Effects of Intracarotid and Intraventricular Injections of Hypertonic Solutions on Electrical Activity of the Rabbit Brain

¹ From the Department of Anatomy, University of California, Los Angeles, and the Investigative Medicine Service, Veterans Administration Hospital, Long Beach, California

A study has been made of the effects on the rabbit electroencephalogram of injecting substances known to activate the release of pituitary antidiuretic hormone. Intracarotid injections of hypertonic saline and hypertonic glucose induced a characteristic change in the EEG of various regions of the telencephalon and diencephalon lasting approximately 20 sec. Isotonic saline and hypertonic urea served as control solutions. Hypertonic solutions were ineffective when injected into the external carotid artery. Intraventricular injections of hypertonic saline induced arousal or seizures but no EEG changes comparable to those stimulated by intracarotid injections. Repeated intracarotid injections of hypertonic saline eventually caused, in more than half of the animals, seizures which always started in the amygdala and/or hippocampus and often remained localized there.