| Abstract: |
| Networks of neurons and synapse play a key role of communication in the brain. Presynaptic terminals release neurotransmitters either in response to action potential or spontaneously independent of presynaptic activity. Spontaneous neurotransmission has an independent role in neuronal communication
that is distinct from that of evoked release. However, the process of spontaneous
neurotransmitter release is still unclear. We develop a mathematical model in 3-D to emulate spontaneous and evoked neurotransmissions resulted from glutamate release
within a single synapse. We propose numerical methods for solving piecewise continuous
heat di usion equation, estimate and verify its errors of second order accuracy. In order to
identify the spatial relation between spontaneous and evoked glutamate releases, we consider
quantitative factors, such as the size of synapses, inhomogeneity of diffusion coefficients, the
geometry of synaptic cleft, and the release rate of neurotransmitter, that will affect postsynaptic
currents. We conclude quantitatively when a synaptic size is larger, the cleft space is less diffusive in the central area than the edge area, if the geometry synaptic cleft has a narrower gap in the center and if glutamate release is slower, then there is a better chance for independence of
two modes of currents from spontaneous and evoked release. The computed results match
well with existing experimental fi ndings and provide a quantitative map of boundaries of
physical constraints for having independent synaptic fusion events. |
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