Known as HM, the man standing before Dr. Brenda Milner was a mystery to the young scientist—and to himself. He could remember events from before undergoing brain surgery—a bilateral medial temporal lobe resection to remedy his epilepsy—but was now unable to form new memories. Told his doctor’s name, HM would forget it as soon as he was distracted by new stimuli.
And yet Milner, a British expatriate who had been trained by McGill psychology pioneer Donald Hebb, persisted. Through her testing of HM, she found that the surgery didn’t interfere with his capability for certain kinds of learning, in particular the acquisition of new motor skills. With this revelation, Milner provided early evidence that humans have multiple-memory systems which govern different tasks (like language), opening the way for a greater understanding of how the brain works. HM became one of the most important case studies in cognitive neuroscience, thus ensuring he would never be forgotten.