Current Search: Neural transmission. (x)
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- Title
- Molecular Mechanisms Of CaV2.1 Expression and Functional Organization at the Presynaptic Terminal.
- Creator
- Das, Brati, Young, Samuel M., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Neuronal circuit output is dependent on the embedded synapses’ precise regulation of Ca2+ mediated release of neurotransmitter filled synaptic vesicles (SVs) in response to action potential (AP) depolarizations. A key determinant of SV release is the specific expression, organization, and abundance of voltage gated calcium channel (VGCC) subtypes at presynaptic active zones (AZs). In particular, the relative distance that SVs are coupled to VGCCs at AZs results in two different modes of SV...
Show moreNeuronal circuit output is dependent on the embedded synapses’ precise regulation of Ca2+ mediated release of neurotransmitter filled synaptic vesicles (SVs) in response to action potential (AP) depolarizations. A key determinant of SV release is the specific expression, organization, and abundance of voltage gated calcium channel (VGCC) subtypes at presynaptic active zones (AZs). In particular, the relative distance that SVs are coupled to VGCCs at AZs results in two different modes of SV release that dramatically impacts synapse release probability and ultimately the neuronal circuit output. They are: “Ca2+ microdomain,” SV release due to cooperative action of many loosely coupled VGCCs to SVs, or “Ca2+ nanodomain,” SV release due to fewer more tightly coupled VGCCs to SVs. VGCCs are multi-subunit complexes with the pore forming a1 subunit (Cav2.1), the critical determinant of the VGCC subtype kinetics, abundance, and organization at the AZ. Although in central synapses Cav2.2 and Cav2.1 mediate synchronous transmitter release, neurons express multiple VGCC subtypes with differential expression patterns between the cell body and the pre-synapse. The calyx of Held, a giant axosomatic glutamatergic presynaptic terminal that arises from the globular bushy cells (GBC) in the cochlear nucleus, exclusively uses Cav2.1 VGCCs to support the early stages of auditory processing. Due to its experimental accessibility the calyx provides unparalleled opportunities to gain mechanistic insights into Cav2.1 expression, organization, and SV release modes at the presynaptic terminal. Although many molecules are implicated in mediating Cav2.1 expression and SV to VGCC coupling through multiple binding domains on the C-terminus of the Cav2.1 a1 subunit, the underlying fundamental molecular mechanisms remain poorly defined. Here, using viral vector mediated approaches in combination with Cav2.1 conditional knock out transgenic mice, we demonstrate that that there a two independent pathways that control Cav2.1 expression and SV to VGCC coupling at the calyx of Held. These implications for the regulation of synaptic transmission in CNS synapses are discussed.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004584
- Subject Headings
- Synapses., Neural transmission., Cellular signal transduction.
- Format
- Document (PDF)
- Title
- Path selection through a three-stage switching network using neural networks.
- Creator
- Keskiner, Haluk., Florida Atlantic University, Pandya, Abhijit S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Several neural network applications solving practical problems in communications are presented. A neural network algorithm to select paths through a three stage switching network is developed. An analysis of the dynamics of the neural network and a convergence proof are provided. With the help of computer simulations, a four dimensional region for the valid combinations of the neural network parameters was discovered. An analysis is performed to determine the characteristics of this region....
Show moreSeveral neural network applications solving practical problems in communications are presented. A neural network algorithm to select paths through a three stage switching network is developed. An analysis of the dynamics of the neural network and a convergence proof are provided. With the help of computer simulations, a four dimensional region for the valid combinations of the neural network parameters was discovered. An analysis is performed to determine the characteristics of this region. The behavior of the neural network algorithm for different switching network configurations and varying traffic patterns were investigated. The effect of initial state of the neural network and heuristic improvements to the algorithm is provided. A comparative analysis of the neural network path selection algorithm against a sequential search method is also given.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14741
- Subject Headings
- Neural networks (Computer science), Packet switching (Data transmission)
- Format
- Document (PDF)
- Title
- Regulation of rapid signaling at the cone ribbon synapse via distinct pre- and postsynaptic mechanisms.
