Differential effects of active attention and age on event-related potentials to visual and olfactory stimuli

Normal aging impairs olfactory functioning both centrally and peripherally. The P3 peak of the event-related potential (ERP), evoked by active response to a target stimulus, is considered a reflection of central cognitive processing. It can also be evoked in a passive task to both auditory and visual stimuli. Our goal was to investigate whether age influences amplitude and latency of the ERP differentially in active and passive tasks to olfactory stimuli. Olfactory and visual event-related potentials were elicited with a single stimulus paradigm in separate active and passive task response conditions. Participants included 30 healthy individuals from three age groups, young, middle age, and older adults. Results indicated that P3 ERP latency increased with age in both sensory modalities. P3 latencies for active versus passive tasks were similar across age groups for visual ERPs, but in the olfactory modality, older adults demonstrated significantly longer latencies in the passive task compared to the active task. Future directions should include research on specific clinical populations utilizing active versus passive task conditions.

Research Highlights
► Latencies in both stimulus modalities were longer for older participants compared to young participants.
► Greater age-related P3 latency differences were demonstrated in the olfactory modality (η2 = .81) compared to the visual modality (η2 = .46) along the central electrode sites.
► In the visual modality active condition P3 latencies were shorter than in the passive condition with no interactions of age group.
► In the olfactory modality, however, young and middle age participants produced similar latencies in the conditions, but older participants produced much longer latencies in the passive condition compared to the active condition.
► These results demonstrate that in the olfactory modality the P3 is relatively similar regardless of active or passive presentation in young and middle aged individuals, however older adults are sensitive to task condition.