The National Institutes of Health set an ambitious $4.5 billion price tag on its part of President Obama’s Brain Initiative on Thursday, stamping it as an effort on the scale of the Human Genome Project.

The goals of the Brain Initiative were clearly grand when Mr. Obama announced it a year ago — nothing less than developing and applying new technology to crack the toughest unsolved puzzles of how the brains of humans and animals function. The hope is to lay a foundation for future advances in the medical treatment of brain disorders.

But the initiative began with $110 million budgeted for 2014, shared by three major entities: the National Science Foundation; the Defense Advanced Research Projects Agency; and the N.I.H., which has a $40 million share.

By calling for such a major commitment, to be spread over 12 years, the institutes answered concerns among neuroscientists about the initial level of funding.