Recognition memory for emotional faces in amnestic mild cognitive impairment: an event-related potential study

This study examined the temporal course of emotional face recognition in amnestic mild cognitive impairment (aMCI). Patients and healthy controls (HC) performed a face recognition task, giving old/new responses to previously studied and novel faces displaying a negative or neutral expression. In aMCI patients, recognition accuracy was preserved for negative faces. Event-related potentials (ERPs) revealed disease-related changes in early perceptual components but not in ERP indices of explicit recognition. Specifically, aMCI patients showed impaired recognition effects for negative faces on the amplitudes of N170 and P2, suggesting deficient memory-related processing of negative faces at the stage of structural encoding and during an early recognition stage at which faces are individuated, respectively. Moreover, while a right-lateralized emotion effect specifically observed for correctly recognized faces on the amplitude of N170 was absent in aMCI, a similar emotion effect for successfully recognized faces on P2 was preserved in the patients, albeit with a different distribution. This suggests that in aMCI facilitated processing of successfully recognized emotional faces starts later in the processing sequence. Nonetheless, an early frontal old/new effect confined to negative faces and a parietal old/new effect unaffected by facial emotion were observed in both groups. This indicates that familiarity and conceptual priming processes may specifically contribute to recognition of negative faces in older adults and that aMCI patients can recruit the same retrieval mechanisms as controls, despite disease-related changes on early perceptual ERP components.