Geniculate spikes during epileptic seizures induced in dogs by pentylenetetrazol and bicuculline.

Previous studies have indicated that in cats generalized seizures induced by pentylenetetrazol (PTZ) or bicuculline (BIC) may be preceded by high frequency multi-unit activity in brain-stem structures. This activity is not readily demonstrable using conventional EEG recording bandwidths and precedes the onset of spikes and spikes-wave activity in thalamo-cortical systems. Recording with chronic subdural and depth electrodes during PTZ and BIC-induced seizures in 18 dogs essentially replicated these results. However, a new and consistent finding was that the high frequency discharges accompanying seizure onset were most often seen, and most often appeared first, in the lateral geniculate body, neocortex and hippocampus being involved later. The findings are considered to suggest a significant role for subcortical structures in this particular model of generalized cortico-reticular epilepsy.