Posted in Projects (This page is no longer updated. See NEWS page for the latest updates), Quantitative Neurophysiology with Applied Electric Fields

Davide Reato

 

The aim of this study (the paper can be found here), was to describe a new experimental model of focal epilepsy developed by the group of Giorgio Carmignoto. All the details about the experimental model can be found in Losi et al., 2010 and Gómez-Gonzalo et al., 2010. Briefly, by applying NMDA puffs, it is possible to generate localized seizure-like activity in entorhinal cortex slices. Consecutive puffs drive the network into the hyper-active state.

WIth a model we wanted to describe the onset of seizure generation and to determine whether and how astrocytes play a role in that. In fact, as shown experimentally in Gómez-Gonzalo et al., 2010, astrocytic activity seems to modulate the number of puffs necessary to generate the ictal discharge (threshold).

To be able to simulate a network of neurons and astrocytes, we considered simplified descriptions for both cell types. For neurons, we used Izhikevich’s single neurons model as in Izhikevich 2003 (more details can be found on Izhikevich’s website and in his beautiful book).

For astrocytes, we focused on one particular feedback signaling between neurons and astrocytes, involving calcium changes in the astrocyte and consequent possible glutamate release.

To do so, we considered a simple set of equations to reproduce qualitatively this behavior. While the model lacks of any biophysical specific description it was able to reproduce basic features of calcium dynamics and glutamate release like:

  • Transient calcium responses proportional to the level of neuronal activity
  • Calcium oscillations
  • Transient releases of glutamate

Some Matlab code can be found here.

While the model needs to be improved, it was a first attempt to give a simple description of neuron-astrocyte interaction suitable for large scale network simulations.