Academic literature on the topic 'WW 3881'
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Journal articles on the topic "WW 3881":
Utomo, Muhajir, Irwan Sukri Banuwa, Henrie Buchari, Yunita Anggraini, and Berthiria. "Long-term Tillage and Nitrogen Fertilization Effects on Soil Properties and Crop Yields." JOURNAL OF TROPICAL SOILS 18, no. 2 (June 12, 2013): 131. http://dx.doi.org/10.5400/jts.2013.v18i2.131-139.
Chen, C. "WWP1 (WW domain containing E3 ubiquitin protein ligase 1)." Atlas of Genetics and Cytogenetics in Oncology and Haematology, no. 5 (February 2011). http://dx.doi.org/10.4267/2042/38581.
Dissertations / Theses on the topic "WW 3881":
Evangelista, Roberta. "Network mechanisms regulating the generation of sharp wave-ripple complexes in the hippocampus." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20567.
Sharp wave-ripple complexes (SWRs) are events of coordinated network activity originating in the hippocampus. SWRs are thought to mediate the consolidation of explicit memories, but the mechanisms underlying their occurrence remain obscure. Pyramidal cells (PYR) and parvalbumin-positive basket cells (PV+BCs) preferentially fire during SWRs and are almost silent outside. SWRs emerge spontaneously or by activating PYR or PV+ cells. To understand how the activation of PV+ interneurons can result in an increase of PYR firing, I explore how the interaction of excitatory neurons (PYR) and two groups of interneurons (PV+BCs and a class of anti-SWR cells) contributes to the initiation, termination, and incidence of SWRs. First, I show that a biophysically constrained network of spiking neurons can exhibit spontaneous transitions from a non-SWR state to a SWR state, in which active PV+BCs disinhibit PYR by suppressing anti-SWR cells. SWR events can be triggered by activating PYR or PV+BCs, or inactivating anti-SWR cells. Short-term synaptic depression at the PV+BCs-to-anti-SWR cells connections regulates the termination of SWR events. The coexistence of states for intermediate values of the depression allows to study the network behavior in terms of bistability. To this end, I consider a mean-field approximation of the spiking network, where conditions for the emergence of a bistable configuration are derived analytically. This allows to unveil the mechanisms regulating the existence of bistable disinhibitory networks. The model predicts the existence of a class of anti-SWR cells. In the last part of this work, I show the first experimental evidence for CA3 interneurons anti-modulated with respect to SWRs, and discuss their involvement in the SWR generation process. Overall, the results of this thesis elucidate the role of interneurons in SWR generation and broaden our understanding of the microcircuits supporting the dynamics of memory-related networks.
Ciolli, Mattioli Camilla. "Post-transcriptional mechanisms contributing to RNA and protein localization: study of local translation and alternative 3′UTRs in induced neurons." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20702.
Asymmetric distribution of mRNA and proteins inside a cell defines polarity, which allow tight regulation of gene expression in space and time. In this thesis I investigated how asymmetric distribution characterizes the somatic and neuritic compartments of in induced neurons, in terms of transcriptome and translatome. Spatial ribosome profiling analysis revealed that half of the local proteome is defined by mRNA localization and local translation. These, are processes accomplished by the synergistic activity of trans- and cis-acting elements. I focused on MOV10 as trans-acting element, and on alternative 3′UTRs as cis-elements, to investigate their role in asymmetry. MOV10 is an RNA helicase which participates to many aspects of RNA metabolism. With RIP and PAR-CLIP I showed that MOV10 targets are localized to the neurites, consistently with MOV10-neuritic localization, and that MOV10 might be involved in translational repression. Indeed, among MOV10 protein interactors, I identified several proteins involved in translational repression, i.e. AGO2, FMR1, and TRIM71. On the side of cis-elements, I performed mapping of alternative 3′UTRs. This analysis identified several genes expressing differentially localized 3′UTR isoforms. In particular, I focused on Cdc42. I showed that the two isoforms of Cdc42 are differentially localized at mRNA level, and that the 3′UTR is the driver of mRNA and protein localization. Moreover, I identified several RBPs that might be involved in Cdc42 localization. This analysis points to usage of alternative 3′UTR isoforms as a novel mechanism to provide for differential localization of functionally diverse alternative protein isoforms.
Sigl-Glöckner, Johanna. "Cellular structure and sexual development of somatosensory cortex." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21034.
