"Interaction between Cellular Voltage-Sensitive Conductance and Network Parameters in a Model of the Neocortex Can Generate Epileptiform Bursting"
W. van Drongelen, H. C. Lee, H. Koch, F. Elsen, M. S. Carroll, M. Hereld, R. L. Stevens,
Proc. IEEE 26th Annual International Conference of Engineering in Medicine and Biology Society, vol. 2, no. 1, , pp. 4003-4005. Also Preprint ANL/MCS-P1172-0604
Preprint Version: [pdf]
We examined the effects of both intrinsic neuronal membrane properties and network parameters on oscillatory activity in a model of the neocortex. A scalable network model with six different cell types was built with the pGENESIS neural simulator. The neocortical network consisted of two types of pyramidal cells and four types of inhibitory interneurons. All cell types contained both fast sodium and delayed rectifier potassium channels for generation of action potentials. A subset of the pyramidal neurons contained an additional slow-inactivating (persistent) sodium current (NaP). The neurons with the NaP current showed spontaneous bursting activity in the absence of external stimulation. The model also included a routine to calculate a simulated electroencephalogram trace from the population activity. This revealed emergent network behavior, which ranged from desynchronized activity to different types of seisurelike bursting patterns. At settings with weaker excitatory network effects, the propensity to generate seizurelike behavior increased. Strong excitatory network connectivity destroyed oscillatory behavior, whereas weak connectivity enhanced the relative importance of the spontaneously bursting cells. Our findings contradict the general opinion that strong excitatory synaptic or insufficient inhibition effects are associated with seizure initiation, but our results agree with previously reported behavior in the neocortex.