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.