Fabiani Monica, Low Kathy A, Wee Emily, Sable Jeffrey J, Gratton Gabriele
University of Illinois at Urbana-Champaign, IL 61801, USA.
J Cogn Neurosci. 2006 Apr;18(4):637-50. doi: 10.1162/jocn.2006.18.4.637.
Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent with repeated stimulation in older adults than in younger adults, whereas the effects of delay were similar in the two groups. A mismatch negativity (MMN) was elicited by the first stimulus in deviant trains. This MMN was larger for 1- than 5-sec delay, but did not differ across groups. These data suggest that age-related changes in sensory processing are likely due to inefficient filtering of repeated information, rather than to faster sensory memory decay. This inefficient filtering may be due to, or interact with, reduced attention control. Furthermore, it may increase the noise levels in the information processing system and thus contribute to problems with working memory and speed of processing.
认知衰老理论强调，在正常衰老过程中，抑制过程和注意力控制的效率会降低，这反过来可能导致工作记忆功能下降。因此，这些与年龄相关的变化，有些可能是由于感觉记忆衰退更快，或者是由于对无关感觉信息的过滤效率低下（感觉门控）。在这里，我们记录了年轻和年长成年人在被动聆听音列时的事件相关脑电位和事件相关光信号。为了确定年龄是否在短时间间隔内对感觉记忆模板的衰退有不同影响，音列之间的间隔分别为１秒或５秒。为了确定年龄是否会影响对未注意到的重复刺激的反应抑制，我们评估了连续音列刺激引发的大脑活动。一些音列以持续时间较短的刺激开始（异常音列）。结果显示，与年轻成年人相比，年长成年人对音调的电反应和光反应在重复刺激下更持久，而两组中延迟的影响相似。异常音列中的第一个刺激引发了失配负波（MMN）。这个MMN在延迟1秒时比延迟5秒时更大，但在不同组之间没有差异。这些数据表明，与年龄相关的感觉处理变化可能是由于对重复信息的过滤效率低下，而不是由于感觉记忆衰退更快。这种低效的过滤可能是由于注意力控制降低，或者与之相互作用。此外，它可能会增加信息处理系统中的噪声水平，从而导致工作记忆和处理速度出现问题。
