scholarly journals Local design principles at hippocampal synapses revealed by an energy-information trade-off

2019 ◽  
Author(s):  
Gaurang Mahajan ◽  
Suhita Nadkarni
Keyword(s):  
Information Transfer ◽  
Design Principles ◽  
Short Term ◽  
Vesicle Release ◽  
Efficient Manner ◽  
Heterogeneous Distribution ◽  
Trade Off ◽  
Release Probability ◽  
Wide Range ◽  
Hippocampal Synapses

AbstractSynapses across different brain regions display distinct structure-function relationships. We investigate the interplay of fundamental design principles that shape the transmission properties of the excitatory CA3-CA1 pyramidal cell connection, a prototypic synapse for studying the mechanisms of learning in the hippocampus. This small synapse is characterized by probabilistic release of transmitter, which is markedly facilitated in response to naturally occurring trains of action potentials. Based on a physiologically realistic computational model of the CA3 presynaptic terminal, we show how unreliability and short-term dynamics of vesicle release work together to regulate the trade-off of information transfer versus energy use. We propose that individual CA3-CA1 synapses are designed to operate at close to maximum possible capacity of information transfer in an efficient manner. Experimental measurements reveal a wide range of vesicle release probabilities at hippocampal synapses, which may be a necessary consequence of long-term plasticity and homeostatic mechanisms that manifest as presynaptic modifications of release probability. We show that the timescales and magnitude of short-term plasticity render synaptic information transfer nearly independent of differences in release probability. Thus, individual synapses transmit optimally while maintaining a heterogeneous distribution of presynaptic strengths indicative of synaptically-encoded memory representations. Our results support the view that organizing principles that are evident on higher scales of neural organization percolate down to the design of an individual synapse.

scholarly journals RIM-binding protein 2 regulates release probability by fine-tuning calcium channel localization at murine hippocampal synapses

2016 ◽  
Vol 113 (41) ◽  
pp. 11615-11620 ◽  
Author(s):  
M. Katharina Grauel ◽  
Marta Maglione ◽  
Suneel Reddy-Alla ◽  
Claudia G. Willmes ◽  
Marisa M. Brockmann ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Autism Spectrum ◽  
Fine Tuning ◽  
Model Systems ◽  
Short Term ◽  
Superresolution Microscopy ◽  
Release Probability ◽  
Spatial Coupling ◽  
Hippocampal Synapses ◽  
Initial Release

The tight spatial coupling of synaptic vesicles and voltage-gated Ca2+ channels (CaVs) ensures efficient action potential-triggered neurotransmitter release from presynaptic active zones (AZs). Rab-interacting molecule-binding proteins (RIM-BPs) interact with Ca2+ channels and via RIM with other components of the release machinery. Although human RIM-BPs have been implicated in autism spectrum disorders, little is known about the role of mammalian RIM-BPs in synaptic transmission. We investigated RIM-BP2–deficient murine hippocampal neurons in cultures and slices. Short-term facilitation is significantly enhanced in both model systems. Detailed analysis in culture revealed a reduction in initial release probability, which presumably underlies the increased short-term facilitation. Superresolution microscopy revealed an impairment in CaV2.1 clustering at AZs, which likely alters Ca2+ nanodomains at release sites and thereby affects release probability. Additional deletion of RIM-BP1 does not exacerbate the phenotype, indicating that RIM-BP2 is the dominating RIM-BP isoform at these synapses.

scholarly journals Principles of niche expansion

2018 ◽  
Vol 285 (1893) ◽  
pp. 20182603 ◽  
Author(s):  
Henrik Sjödin ◽  
Jörgen Ripa ◽  
Per Lundberg
Keyword(s):  
General Theory ◽  
Evolutionary Model ◽  
Resource Acquisition ◽  
Short Term ◽  
Trade Off ◽  
Niche Expansion ◽  
Niche Variation ◽  
Wide Range ◽  
Niche Variation Hypothesis ◽  
Resource Diversity

Niche expansion is attained by adaptations in two generalized phenotypical traits—niche position and niche width. This gives room for a wide range of conceptual ways of niche filling. The niche variation hypothesis reduces the range by predicting that expansion occurs by increasing variation in niche position, which has been debated on empirical and theoretical grounds as also other options seem possible. Here, we propose a general theory of niche expansion. We review empirical data and show with an eco-evolutionary model how resource diversity and a trade-off in resource acquisition steer niche evolution consistent with observations. We show that the range can be reduced to a discrete set of two orthogonal ways of niche filling, through (1) strict phenotypical differentiation in niche position or (2) strict individual generalization. When individual generalization is costly, niche expansion undergoes a shift from (2) to (1) at a point where the resource diversity becomes sufficiently large. Otherwise, niche expansion always follows (2), consistent with earlier results. We show that this either–or response can operate at both evolutionary and short-term time scales. This reduces the principles of niche expansion under environmental change to a notion of orthogonality, dictated by resource diversity and a resource-acquisition trade-off.

