Abstract and Keywords
This chapter reviews the effects of aging on a variety of ERP components. These include the relatively early-latency P50, N1 and P2 potentials, which are thought to reflect primarily the processing of sensory aspects of experience. Although more data are required, study of these components suggests that older adults do not exhibit sensory deficits per se but may exhibit deficiencies in inhibitory processing at the relatively early stages of information processing. Other longer-latency components, such as the N2b, P3a (novelty P3) and P3b reflect higher-order cognitive functions and are modulated more by task characteristics than by the sensory properties of the events that elicit them. Age-related studies indicate prolonged latency of the N2b and P3b, consistent with the general slowing reported in the behavioral literature. The P3a, a neural sign of the orienting response thought to depend upon prefrontal cortex and its interconnections, does not habituate in older adults, suggesting that older adults continue to recruit prefrontal cortical mechanisms for events that should no longer capture their attention. Several ERP modulations are defined on the basis of a difference between electrical activity in one condition compared to that in another. These comprise the mismatch negativity, reflecting relatively automatic deviance detection, the parietal old/new or episodic memory (EM) effect, an index of recollective processing, the N400, a measure of semantic processing, the error-related negativity (ERN) and the medial-frontal negativity (MFN), the latter two reflecting executive aspects of cognition. Studies of the MMN indicate less sensitivity to deviance as we age. The parietal EM effect is sometimes smaller in older relative to young adults, suggesting an age-related reduction in the quality of information retrieved from episodic memory. The N400 literature indicates that, although the N400 shows age-related diminution, semantic processing is generally intact in older adults. Too little is known about the ERN and MFN to come to conclusions at this time. In general, this review indicates a mixed picture of spared and impaired cognitive functions as individuals age.
Keywords: cognitive aging, deviance detection, executive function, recollection, event-related potential (ERP), mismatch negativity, parietal EM effect, error-related negativity, medial-frontal negativity, P50, N1 (N100), P2 (P200), N400, N2b, P3a, P3b
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