| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2001: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
To assess effects of normal aging and Parldnson's disease (PD) on memory, we examined the N400 component of event-related potentials (ERPs) during lexical decision and recognition memory tasks. To elicit ERPs during the lexical decision task, some words were repeated immediately after the initial presentation (2sec), while others Were repeated after five intervening words (12sec) or after 2 to 4minutes. Subjects were required to respond to occasional non words. The mean N400 amplitude was smaller In patients with PD than in young and elderly healthy groups, but there was no difference between the two healthy groups. In both healthy groups, N400 was attenuated for repeated words. In PD patients, attenuation was noted only for immediate repetitions. For the recognition memory task, words were repeated Immediately after Initial presentation (3sec), while others were repeated after one Intervening word (6sec) or six Intervening words (21sec). Subjects were requested to push a button with the right thumb upon first presentation of a word and with the left thumb upon repeat presentation. Compared to the young healthy group, elderly group showed reduced accuracy In recognizing repeated words after 3 and 21 sec. Compared to elderly healthy group, PD patients showed decreased accuracy in recognizing repeated words after 21 sec. PD patients showed lower N400 amplitudes than elderly healthy subjects. The N400 In the young group showed attenuation for all repetitions, while attenuations In the elderly group andTO group were noted only for repeated words after 3 and6sec. These data suggest that in normal aging, Implicit memory assessed by the lexical decision task is relatively preserved compared to explicit memory, while both implicit and explicit memory functions were Impaired in patients with PD. In addition, memory deficits in PD may result, at least partly from the Impairment of context integration process.
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