Old-New Recognition Memory Revisited.

Identifying old items during recognition memory tasks elicits widespread cortical responses. Recent results suggest that a distributed network, labeled the Parietal Memory Network (PMN), responds to old items potentially reflecting mnemonic familiarity. An independent, parallel line of evidence suggests that the same network responds to salient stimuli in non-mnemonic contexts, referring to the network as the Salience Network (SAL). Here we examined responses during old-new recognition and non-mnemonic detection tasks in intensively scanned individuals to directly contrast component processes related to mnemonic familiarity with more general processes associated with target detection. In an oddball detection paradigm devoid of traditional memory demands, SAL/PMN was robustly activated. SAL/PMN was also activated by old words in a standard old-new recognition task, thus reproducing both previously reported effects. In a critical oppositional contrast, recognition was examined when the task was to detect uncommon old words versus when the task was to detect uncommon new words. SAL/PMN was activated during the detection of targets even when those targets were new items, consistent with a response to the task relevance of the targets not mnemonic familiarity. Exploratory analyses further suggested that a right-lateralized network, referred to as Frontoparietal Network B (FPN-B), responds to mnemonic familiarity. These results revise our understanding of brain networks contributing to old-new recognition separating component processes common to many forms of target detection task from processes preferentially associated with mnemonic history.