Drive over the Charles from Cambridge to Allston and suddenly, one side of Western Avenue turns into a huge, empty lot barely hidden behind a row of temporary fences. Much of the site is actually the foundation of what was supposed to be Harvard’s 600,000-square-foot, $1 billion Science Center. But the crash of 2008 put the project on hold in mid-construction.

A few blocks down, past the business school, grad student housing and the neon “FLINT Cleaners” sign, is one piece of the project that did get finished. In exchange for taking over 350 acres in the residential neighborhood, the university agreed to open a community center-type effort called the Harvard Allston Education Portal. The center offers “mentoring” for local students, lectures by Harvard faculty and tickets to football games at nearby Harvard Stadium.

That’s where provost and neurobiologist Steven Hyman found himself Tuesday night. Hyman usually gives talks at meetings of Harvard faculty, the Institute of Medicine or the Neuroethics Society. Instead, the former head of the National Institutes of Mental Health explained the neurobiology of addiction to a group of about 50 Allstonians, including the young, the gray, the rumpled, and the urban hip.

A story about the event on Harvard’s Gazette website said the lecture series is “designed to open Harvard’s academic workings to neighbors in nearby communities”

Friendly and unpretentious, Hyman kept the small crowd’s attention with his explanation of how drugs mimic brain chemicals. Sometimes, the presentation strayed toward the technical, but Hyman did a good job pulling it back.

“Just ignore that side of the slide,” he said as he displayed a PowerPoint table with acronyms and symbols for different cell receptors. Still, he said he “couldn’t resist showing a few chemical formulas” just to point out the similarities between amphetamine and dopamine.

After the talk, some of the Harvard neighbors lined up to ask Hyman follow-up questions, while other queued up at the generous cookie-veggie-cheese table.

For more on the portal, click here.