Can medial temporal lobe regions distinguish true from false? An event-related functional MRI study of veridical and illusory recognition memory

摘要

To investigate the types of memory traces recovered by the medialtemporal lobe (MTL), neural activity during veridical and illusoryrecognition was measured with the use of functional MRI (fMRI). Twelvehealthy young adults watched a videotape segment in which two speakersalternatively presented lists of associated words, and then thesubjects performed a recognition test including words presented in thestudy lists (True items), new words closely related to studied words(False items), and new unrelated words (New items). The main findingwas a dissociation between two MTL regions: whereas the hippocampus wassimilarly activated for True and False items, suggesting the recoveryof semantic information, the parahippocampal gyrus was more activatedfor True than for False items, suggesting the recovery of perceptualinformation. The study also yielded a dissociation between twoprefrontal cortex (PFC) regions: whereas bilateral dorsolateral PFC wasmore activated for True and False items than for New items, possiblyreflecting monitoring of retrieved information, left ventrolateral PFCwas more activated for New than for True and False items, possiblyreflecting semantic processing. Precuneus and lateral parietal regionswere more activated for True and False than for New items.Orbitofrontal cortex and cerebellar regions were more activated forFalse than for True items. In conclusion, the results suggest thatactivity in anterior MTL regions does not distinguish True from False,whereas activity in posterior MTL regions does.