With the Presidential Young Investigator Award, Dr. Peralta, a cellular and molecular neurobiologist, will continue to unravel the mechanisms by which neurotransmitters act in the brain. He has already made major advances in this field when he isolated the molecular clones encoding five related but distinct subtypes of the muscarinic acetylcholine receptors. These cholinergic receptors regulate the activity of potassium, calcium and chloride ion channels involved in neurotransmission. In addition, muscarinic receptors control a variety of physiological responses involved in heart rate and breathing. Dr. Peralta is now concentrating on the second messenger system regulated by each of the receptor subtypes and has found that the different receptor subtypes regulated different systems. Moreover, he is finding that the subtypes also evoke differences in the kinetics and magnitude of calcium release. Since calcium dependent events are critical for neurotransmitter secretion, Dr. Peralta's work will have a major impact on elucidating the mechanisms that are likely to play a role in neuronal communication within the brain.