Abstract
Seizure discharges were investigated in the exposed dorsal hippocampus of the rabbit paralyzed with succinylcholine.
1. Tonic and/or clonic seizure discharges lasting about 10-20 sec. were elicited by direct electrical stimulation of the hippocampus. In the tonic phase of seizure discharge potentials were discharged at a rate of 20-40 per sec.
2. The seizure potentials showed the maximal amplitude in a range of 0.5-0.8mm. below the ependymal surface, being always negative in sign in this range.
3. The slow spike in response to stimulation of the alveus was abolished only by the seizure discharge of tonic pattern and recovered rapidly when the seizure discharge abated.
4. The slow wave in response to stimulation of the level of the basal dendrites of the hippocampal pyramids was abolished completely by the seizure discharge and was depressed for a considerably long time after the seizure discharge had subsided.
5. The wave and spike-like potential in response to stimulation of the level of the somata and apical dendrites of the hippocampal pyramids was augmented by the seizure discharge at least in the initial phase of seizure, being attenuated towards the end of seizure discharge. The wave and spike-like potential suffered postictal depression.
6. From these findings it was concluded that the somata and apical dendrites of the hippocampal pyramids are activated in the seizure discharge.
