Encoding- and retrieval-related brain activity underlying false recognition.

We examined the neural activity associated with true and false recognition during both encoding and retrieval using the Remember/Know procedure to separate recollection (i.e., mental reinstatement of experienced events during which unique details of a memory are recalled) and familiarity (i.e., mental awareness that an event has been experienced previously without the unique details of the event) in recognition memory. Neuroimaging data at retrieval revealed that the right parahippocampal gyrus was activated during recollection-based true recognition compared with familiarity-based true recognition, indicating the item-specific retrieval of visual details. This effect in the right parahippocampal gyrus was not observed for false recognition. Contrary to our expectation, the reactivation effect in early visual cortex was not observed during true recognition, as opposed to false recognition. Neuroimaging data at encoding revealed that the right visual cortex (the right occipitotemporal sulcus) was activated during the encoding of items that yielded recollection-based true recognition compared with familiarity-based true recognition, indicating item-specific visual processing. This effect in the right visual cortex was not observed for false recognition. These results suggest that the subjective feeling of Remember/Know with respect to both veridical and false memories varies with the neural activity during both encoding and retrieval.