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NJIT Mathematical Biology Seminar

Tuesday, September 11, 2007, 4:00pm
Cullimore Hall 611
New Jersey Institute of Technology

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The transition from normal to hyper-excitable epileptic activity in a medial entorhinal crotex layer II stellate cell model

Horacio G. Rotstein

New Jersey Institute of Technology

This talk concerns the biophysical mechanism underlying the transition from the theta to a hyper-excitable ("epileptic") regime in medial entorhinal cortex layer II (MEC-II) stellate cells (SCs) as a result of recurrent excitatory connectivity among SCs and lack of enough inhibitory regulation. The existence of recurrent connections among SCs in slices of MECwas recently uncover by Kumar et al [*]. In addition they show that these connections are "similar" in control and epileptic pilocarpine-treated rats while recurrent inhibitory circuits are reduced in epileptic tissue as compared to control ones. In this talk we present a biophysical (conductance based) single compartment model that reproduces the experimental findings. We show that there is an abrupt transition in the SCs firing frequency as the maximal synaptic conductance increases through a critical value. Using dynamical systems techniques we explain the mechanim underlying this transition.

[*] Kumar, S. S., Jin, X. Buckmaster, P. S., Huguenard, J. R. J. (2007) Recurrent circuits in layer II of medial entorhinal cortex in a model of temporal lobe epilepsy. Neurosci. 27:1239-1246.