تغییرات وابسته به سن پتانسیلهای برانگیخته شنوایی: اثر دشواری کار
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|36974||2007||13 صفحه PDF||سفارش دهید||7614 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Biological Psychology, Volume 76, Issue 3, October 2007, Pages 196–208
The goal of this study was to evaluate the patterns of age-dependent changes of P3 components of auditory event-related potentials exploring the effects of task difficulty. The participants (age span: 19–68 years, n = 55, divided into five age groups) took part in an easy and in a difficult two-tone oddball frequency discrimination task with speed or accuracy instructions, and in a novelty oddball task. The latency of the P3 components increased with aging. While in the easy task a linear P3b latency increase could be seen, in the difficult tasks (difficult frequency discrimination or distracting novel stimuli) an accelerated latency increase was observed for the P3b and P3a. In the two-tone oddball paradigm age had no effect on P3b amplitude, but in the novelty oddball task the amplitude of P3 potentials decreased with age. These results indicate that distracting stimuli increase task demands, and in difficult tasks decay can be observed more easily due to the accumulation of various processing mechanisms characterizing aging.
According to one of the most influential theories (Bashore, 1990 and Salthouse, 2000) cognitive aging is due to the slowing of central nervous system functions, and consequently the slowing of mental processing. The reduced processing speed may probably be caused by the limited time available for the simultaneous operations, leading eventually to a decline of performance (Salthouse, 1996). A considerable body of data show impairments of inhibitory processes in elderly (Hasher and Zacks, 1988). These effects can mostly be related to structural and functional changes of the frontal structures which involve the shrinkage of cortical neurons (Haug and Eggers, 1991), the reduction of the number of synapses (Huttenlocher, 1979), the decrease of the number of cholinergic receptors, and that of the amount of various neurotransmitters (Adolfsson et al., 1979 and Goldman-Rakic and Brown, 1981). In the present study the process of cognitive aging was investigated by analyzing P300 potentials evoked in a “two-tone” and a “novelty oddball” paradigm. Typically, in the two-tone oddball task two different stimuli are presented, and the participant has to discriminate the standard tone from the target for example by a button press. In the novelty oddball paradigm additional “novel” stimuli, to which no response is required, are also presented.
نتیجه گیری انگلیسی
The present study confirmed earlier findings according to which P3b latency increases with advancing age. Nevertheless, our data show that the pattern – linear or curvilinear – of this change depends on task difficulty. The latency of P3b component is slowed down by more difficult stimulus discrimination and distracting stimuli as well, and these effects accumulate with advancing age. Our results confirm the possibility that the slowing of these single processes may interfere with each other eliciting an even more conspicuous delay of the processes reflected by increasing P3a and P3b latencies in more demanding conditions. The amplitude decrease of the P3 observed only in the novelty oddball condition may show that this paradigm is more appropriate for the study of aging on sensory perceptual processing.