Memory and the Hippocampal Complex
FOR at least 75 years psychologists have debated whether there is a single mechanism for human memory or two separate mechanisms of differing permanence. William James, on the basis of introspective analysis, first defined two categories of memory, primary and secondary.1Primary memory dealt with the just-elapsed portion of an ongoing event, ... the rearward portion of the present space of time... Secondary memory served to recall events that had ... already once dropped from consciousness... Subsequent authors have renamed James' two memory mechanisms, calling the first immediate, short-term, or recent memory2-6and the second delayed, long-term, or distant memory.2,3,7Though the two postulated phases of memory have been rechristened, today there is less agreement than ever as to whether a dualistic or a monistic theory of memory is correct. During the last decade a number of authors have noted that patients with bilateral lesions of the hippocampal complexes