546 research outputs found

    Phase specific morphological changes induced by social experience in two forebrain areas of the zebra finch

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    Rollenhagen A, Bischof H-J. Phase specific morphological changes induced by social experience in two forebrain areas of the zebra finch. Behavioural Brain Research. 1994;65(1):83-88.We examined the changes of spine density in Golgi preparations of two different areas of the forebrain of the zebra finch, the ANC (Archi-Neostriatum caudale) and MNH (medial Neo-Hyperstriatum) during development, after transferring male birds from isolation to a social condition (exposure to a female for 1 week), and after a second isolation period. MNH and ANC are two of four brain regions which are strongly activated if a male bird is exposed to a female after some time of isolation. The results of our study can be summarized as follows. 1: a peak-decline trend is observed in ANC, but not in MNH. 2: rearing conditions do not affect the development of both areas until day 70. 3: from 80 days of age, isolation leads to reduced spine density within ANC, but to enhanced spine density within MNH. 4: short social contact after isolation diminishes or eliminates the effects of isolation by an enhancement of spine density in ANC and a reduction of spine density within MNH. 5: the effects of short social rearing after isolation are reversible within ANC, but not within MNH. We presume that the alterations of spine density, which are induced by changes in social conditions, are restricted to ages older than 70 days by hormonal factors. We propose that the complexity of the ANC neuronal net follows the complexity of the social environment, and that the level of arousal is the most important factor influencing the complexity. We further suppose that the reduction of spines within MNH is the anatomical manifestation of an imprinting process, which has been shown to occur in the same experimental situation as we used it in our study

    application of the singular evolutive interpolated Kalman filter

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    Sea-ice, Finite Element Sea-Ice Model, Kalman Filter, Data Assimilation. - The Arctic region is sensitive to climate change. Since the Arctic sea-ice cover influences the surface heat budget of the Earth the observed sea-ice decline is seen as an indication of global warming. Furthermore, the dynamics of sea ice plays an important role for the sea-ice mass distribution in the Arctic, for the production of dense, cold, and salty water in the Arctic Ocean, which contributes to the thermohaline circulation, and also for the freshwater budget of the Nordic Seas. Thus, a realistic description of sea-ice motion is important to draw conclusions for the mass transport and sea-ice mass distribution. The Finite-Element Sea-Ice Model simulates the large-scale physical sea-ice processes like the sea-ice growth and circulation realistically. The model domain covers the entire Arctic Ocean and its marginal seas. Together with the Singular Evolutive Interpolated Kalman (SEIK) Filter and remotely sensed sea-ice drift observations this sea-ice model is applied for data assimilation to investigate details of the sea-ice dynamics. So far, drift assimilation has been carried out to analyze and modify only the drift field with subsequent computation of the advection or redistribution of ice mass which corresponds more to the physical model behavior than a statistical analysis that the SEIK Filter provides. The sea-ice drift data assimilation with the SEIK Filter achieves drift modification and furthermore changes in the two other sea-ice variables concentration and thickness. The modifications of these "unobserved variables" (within the meaning of data assimilation) are validated and it is found that they are in good agreement for at least 2 months for the sea-ice thickness and even 4 months for the sea-ice concentration which is the longest period examined. The drift improvement is achieved due to the sea-ice concentration and ...thesi

    Die bösliche Verlassung in kritischer Betrachtung

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    Transcutaneous Immunization with Toxin-Coregulated Pilin A Induces Protective Immunity against Vibrio cholerae O1 El Tor Challenge in Mice

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    Toxin-coregulated pilin A (TcpA) is the main structural subunit of a type IV bundle-forming pilus of Vibrio cholerae, the cause of cholera. Toxin-coregulated pilus is involved in formation of microcolonies of V. cholerae at the intestinal surface, and strains of V. cholerae deficient in TcpA are attenuated and unable to colonize intestinal surfaces. Anti-TcpA immunity is common in humans recovering from cholera in Bangladesh, and immunization against TcpA is protective in murine V. cholerae models. To evaluate whether transcutaneously applied TcpA is immunogenic, we transcutaneously immunized mice with 100 mug of TcpA or TcpA with an immunoadjuvant (cholera toxin [CT], 50 mug) on days 0, 19, and 40. Mice immunized with TcpA alone did not develop anti-TcpA responses. Mice that received transcutaneously applied TcpA and CT developed prominent anti-TcpA immunoglobulin G (IgG) serum responses but minimal anti-TcpA IgA. Transcutaneous immunization with CT induced prominent IgG and IgA anti-CT serum responses. In an infant mouse model, offspring born to dams transcutaneously immunized either with TcpA and CT or with CT alone were challenged with 10(6) CFU (one 50% lethal dose) wild-type V. cholerae O1 El Tor strain N16961. At 48 h, mice born to females transcutaneously immunized with CT alone had 36% +/- 10% (mean +/- standard error of the mean) survival, while mice born to females transcutaneously immunized with TcpA and CT had 69% +/- 6% survival (P \u3c 0.001). Our results suggest that transcutaneous immunization with TcpA and an immunoadjuvant induces protective anti-TcpA immune responses. Anti-TcpA responses may contribute to an optimal cholera vaccine

