Permanent Present Tense
Author: Suzanne Corkin
Henry Molaison, known throughout his life as Patient H.M, is the fateful neuroscience patient whose misfortune completely redefined our understanding of the inner workings of the brain. This book explores the amnesia Henry developed following unprecedented brain surgery for severe epilepsy, a unique disability that made him ‘the gold standard for the study of amnesia’ (page 47). Whilst the operation came at a ‘tremendous cost to him and his family‘, the permanent amnesia it generated turned out to be an unexpected boon to science, ‘a priceless gain in the quest for the underpinnings of learning and memory‘ (xv and page 50). The book established Henry’s impact on the course of neuroscience, an extraordinary development reflected by the observation that ‘by the 1990s, he was invoked as a case study in nearly every textbook that addressed memory’ (page 265). As the neuropsychologist who knew ‘more about Henry than any living person’, and as his eventual ‘sole keeper’, the author was well-placed to document his cognitive impairment, and the effect this had on his personality and wider family (pages 206-and 265). The author dedicated this ‘exploration of the science of memory‘ as ‘a tribute to Henry’, arguing that ‘by carefully examining one patient over time, we can fill in the gaps in our knowledge about how individual brains function and change throughout life, in health and disease‘ (pages xvi and 313).
The central theme of the book is the aftermath of the ‘risky surgical intervention’ Henry endured, a procedure that almost totally abolished his ability to convert short-term memory into long-term storage (pages xii, xvi and 53). The surgery to both sides of the brain, performed by William Beecher Scoville, was the first to be done for epilepsy, and the catastrophic result was such that Henry ‘could no longer remember the faces of people he met, places he visited, or moments he lived through’. Living in what the author eloquently characterised as ‘a permanent present tense‘, the book explained why Henry’s inability to form new memories meant he could neither ‘construct an autobiography as his life unfolded’, nor could he ‘imagine the future anymore than he could remember the past‘ (page 235-236). The author portrayed how Henry’s experiences ‘slipped out of his consciousness seconds after they happened’, and how he was ‘trapped in the here and now’, unable as he was to ‘travel consciously back in time from one episode to another’ (pages xii and 234). Perhaps to lighten the gloom of Henry’s circumstances, the author philosophised on the positive aspects of his predicament; for example she said ‘unencumbered by recollections from the past, and speculations about the future’, Henry was able to live ‘in the here and now’. Further reflecting on the potential benefits of forgetting, she said his amnesia freed him ‘from the moorings that keep us anchored in time, attachments that can sometimes be burdensome’ (pages 74 and 75).
A compelling feature of the book is its depiction of how surgery transformed Henry’s personality as much as it degraded his memory. The portrait the author painted of Henry was of ‘a pleasant, engaging, docile man with a keen sense of humour’, but because his ‘sense of self‘ was fragmentary and rudimentary, he was ‘largely unable even to evaluate his own physical state‘ (pages xv 207- 209). The book maintained that Henry’s capacity for emotion was strikingly preserved, observing for example that he felt grief for ‘lost loved ones’, and displayed what the author described as ‘dark episodes‘ during which became ‘frustrated, sad, aggressive, or uneasy’, and exhibited ‘totally unexpected and unprecedented rage‘ (pages 209, 99 and 104). In contrast to his profound amnesia, it was astonishing that Henry not only maintained ‘an excellent vocabulary‘, but he also retained ‘an impressive knowledge of world events and celebrities’ although ‘this knowledge was frozen in time, an archive of information from the first half of the twentieth century’ (page264). Extraordinarily, and most significantly, the book demonstrated that Henry could learn new skills because his non-declarative or implicit memory, unlike his semantic or general knowledge memory, was well-preserved (pages 117, 151-158, and 264).
It is in recounting the details of what Henry taught us about the nature of memory that his impact on neuroscience becomes clear. For example it is Henry’s case that first demonstrated the singular importance of the hippocampus in building the associations that are required to lay down memory, and it was his surgery that demonstrated that damage to both hippocampi results in profound amnesia (pages 31 and 127). It was also from Henry that scientists learnt that memory was not localised to one part of the brain, but that autobiographical memory depends on the hippocampal system, whilst semantic memory relies on a functional cortex. This, the book argued, explains why Henry remained ‘intelligent, articulate, and perceptive’ even though he had lost the ability to remember (pages xvi-xviii, 130, 223, and 230). Henry also played a fundamental role in validating the dual-process theory of memory formation whereby ‘cortical processes mediate short-term memory, and medial temporal lobe processes mediate long-term memory’. It was also Henry’s case that established ‘the important theoretical distinction between declarative or explicit memory…and non-declarative or implicit memory‘ (pages 58-61 and 117).
As much as the book was about Henry and the science of memory, it was also a detailed history of the key players who unravelled the mystery of Henry’s brain. Perhaps the most important actor in this regard was Brenda Milner, the neuropsychologist who carried out the initial ingenious assessments of Henry which revealed the real nature of memory. Milner’s comprehensive testing included ‘every cognitive test she could lay her hands on’, and the results of these tests, published in the seminal paper she co-authored with Scoville, ‘revolutionized the science of memory’ (pages 46 and xiv). The author also noted the connecting role played by the famous Canadian neurosurgeon Wilder Penfield, Milner’s collaborator at the influential Montreal Neurological Institute, who linked her up with Scoville to study Henry (pages 36-41). The book also features many other historical personalities such as the psychosurgeons Walter Freeman, James Watts, Gottlieb Burckhardt, Ludwig Puusepp, Antonio Egaz Moniz, and Almeida Lima (pages 21-27). There was also an extensive coverage of several neuropsychological concepts such as Hebb’s postulate, synaptic plasticity, information theory, the depth-of-processing effect, long-term potentiation, conditioned responses, perceptual learning, priming, linguistic ambiguity, and mental schemas (pages 55-57, 116-120, 131-135, 182-187, 190-199, 238, 261).
This is a dispassionate account of the neuroscience of memory, an academic work written in the style of historical non-fiction. Using very simple prose, the book conveyed many scientific concepts in an easily understood format. The author carefully elaborated the complex ideas related to memory, and she complements the text with very helpful illustrative pictures. She also enhanced her perspective of memory and learning with an excellent biographical account of Henry Molaison, showing how the study of one man can make such an immense contribution to the understanding of how the brain learns and remembers. In many places, the capacities the author attributed to Henry seemed more than could be possible by the severity of his disability, and this discrepancy has been picked upon by other experts who studied Henry. This book is however an important insight into the life of one of the most important patients in history, and an indispensable primer into the science of memory.
This book is not just a biography of a very important patient, but a masterclass in the neuroscience of memory and learning. It is also a historical guide to the field, and a lesson to all doctors on recognising and using every opportunity to study unique patients. It underscores the value of close observation and detailed study in the advancement of science. It is excellently written and thoroughly researched, and I recommend it to all doctors.
Publisher, Place, Year: Basic Books, New York, 2013
Number of chapters: 13
Number of pages: 364
Star rating: 5