H.M. is, arguably, the most famous patient in the history of psychology and neuroscience. He was studied intensively for more than fifty years by hundreds of scientists (including, briefly, the author of this review); he died in 2008, and his brain is still being analyzed. Permanent Present Tense, by Suzanne Corkin, is the story of how these investigations led to a fundamental revolution in our understanding of the human brain and, particularly, of the organization and varieties of memory. Her accessible book places his story in the context of past and present research on memory and describes many of the questions initiated by research on H.M. It is a scientifically exciting and personally moving portrait of a man whose life and brain ended up being devoted to the science of memory.
By the time he was 24, in 1950, H.M. (a k a Henry) had developed severe epilepsy, perhaps from a bicycle accident years earlier, and was referred to the neurosurgeon William Beecher Scoville, who had performed many frontal lobotomies on patients diagnosed as “psychotic.” Scoville had been unsatisfied with the results of frontal lobotomies and was trying a new surgery, bilateral medial temporal lobotomy, in another attempt to treat psychosis. Two of his psychotic patients happened by chance to suffer from epilepsy, and temporal lobotomies had the unexpected effect of reducing their seizures. By 1953, Henry’s epileptic episodes had become more frequent and incapacitating, and Scoville decided to perform a medial temporal lobotomy on him to treat it. He removed, from both sides of H.M.’s brain, a large portion of the medial temporal lobes, including portions of the hippocampus, most of the amygdala, and parts of the adjacent cerebral cortex such as the perirhinal and parahippocampal cortex. After the surgery, H.M.’s seizures diminished significantly, yet the patient could not remember anything that had happened since the procedure, nor could he recognize anybody new or recall a conversation that had transpired a few minutes earlier. He left the hospital with devastating amnesia and could no longer form new memories.
The pioneering neurosurgeon Wilder Penfield, founder of the Montreal Neurological Institute, had been successfully performing unilateral temporal lobe surgery for the treatment of temporal lobe epilepsy. Two of his many patients had developed memory problems after the surgery; it turned out that the unoperated-upon parts of the temporal lobes were abnormal, giving them bilateral temporal lobe damage, as was later the case for H.M. These two patients had their memory examined by Brenda Milner, a McGill University graduate student collaborating with Penfield. When Milner presented their research at the 1954 meeting of the American Neurological Association, Scoville realized the similarity to H.M.’s case and called Penfield, who then sent Milner to examine him. Thus began the modern science of memory.
H.M. turned out to be an ideal subject for the study of memory. Milner found him to be highly intelligent and willing to sit for hours of testing. His perceptual and cognitive abilities, other than memory, were intact. He was able to focus his attention on the task immediately at hand as well as anyone. He was usually very good-tempered and eager to cooperate. He never got bored or restless, perhaps because everything was continually new to him.
Although memory has been a central topic since the founding of experimental psychology in the middle of the nineteenth century, and the effect of brain injury on memory had been studied before Milner’s work on H.M., little was known about the role of different brain areas in memory. The hippocampus was thought to be involved in smell because of its connections with the olfactory system. One widespread view in the early twentieth century, based on the research of Karl Lashley, was that complex memories were distributed throughout the cerebral cortex and therefore could not be localized.