EXP. I EVALUATED A. E. FISHER AND J. N. COURY'S (SEE 37:4) SUGGESTION THAT HIPPOCAMPAL AFTERDISCHARGES MIGHT BE RESPONSIBLE FOR CARBACHOL-INDUCED DRINKING IN RATS, AND DEMONSTRATED THAT CARBACHOL CAN INDUCE DRINKING WITHOUT SIMULTANEOUS SEIZURE ACTIVITY; AN UNEXPECTED FINDING WAS THAT CARBACHOL INCREASED HIPPOCAMPAL SLOW-WAVE ACTIVITY. EXP. II SHOWED THAT CARBACHOL IN THE PREOPTIC AREA CAUSED BOTH EEG AROUSAL PATTERNS AND BEHAVIORAL AROUSAL, BUT INHIBITED HEART RATE; INJECTIONS IN THE ZONA INCERTA DID NOT PRODUCE AROUSAL AND WERE LESS EFFECTIVE IN INHIBITING HEART RATE. THE CONTRAST BETWEEN THESE RESULTS AND THOSE OBTAINED IN CATS, WHERE PREOPTIC CHOLINERGIC STIMULATION IS HYPNOGENETIC, SUGGESTS A RADICAL DIFFERENCE BETWEEN THE 2 SPECIES IN THE CHEMICAL CODING OF BEHAVIOR. (17 REF.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)