Complementary neural mechanisms for tracking items in human working memory

Recognition of a specific visual target among equally familiar distracters requires neural mechanisms for tracking items in working memory. Event-rela ted functional magnetic resonance imaging revealed evidence for two such me chanisms: (i) Enhanced neural responses, primarily in the frontal cortex, w ere associated with the target and were maintained across repetitions of th e target. (ii) Reduced responses, primarily in the extrastriate visual cort ex, were associated with stimulus repetition, regardless of whether the sti mulus was a target or a distracter, These complementary neural mechanisms t rack the status of familiar items in working memory, allowing for the effic ient recognition of a currently relevant object and rejection of irrelevant distracters.