Much of the cognitive neuroscience of memory has taken advantage of lesion-behavior studies, which assess behavioral deficits that ensue from damage to targeted parts of the brain. For example, lesions to the medial temporal lobe, buried deep in the brain, often produce profound anterograde amnesia.

In the mid-1980s functional neuroimaging began to play an increasingly important role in enhancing our understanding of the organization of memory in the human brain. Two of the main functional neuroimaging methods, positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), measure signals related to blood flow or oxygenation. Both methods are based on the correlation of blood flow and neuronal activity: as is the case with muscles, blood flows more briskly in those parts of the brain that are the most active neuronally. PET can capture a single time-lapse image of forty seconds of blood flow. Methodological necessity dictated that...