Preserved executive function in high‐performing elderly is driven by large‐scale recruitment of prefrontal cortical mechanisms

High‐density electrical mapping of event‐related potentials was used to investigate the neural processes that permit some elderly subjects to preserve high levels of executive functioning. Two possibilities pertain: (1) high‐performance in elderly subjects is underpinned by similar processing mechanisms to those seen in young adults; that is, these individuals display minimal functional decay across the lifespan, or (2) preserved function relies on successfully recruiting and amplifying control processes to compensate for normal sensory‐perceptual decline with age. Fifteen young and nineteen elderly participants, the latter split into groups of high and low performers, regularly alternated between a letter and a number categorization task, switching between tasks every third trial (AAA‐BBB‐AAA…). This allowed for interrogation of performance during switch, repeat, and preparatory pre‐switch trials. Robust effects of age were observed in both frontal and parietal components of the task‐switching network. Greatest differences originated over prefrontal regions, with elderly subjects generating amplified, earlier, and more differentiated patterns of activity. This prefrontal amplification was evident only in high‐performing (HP) elderly, and was strongest on pre‐switch trials when participants prepared for an upcoming task‐switch. Analysis of the early transient and late sustained activity using topographic analyses and source localization collectively supported a unique and elaborated pattern of activity across frontal and parietal scalp in HP‐elderly, wholly different to that seen in both young and low‐performing elderly. On this basis, we propose that preserved executive function in HP‐elderly is driven by large‐scale recruitment and enhancement of prefrontal cortical mechanisms. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.