The origins of forgetting in a case of isolated retrograde amnesia following a haemorrhage: evidence from functional imaging

Following a left superior dorsolateral prefrontal haemorrhage, a man in his 40s presented with a dense isolated retrograde amnesia for 19 years preceding the stroke. This period of his life contained many highly stressful situations. Functional neuroimaging using PET was carried out while he attempted to recall events using family snapshots as stimuli. There were three conditions - those where the stimuli related to the amnesic period and in which he had been present at the event (amnesic-present condition), analogous events from outside that period (non-amnesic present condition) and events where he was not present (not-present condition). Activation in the amnesic-present condition differed significantly from the other two conditions in three cortical regions. Activation was greater in part of the precuneus, but less in both the right posterior ventrolateral frontal cortex and in a region close to the lesion. We argue that an explanation in terms of malingering can be rejected and instead propose that this deficit can be explained by the fact that the recursive self-cueing of memory traces characteristic of autobiographical retrieval was not properly triggered.