    Особливості дослідження соціокультурної варіативності інтонації мовлення

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    (uk) У статті обґрунтовано специфіку процедури дослідження соціокультурної варіативності інтонації англійського мовлення. На основі проведеного експериментально-фонетичного дослідження розглянуто методологію, основні процедури й методи вивчення варіативних характеристик інтонації, що дозволяють виявити інваріант та соціокультурні варіантні просодичні реалізації.(en) The paper explores thespecific research procedure of sociocultural variability of intonation of English oral speech. On the basis of experimental phonetic research the author discusses the methodology, main procedures and methods of research of intonation variant features which allow revealing the invariant and sociocultural variant prosodic realizations

    Mechanisms of Object Representation in Inferotemporal Cortex

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    The inferotemporal cortex in primates is thought to be the primary region that subserves object recognition. The studies presented here help to elucidate the role of IT in higher visual processing by addressing three specific outstanding issues. In the first study, we sought to determine whether IT neurons respond similarly to patterns that are perceptually confused. We considered a behavioral phenomenon whereby lateral mirror images are confused more frequently than vertical mirror images. By presenting mirror images to the monkey while simultaneously recording from IT neurons, we found that neurons differentiate less effectively between lateral mirror images than between vertical mirror images. This phenomenon may underlie the perceptual confusion documented in behavioral studies.In the second study, we sought to determine whether activity in IT reflects experience-based changes in perception. We tested this by first training monkeys to discriminate shape orientation. We then recorded from IT neurons while monkeys performed an orientation discrimination task with trained orientations, and passively viewed orientations of trained and untrained shapes. We found that training to discriminate between orientations of a shape significantly increases the ability of IT neurons to discriminate between those same orientations. This neuronal selectivity correlated with the monkeys' ability to discriminate orientation. These data suggest that training-induced changes in perception are supported by processes in IT.Some IT neurons respond to the onset of a visual stimulus by firing a series of bursts at a frequency of around 5 Hz. One explanation for this phenomenon is that stimuli in the visual scene compete, with alternating success, for processing resources in IT. In the third study, we tested this by examining the oscillatory activity of IT neurons in response to the presentation of multiple stimuli, a central "preferred" image and a peripheral "non-preferred" image. We observed that the onset of a central pattern in the presence of the peripheral stimulus elicited strong oscillations phase-locked to pattern-onset. Onset of the peripheral stimulus in the presence of the central pattern elicited a succession of inhibitory troughs phase-locked to stimulus-onset. These results are congruent with a model of mutual inhibition of competing neuronal populations

    The Mossy Fiber Bouton: the “Common” or the “Unique” Synapse?

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    Synapses are the key elements for signal processing and plasticity in the brain. They are composed of nearly the same structural subelements, an apposition zone including a pre- and postsynaptic density, a cleft and a pool of vesicles. It is, however, their actual composition that determines their different behavior in synaptic transmission and plasticity. Here, we describe and discuss the structural factors underlying the unique functional properties of the hippocampal mossy fiber (MF) synapse. Two membrane specializations, active zones (AZs; transmitter release sites), and puncta adherentia (PA), putative adhesion complexes were found. On average, individual boutons had ∼20 AZs with a mean surface area of 0.1 μm2 and a short distance of 0.45 μm between individual AZs. Mossy fiber boutons (MFBs) and their target structures were isolated from each other by astrocytes, but fine glial processes never reached the AZs. Therefore, two structural factors are likely to promote synaptic cross-talk: the short distance and the absence of fine glial processes between individual AZs. Thus, synaptic crosstalk may contribute to the high efficacy of hippocampal MF synapses. On average, an adult bouton contained ∼16,000 synaptic vesicles; ∼600 vesicles were located within 60 nm from the AZ, ∼4000 between 60 nm and 200 nm, and the remaining beyond 200 nm, suggesting large readily releasable, recycling, and reserve pools. Thus, the size of the three pools together with the number and distribution of AZs underlie the unique extent of synaptic efficacy and plasticity of the hippocampal MF synapse

    Structural and Functional Aberrations in the Cerebral Cortex of Tenascin-C Deficient Mice

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    The extracellular matrix glycoprotein tenascin-C (TNC) has been implicated in neural development and plasticity but many of its functions in vivo remain obscure. Here we addressed the question as to whether the constitutive absence of TNC in mice affects cortical physiology and structure. Defined major cell populations (neurons and inhibitory neuronal subpopulations, astrocytes, oligodendrocytes and microglia) were quantified in the somatosensory and motor cortices of adult TNC deficient (TNC−/−) and wild-type (TNC+/+) mice by immunofluorescence labelling and stereology. In both areas studied we found abnormally high neuronal density, astrogliosis, low density of parvalbumin-positive interneurons and reduced ratios of oligodendrocytes to neurons and of inhibitory to excitatory neurons in the TNC deficient as opposed to the non-deficient animals. Analysis of Golgi-impregnated layer V pyramidal neurons in TNC−/− animals showed aberrant dendrite tortuosity and redistribution of stubby spines within first- to third-order dendritic arbors. Significantly enhanced responses upon whisker stimulation were recorded epicranially over the barrel and the motor cortices of TNC−/− as compared to TNC+/+ animals, and this effect might be associated with the diminished inhibitory circuitry. These results indicate that TNC is essential for normal cortical development and functio
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