- Creator
- Rowan, Matthew JM., Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Background: Light-adaptation is a multifaceted process in the retina that helps adjust the visual system to changing illumination levels. Many studies are focused on the photochemical mechanism of light-adaptation. Neural network adaptation mechanisms at the photoreceptor synapse are largely unknown. We find that large, spontaneous Excitatory Amino Acid Transporter (EAATs) activity in cone terminals may contribute to cone synaptic adaptation, specifically with respect to how these signals...
Show moreBackground: Light-adaptation is a multifaceted process in the retina that helps adjust the visual system to changing illumination levels. Many studies are focused on the photochemical mechanism of light-adaptation. Neural network adaptation mechanisms at the photoreceptor synapse are largely unknown. We find that large, spontaneous Excitatory Amino Acid Transporter (EAATs) activity in cone terminals may contribute to cone synaptic adaptation, specifically with respect to how these signals change in differing conditions of light. EAATs in neurons quickly transport glutamate from the synaptic cleft, and also elicit large thermodynamically uncoupled Cl- currents when activated. We recorded synaptic EAAT currents from cones to study glutamate-uptake events elicited by glutamate release from the local cone, and from adjacent photoreceptors. We find that cones are synaptically connected via EAATs in dark ; this synaptic connection is diminished in light-adapted cones. Methods: Whole-cell patch-clamp was performed on dark- and transiently light-adapted tiger salamander cones. Endogenous EAAT currents were recorded in cones with a short depolarization to -10mV/2ms, while spontaneous transporter currents from network cones were observed while a local cone holding at -70mV constantly. DHKA, a specific transporter inhibitor, was used to identify EAAT2 currents in the cone terminals, while TBOA identified other EAAT subtypes. GABAergic and glycinergic network inputs were always blocked with picrotoxin and strychnine. Results: Spontaneous EAAT currents were observed in cones held constantly at -70mV in dark, indicating that the cones received glutamate inputs from adjacent photoreceptors. These spontaneous EAAT currents disappeared in presence of a strong light, possibly because the light suppressed glutamate releases from the adjacent photoreceptors. The spontaneous EAAT currents were blocked with TBOA, but not DHKA, an inhibitor for EAAT2 subtype, suggesting that a, non-EAAT 2 subtype may reside in a basal or perisynaptic area of cones, with a specialized ability to bind exocytosed glutamate from adjacent cones in dark. Furthermore, these results could be artificially replicated by dual-electrode recordings from two adjacent cones. When glutamate release was elicited from one cone, the TBOA-sensitive EAAT currents were observed from the other cone. Conclusions: Cones appear to act like a meshwork, synaptically connected via glutamate transporters. Light attenuates glutamate release and diminishes the cone-cone synaptic connections. This process may act as an important network mechanism for cone light adaptation.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3337186
- Subject Headings
- Synapses, Neural transmission, VIsual perception, Presynaptic receptors, Molecular neurobiology, Glutamic acid, Neural receptors, Cellular signal transduction, Retina, Cytology
- Format
- Document (PDF)
- Title
- Chronic variable stress affects hippocampal neurotrophic factor gene expression in the novelty-seeking phenotype: epigenetic regulation.
- Creator
- Oztan, Ozge., Charles E. Schmidt College of Medicine
- Abstract/Description
-
Experimentally naive rats exhibit varying degrees of novelty exploration. Some rats display high rates of locomotor reactivity to novelty (high responders; HR), and others display low rates (low responders; LR). The novelty-seeking phenotype (LRHR) is introduced as a model of stress responsiveness. In this thesis I examined effects of chronic variable physical and social stress or control handling on the levels of various neurotrophins in the hippocampus, and changes in mossy fibre terminal...
