Silicon Valley venture capitalist and longtime USC benefactor Mark Stevens has donated another $50 million to the university for a brain research institute, USC officials were set to announce Wednesday.

Stevens, 55, a USC alumnus, and his wife, Mary, are endowing and naming the Mark and Mary Stevens Neuroimaging and Informatics Institute, which is one of the leading brain research facilities in the nation. Stevens spent more than 20 years as one of five voting partners of Sequoia Capital, one of Silicon Valley’s most prolific venture capital firms; he currently is affiliated with S-Cubed Capital. Forbes lists his net worth at $1.7 billion.

The institute, launched two years ago, has a team of 130 faculty and staff who have been researching preventions and cures for traumatic brain injuries and diseases such as Alzheimer’s and schizophrenia.

“The field of neuroscience represents the next great frontier of medical research in the 21st century,” Mark Stevens said in a statement. “Consequently, we believe that the tremendously talented team and the interdisciplinary nature of the institute’s work will yield meaningful understanding of this frontier in the future.”

This is the third USC academic center funded by the Stevens family. In 2004, the couple donated $24 million for the Stevens Center for Innovation; a few years later they donated $10 million for the Stevens Academic Center for student-athletes.

The Stevens’ latest gift is part of USC’s $6 billion capital campaign launched four years ago as one of the most ambitious fundraising campaigns in the history of higher education. So far, the university has raised $4 billion.

Stevens earned a bachelor of arts degree in economics and a bachelor of science degree in electrical engineering in 1981 and a master of science degree in computer engineering in 1984, all from USC. He is a member of the university’s Board of Trustees.