Dr. George Tickner, a founding member and the original rhythm guitarist for the arena rock band Journey, has died at age 76.

Former bandmate Neal Schon confirmed Tickner’s death in a Facebook tribute on Thursday. He offered no details about the cause.

“Rest peacefully, Dr. George Tickner. you will be missed immensely! Thank you for your incomparable contributions to Journey’s early years,” Schon wrote.

Tickner was the rock group’s first rhythm guitarist, joining the band in the early ’70s when it was assembled by Santana manager Herbie Herbert. Tickner left Journey before the group made it big, quitting in 1975 to pursue his medical degree after receiving a full scholarship to Stanford University.

Tickner was still with Journey for its 1975 self-titled debut. After leaving the group, he was credited as a songwriter on the subsequent albums “Look Into The Future” (1976) and “Next” (1977).

Journey found major fame after the addition of vocalist Steve Perry in 1977. The band’s first album with the singer, 1978′s “Infinity,” included their early hits “Wheel In The Sky” and “Lights.”

During Journey’s first years, the band included Schon, Tickner, keyboard player and vocalist Gregg Rolle, bassist Ross Valory and drummer Prairie Prince. Prince was later replaced by David Bowie drummer Aynsley Dunbar.

The band’s current lineup includes Schon, Jonathan Cain, Deen Castronovo, Arnel Pineda, Jason Derlatka and Todd Jensen.