Betsy DeVos, the billionaire school choice advocate selected by President Donald J. Trump to serve as education secretary, is a strong supporter of using biofeedback technology to help children and teenagers enhance their performance in school.

Ms. DeVos and her husband, Richard DeVos Jr., are major financial backers of Neurocore, a Michigan company that operates drug-free “brain performance centers” that claim to have worked with 10,000 children and adults to overcome problems with attention deficit disorder, autism, sleeplessness and stress.

In an agreement with the Office of Government Ethics made public Friday, Ms. DeVos said that she had stepped down from the Neurocore board but that she would retain her financial interest in the company. She valued that stake at $5 million to $25 million in her financial disclosure statement.

On Friday evening, Senator Lamar Alexander of Tennessee, the Republican chairman of the Health, Education, Labor and Pensions Committee, said he would delay the initial vote on Ms. DeVos’s nomination by a week, until Jan. 31, as Democrats argued that the process had been rushed through, without enough time to answer remaining questions about her financial disclosures.