Research, Clinical Practice, Consultancy
Mind and Memory: Living with Developmental Amnesia
It was a glorious summer’s day in London, the 1st of July 1997. Across town, the Wimbledon season was in full swing. Meanwhile, at the Great Ormond Street Institute of Child Health, a team of neuroscientists embarked on another type of challenge. Mort Mishkin, Endel Tulving, David Gadian and I had organised a day of games and tests we hoped would provide a breakthrough in our understanding of memory disorders. Among other activities, we planned to take a teenager out to lunch!
Jon suffered from developmental amnesia linked to the loss of a portion of his hippocampi in infancy, the part of the brain responsible for encoding, storing and retrieving personal recollections. He had already been a participant in various neurological studies since the age of eleven; now, he had agreed to spend the better part of his day performing memory tasks with us. For our part, we couldn’t believe our luck. Most amnesia studies up to then had been conducted on people who suffered brain injuries in adulthood, and had already developed a normal framework for storing their memories. In Jon’s case, however, those standard frameworks had never had a chance to develop. His experience was unique, and offered insights into how memories are formed and stored in the brain.
We spent that morning setting Jon various memory-related tests, in order to gain an overall picture of his cognitive abilities. He proved to be an able communicator, perfectly capable of carrying on a conversation about the causes of World War I. He used complex language to express his ideas, and had a detailed grasp of historical events, such as the assassination of Archduke Ferdinand. Equally impressive was his awareness of current events, including the imminent British hand-over of Hong Kong to China. The problems came when we asked him to identify the source of his knowledge. He could not explain how he “knew what he knew.” Where he had come across the information? Was it in a book, a class, a film? He had no idea.
In further tests, Jon had difficulty recalling words he had recently learned, but was able to identify those same words with a high level of accuracy on a list. Clearly, he was capable of retaining facts, but less adept at processing his own experiences. So we came up with another tactic to explore this phenomenon. We decided to test Jon’s capacity to make memories on the fly by taking him out to lunch, and asking him about the experience immediately afterwards.
The outing was carefully prepared. Gadian, Mishkin, and I accompanied Jon to a nearby restaurant, while Tulving stayed behind to develop a set of questions that would test his retention. We took photographs of landmarks we passed along the way. On his return to the Institute, we asked Jon questions about his lunch break, requesting details such as who it was who went out to lunch, how many chairs there were at the table, who was sitting to the left and right of him, what topics were discussed, what landmarks he remembered from the walk, and so on.
His answers were revealing. Though Tulving had not joined the lunch party, Jon remembered us all going out to lunch together. While a chair had actually been removed from the lunch table, Jon remembered one being added. He could not recall the actual seating arrangement. Though he remembered a discussion about Europe and America over the meal, the specifics of the conversation – Britain’s colonies, then British and American football – were lost. His recollection of landmarks was patchy; although he remembered four out of the ten photographs, he did not remember where they were in relation to the restaurant. This was when he admitted to us that he had difficulty seeing images in his mind.
Jon seldom produced a “can’t remember” response to our questions. Instead, he provided answers that were reasonable within the context, and came up with scenarios based on generalities rather than specific details. This led to the conclusion that he could not distinguish between “knowing” and “recollecting”, as he had never known what it was to “remember”. The information was simply there, with varying degrees of accuracy.
Later experiments would corroborate these initial thoughts. Jon’s performance could be enhanced by certain learned memory techniques, but his framework for forming and retrieving memories appeared to be aided by familiarity, in other words through parts of the brain adjacent to the hippocampus. The resulting memories were not high fidelity, which might explain why Jon, when asked what he recalled about his lunchtime outing, could remember something about chairs, but not the specific fact that a chair had been removed from the table. His memory system processed the gist of events, not their full detail, leaving him with an impressionistic idea of what had occurred.
Human memory is a distinctive faculty. By nature, we are creatures who possess not only a notion of a personal past and future, but a sense of our place in a collective history. Such capacities must in part be due to the inter-generational transmission of information through language. While those processes are, of course, rooted in a biological make-up shared with other animals, their evolutionary unfolding in the human species has resulted in our capacity to define who we are. We do this by telling ourselves stories – as individuals, as communities, and as a species.
Because of his unique condition and circumstances, Jon gave us an incredible gift on that memorable July day. Through his contributions, our team was able to open a window on how the brain processes personal experience, and how much our retention of that experience is dependent on the ability to string together a series of events in a coherent narrative. Memory, in other words, is a story. And without Jon’s story, the story of the study of developmental amnesia would be woefully incomplete.