Altered face perception in amnestic mild cognitive impairment: Evidence from representational similarity analysis of event-related potential.

BackgroundStructural changes in medial temporal lobes including the fusiform gyrus, a critical area in face recognition, precede the progression of amnestic mild cognitive impairment (aMCI) to Alzheimer's disease (AD). However, how the neural correlates of face processing altered in aMCI, as well as their association with cognitive impairments, remain unclear.ObjectiveUsing electroencephalogram (EEG), we explored the electrophysiological markers of face-specific visual processing alterations in aMCI and examined their relationship with cognitive deficits.MethodsWe recruited participants with aMCI (n = 32) and healthy controls (HC, n = 41) and used a passive viewing task to measure the event-related potential (ERP) in response to faces and non-face objects. To compare face processing in aMCI patients and HCs, we adopted mass univariate analysis and representational similarity analysis (RSA) to explore aMCI-related alterations in ERPs.ResultsWe found that face inversion effect (FIE) in P1 amplitudes was absent in aMCI patients. Also, compared to HCs, aMCI patients exhibited a lack of right hemisphere advantage in N170 in response to faces. Furthermore, representation similarity analysis of ERP in posterior-temporal regions revealed that aMCI patients represent face and non-face objects distinctively from HCs in the early processing stage. Additionally, the FIE in P1 amplitude positively correlated to aMCI patients' visuospatial functions.ConclusionsThese findings showed aMCI-related changes in the early perceptual processing of faces and highlights the potential of the FIE in P1 amplitude and ERP patterns over occipital-temporal regions as electrophysiological markers for aMCI and AD.