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19
OM&P
Section COMPUTATIONAL NEUROSCIENCE
were previously explained by different theories. We also discuss the limitations of previous theories, particularly that viewing addiction as a habit-based disorder can be fundamentally inconsistent with certain aspect of addiction.
Electro-Diffusion in Dendritic Spines and the I-V Relation
David Holcman*
Ecole Normale Superieure, France. * Presenting e-mail: david.holcman@ens.fr
Electrical activity of dendritic spines in cellular microdomains in general remains unclear unresolved. The electrical current is carried by moving ions and induces a local change in the voltage, which can modulate the opening of channels and contribute to the initiation of an action potential. The ionic flow in dendritic spines is driven by the coupled electric field to the charge densities that interact through the non-cylindrical spine geometry.
Due to small nanometric scale and the charge-voltage interaction, the voltage-current (I-V) relation and its regulation by geometry remains difficult to investigate. I will present here our recent effort to deconvolve the response of the slow genetically encoded voltage sensor in hippocampal neurons and to compute from the electro-diffusion theory, the electric field and the ionic flows in the spine head. We resolve here the I-V relation and extract the spine resistance, which is certainly insufficient to characterize the nonlinear I-V interaction. Coll. R. Yuste (Columbia).
Delayed and Asynchronous Neurotransmitter Release
Maciej (Martin) Krupa* Inria, France.
* Presenting e-mail: maciej.p.krupa@gmail.com
Asynchronous release of neurotransmitter is an important phenomenon known to occur in certain neurons. It is linked to short term synaptic plasticity, memory formation, modulation of inhibition, etc.
We have designed a model system describing the exocytotic cycle of vesicles at excitatory and inhibitory synapses that accounts for asynchronous release. Our system models the interaction of the SNARE and SM proteins and predicts a delayed inertial protein unbinding associated with the SNARE complex assembly immediately after vesicle priming. The underlying mathematical mechanism is bifurcation delay, which is a phenomenon known to occur in systems with multiple time-scales.
Fig.1. Time-coded neurotransmitter release at excitatory and inhibitory synapses, S. Rodrigues, M. Desroches, M. Krupa, J. Cortes, T. J. Sejnowski, A. B. Ali, PNAS 2016
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Odvnamis transcriliea; ailurcaion
Qtwa Mifilíbría i ■ s-iab.a. I imslaiiiej of Hie fuilBysera
58 Opera Med Physiol 2016 Vol. 2 (S1)
