Electroencephalographic study of iron-induced chronic focal cortical epilepsy in rat: propagation of cortical epileptic activity to substantia nigra and thalamus.

Cortical epileptic focus was produced by an intracortical injection of FeCl3 in rat cerebral cortex using standard techniques. How after its onset in the cortical focus, the epileptiform activity evolved with time in the thalamus and substantia nigra has been determined. To study the propagation of the epileptiform activity, the local EEG and multiple unit action potentials were recorded from these structures simultaneously with the cortical epileptiform EEG. The results showed that in thalamus and substantia nigra epileptiform activity appeared simultaneously with that in the cortical focus. Intensity of epileptic activity in thalamus and substantia nigra on the whole increased in parallel with that in the cortical focus. The results suggest that the thalamic and nigral epileptiform activity may reinforce the cortical epileptiform activity.