In what is believed to be the largest private gift yet to support scientific research on cannabis, a donor is giving $9 million to support Harvard and MIT work on cannabis and its effects on the brain.

The money comes from the marijuana industry itself, in a way. The donor, Manhattan-based investor Bob Broderick, made tens of millions of dollars by investing in the legal marijuana industry in Canada, he says.

Now, as states around this country legalize marijuana, he's funneling some of that money to help fill what's widely seen as an urgent need for solid research on how cannabis affects the brain.

"I saw an opportunity to take a kind of a leadership position in getting these two great cultural institutions involved in the discussion of cannabis in the country," he says.

He also wants to combat any lingering taboo against doing research on cannabis, Broderick says.

"People take risks when they say, 'I'm going to start doing cannabis work,' " he says. "For a young researcher at MIT or Harvard to say, 'I'm going to pivot my career and study the effects of cannabis,' I don't think that's something that would have happened five years ago."

But now, he says, he can offer money "from the cannabis world" that can go back into learning more about cannabis products. "And that's going to be good for all of us," he adds. "A majority of Americans live in a regulatory environment that has either medical or recreational cannabis."

There's a lot to learn. We know incredibly little about the cannabis compounds called cannabinoids, says Harvard Medical School professor of neurobiology Bruce Bean.

"Two of them have been studied in some detail — THC and CBD," he says. "Even for those, I have to say our knowledge is very, very sparse in terms of how they actually have their effects on the brain. But for many of the other hundred cannabinoids or so we know — we really know nothing."

We don't even really understand how cannabis can help users with their pain and sleep problems, he says.

Cannabis companies have been funding clinical research aimed at showing how cannabis can be used to treat certain medical conditions, Broderick says. But they haven't been backing research to understand the basic biology of cannabis.