Show moreExperimentally naive rats exhibit varying degrees of novelty exploration. Some rats display high rates of locomotor reactivity to novelty (high responders; HR), and others display low rates (low responders; LR). The novelty-seeking phenotype (LRHR) is introduced as a model of stress responsiveness. In this thesis I examined effects of chronic variable physical and social stress or control handling on the levels of various neurotrophins in the hippocampus, and changes in mossy fibre terminal fields in LRHR rats. A positive correlation is seen between histone deacetylase 2 and brain-derived neurotrophic factor (BDNF) levels both of which are oppositely regulated in LRHR CA3 fields in response to chronic social stress. Increase in BDNF levels in CA3 field accompanied increase in supra-pyramidal mossy fibre terminal field size (SP-MF) in HRs, and decrease in BDNF levels accompanied decrease in SP-MF volume in LRs. Epigenetic regulation of neurotrophic support underlying these structural changes is discussed.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/215290
- Subject Headings
- Rats as laboratory animals, Cellular signal transduction, Gene expression, Hippocampus (Brain), Physiology, Neural transmission, Genetic regulation
- Format
- Document (PDF)
- Title
- Development of a novel assay for in vivo screening of neuromodulatory drugs and targeted disruption of cholinergic synaptic transmission in Drosophila melanogaster.
- Creator
- Mejia, Monica, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Finding novel compounds that affect neuronal or muscular function is of great interest, as they can serve as potential pharmacological agents for a variety of neurological disorders. For instance, conopeptides have been developed into powerful drugs like the painkiller PrialtTM. Most conopeptides, however, have yet to be characterized, revealing the need for a rapid and straightforward screening method. We have designed a novel bioassay, which allows for unbiased screening of biological...
Show moreFinding novel compounds that affect neuronal or muscular function is of great interest, as they can serve as potential pharmacological agents for a variety of neurological disorders. For instance, conopeptides have been developed into powerful drugs like the painkiller PrialtTM. Most conopeptides, however, have yet to be characterized, revealing the need for a rapid and straightforward screening method. We have designed a novel bioassay, which allows for unbiased screening of biological activity of compounds in vivo against numerous molecular targets on a wide variety of neurons and muscles in a rapid and straightforward manner. For this, we paired nanoinjection of compounds with electrophysiological recordings from the Giant Fiber System of Drosophila melanogaster, which mediates the escape response of the fly.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362560
- Subject Headings
- Drosophila melanogaster, Genetics, Drosophila melanogaster, Life cycles, Insects, Physiology, Developmental neurobiology, Neural transmission, Cholinergic mechanisms
- Format
- Document (PDF)
- Title
- Protecting Synaptic Function From Acute Oxidative Stress: A Novel Role For Big K+ (BK) Channels And Resveratrol-Like Compounds.
- Creator
- Bollinger, Wesley L., Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
Oxidative stress causes neural damage and inhibits essential cellular processes, such as synaptic transmission. Despite this knowledge, currently available pharmaceutical agents cannot effectively protect neural cells from acute oxidative stress elicited by strokes, heart attacks, and traumatic brain injuries in a real life clinical setting. Our lab has developed an electrophysiology protocol to identify novel drugs that protect an essential cellular process (neurotransmission) from acute...
Show moreOxidative stress causes neural damage and inhibits essential cellular processes, such as synaptic transmission. Despite this knowledge, currently available pharmaceutical agents cannot effectively protect neural cells from acute oxidative stress elicited by strokes, heart attacks, and traumatic brain injuries in a real life clinical setting. Our lab has developed an electrophysiology protocol to identify novel drugs that protect an essential cellular process (neurotransmission) from acute oxidative stress-induced damage. Through this doctoral dissertation, we have identified three new drugs, including a Big K+ (BK) K+ channel blocker (iberiotoxin), resveratrol, and a custom made resveratrol-like compound (fly2) that protect synaptic function from oxidative stress-induced insults. Further developing these drugs as neuroprotective agents may prove transformative in protecting the human brain from acute oxidative stress elicited by strokes, heart attacks, and traumatic brain injuries. Inhibiting the protein kinase G (PKG) pathway protects neurotransmission from acute oxidative stress. This dissertation has expanded upon these findings by determining that the PKG pathway and BK K+ channels function through independent biochemical pathways to protect neurotransmission from acute oxidative stress. Taken together, this dissertation has identified two classes of compounds that protect neurotransmission from acute oxidative stress, including resveratrol-like compounds (resveratrol, fly2) and a BK K+ channel inhibitor (iberiotoxin). Further developing these drugs in clinical trials may finally lead to the development of an effective neuroprotective agent.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00013054
- Subject Headings
- Neural transmission., Oxidative stress., Large-Conductance Calcium-Activated Potassium Channels., Neuroprotective Agents.
