This episode's headline: Sex and the Brain; News Maker; Conversation; Goodbye Party; From the Heartland; The People, Yes. The guests include SIMON LeVAY, Salk Institute; LARRY AGRAN, Dem. Pres. Candidate; ALEXI SERGEYEV, Communist Central Committee; CORRESPONDENTS: JEFFREY KAYE; ROGER MUDD; CHARLES KRAUSE; ROGER ROSENBLATT; JIM FISHER. Byline: In New York: ROBERT MacNeil; In Washington: JUDY WOODRUFF