scholarly journals Local Design Principles at Hippocampal Synapses Revealed by an Energy-Information Trade-Off

eNeuro ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. ENEURO.0521-19.2020
Author(s):  
Gaurang Mahajan ◽  
Suhita Nadkarni
Keyword(s):  
Design Principles ◽  
Trade Off ◽  
Hippocampal Synapses ◽  
Energy Information

scholarly journals Author Correction: Presynaptic endoplasmic reticulum regulates short-term plasticity in hippocampal synapses

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nishant Singh ◽  
Thomas Bartol ◽  
Herbert Levine ◽  
Terrence Sejnowski ◽  
Suhita Nadkarni
Keyword(s):  
Endoplasmic Reticulum ◽  
Short Term ◽  
Short Term Plasticity ◽  
Hippocampal Synapses

scholarly journals Diagnostic Capabilities of a Smartphone- Based Low-Cost Microscope

2020 ◽  
Vol 6 (3) ◽  
pp. 522-525
Author(s):  
Dorina Hasselbeck ◽  
Max B. Schäfer ◽  
Kent W. Stewart ◽  
Peter P. Pott
Keyword(s):  
Low Cost ◽  
Field Of View ◽  
Parasitic Diseases ◽  
Optical Parameters ◽  
Trade Off ◽  
Resource Limited ◽  
Wide Range ◽  
Diagnostic Applications ◽  
Diagnostic Capabilities

AbstractMicroscopy enables fast and effective diagnostics. However, in resource-limited regions microscopy is not accessible to everyone. Smartphone-based low-cost microscopes could be a powerful tool for diagnostic and educational purposes. In this paper, the imaging quality of a smartphone-based microscope with four different optical parameters is presented and a systematic overview of the resulting diagnostic applications is given. With the chosen configuration, aiming for a reasonable trade-off, an average resolution of 1.23 μm and a field of view of 1.12 mm2 was achieved. This enables a wide range of diagnostic applications such as the diagnosis of Malaria and other parasitic diseases.

scholarly journals Debt Maturity and the Dynamics of Leverage

2021 ◽  
Author(s):  
Thomas Dangl ◽  
Josef Zechner
Keyword(s):  
Transaction Costs ◽  
Financial Distress ◽  
Cash Flows ◽  
Debt Maturity ◽  
Corporate Debt ◽  
Short Term ◽  
Trade Off ◽  
Maturity Structure

Abstract This paper shows that short debt maturities commit equityholders to leverage reductions when refinancing expiring debt in low-profitability states. However, shorter maturities lead to higher transaction costs since larger amounts of expiring debt need to be refinanced. We show that this trade-off between higher expected transaction costs against the commitment to reduce leverage in low-profitability states motivates an optimal maturity structure of corporate debt. Since firms with high costs of financial distress and risky cash flows benefit most from committing to leverage reductions, they have a stronger motive to issue short-term debt. Evidence supports the model’s predictions.

Effects of Atovaquone on the Ultrastructural Morphology of Pneumocystis Carinii

1997 ◽  
Vol 3 (S2) ◽  
pp. 81-82
Author(s):  
M.P. Goheen ◽  
M.S. Bartlett ◽  
M.M. Shaw ◽  
S.R. Meshnick ◽  
J.W. Smith
Keyword(s):  
Adverse Reactions ◽  
Pneumocystis Carinii ◽  
Spinner Flask ◽  
Short Term ◽  
Human Embryonic Lung ◽  
Transmission Electron ◽  
Significant Incidence ◽  
Wide Range ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome

Pneumocystis carinii pneumonia (PCP) occurs at some time in most patients with acquired immunodeficiency syndrome (AIDS). Trimethoprim/sulfamethoxazole or pentamidine isothionate are the traditional modes of therapy for treatment and prophylaxis of PCP. Unfortunately these drugs are associated with a significant incidence of adverse side effects particularly in patients with AIDS. Toxicity and a growing concern that P. carinii strains are becoming resistant to these compounds is providing the impetus for the search for additional drugs to combat P. carinii. Atovaquone, developed as an antimalarial agent, has activity against a wide range of other organisms, including Toxoplasma sp. and P. carinii, with a lower incidence of adverse reactions during clinical trials. Atovaquone inhibits mitochondrial respiration in P. falciparum and P. carinii. In this study transmission electron microscopy (TEM) was used to observe the effects of atovaquone on P. carinii organisms in short term spinner flask culture.Spinner flask cultures of human embryonic lung cells were inoculated with P. carinii from infected rat lung.

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