Henry Gustav Molaison was 27, a shy, intelligent young man, when he underwent an experimental operation to relieve his severe epilepsy. The surgeon extracted two slivers of gray matter from either side of his brain, including his hippocampus, which, at the time, no one knew was the center of memory consolidation. Henry’s amnesia was immediate and profound, and the “purity of his disorder”—he was otherwise cognitively normal—made him a much sought-after study subject. His loss would be science’s gain. In the reams of medical literature that cited him, he was known only as H.M.
In the name of science, Henry tried to learn new words, identify old photographs, and more. Researchers tested every facet of his memory, scanned his brain with increasingly sophisticated technology, and experiment by experiment teased out how memory works. Different types of memory engage different circuits in the brain. Henry’s short-term memory (which lasted about 30 seconds) was intact, but without a hippocampus, his immediate experiences never converted to long-term memories. He could sometimes pick up new facts, such as celebrity names in the news, and learn motor skills, such as how to use a walker in old age—evidence of an unconscious memory still at work.
Corkin intends her book as both an exploration of the science of memory and a tribute to Henry, who died in 2008. She characterizes him as gentle and good-humored, a cooperative study subject, although the surgery dulled his emotions. Troublingly, she never explains how Henry was able to give consent for these studies.
The strange thing about reading Permanent Present Tense is that—despite an abundance of jargon and its gloss over the knottier questions—with every page you realize more how much of living is remembering. Without memory, you would never make a new friend, learn a new word or look forward to tomorrow. For 55 years, Henry never did.
