Hippocampal Seizures and Their Propagation

STIMULATION of various parts of the rhinencephalon is known to produce seizure-like electrical after-discharges in the cerebral cortex. Kaada¹has recently explored this subject at length and reviewed the pertinent literature. In recent studies²it has been shown that stimulation of the dorsal fornix and the fimbria hippocampi in the guinea pig and cat leads to cerebral and cerebellar afterdischarges. Although they appear to spread over neural pathways and can be induced by stimulation of the fibers of the fimbria alone,2cthe precise routes involved are not yet clear, and the possible role of volume conduction in their propagation is not yet settled. The participation of subcortical structures, as well as their importance in the maintenance of the after-discharges, is also a matter requiring further study. Finally, the effects of stimulation of the fimbria in unanesthetized and unparalyzed animals is of interest, for, although Penfield and Erickson