Published online by Cambridge University Press: 01 March 2010
Age-dependent changes in cognition
Characterizing the neural basis of normal age-dependent changes in cognition can have important clinical implications, particularly in the case of neurodegenerative disorders where a decline in cognitive function may have prognostic value. In recent years, the application of MEG to investigate age-related changes in the profile of cognitive processing among neurologically intact individuals across the lifespan has increased. For example, a study by Kovacevic and colleagues employing the auditory oddball paradigm found that the amplitude of the early M50 component increased in elderly relative to young controls. This finding led the authors to suggest that the capacity to inhibit repetitive auditory stimuli diminishes as a function of age. Furthermore, this study also found the peak onset of the late activity evoked by rare tones, corresponding to the P300 event-related complex, also increased with age. Aine and coworkers replicated this age-dependent increase in the amplitude of the M50 component in the context of an auditory incidental verbal-learning task and noted a similar effect for later components ranging from ∼100 to ∼800 ms. These results suggested that potential age-related deficits of inhibition may also be manifest in late components related to higher cognitive functions. A subsequent study by Aine and associates further examined the effects of normal aging on cognition during the visual delayed-match-to-sample paradigm and found that although the latency and amplitude of the M100 and M300 peaks were different between young and elderly controls, they were not related to differences in behavioral performance. The authors concluded that these evoked-response components might reflect the use of different cognitive strategies by the young and elderly during episodic memory processing.