ABSTRACT
In general, localized cortical brain damage in humans has little effect on old memories but if it does, most of the loss usually fills in over a few years (Squire, 1987). This is an observation in line with Lashley’s famous notion of the distributed nature of memory (Lashley, 1950). One of the most well-investigated behavioral deficits following fairly localized cortical lesions in man is that of a relatively pure, so-called “anterograde amnesia,” characterized by the inability to learn anything new following neural insult except for implicit, procedural tasks (Squire, 1987). Although lesions in several locations are reported to produce varying degrees of this symptomatology, the densely amnestic patient, such as H. M., presumably has fairly circumscribed bilateral lesions in the medial temporal lobe critically involving hippocampal gyrus and perhaps amygdala (Mishkin & Petri, 1984).
