In 1954, in Montréal, a man with epilepsy underwent a brain operation to remove the abnormal hippocampi in both hemispheres causing his seizures. The patient, who is now known in psychological literature by his initials, H. M. Following his recovery, H. M. no longer was able to retain information in memory. He could not form any new memory engrams. He still had his OLD memories, that is, the engrams that had formed in his brain before his surgery were still in place. Even with no medial temporal lobes (no hippocampi) one can store some declarative (conscious) memories, and acquire new semantic (fact) knowledge, at least temporarily, when new knowledge can be anchored to mental representations established before surgery.