SIMULATION STUDY FOR THE TRANSITION FROM SPINDLES TO SPIKE AND WAVE EPILEPTOGENESIS

A mathematical model is presented, based on existing anatomical and ph ysiological data, which simulates the behaviour of representative type s of cortical cells. It is used to test whether a set of synaptic conn ections of these cells exists, which, paced by the same rhythmical tha lamic input, could produce spindles under normal conditions and spike and wave discharges (SW) under conditions of cortical hyperexcitabilit y. This is possible if the interneurons do not provide recurrent excit atory or inhibitory input on themselves, if the thalamic afferents con tact the cortical projecting pyramidal cells through local excitatory neurons, and if the inhibitory interneurons receive input only from th e pyramidal cells. The results suggest that an increase of all cortica l synaptic actions (both excitatory and inhibitory) is sufficient for the transition from spindles to the first stages in the development of SW discharges in the cortex, whereas the thalamus can be driven to th e SW characteristic frequency at the immediate next stages.