A developmental study of the effect of temporal order on the ERPs elicited by novel environmental sounds.

Event-related brain potentials (ERPs) were recorded from 16 subjects in each of the following age groups, 5-7, 9-11, 14-16, and 20-28 years of age. Subjects performed a novelty oddball task, in which frequent, standard tones (80% probability) were intermixed with infrequent tones to which the subject responded (10%), along with 48 unique novel, environmental sounds (10%). Analyses focused on the effects of temporal order (either serial order within the block or block number) in interaction with age group on the ERPs to the novel sounds. The amplitude and scalp distribution of two ERP components were analyzed, the 'novelty P3,' assumed to reflect aspects of the orienting response, and the P32, a component that may be synonymous with the P3b. Evidence suggests that the frontal aspect of the scalp distribution of the novelty P3 depends upon the integrity of the prefrontal cortex. Temporal order produced systematic (primarily linear) reductions in novelty P3 amplitude that were greater at frontal than posterior electrode sites. The P3(2) did not show consistent effects of temporal order. Both of these phenomena were highly similar for all four age groups. It is concluded that the brain's response to novelty is similar across a wide age range, involving a neural circuit with both frontal and posterior elements.