A three-stage neurocognitive model of facial age processing: Evidence from ERP, oscillatory dynamics, and functional connectivity.

Older faces evoked larger N170 amplitudes compared to younger faces during the structural encoding stage.

• ERP component-based analysis identified the N170 as a stage-specific marker of structural encoding of facial age.
• The N170 effect was observed over occipital and temporo-occipital sensors.
• Mass-univariate analysis confirmed a significant early time band of 70–168 ms over occipital and temporo-occipital sensors.
• The oldest faces (70 years) showed the strongest differentiation relative to younger faces.

Older faces produced reduced P2 responses, indexing the prototype matching stage of facial age processing.

• The P2 component showed reduced amplitude for older faces, suggesting differential neural processing during prototype matching.
• Mass-univariate analysis identified a corresponding significant time band of 228–286 ms.
• This stage was characterized as involving localized processing without large-scale network engagement.
• Only local theta activity (4–8 Hz) remained during the prototype matching stage (~200–300 ms).

Older faces elicited enhanced late positive potentials (LPP), reflecting age-related affective evaluation in the late processing stage.

• The LPP was identified as a marker of the affective evaluation stage occurring after 300 ms.
• Mass-univariate analysis confirmed a significant late time band of 342–800 ms over occipital and temporo-occipital sensors.
• LPP modulations were interpreted as reflecting age-related affective processing.
• The oldest faces (70 years) showed the strongest differentiation from younger faces across all three identified time bands.

Early facial age encoding (~100–200 ms) was accompanied by increased theta and alpha power along with widespread phase-based connectivity, indicating global neural coordination.

• Time-frequency analysis revealed increased theta (4–8 Hz) and alpha (8–13 Hz) power during early encoding (~100–200 ms).
• Widespread theta/alpha phase-based functional connectivity was observed during this early stage.
• This global coordination pattern was interpreted as supporting initial age information extraction from faces.
• The early stage corresponded to the structural encoding phase of the proposed three-stage model.

The prototype matching stage (~200–300 ms) was characterized by only local theta activity without large-scale network engagement.

• During prototype matching, widespread phase-based connectivity observed in the early stage was absent.
• Only localized theta activity (4–8 Hz) persisted during the ~200–300 ms window.
• This finding suggests a shift from globally coordinated to locally restricted neural processing between stages one and two.
• The pattern indicates that prototype matching does not require large-scale network engagement.

Facial age processing shows a dynamic shift from early global neural coordination to later localized processing.

• The overall pattern across ERP, time-frequency, and functional connectivity analyses supported a progression from global to local processing.
• Early global coordination (~100–200 ms) involved widespread theta/alpha phase-based connectivity.
• The middle stage (~200–300 ms) showed localized theta activity only.
• The late stage (>300 ms) was indexed by LPP modulations reflecting affective processing.
• This dynamic shift provides a mechanistic account of how the brain extracts age information from faces.

EEG was recorded during age judgments of faces from four age groups spanning the lifespan.

• Participants made age judgments of faces representing four age groups: 10, 30, 50, and 70 years.
• Analyses combined event-related potentials (component-based and mass-univariate), time-frequency analysis, and functional connectivity measures.
• Mass-univariate analysis (MUA) identified three significant time bands: 70–168 ms, 228–286 ms, and 342–800 ms.
• Significant effects were localized over occipital and temporo-occipital sensors.