- Format
- Document (PDF)
- Title
- Neural network based routing optimization for ATM switching networks.
- Creator
- Sen, Ercan., Florida Atlantic University, Pandya, Abhijit S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
This dissertation proposes amodular Artificial Neural Network (ANN) based buffer allocation and routing control model for ATM switching networks. The proposed model considers limited buffer capacity which can adversely impact the switching performance of ATM switching networks. The proposed ANN based approach takes advantage of the favorable control characteristics of neural networks such as high adaptability and high speed collective computing power for effective buffer utilization. The...
Show moreThis dissertation proposes amodular Artificial Neural Network (ANN) based buffer allocation and routing control model for ATM switching networks. The proposed model considers limited buffer capacity which can adversely impact the switching performance of ATM switching networks. The proposed ANN based approach takes advantage of the favorable control characteristics of neural networks such as high adaptability and high speed collective computing power for effective buffer utilization. The proposed model uses complete sharing buffer allocation strategy and enhances its performance for high traffic loads by regulating the buffer allocation process dynamically via a neural network based controller. In this study, we considered the buffer allocation problem in the context of routing optimization in ATM networks. The modular structure of the proposed model separates the buffer allocation from the actual routing of ATM cells through the switching fabric and allows adaptation of the neural control for routing to different switching structures. The influence of limited buffer capacity, routing conflicts, statistical correlation between arriving ATM cells and cell burst length on ATM switching performance are analyzed and illustrated through computer simulation.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/12491
- Subject Headings
- Asynchronous transfer mode, Packet switching (Data transmission), Neural networks (Computer science)
- Format
- Document (PDF)
- Title
- Estimation of Internet transit times using a fast-computing artificial neural network (FC-ANN).
- Creator
- Fasulo, Joseph V., Florida Atlantic University, Neelakanta, Perambur S.
- Abstract/Description
-
The objective of this research is to determine the macroscopic behavior of packet transit-times across the global Internet cloud using an artificial neural network (ANN). Specifically, the problem addressed here refers to using a "fast-convergent" ANN for the purpose indicated. The underlying principle of fast-convergence is that, the data presented in training and prediction modes of the ANN is in the entropy (information-theoretic) domain, and the associated annealing process is "tuned" to...
Show moreThe objective of this research is to determine the macroscopic behavior of packet transit-times across the global Internet cloud using an artificial neural network (ANN). Specifically, the problem addressed here refers to using a "fast-convergent" ANN for the purpose indicated. The underlying principle of fast-convergence is that, the data presented in training and prediction modes of the ANN is in the entropy (information-theoretic) domain, and the associated annealing process is "tuned" to adopt only the useful information content and discard the posentropy part of the data presented. To demonstrate the efficacy of the research pursued, a feedforward ANN structure is developed and the necessary transformations required to convert the input data from the parametric-domain to the entropy-domain (and a corresponding inverse transformation) are followed so as to retrieve the output in parametric-domain. The fast-convergent or fast-computing ANN (FC-ANN) developed is deployed to predict the packet-transit performance across the Internet. (Abstract shortened by UMI.)
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12835
- Subject Headings
- Neural networks (Computer science), Information theory, Packet switching (Data transmission), Internet
- Format
- Document (PDF)