THIS IS WHAT happens when a mouse trips out: It becomes more curious about other mice and more likely to socialize with them for long periods of time. It becomes less likely to glug massive amounts of alcohol. It wriggles, quavering, like a wet dog shaking off rain. And its head twitches, rapidly, side to side. 

Because a mouse on LSD cannot tell you that colors seem brighter or the walls are melting or a guitar solo somehow sounds purple, these head twitches are of tremendous importance to chemist Jason Wallach. "If you want to know if a compound is likely to cause a psychedelic effect in humans," says Wallach, speaking from his tiny office in the Discovery Center at Saint Joseph's University in Philadelphia, "you look to the mice, to that twitching." 

These twitch tests—and countless others—are part of Wallach's mind-bending new mandate, sparked by a late-2019 meeting with the heads of a company called Compass Pathways. The UK-based biotech firm was eyeing the possibilities of developing psychedelic drugs for use in mental health therapies. Its core product was psilocybin, the psychoactive compound in magic mushrooms. But it needed new chemicals, engineered to deliver consistent, optimized, and potentially radical results. And that meant new chemists. By August 2020, Compass had inked a two-year, $500,000 "sponsored research agreement" with Wallach and the university. The Discovery Center was born.

A few years in, with continued support from the company, Wallach has cooked up scores of novel psychedelics, mailed them off to partner labs for testing on those mice, and then waited—and hoped—for the telltale twitch results. The chemist, 36 and pale, face framed by a rough red beard and rectangular glasses, can hem and haw a bit when it comes to specifics: "Compass doesn't want me to give out numbers. I'll say we've made a lot." It's in the neighborhood of 150 new drugs, all of which can potentially be patented and sold by Compass.