Frontal positivity discriminates true from false recognition

Lesion studies have indicated a presumably recollection-based involvement of the prefrontal cortex in the discrimination of true and false recognition. ERP studies of word list recognition, on the other hand, generally did not yield such effects in the time range associated with recollection processes which might relate to variables like study-test shifts of context. The present study aimed to further explore ERP correlates of true and false recognition, using an experimental procedure which emphasized recollection of item-specific information. Young healthy subjects performed a word recognition task, in which items previously presented (targets), semantically related distractors (lures), and unrelated new items (distractors) had to be classified as old or new followed by a remember/know judgment for old items. Items were presented visually during both study and test. Correct old responses to targets elicited significantly more pronounced positive waveforms in comparison to correct rejections of distractors (old/new effect) between 400 and 700 ms after stimulus onset at all left and central electrode positions. A significant old/new effect for false alarms to lures was observed only at the left parietal electrode. ERPs associated with hits and false alarms to lures were similar at parietal but differed at frontal electrode positions. This pattern of results suggests a differential processing of true and false recognition in frontal and posterior brain regions when item-specific recollection is facilitated. Our findings support the assumption of monitoring processes in parallel to the recollection of item-specific information in recognition memory, which might become affected by illusory sensory information generated by posterior areas.