Atypical event-related potentials in patients with mild cognitive impairment: An identification-priming study

Our goal was to verify whether behavioral and electrophysiological measures of visual object priming can differentiate between patients with mild cognitive impairment (MCI) and elderly control subjects.

An identification-priming paradigm with spatially filtered stimuli was used. Subjects were presented with complete forms of the stimuli in the study phase. In the subsequent test phase, studied items were repeated in an ascending sequence of spatially filtered stimuli, following a coarse-to-fine order. Event-related potentials and behavioral measures were recorded.

Behavioral priming effects were observed in the elderly and in MCI participants. None of the well-known event-related potential indices of stimulus repetition emerged in the MCI group. In elderly controls, stimulus repetition was associated with a frontal modulation, likely indexing familiarity. Priming effects in the MCI group were probably based on memory mechanisms altered by degenerative pathology.

Event-related potentials hold great potential for the early detection of subjects at risk for dementia, because they may reveal possible functional brain abnormalities that are not detectable at clinical or behavioral levels.