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Chemical synapses transmit information via the release of neurotransmitter-filled vesicles from the presynaptic terminal. Using computational modeling, we predict that the limited availability of neurotransmitter resources in combination with the spontaneous release of vesicles limits the maximum degree of enhancement of synaptic transmission. This gives(More)
The tripartite synapse denotes the junction of a pre- and postsynaptic neuron modulated by a synaptic astrocyte. Enhanced transmission probability and frequency of the postsynaptic current-events are among the significant effects of the astrocyte on the synapse as experimentally characterized by several groups. In this paper we provide a mathematical(More)
Based on recent experimental data, we design a model for neuronal membrane potentials that incorporates the influence of the surrounding glia (dressed neurons). A neurotransmitter released into the synaptic cleft triggers a Ca(2+) response in nearby glial cells that spreads as a Ca(2+) wave and interacts with other synapses via the release of glutamate from(More)
Most modeling studies of neurons and neuronal networks are based on the assumption that the neurons are isolated from their normal environment. Based on recent experimental data we put forward a model for neurons that incorporates the influence of the surrounding glia (dressed neurons). We predict seizurelike spontaneous oscillations in the absence of(More)
We study local calcium dynamics leading to a vesicle fusion in a stochastic, and spatially explicit, biophysical model of the CA3-CA1 presynaptic bouton. The kinetic model for vesicle release has two calcium sensors, a sensor for fast synchronous release that lasts a few tens of milliseconds and a separate sensor for slow asynchronous release that lasts a(More)
Recently, upregulation of metabotropic glutamate receptors (mGluRs) on hippocampal astrocytes in epileptic tissues has become part of the etiology of epilepsy and suggests the involvement of astrocytes in the disease. Through computational modeling, we have shown in previous work that upregulated mGluRs on astrocytes can give rise to positive feedback in(More)
Although the CA3-CA1 synapse is critically important for learning and memory, experimental limitations have to date prevented direct determination of the structural features that determine the response plasticity. Specifically, the local calcium influx responsible for vesicular release and short-term synaptic facilitation strongly depends on the distance(More)
We study the calcium-induced vesicle release into the synaptic cleft using a deterministic algorithm and MCell, a Monte Carlo algorithm that tracks individual molecules. We compare the average vesicle release probability obtained using both algorithms and investigate the effect of the three main sources of noise: diffusion, sensor kinetics and fluctuations(More)
Neurons communicate at chemical synapses, where neurotransmitter released from a nerve terminal of the presynaptic neuron signals to the postsynaptic neuron that an event has occurred. The release is triggered by the entry of calcium ions into the nerve terminal. Previously the chemical reactions underlying neurotransmitter release were studied in a giant(More)
Ongoing electrical activity can initiate a positive feedback loop via Inositol Triphosphate Receptors (IP 3 Rs) and Ryanodine Receptors (RyRs) on the Endoplasmic Receptors (ER) that can lead to release of calcium from the ER. We investigated how the presence of this additional source of calcium in the presynaptic terminals in addition to the Voltage(More)