SEYMOUR BENZER, 86 Pioneer of neuroscience

Seymour Benzer, a groundbreaking biologist whose work linking behavior and genes laid the foundation for modern neuroscience, died of a stroke Friday at Huntington Hospital in Pasadena, Calif., said Jill Perry, a spokeswoman for the California Institute of Technology, where Dr. Benzer was professor emeritus.

Dr. Benzer's research in the 1960s countered the common belief that human behavior was shaped primarily by environment, giving genetics a far bigger role than they were previously assigned.