical conditional knock-outs, we found excessive excitatory synapse formation and maturation in the cortices of P21 zQ175, which was lost by 5 weeks. Together, our findings reveal that cortical Htt is required for the correct establishment of cortical and striatal excitatory circuits, and this function of Htt is lost when the mutant Htt is present.