Functionally specialized circuits in the mammalian neocortex contain different neuronal cell-types, which process information depending on their physiology, morphology and synaptic connectivity. This doctoral thesis explores two functionally distinct cortical circuits, namely its input (Chapters 2 to 4) and output (Chapter 5) structures, layer 4 and layer 5 respectively. The first part of the thesis comprises three studies that examine the processing of genital touch in the cortical input layer, layer 4. We investigated how layer 4 and its inputs are structurally refined during puberty, a time when genital touch gains biological relevance. Earlier work from layer 4 of barrel cortex suggested that somatosensory cortex contains a topographic representation of the body surface. We find that the part of this body map that processes genital touch expands significantly during puberty and that this expansion could be advanced by the early experience of sexual touch. Our data further suggests that this expansion is not due to differences in the peripheral innervation of genitals. Finally, chronic imaging of excitatory neurons within layer 4 revealed cell-type specific functional and structural changes within genital cortex during puberty. The second part of this thesis focuses on the cellular specialization of the cortical output layer, layer 5, which contains different types of excitatory projection neurons. We investigated genomic differences as novel mechanism underlying projection neuron diversity. Our data suggests that some exceptionally large projection neurons may contain an increased DNA content, a phenomenon also referred to as polyploidy. Overall, this thesis highlights two novel instances of cellular specialization in the cortex: (i) Within the cortical input layer, we observed development and experience driven changes in the area which processes genital touch. (ii) Within the cortical output layer, we identified putatively polyploid projection neurons.
Benda, Jan. "Single neuron dynamics." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2002. http://dx.doi.org/10.18452/14684.
The single neuron is the basic element of information processing in nervous systems. In this thesis several properties of the dynamics of the generation of spikes are investigated theoretically as well as experimentally. Phase oscillators of different complexity are introduced as models to predict the timing of spikes. The neuron's intensity-response curve is used as a basic parameter in these models to make them easily applicable to real neurons. As a second important aspect of the spiking dynamics, the neuron's phase-resetting curve is used to extend the models. The phase oscillators turn out to be a good approximation of the spiking behavior of a neuron as long as it is stimulated in its super-threshold regime. However, it is shown by comparison with conductance-based models that these models, as well as all other one-dimensional models including the common integrate-and-fire model, fail, if the neuron is stimulated with currents fluctuating around its threshold. Spike-frequency adaptation is a common feature of many neurons. For various ionic currents, as a possible reason for adaptation, a general phenomenological model for the firing rate of adapting neurons is derived from their biophysical properties. This model is defined by the neuron's intensity-response curves and an adaptation time-constant. By means of this model the high-pass properties of spike-frequency adaptation can be quantified. Also the role of adaptation in supression of background noise is discussed. Both the phase oscillators and the adaptation-model are tested on auditory receptor neurons of locusts and the AN1, a primary auditory interneuron of the cricket {Teleogryllus oceanicus}. In both cases the models are in good agreement with the experimental data. By means of the models it is shown that adaptation in the receptor neurons is caused by ionic currents of the spike generator while in the interneuron it is the input which is already adapting. In addition, the influence of spike-frequency adaptation on the recognition of courtship songs is analysed.
Kruscha, Alexandra. "Information transmission by the synchronous activity of neuronal populations." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18391.
Populations of sensory neurons encode information about the environment into electrical pulses, so called action potentials or spikes. Neurons in the brain process these pulses further by using different readout strategies. Integrator cells sum up all incoming action potentials and are thus sensitive to the overall activity of a presynaptic population. Coincidence detectors, on the other hand, are activated by the synchronous firing of the afferent population. The main question of this thesis is: What information about a common time-dependent stimulus is encoded in the synchronous spikes of a neuronal population in comparison to the sum of all spikes? We approach this question within the framework of spectral analysis of stochastic processes, which allows to assess which frequency components of a signal are predominantly encoded. Here, in contrast to earlier studies, a synchronous event does not necessarily mean that all neurons of the population fire simultaneously, but that at least a prescribed fraction ('synchrony threshold') needs to be active within a small time interval. We derive analytical expressions of the correlation statistics which are compared to numerical simulations and experiments on weakly electric fish. We show that the information transmission of the synchronous output depends highly on the synchrony threshold. We uncover a symmetry in the synchrony threshold, unveiling the similarity in the encoding capability of the common firing and the common silence of a population. Our results demonstrate that the synchronous output can act as a band-pass filter of information, i.e. it extracts predominantly fast components of a stimulus. If signals in different frequency regimes are concurrently present, the selection of synchronous firing events can thus be a tool to separate these signals.
Steup, Andreas. "Expression und Funktion neuronaler Leitmoleküle im Hippokampus." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2001. http://dx.doi.org/10.18452/14722.
