By Maria Di Mento

The New York investment managers Stanley and Fiona Druckenmiller have given $705-million to their Druckenmiller Foundation this year, the couple announced today.

The couple are among the wealthiest Americans: Forbes magazine pegged their wealth at $3.5-billion in October.

The donation is significant in a year when most other wealthy Americans have been reluctant to commit to big gifts. Only five other donations of $100-million or more have been announced by America’s wealthy so far this year.

The foundation, which the couple established in 1993, primarily supports medical research, education, and efforts to fight poverty. Its most-recent grants include $100-million awarded in July to New York University Langone Medical Center to establish a neuroscience institute. In past years, the foundation has supported the New York Stem Cell Foundation and cancer research programs.

The couple have given a total of $46-million to Langone Medical Center before the most recent gift, and in 2006 they gave $25-million to the Harlem Children’s Zone, where Mr. Druckenmiller, 56, serves as chairman of the Board of Trustees. They have also previously donated money to Bowdoin College, the Spence School, Human Rights Watch, and the Robin Hood Foundation.

Ms. Druckenmiller, a 47-year-old former portfolio manager at the Dreyfus Corporation, has served as a trustee of Langone Medical Center since 2006 and said in a written statement that she and her husband believe scientific discoveries in neuroscience and stem cell-research will one day benefit and lengthen many people’s lives.

“Every family is affected in one way or another by brain disorders or brain aging,” said Ms. Druckenmiller. “The brain is one of the last great frontiers in medicine and advances in related research could help both the individual and society function at a higher level.”