Composer Tobias Picker has five operas to his credit, with commissions from the LA Opera and the Metropolitan Opera, among others, and serious acclaim. But his sixth opera, which makes its world premiere at the Opera Theatre of St. Louis this June, will have particular personal resonance. The librettist writing the words to go with Picker’s music is his husband, Dr. Aryeh Lev Stollman. And while Stollman has written three novels, this is his first time writing an opera libretto. Still, he brings a particular expertise to the show, which is an adaptation of Dr. Oliver Sacks’ nonfiction medical drama “Awakenings.” Like Sacks, Stollman is a physician who studies the nervous system (Stollman is a neuroradiologist; Sacks was a neurologist).