In this work, the semaphorins Sema3A and Sema3C as well as Netrin-1 and their receptors, the neuropilins and DCC, were investigated regarding their expression and functional properties on outgrowing axons, which are forming the intrinsic and afferent hippocampal projections. Because of the already well known expression patterns of Sema3A, this work focused on the expression of the receptor of Sema3A, NP-1. From embryonic stage E17 on, NP-1 is expressed in the entorhinal cortex, the subiculum and the hippocampal Anlage. A strong postnatal expression of NP-1 in the CA3-region could be detected, while the expression pattern in the CA1-region, the dentate gyrus and the entorhinal cortex was weaker. Additionally, the expression patterns of Sema3C and NP-2 were investigated in greater detail. At birth (P0), Sema3C was expressed in the dentate gyrus and the cornu ammonis region. The expression of its receptor NP-2 could be detected at the same timepoint P0 in the dentate gyrus and the CA3-region and, less pronounced, in the CA1-region.There could not be detected any expression of Sema3C or NP-2 in the entorhinal cortex. In functional coculture studies between with Sema3A or Sema3C transfected cell clusters and neuronal explants from subregions of the hippocampal formation, these factors were investigated for their influence on axonal outgrowth within a three-dimensional collagen gel matrix. Sema3A has repulsive properties on explants from the dentate gyrus, the CA1- and CA3- regions and the entorhinal cortex. I the resulting model, the interaction between Sema3A and NP-1 influences the ingrowth and/or the termination of entorhinal fibers into the molecular layer of the dentate gyrus by a repulsive barrier formed by Sema3A. The same barrier also acts on mossy fibers to allow them to grow only in direction of the CA3-region. Sema3C has repulsive properties on fibers from the medial septum and shapes the ingrowth of these fibers along the cornu ammonis region into the hippocampus. Additionally, the expression patterns of Netrin-1 and DCC and their functional properties in the hippocampus were investigated. Netrin-1 is already expressed in the cortex at E17, although the onset of expression in the hippocampus is at P1. In the dentate gyrus, a weak signal could be detected, but no signal was found in the entorhinal cortex. In the cornu ammonis region, however, Netrin-1 showed a strong expression signal. The Netrin-1 receptor DCC could be detected as early as E15 with a diffuse distribution in the hippocampal Anlage. From P1 on, these signals could be distinguished in the dentate gyrus and the CA1-CA3-regions. Netrin-1 showed attractive properties only on fibers from explants of the dentate gyrus and the CA3-region, which form the hippocampal commissure. These results confirm previous findings from Netrin-1 and DCC deficient animals in which the absence of the hippocampal commissure was described.
Berndt, Nikolaus. "Theoretische Untersuchungen zur Kopplung von neuronaler Erregung und neuronalem Energiestoffwechsel." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16668.
The first part of this work deals with the influence of ion currents on the generation of action potentials (APs). Chapter 1 shows the influence of chloride on the fidelity of APs and cellular volume regulation. In chapter 2 we show that sufficiently large leak currents function as important stabilizers of the membrane potential and thus are required to allow robust AP firing. The second part deals with the energy metabolism of neuronal cells. In chapter 3 we determine the relative oxygen consumption rate of hippocampal brain slices under different activity states. We show that a hemodynamic response is necessary for sufficient oxygen supply during highly active states. We conclude that the effort spent on the structure of the vascular system is economized to just match the neuronal energy demand. In chapter 4 we use a model of the neuronal energy metabolism developed by us to show how the characteristics of NAD(P)H fluorescence curves relies on the cellular glycolytic and respirational activity. In addition we show how the ability of neuronal cells to use lactate instead of glucose as energy delivering substrate depends on their respective glycolytic and respiratory activity. Since a reduced activity of brain α-ketoglutarate dehydrogenase complex (KGDHC) occurs in a number of neurodegenerative diseases, we examined the influence of a reduced KGDHC activity on the neuronal energy metabolism and show how it leads to a compromised neuronal functionality. In addition we developed a detailed kinetic model of the respiratory chain (RC) and identified the possible sites for production of reactive oxygen species (ROS) by the RC. We show that a reduced KGDHC activity should decrease ROS production by the RC.
Blankenburg, Sven. "Theoretical mechanisms of information filtering in stochastic single neuron models." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17577.
Neurons transmit information about time-dependent input signals via highly non-linear responses, so-called action potentials or spikes. This type of information transmission can be frequency-dependent and allows for preferences for certain stimulus components. A single neuron can transmit either slow components (low pass filter), fast components (high pass filter), or intermediate components (band pass filter) of a time-dependent input signal. Using methods developed in theoretical physics (statistical physics) within the framework of information theory, in this thesis, cell-intrinsic mechanisms are being investigated that can lead to frequency selectivity on the level of information transmission. Various stochastic single neuron models are examined numerically and, if tractable analytically. Ranging from simple spiking models to complex conductance-based models with and without nonlinearities, these models include integrator as well as resonator dynamics. First, spectral information filtering characteristics of different types of stochastic current-based integrator neuron models are being studied. Subsequently, the simple deterministic PIF model is being extended with a stochastic spiking rule, leading to positive correlations between successive interspike intervals (ISIs). Thereafter, models are being examined which show subthreshold resonances (so-called resonator models) and their effects on the spectral information filtering characteristics are being investigated. Finally, the spectral information filtering properties of stochastic linearnonlinear cascade neuron models are being researched by employing different static nonlinearities (SNLs). The trade-off between frequency-dependent signal transmission and the total amount of transmitted information will be demonstrated in all models and constitutes a direct consequence of the nonlinear formulation of the models.